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19 Nov 2018 at 01:33
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Bibliography on: Evolution of Multicelluarity


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RJR: Recommended Bibliography 19 Nov 2018 at 01:33 Created: 

Evolution of Multicelluarity

Created with PubMed® Query: (evolution OR origin) AND (multicellularity OR multicellular) NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2018-11-16

Shekhar Saxena A, Salomon MP, Matsuba C, et al (2018)

Evolution of the mutational process under relaxed selection in Caenorhabditis elegans.

Molecular biology and evolution pii:5184273 [Epub ahead of print].

The mutational process varies at many levels, from within genomes to among taxa. Many mechanisms have been linked to variation in mutation, but understanding of the evolution of the mutational process is rudimentary. Physiological condition is often implicated as a source of variation in microbial mutation rate and may contribute to mutation rate variation in multicellular organisms.Deleterious mutations are a ubiquitous source of variation in condition. We test the hypothesis that the mutational process depends on the underlying mutation load in two groups of Caenorhabditis elegans mutation accumulation (MA) lines that differ in their starting mutation loads. "First-Order MA" (O1MA) lines maintained under minimal selection for ∼250 generations were divided into high-fitness and low-fitness groups and sets of "second-order MA" (O2MA) lines derived from each O1MA line were maintained for ∼150 additional generations. Genomes of 48 O2MA lines and their progenitors were sequenced. There is significant variation among O2MA lines in base-substitution rate (µbs), but no effect of initial fitness; the indel rate is greater in high-fitness O2MA lines. Overall, µbs is positively correlated with recombination and proximity to short tandem repeats and negatively correlated with 10 bp and 1 Kb GC content. However, probability of mutation is sufficiently predicted by the three-nucleotide motif alone. ∼90% of the variance in standing nucleotide variation is explained by mutability. Total mutation rate increased in the O2MA lines, as predicted by the "drift barrier" model of mutation rate evolution. These data, combined with experimental estimates of fitness, suggest that epistasis is synergistic.

RevDate: 2018-11-16

Rebolleda-Gómez M, M Travisano (2018)

The Cost of Being Big: Local Competition, Importance of Dispersal, and Experimental Evolution of Reversal to Unicellularity.

The American naturalist, 192(6):731-744.

Multicellularity provides multiple benefits. Nonetheless, unicellularity is ubiquitous, and there have been multiple cases of evolutionary reversal to a unicellular organization. In this article, we explore some of the costs of multicellularity as well as the possibility and dynamics of evolutionary reversals to unicellularity. We hypothesize that recently evolved multicellular organisms would face a high cost of increased competition for local resources in spatially structured environments because of larger size and increased cell densities. To test this hypothesis we conducted competition assays, computer simulations, and selection experiments using isolates of Saccharomyces cerevisiae that recently evolved multicellularity. In well-mixed environments, multicellular isolates had lower growth rates relative to their unicellular ancestor because of limitations of space and resource acquisition. In structured environments with localized resources, cells in both multicellular and unicellular isolates grew at a similar rate. Despite similar growth, higher local density of cells in multicellular groups led to increased competition and higher fitness costs in spatially structured environments. In structured environments all of the multicellular isolates rapidly evolved a predominantly unicellular life cycle, while in well-mixed environments reversal was more gradual. Taken together, these results suggest that a lack of dispersal, leading to higher local competition, might have been one of the main constraints in the evolution of early multicellular forms.

RevDate: 2018-11-15

Ayoubian H, Ludwig N, Fehlmann T, et al (2018)

Infection of cell lines derived from diffuse large B-cell lymphoma (DLBCL) with the Epstein-Barr virus (EBV) alters the miRNA loading of the Ago2-complex.

Journal of virology pii:JVI.01297-18 [Epub ahead of print].

Diffuse large B-cell lymphoma (DLBCL) is an aggressive lymphoid tumor which is occasionally Epstein-Barr virus (EBV)-positive and is further subtyped as activated B-cell (ABC) and germinal center B-cell (GCB) DLBCL, which has implications for prognosis and treatment.We performed Ago2-RNA immunoprecipitation followed by high throughput RNA sequencing (Ago2-RIP-Seq) to capture functionally active miRNAs in EBV-negative ABC-DLBCL and GC-DLBCL cell lines and their EBV-infected counterparts. In parallel, total miRNomes of these cells were sequenced to capture the cellular miRNA profile for comparison with the functionally active profile. Selected miRNAs with differential abundance were validated using RT-qPCR and Northern Blot. We found 6 miRNAs with differential abundance (2 upregulated and 4 downregulated miRNAs) between EBV-neg. and pos. ABC-DLBCL, and 12 miRNAs with differential abundance (3 upregulated and 9 downregulated miRNAs) between EBV-neg and -pos GC-DLBCL. Eight and twelve miRNAs were confirmed using RT-qPCR in ABC-DLBCL and GC-DLBCL, respectively. Selected miRNs were analyzed in additional type I/II vs. type III EBV latency DLBCL cell lines. Furthermore, up regulation of miR-221-3p and down regulation of let-7c-5p in ABC-DLBCL and up regulation of miR-363-3p and down regulation of 423-5p in GC-DLBCL was verified using RIP-Northern blot.Our comprehensive sequence analysis of the DLBCL miRNomes identified sets of deregulated miRNAs in the Ago2-RIP-seq. Our Ago2-IP-seq miRNomes profile could be considered as an important data set for detection of deregulated functionally active miRNAs in DLBCL and could possibly lead to identification of miRNAs as biomarkers for classification of DLBCL or even as targets for personalized targeted treatment.Importance: Diffuse large B-cell lymphoma (DLBCL) is a highly aggressive tumor of lymphoid origin which is occasionally Epstein-Barr virus (EBV)-positive. MicroRNAs are found in most multicellular organisms and even in viruses such as EBV. They regulate the synthesis of proteins by binding to their cognate messenger RNA (mRNA). MicroRNAs are tethered to their target mRNAs by "Argonaute" proteins. Here we compared the overall content of by differential loading of the Ago2-complex in comparison to the overall content of miRNAs in two DLBCL cell lines and their EBV-converted counterparts. In all cell lines, the Ago2-load was different from the overall expression of miRNAs. In addition, the loading of the Ago2-complex was changed upon infection with EBV. This indicates that the virus changes not only the overall content of miRNAs but also influences the expression of proteins by affecting the Ago-complexes.

RevDate: 2018-11-15
CmpDate: 2018-11-15

Thomas F, Kareva I, Raven N, et al (2018)

Evolved Dependence in Response to Cancer.

Trends in ecology & evolution, 33(4):269-276.

Evolved dependence is a process through which one species becomes 'dependent' on another following a long evolutionary history of interaction. This happens when adaptations selected in the first species for interacting lead to fitness costs when the second species is not encountered. Evolved dependence is frequent in host-parasite interactions, where hosts may achieve a higher fitness in the presence of the parasite than in its absence. Since oncogenic manifestations are (i) ubiquitous across multicellular life, (ii) involved in parasitic-like interactions with their hosts, and (iii) have effectively driven the selection of numerous adaptations, it is possible that multicellular organisms display evolved dependence in response to oncogenic processes. We provide a comprehensive overview of the topic, including the implications for cancer prevention and treatment.

RevDate: 2018-11-14

Schneider P, Greischar MA, Birget PLG, et al (2018)

Adaptive plasticity in the gametocyte conversion rate of malaria parasites.

PLoS pathogens, 14(11):e1007371 pii:PPATHOGENS-D-18-00778 [Epub ahead of print].

Sexually reproducing parasites, such as malaria parasites, experience a trade-off between the allocation of resources to asexual replication and the production of sexual forms. Allocation by malaria parasites to sexual forms (the conversion rate) is variable but the evolutionary drivers of this plasticity are poorly understood. We use evolutionary theory for life histories to combine a mathematical model and experiments to reveal that parasites adjust conversion rate according to the dynamics of asexual densities in the blood of the host. Our model predicts the direction of change in conversion rates that returns the greatest fitness after perturbation of asexual densities by different doses of antimalarial drugs. The loss of a high proportion of asexuals is predicted to elicit increased conversion (terminal investment), while smaller losses are managed by reducing conversion (reproductive restraint) to facilitate within-host survival and future transmission. This non-linear pattern of allocation is consistent with adaptive reproductive strategies observed in multicellular organisms. We then empirically estimate conversion rates of the rodent malaria parasite Plasmodium chabaudi in response to the killing of asexual stages by different doses of antimalarial drugs and forecast the short-term fitness consequences of these responses. Our data reveal the predicted non-linear pattern, and this is further supported by analyses of previous experiments that perturb asexual stage densities using drugs or within-host competition, across multiple parasite genotypes. Whilst conversion rates, across all datasets, are most strongly influenced by changes in asexual density, parasites also modulate conversion according to the availability of red blood cell resources. In summary, increasing conversion maximises short-term transmission and reducing conversion facilitates in-host survival and thus, future transmission. Understanding patterns of parasite allocation to reproduction matters because within-host replication is responsible for disease symptoms and between-host transmission determines disease spread.

RevDate: 2018-11-14
CmpDate: 2018-11-14

Milholland B, Dong X, Zhang L, et al (2017)

Differences between germline and somatic mutation rates in humans and mice.

Nature communications, 8:15183 pii:ncomms15183.

The germline mutation rate has been extensively studied and has been found to vary greatly between species, but much less is known about the somatic mutation rate in multicellular organisms, which remains very difficult to determine. Here, we present data on somatic mutation rates in mice and humans, obtained by sequencing single cells and clones derived from primary fibroblasts, which allows us to make the first direct comparison with germline mutation rates in these two species. The results indicate that the somatic mutation rate is almost two orders of magnitude higher than the germline mutation rate and that both mutation rates are significantly higher in mice than in humans. Our findings demonstrate both the privileged status of germline genome integrity and species-specific differences in genome maintenance.

RevDate: 2018-11-13

García-Jiménez B, García JL, J Nogales (2018)

FLYCOP: metabolic modeling-based analysis and engineering microbial communities.

Bioinformatics (Oxford, England), 34(17):i954-i963.

Motivation: Synthetic microbial communities begin to be considered as promising multicellular biocatalysts having a large potential to replace engineered single strains in biotechnology applications, in pharmaceutical, chemical and living architecture sectors. In contrast to single strain engineering, the effective and high-throughput analysis and engineering of microbial consortia face the lack of knowledge, tools and well-defined workflows. This manuscript contributes to fill this important gap with a framework, called FLYCOP (FLexible sYnthetic Consortium OPtimization), which contributes to microbial consortia modeling and engineering, while improving the knowledge about how these communities work. FLYCOP selects the best consortium configuration to optimize a given goal, among multiple and diverse configurations, in a flexible way, taking temporal changes in metabolite concentrations into account.

Results: In contrast to previous systems optimizing microbial consortia, FLYCOP has novel characteristics to face up to new problems, to represent additional features and to analyze events influencing the consortia behavior. In this manuscript, FLYCOP optimizes a Synechococcus elongatus-Pseudomonas putida consortium to produce the maximum amount of bio-plastic (PHA, polyhydroxyalkanoate), and highlights the influence of metabolites exchange dynamics in a four auxotrophic Escherichia coli consortium with parallel growth. FLYCOP can also provide an explanation about biological evolution driving evolutionary engineering endeavors by describing why and how heterogeneous populations emerge from monoclonal ones.

Code reproducing the study cases described in this manuscript are available on-line: https://github.com/beatrizgj/FLYCOP.

Supplementary information: Supplementary data are available at Bioinformatics online.

RevDate: 2018-11-09

Morris JJ (2018)

What is the hologenome concept of evolution?.

F1000Research, 7:.

All multicellular organisms are colonized by microbes, but a gestalt study of the composition of microbiome communities and their influence on the ecology and evolution of their macroscopic hosts has only recently become possible. One approach to thinking about the topic is to view the host-microbiome ecosystem as a "holobiont". Because natural selection acts on an organism's realized phenotype, and the phenotype of a holobiont is the result of the integrated activities of both the host and all of its microbiome inhabitants, it is reasonable to think that evolution can act at the level of the holobiont and cause changes in the "hologenome", or the collective genomic content of all the individual bionts within the holobiont. This relatively simple assertion has nevertheless been controversial within the microbiome community. Here, I provide a review of recent work on the hologenome concept of evolution. I attempt to provide a clear definition of the concept and its implications and to clarify common points of disagreement.

RevDate: 2018-11-09

Pönisch W, Eckenrode KB, Alzurqa K, et al (2018)

Pili mediated intercellular forces shape heterogeneous bacterial microcolonies prior to multicellular differentiation.

Scientific reports, 8(1):16567 pii:10.1038/s41598-018-34754-4.

Microcolonies are aggregates of a few dozen to a few thousand cells exhibited by many bacteria. The formation of microcolonies is a crucial step towards the formation of more mature bacterial communities known as biofilms, but also marks a significant change in bacterial physiology. Within a microcolony, bacteria forgo a single cell lifestyle for a communal lifestyle hallmarked by high cell density and physical interactions between cells potentially altering their behaviour. It is thus crucial to understand how initially identical single cells start to behave differently while assembling in these tight communities. Here we show that cells in the microcolonies formed by the human pathogen Neisseria gonorrhoeae (Ng) present differential motility behaviors within an hour upon colony formation. Observation of merging microcolonies and tracking of single cells within microcolonies reveal a heterogeneous motility behavior: cells close to the surface of the microcolony exhibit a much higher motility compared to cells towards the center. Numerical simulations of a biophysical model for the microcolonies at the single cell level suggest that the emergence of differential behavior within a multicellular microcolony of otherwise identical cells is of mechanical origin. It could suggest a route toward further bacterial differentiation and ultimately mature biofilms.

RevDate: 2018-11-08

Gao A, Shrinivas K, Lepeudry P, et al (2018)

Evolution of weak cooperative interactions for biological specificity.

Proceedings of the National Academy of Sciences of the United States of America pii:1815912115 [Epub ahead of print].

A hallmark of biological systems is that particular functions and outcomes are realized in specific contexts, such as when particular signals are received. One mechanism for mediating specificity is described by Fisher's "lock and key" metaphor, exemplified by enzymes that bind selectively to a particular substrate via specific finely tuned interactions. Another mechanism, more prevalent in multicellular organisms, relies on multivalent weak cooperative interactions. Its importance has recently been illustrated by the recognition that liquid-liquid phase transitions underlie the formation of membraneless condensates that perform specific cellular functions. Based on computer simulations of an evolutionary model, we report that the latter mechanism likely became evolutionarily prominent when a large number of tasks had to be performed specifically for organisms to function properly. We find that the emergence of weak cooperative interactions for mediating specificity results in organisms that can evolve to accomplish new tasks with fewer, and likely less lethal, mutations. We argue that this makes the system more capable of undergoing evolutionary changes robustly, and thus this mechanism has been repeatedly positively selected in increasingly complex organisms. Specificity mediated by weak cooperative interactions results in some useful cross-reactivity for related tasks, but at the same time increases susceptibility to misregulation that might lead to pathologies.

RevDate: 2018-11-08

Palmer WH, Joosten J, Overheul GJ, et al (2018)

Induction and suppression of NF-κB signalling by a DNA virus of Drosophila.

Journal of virology pii:JVI.01443-18 [Epub ahead of print].

Interactions between the insect immune system and RNA viruses have been extensively studied in Drosophila, where RNA interference, NF-κB and JAK-STAT pathways underlie antiviral immunity. In response to RNA interference, insect viruses have convergently evolved suppressors of this pathway that act by diverse mechanisms to permit viral replication. However, interactions between the insect immune system and DNA viruses have received less attention, primarily because few Drosophila-infecting DNA virus isolates are available. Here, we use a recently-isolated DNA virus of Drosophila melanogaster, Kallithea virus (family Nudiviridae), to probe known antiviral immune responses and virus evasion tactics in the context of DNA virus infection. We find that fly mutants for RNA interference and Immune deficiency (Imd), but not Toll, pathways are more susceptible to Kallithea virus infection. We identify the Kallithea virus-encoded protein gp83 as a potent inhibitor of Toll signalling, suggesting that Toll mediates antiviral defense against Kallithea virus infection, but that it is suppressed by the virus. We find that Kallithea virus gp83 inhibits Toll signalling through the regulation of NF-κB transcription factors. Furthermore, we find that gp83 of the closely related Drosophila innubila nudivirus (DiNV) suppresses D. melanogaster Toll signalling, suggesting an evolutionary conserved function of Toll in defense against DNA viruses. Together, these results provide a broad description of known antiviral pathways in the context of DNA virus infection and identify the first Toll pathway inhibitor in a Drosophila virus, extending the known diversity of insect virus-encoded immune inhibitors.IMPORTANCE Co-evolution of multicellular organisms and their natural viruses may lead to an intricate relationship in which host survival requires effective immunity, and virus survival depends on evasion of such responses. Insect antiviral immunity, and reciprocal virus immune suppression tactics, have been well-studied in Drosophila melanogaster, primarily during RNA, but not DNA, virus infection. Therefore, we describe interactions between a recently-isolated Drosophila DNA virus (Kallithea virus - KV) and immune processes known to control RNA viruses, such as RNAi and Imd pathways. We find that KV suppresses the Toll pathway, and identify gp83 as a KV-encoded protein that underlies this suppression. This immunosuppressive ability is conserved in another nudivirus, suggesting the Toll pathway has conserved antiviral activity against DNA nudiviruses, which have evolved suppressors in response. Together, these results indicate that DNA viruses induce and suppress NF-κB responses, and advance the application of KV as a model to study insect immunity.

RevDate: 2018-11-06

Joo S, Wang MH, Lui G, et al (2018)

Common ancestry of heterodimerizing TALE homeobox transcription factors across Metazoa and Archaeplastida.

BMC biology, 16(1):136 pii:10.1186/s12915-018-0605-5.

BACKGROUND: Complex multicellularity requires elaborate developmental mechanisms, often based on the versatility of heterodimeric transcription factor (TF) interactions. Homeobox TFs in the TALE superclass are deeply embedded in the gene regulatory networks that orchestrate embryogenesis. Knotted-like homeobox (KNOX) TFs, homologous to animal MEIS, have been found to drive the haploid-to-diploid transition in both unicellular green algae and land plants via heterodimerization with other TALE superclass TFs, demonstrating remarkable functional conservation of a developmental TF across lineages that diverged one billion years ago. Here, we sought to delineate whether TALE-TALE heterodimerization is ancestral to eukaryotes.

RESULTS: We analyzed TALE endowment in the algal radiations of Archaeplastida, ancestral to land plants. Homeodomain phylogeny and bioinformatics analysis partitioned TALEs into two broad groups, KNOX and non-KNOX. Each group shares previously defined heterodimerization domains, plant KNOX-homology in the KNOX group and animal PBC-homology in the non-KNOX group, indicating their deep ancestry. Protein-protein interaction experiments showed that the TALEs in the two groups all participated in heterodimerization.

CONCLUSIONS: Our study indicates that the TF dyads consisting of KNOX/MEIS and PBC-containing TALEs must have evolved early in eukaryotic evolution. Based on our results, we hypothesize that in early eukaryotes, the TALE heterodimeric configuration provided transcription-on switches via dimerization-dependent subcellular localization, ensuring execution of the haploid-to-diploid transition only when the gamete fusion is correctly executed between appropriate partner gametes. The TALE switch then diversified in the several lineages that engage in a complex multicellular organization.

RevDate: 2018-11-05

Ten Tusscher K (2018)

Of mice and plants; Comparative Developmental Systems Biology.

Developmental biology pii:S0012-1606(18)30612-2 [Epub ahead of print].

Multicellular animals and plants represent independent evolutionary experiments with complex multicellular bodyplans. Differences in their life history, a mobile versus sessile lifestyle, and predominant embryonic versus postembryonic development, have led to the evolution of highly different body plans. However, also many intriguing parallels exist. Extension of the vertebrate body axis and its segmentation into somites bears striking resemblance to plant root growth and the concomittant prepatterning of lateral root competent sites. Likewise, plant shoot phyllotaxis displays similarities with vertebrate limb and digit patterning. Additionally, both plants and animals use complex signalling systems combining systemic and local signals to fine tune and coordinate organ growth across their body. Identification of these striking examples of convergent evolution provides support for the existence of general design principles: the idea that for particular patterning demands, evolution is likely to arrive at highly similar developmental patterning mechanisms. Furthermore, focussing on these parallels may aid in identifying core mechanistic principles, often obscured by the highly complex nature of multiscale patterning processes.

RevDate: 2018-11-03

Bull JK, Flynn JM, Chain FJJ, et al (2018)

Fitness and Genomic Consequences of Chronic Exposure to Low Levels of Copper and Nickel in Daphnia pulex Mutation Accumulation Lines.

G3 (Bethesda, Md.) pii:g3.118.200797 [Epub ahead of print].

In at least some unicellular organisms, mutation rates are temporarily raised upon exposure to environmental stress, potentially contributing to the evolutionary response to stress. Whether this is true for multicellular organisms, however, has received little attention. This study investigated the effects of chronic mild stress, in the form of low-level copper and nickel exposure, on mutational processes in Daphnia pulex using a combination of mutation accumulation, whole genome sequencing and life-history assays. After over 100 generations of mutation accumulation, we found no effects of metal exposure on the rates of single nucleotide mutations and of loss of heterozygosity events, the two mutation classes that occurred in sufficient numbers to allow statistical analysis. Similarly, rates of decline in fitness, as measured by intrinsic rate of population increase and of body size at first reproduction, were negligibly affected by metal exposure. We can reject the possibility that Daphnia were insufficiently stressed to invoke genetic responses as we have previously shown rates of large-scale deletions and duplications are elevated under metal exposure in this experiment. Overall, the mutation accumulation lines did not significantly depart from initial values for phenotypic traits measured, indicating the lineage used was broadly mutationally robust. Taken together, these results indicate that the mutagenic effects of chronic low-level exposure to these metals are restricted to certain mutation classes and that fitness consequences are likely minor and therefore unlikely to be relevant in determining the evolutionary responses of populations exposed to these stressors.

RevDate: 2018-11-02

Yap GS, WC Gause (2018)

Helminth Infections Induce Tissue Tolerance Mitigating Immunopathology but Enhancing Microbial Pathogen Susceptibility.

Frontiers in immunology, 9:2135.

Helminths are ubiquitous and have chronically infected vertebrates throughout their evolution. As such helminths have likely exerted considerable selection pressure on our immune systems. The large size of multicellular helminths and their limited replicative capacity in the host necessarily elicits different host protective mechanisms than the immune response evoked by microbial pathogens such as bacteria, viruses and intracellular parasites. The cellular damage resulting from helminth migration through tissues is a major trigger of the type 2 and regulatory immune responses, which activates wound repair mechanisms that increases tissue tolerance to injury and resistance mechanisms that enhance resistance to further colonization with larval stages. While these wound healing and anti-inflammatory responses may be beneficial to the helminth infected host, they may also compromise the host's ability to mount protective immune responses to microbial pathogens. In this review we will first describe helminth-induced tolerance mechanisms that develop in specific organs including the lung and the intestine, and how adaptive immunity may contribute to these responses through differential activation of T cells in the secondary lymphoid organs. We will then integrate studies that have examined how the immune response is modulated in these specific tissues during coinfection of helminths with viruses, protozoa, and bacteria.

RevDate: 2018-10-31

Darris C, Revert F, Revert-Ros F, et al (2018)

Unicellular ancestry and mechanisms of diversification of Goodpasture-antigen binding protein.

The Journal of biological chemistry pii:RA118.006225 [Epub ahead of print].

The emergence of the basement membrane (BM), a specialized form of extracellular matrix, was essential in the unicellular transition to multicellularity. Yet, the mechanism is unknown. Goodpasture antigen-binding protein (GPBP), aBM protein, was uniquely poised to play diverse roles in this transition owing to its multiple isoforms (GPBP-1, -2 and -3) with varied intracellular and extracellular functions (ceramide trafficker and protein kinase). We sought to determine the evolutionary origin of GPBP isoforms. Our findings reveal the presence of GPBP in unicellular protists, with GPBP-2 as the most ancient isoform.In vertebrates GPBP-1 assumed extracellular function which is further enhanced by membrane bound GPBP-3 in mammalians, while GPBP-2 retained intracellular function. Moreover, GPBP-2 possesses a dual intracellular/extracellular functionin cnidarians, an early non-bilaterian group. We conclude that GPBP functioning both inside and outside the cell was of fundamental importance for the evolutionary transition to animal multicellularity and tissue evolution.

RevDate: 2018-10-30
CmpDate: 2018-10-30

Gao Q, Xu S, Zhu X, et al (2018)

Genome-wide identification and characterization of the RIO atypical kinase family in plants.

Genes & genomics, 40(6):669-683.

Members of the right open reading frame (RIO) atypical kinase family are present in all three domains of life. In eukaryotes, three subfamilies have been identified: RIO1, RIO2, and RIO3. Studies have shown that the yeast and human RIO1 and RIO2 kinases are essential for the biogenesis of small ribosomal subunits. Thus far, RIO3 has been found only in multicellular eukaryotes. In this study, we systematically identified members of the RIO gene family in 37 species representing the major evolutionary lineages in Viridiplantae. A total of 84 RIO genes were identified; among them, 41 were classified as RIO1 and 43 as RIO2. However, no RIO3 gene was found in any of the species examined. Phylogenetic trees constructed for plant RIO1 and RIO2 proteins were generally congruent with the species phylogeny. Subcellular localization analyses showed that the plant RIO proteins were localized mainly in the nucleus and/or cytoplasm. Expression profile analysis of rice, maize, and Arabidopsis RIO genes in different tissues revealed similar expression patterns between RIO1 and RIO2 genes, and their expression levels were high in certain tissues. In addition, the expressions of plant RIO genes were regulated by two drugs: mycophenolic acid and actinomycin D. Function prediction using genome-wide coexpression analysis revealed that most plant RIO genes may be involved in ribosome biogenesis. Our results will be useful for the evolutionary analysis of the ancient RIO kinase family and provide a basis for further functional characterization of RIO genes in plants.

RevDate: 2018-10-30
CmpDate: 2018-10-30

Nishiyama E, K Ohshima (2018)

Cross-Kingdom Commonality of a Novel Insertion Signature of RTE-Related Short Retroposons.

Genome biology and evolution, 10(6):1471-1483.

In multicellular organisms, such as vertebrates and flowering plants, horizontal transfer (HT) of genetic information is thought to be a rare event. However, recent findings unveiled unexpectedly frequent HT of RTE-clade LINEs. To elucidate the molecular footprints of the genomic integration machinery of RTE-related retroposons, the sequence patterns surrounding the insertion sites of plant Au-like SINE families were analyzed in the genomes of a wide variety of flowering plants. A novel and remarkable finding regarding target site duplications (TSDs) for SINEs was they start with thymine approximately one helical pitch (ten nucleotides) downstream of a thymine stretch. This TSD pattern was found in RTE-clade LINEs, which share the 3'-end sequence of these SINEs, in the genome of leguminous plants. These results demonstrably show that Au-like SINEs were mobilized by the enzymatic machinery of RTE-clade LINEs. Further, we discovered the same TSD pattern in animal SINEs from lizard and mammals, in which the RTE-clade LINEs sharing the 3'-end sequence with these animal SINEs showed a distinct TSD pattern. Moreover, a significant correlation was observed between the first nucleotide of TSDs and microsatellite-like sequences found at the 3'-ends of SINEs and LINEs. We propose that RTE-encoded protein could preferentially bind to a DNA region that contains a thymine stretch to cleave a phosphodiester bond downstream of the stretch. Further, determination of cleavage sites and/or efficiency of primer sites for reverse transcription may depend on microsatellite-like repeats in the RNA template. Such a unique mechanism may have enabled retroposons to successfully expand in frontier genomes after HT.

RevDate: 2018-10-28

Niklas KJ, Wayne R, Benítez M, et al (2018)

Polarity, planes of cell division, and the evolution of plant multicellularity.

Protoplasma pii:10.1007/s00709-018-1325-y [Epub ahead of print].

Organisms as diverse as bacteria, fungi, plants, and animals manifest a property called "polarity." The literature shows that polarity emerges as a consequence of different mechanisms in different lineages. However, across all unicellular and multicellular organisms, polarity is evident when cells, organs, or organisms manifest one or more of the following: orientation, axiation, and asymmetry. Here, we review the relationships among these three features in the context of cell division and the evolution of multicellular polarity primarily in plants (defined here to include the algae). Data from unicellular and unbranched filamentous organisms (e.g., Chlamydomonas and Ulothrix) show that cell orientation and axiation are marked by cytoplasmic asymmetries. Branched filamentous organisms (e.g., Cladophora and moss protonema) require an orthogonal reorientation of axiation, or a localized cell asymmetry (e.g., "tip" growth in pollen tubes and fungal hyphae). The evolution of complex multicellular meristematic polarity required a third reorientation of axiation. These transitions show that polarity and the orientation of the future plane(s) of cell division are dyadic dynamical patterning modules that were critical for multicellular eukaryotic organisms.

RevDate: 2018-10-26

Castiglione GM, BS Chang (2018)

Functional trade-offs and environmental variation shaped ancient trajectories in the evolution of dim-light vision.

eLife, 7: pii:35957.

Trade-offs between protein stability and activity can restrict access to evolutionary trajectories, but widespread epistasis may facilitate indirect routes to adaptation. This may be enhanced by natural environmental variation, but in multicellular organisms this process is poorly understood. We investigated a paradoxical trajectory taken during the evolution of tetrapod dim-light vision, where in the rod visual pigment rhodopsin, E122 was fixed 350 million years ago, a residue associated with increased active-state (MII) stability but greatly diminished rod photosensitivity. Here, we demonstrate that high MII stability could have likely evolved without E122, but instead, selection appears to have entrenched E122 in tetrapods via epistatic interactions with nearby coevolving sites. In fishes by contrast, selection may have exploited these epistatic effects to explore alternative trajectories, but via indirect routes with low MII stability. Our results suggest that within tetrapods, E122 and high MII stability cannot be sacrificed-not even for improvements to rod photosensitivity.

RevDate: 2018-10-25

Fitzgerald RS (2018)

O2/CO2: Biological Detection to Homeostatic Control.

Advances in experimental medicine and biology, 1071:1-12.

Oxygen (O2) and Carbon Dioxide (CO2) are the two gases to be detected and controlled. Of interest might be a query of the evolutionary origin of each. From the cooling of the Big Bang (~13.8 Billion Years Ago [BYA]) came a quark-gluon plasma from which protons and neutrons emerged, producing H, He, Li. As H and He collapsed into the first stars at ~13.3 BYA carbon and monatomic oxygen were generated. Some 3 billion years ago greater amounts of diatomic oxygen (O2) were provided by earth's photosynthesizing bacteria until earth's atmosphere had sufficient amounts to sustain the life processes of multicellular animals, and finally higher vertebrates. Origin of CO2 is somewhat unclear, though it probably came from the erupting early volcanoes. Photosynthesis produced sugars with O2 a waste product. Animal life took sugars and O2 needed for life. Clearly, animal detection and control of each was critical. Many chapters involving great heroes describe phases involved in detecting each, both in the CNS and in peripheral detectors. The carotid body (CB) has played a crucial role in the detection of each. What reflex responses the stimulated CB generates, and the mechanisms as to how it does so have been a fascinating story over the last 1.5 centuries, but principally over the last 50 years. Explorations to detect these gases have proceeded from the organismal/system/ organ levels down to the sub-cell and genetic levels.

RevDate: 2018-10-23

Kin K, Forbes G, Cassidy A, et al (2018)

Cell-type specific RNA-Seq reveals novel roles and regulatory programs for terminally differentiated Dictyostelium cells.

BMC genomics, 19(1):764 pii:10.1186/s12864-018-5146-3.

BACKGROUND: A major hallmark of multicellular evolution is increasing complexity by the evolution of new specialized cell types. During Dictyostelid evolution novel specialization occurred within taxon group 4. We here aim to retrace the nature and ancestry of the novel "cup" cells by comparing their transcriptome to that of other cell types.

RESULTS: RNA-Seq was performed on purified mature spore, stalk and cup cells and on vegetative amoebas. Clustering and phylogenetic analyses showed that cup cells were most similar to stalk cells, suggesting that they share a common ancestor. The affinity between cup and stalk cells was also evident from promoter-reporter studies of newly identified cell-type genes, which revealed late expression in cups of many stalk genes. However, GO enrichment analysis reveal the unexpected prominence of GTPase mediated signalling in cup cells, in contrast to enrichment of autophagy and cell wall synthesis related transcripts in stalk cells. Combining the cell type RNA-Seq data with developmental expression profiles revealed complex expression dynamics in each cell type as well as genes exclusively expressed during terminal differentiation. Most notable were nine related hssA-like genes that were highly and exclusively expressed in cup cells.

CONCLUSIONS: This study reveals the unique transcriptomes of the mature cup, stalk and spore cells of D. discoideum and provides insight into the ancestry of cup cells and roles in signalling that were not previously realized. The data presented in this study will serve as an important resource for future studies into the regulation and evolution of cell type specialization.

RevDate: 2018-10-18

Miller WB, Torday JS, F Baluška (2018)

Biological Evolution as Defense of 'Self'.

Progress in biophysics and molecular biology pii:S0079-6107(18)30151-2 [Epub ahead of print].

Although the origin of self-referential consciousness is unknown, it can be argued that the instantiation of self-reference was the commencement the living state as phenomenal experientiality. As self-referential cognition is demonstrated by all living organisms, life can be equated with the sustenance of cellular homeostasis in the continuous defense of 'self'. It is proposed that the epicenter of 'self' is perpetually embodied within the basic cellular form in which it was instantiated. Cognition-Based Evolution argues that all of biological and evolutionary development represents the perpetual autopoietic defense of self-referential basal cellular states of homeostatic preference. The means by which these states are attained and maintained is through self-referential measurement of information and its communication. The multicellular forms, either as biofilms or holobionts, represent the cellular attempt to achieve maximum states of informational distinction and energy efficiency through individual and collective means. In this frame, consciousness, self-consciousness and intelligence can be identified as forms of collective cellular phenotype directed towards the defense of fundamental cellular self-reference.

RevDate: 2018-10-16

Skaldin M, Tuittila M, Zavialov AV, et al (2018)

Secreted bacterial adenosine deaminase is an evolutionary precursor of adenosine deaminase growth factor.

Molecular biology and evolution pii:5133304 [Epub ahead of print].

Adenosine deaminases (ADAs) play a pivotal role in regulating the level of adenosine, an important signaling molecule that controls a variety of cellular responses. Two distinct ADAs, ADA1 and adenosine deaminase growth factor (ADGF aka ADA2), are known. Cytoplasmic ADA1 plays a key role in purine metabolism and is widely distributed from prokaryotes to mammals. On the other hand, secreted ADGF/ADA2 is a cell-signaling protein that was thought to be present only in multicellular organisms. Here, we discovered a bacterial homologue of ADGF/ADA2. Bacterial and eukaryotic ADGF/ADA2 possess the dimerization and PRB domains characteristic for the family, have nearly identical catalytic sites, and show similar catalytic characteristics. Most surprisingly, the bacterial enzyme has a signal sequence similar to that of eukaryotic ADGF/ADA2 and is specifically secreted into the extracellular space, where it may potentially control the level of extracellular adenosine. This finding provides the first example of evolution of an extracellular eukaryotic signaling protein from a secreted bacterial analogue with identical activity and suggests a potential role of ADGF/ADA2 in bacterial communication.

RevDate: 2018-10-23

Bråte J, Neumann RS, Fromm B, et al (2018)

Unicellular Origin of the Animal MicroRNA Machinery.

Current biology : CB, 28(20):3288-3295.e5.

The emergence of multicellular animals was associated with an increase in phenotypic complexity and with the acquisition of spatial cell differentiation and embryonic development. Paradoxically, this phenotypic transition was not paralleled by major changes in the underlying developmental toolkit and regulatory networks. In fact, most of these systems are ancient, established already in the unicellular ancestors of animals [1-5]. In contrast, the Microprocessor protein machinery, which is essential for microRNA (miRNA) biogenesis in animals, as well as the miRNA genes themselves produced by this Microprocessor, have not been identified outside of the animal kingdom [6]. Hence, the Microprocessor, with the key proteins Pasha and Drosha, is regarded as an animal innovation [7-9]. Here, we challenge this evolutionary scenario by investigating unicellular sister lineages of animals through genomic and transcriptomic analyses. We identify in Ichthyosporea both Drosha and Pasha (DGCR8 in vertebrates), indicating that the Microprocessor complex evolved long before the last common ancestor of animals, consistent with a pre-metazoan origin of most of the animal developmental gene elements. Through small RNA sequencing, we also discovered expressed bona fide miRNA genes in several species of the ichthyosporeans harboring the Microprocessor. A deep, pre-metazoan origin of the Microprocessor and miRNAs comply with a view that the origin of multicellular animals was not directly linked to the innovation of these key regulatory components.

RevDate: 2018-10-12

Armon S, Bull MS, Aranda-Diaz A, et al (2018)

Ultrafast epithelial contractions provide insights into contraction speed limits and tissue integrity.

Proceedings of the National Academy of Sciences of the United States of America pii:1802934115 [Epub ahead of print].

By definition of multicellularity, all animals need to keep their cells attached and intact, despite internal and external forces. Cohesion between epithelial cells provides this key feature. To better understand fundamental limits of this cohesion, we study the epithelium mechanics of an ultrathin (∼25 μm) primitive marine animal Trichoplax adhaerens, composed essentially of two flat epithelial layers. With no known extracellular matrix and no nerves or muscles, T. adhaerens has been claimed to be the "simplest known living animal," yet is still capable of coordinated locomotion and behavior. Here we report the discovery of the fastest epithelial cellular contractions known in any metazoan, to be found in T. adhaerens dorsal epithelium (50% shrinkage of apical cell area within one second, at least an order of magnitude faster than other known examples). Live imaging reveals emergent contractile patterns that are mostly sporadic single-cell events, but also include propagating contraction waves across the tissue. We show that cell contraction speed can be explained by current models of nonmuscle actin-myosin bundles without load, while the tissue architecture and unique mechanical properties are softening the tissue, minimizing the load on a contracting cell. We propose a hypothesis, in which the physiological role of the contraction dynamics is to resist external stresses while avoiding tissue rupture ("active cohesion"), a concept that can be further applied to engineering of active materials.

RevDate: 2018-10-08

Sperling EA, RG Stockey (2018)

The Temporal and Environmental Context of Early Animal Evolution: Considering All the Ingredients of an "Explosion".

Integrative and comparative biology, 58(4):605-622.

Animals originated and evolved during a unique time in Earth history-the Neoproterozoic Era. This paper aims to discuss (1) when landmark events in early animal evolution occurred, and (2) the environmental context of these evolutionary milestones, and how such factors may have affected ecosystems and body plans. With respect to timing, molecular clock studies-utilizing a diversity of methodologies-agree that animal multicellularity had arisen by ∼800 million years ago (Ma) (Tonian period), the bilaterian body plan by ∼650 Ma (Cryogenian), and divergences between sister phyla occurred ∼560-540 Ma (late Ediacaran). Most purported Tonian and Cryogenian animal body fossils are unlikely to be correctly identified, but independent support for the presence of pre-Ediacaran animals is recorded by organic geochemical biomarkers produced by demosponges. This view of animal origins contrasts with data from the fossil record, and the taphonomic question of why animals were not preserved (if present) remains unresolved. Neoproterozoic environments demanding small, thin, body plans, and lower abundance/rarity in populations may have played a role. Considering environmental conditions, geochemical data suggest that animals evolved in a relatively low-oxygen ocean. Here, we present new analyses of sedimentary total organic carbon contents in shales suggesting that the Neoproterozoic ocean may also have had lower primary productivity-or at least lower quantities of organic carbon reaching the seafloor-compared with the Phanerozoic. Indeed, recent modeling efforts suggest that low primary productivity is an expected corollary of a low-O2 world. Combined with an inability to inhabit productive regions in a low-O2 ocean, earliest animal communities would likely have been more food limited than generally appreciated, impacting both ecosystem structure and organismal behavior. In light of this, we propose the "fire triangle" metaphor for environmental influences on early animal evolution. Moving toward consideration of all environmental aspects of the Cambrian radiation (fuel, heat, and oxidant) will ultimately lead to a more holistic view of the event.

RevDate: 2018-10-26

Stiller JW, Yang C, Collén J, et al (2018)

Evolution and expression of core SWI/SNF genes in red algae.

Journal of phycology [Epub ahead of print].

Red algae are the oldest identifiable multicellular eukaryotes, with a fossil record dating back more than a billion years. During that time two major rhodophyte lineages, bangiophytes and florideophytes, have evolved varied levels of morphological complexity. These two groups are distinguished, in part, by different patterns of multicellular development, with florideophytes exhibiting a far greater diversity of morphologies. Interestingly, during their long evolutionary history, there is no record of a rhodophyte achieving the kinds of cellular and tissue-specific differentiation present in other multicellular algal lineages. To date, the genetic underpinnings of unique aspects of red algal development are largely unexplored; however, they must reflect the complements and patterns of expression of key regulatory genes. Here we report comparative evolutionary and gene expression analyses of core subunits of the SWI/SNF chromatin-remodeling complex, which is implicated in cell differentiation and developmental regulation in more well studied multicellular groups. Our results suggest that a single, canonical SWI/SNF complex was present in the rhodophyte ancestor, with gene duplications and evolutionary diversification of SWI/SNF subunits accompanying the evolution of multicellularity in the common ancestor of bangiophytes and florideophytes. Differences in how SWI/SNF chromatin remodeling evolved subsequently, in particular gene losses and more rapid divergence of SWI3 and SNF5 in bangiophytes, could help to explain why they exhibit a more limited range of morphological complexity than their florideophyte cousins.

RevDate: 2018-10-07

Godwin JL, Spurgin LG, Michalczyk Ł, et al (2018)

Lineages evolved under stronger sexual selection show superior ability to invade conspecific competitor populations.

Evolution letters, 2(5):511-523 pii:EVL380.

Despite limitations on offspring production, almost all multicellular species use sex to reproduce. Sex gives rise to sexual selection, a widespread force operating through competition and choice within reproduction, however, it remains unclear whether sexual selection is beneficial for total lineage fitness, or if it acts as a constraint. Sexual selection could be a positive force because of selection on improved individual condition and purging of mutation load, summing into lineages with superior fitness. On the other hand, sexual selection could negate potential net fitness through the actions of sexual conflict, or because of tensions between investment in sexually selected and naturally selected traits. Here, we explore these ideas using a multigenerational invasion challenge to measure consequences of sexual selection for the overall net fitness of a lineage. After applying experimental evolution under strong versus weak regimes of sexual selection for 77 generations with the flour beetle Tribolium castaneum, we measured the overall ability of introductions from either regime to invade into conspecific competitor populations across eight generations. Results showed that populations from stronger sexual selection backgrounds had superior net fitness, invading more rapidly and completely than counterparts from weak sexual selection backgrounds. Despite comprising only 10% of each population at the start of the invasion experiment, colonizations from strong sexual selection histories eventually achieved near-total introgression, almost completely eliminating the original competitor genotype. Population genetic simulations using the design and parameters of our experiment indicate that this invasion superiority could be explained if strong sexual selection had improved both juvenile and adult fitness, in both sexes. Using a combination of empirical and modeling approaches, our findings therefore reveal positive and wide-reaching impacts of sexual selection for net population fitness when facing the broad challenge of invading competitor populations across multiple generations.

RevDate: 2018-10-03

Booth DS, Szmidt-Middleton H, N King (2018)

Choanoflagellate transfection illuminates their cell biology and the ancestry of animal septins.

Molecular biology of the cell [Epub ahead of print].

As the closest living relatives of animals, choanoflagellates offer unique insights into animal origins and core mechanisms underlying animal cell biology. However, unlike traditional model organisms, such as yeast, flies and worms, choanoflagellates have been refractory to DNA delivery methods for expressing foreign genes. Here we report the establishment of a robust method for expressing transgenes in the choanoflagellate Salpingoeca rosetta, overcoming barriers that have previously hampered DNA delivery and expression. To demonstrate how this method accelerates the study of S. rosetta cell biology, we engineered a panel of fluorescent protein markers that illuminate key features of choanoflagellate cells. We then investigated the localization of choanoflagellate septins, a family of GTP-binding cytoskeletal proteins that are hypothesized to regulate multicellular rosette development in S. rosetta. Fluorescently tagged septins localized to the basal pole of S. rosetta single cells and rosettes in a pattern resembling septin localization in animal epithelia. The establishment of transfection in S. rosetta and its application to the study of septins represent critical advances in the growth of S. rosetta as an experimental model for investigating choanoflagellate cell biology, core mechanisms underlying animal cell biology, and the origin of animals.

RevDate: 2018-10-03

Zhou W, Gao B, S Zhu (2018)

Did cis- and trans-defensins derive from a common ancestor?.

Immunogenetics pii:10.1007/s00251-018-1086-y [Epub ahead of print].

Defensins are small, cysteine-rich, cationic antimicrobial peptides, serving as effectors of the innate immune system and modulators of the adaptive immune system. They extensively exist in multicellular organisms and are divided into cis and trans according to their disulfide bridge connectivity patterns. It has been proposed that these two types of defensins convergently originated from different ancestors. Here, we report the discovery of a structural signature involved in the formation of the cysteine-stabilized α-helix/β-sheet (CSαβ) fold of the cis-defensins in some trans-β-defensins, with only one amino acid indel (CXC vs. CC. C, cysteine; X, any amino acid). The indel of the X residue in the structural signature provides a possible explanation as to why cis- and trans-defensins possess different folds and connectivity patterns of disulfide bridges formed in evolution. Although our attempt to convert the structure type of a present-day trans-defensin with the X residue deleted was unsuccessful due to the low solubility of the synthetic peptide, a combination of data from structural signature, function, and phylogenetic distribution suggests that these defensins may have descended from a common ancestor. In this evolutionary scenario, we propose that a progenitor cis-scaffold might gradually evolve into a trans-defensin after deleting the X residue in specific lineages. This proposal adds a new dimension to more deeply studying the evolutionary relationship of defensins with different folds and of other distantly related proteins.

RevDate: 2018-10-03

Teng Z, Zhang Y, Zhang W, et al (2018)

Diversity and Characterization of Multicellular Magnetotactic Prokaryotes From Coral Reef Habitats of the Paracel Islands, South China Sea.

Frontiers in microbiology, 9:2135.

While multicellular magnetotactic prokaryotes (MMPs) are ubiquitous in marine environments, the diversity of MMPs in sediments of coral reef ecosystems has rarely been reported. In this study, we made an investigation on the diversity and characteristics of MMPs in sediments at 11 stations in coral reef habitats of the Paracel Islands. The results showed that MMPs were present at nine stations, with spherical mulberry-like MMPs (s-MMPs) found at all stations and ellipsoidal pineapple-like MMPs (e-MMPs) found at seven stations. The maximum abundance of MMPs was 6 ind./cm3. Phylogenetic analysis revealed the presence of one e-MMP species and five s-MMP species including two species of a new genus. The results indicate that coral reef habitats of the Paracel Islands have a high diversity of MMPs that bio-mineralize multiple intracellular chains of iron crystals and play important role in iron cycling in such oligotrophic environment. These observations provide new perspective of the diversity of MMPs in general and expand knowledge of the occurrence of MMPs in coral reef habitats.

RevDate: 2018-10-26

Joshi J, V Guttal (2018)

Demographic noise and cost of greenbeard can facilitate greenbeard cooperation.

Evolution; international journal of organic evolution [Epub ahead of print].

Cooperation among organisms, where cooperators suffer a personal cost to benefit others, is ubiquitous in nature. Greenbeard is a key mechanism for the evolution of cooperation, where a single gene or a set of linked genes codes for both cooperation and a phenotypic tag (metaphorically called "green beard"). Greenbeard cooperation is typically thought to decline over time since defectors can also evolve the tag. However, models of tag-based cooperation typically ignore two key realistic features: populations are finite, and that phenotypic tags can be costly. We develop an analytical model for coevolutionary dynamics of two evolvable traits in finite populations with mutations: costly cooperation and a costly tag. We show that an interplay of demographic noise and cost of the tag can induce coevolutionary cycling, where the evolving population does not reach a steady state but spontaneously switches between cooperative tag-carrying and noncooperative tagless states. Such dynamics allows the tag to repeatedly reappear even after it is invaded by defectors. Thus, we highlight the surprising possibility that the cost of the tag, together with demographic noise, can facilitate the evolution of greenbeard cooperation. We discuss implications of these findings in the context of the evolution of quorum sensing and multicellularity.

RevDate: 2018-10-02

Chen X, Köllner TG, Shaulsky G, et al (2018)

Diversity and Functional Evolution of Terpene Synthases in Dictyostelid Social Amoebae.

Scientific reports, 8(1):14361 pii:10.1038/s41598-018-32639-0.

Dictyostelids, or social amoebae, have a unique life style in forming multicellular fruiting bodies from unicellular amoeboids upon starvation. Recently, dictyostelids were found to contain terpene synthase (TPS) genes, a gene type of secondary metabolism previously known to occur only in plants, fungi and bacteria. Here we report an evolutionary functional study of dictyostelid TPS genes. The number of TPS genes in six species of dictyostelids examined ranges from 1 to 19; and the model species Dictyostelium purpureum contains 12 genes. Using in vitro enzyme assays, the 12 TPS genes from D. purpureum were shown to encode functional enzymes with distinct product profiles. The expression of the 12 TPS genes in D. purpureum is developmentally regulated. During multicellular development, D. purpureum releases a mixture of volatile terpenes dominated by sesquiterpenes that are the in vitro products of a subset of the 12 TPS genes. The quality and quantity of the terpenes released from D. purpureum, however, bear little resemblance to those of D. discoideum, a closely related dictyostelid. Despite these variations, the conserved clade of dictyostelid TPSs, which have an evolutionary distance of more than 600 million years, has the same biochemical function, catalyzing the formation of a sesquiterpene protoillud-7-ene. Taken together, our results indicate that the dynamic evolution of dictyostelid TPS genes includes both purifying selection of an orthologous group and species-specific expansion with functional divergence. Consequently, the terpenes produced by these TPSs most likely have conserved as well as species-adaptive biological functions as chemical languages in dictyostelids.

RevDate: 2018-10-09

Lau AYT, Cheng X, Cheng CK, et al (2018)

Discovery of microRNA-like RNAs during early fruiting body development in the model mushroom Coprinopsis cinerea.

PloS one, 13(9):e0198234 pii:PONE-D-18-14545.

Coprinopsis cinerea is a model mushroom particularly suited for the study of fungal fruiting body development and the evolution of multicellularity in fungi. While microRNAs (miRNAs) have been extensively studied in animals and plants for their essential roles in post-transcriptional regulation of gene expression, miRNAs in fungi are less well characterized and their potential roles in controlling mushroom development remain unknown. To identify miRNA-like RNAs (milRNAs) in C. cinerea and explore their expression patterns during the early developmental transition of mushroom development, small RNA libraries of vegetative mycelium and primordium were generated and putative milRNA candidates were identified following the standards of miRNA prediction in animals and plants. Two out of 22 novel predicted milRNAs, cci-milR-12c and cci-milR-13e-5p, were validated by northern blot and stem-loop reverse transcription real-time PCR. Cci-milR-12c was differentially expressed whereas the expression levels of cci-milR-13e-5p were similar in the two developmental stages. Target prediction of the validated milRNAs resulted in genes associated with fruiting body development, including pheromone, hydrophobin, cytochrome P450, and protein kinase. Essential genes for miRNA biogenesis, including three coding for Dicer-like (DCL), one for Argonaute (AGO), one for AGO-like and one for quelling deficient-2 (QDE-2) proteins, were also identified in the C. cinerea genome. Phylogenetic analysis showed that the DCL and AGO proteins of C. cinerea were more closely related to those in other basidiomycetes and ascomycetes than to those in animals and plants. Taken together, our findings provided the first evidence for milRNAs in the model mushroom and their potential roles in regulating fruiting body development. New information on the evolutionary relationship of milRNA biogenesis proteins across kingdoms has also provided new insights for guiding further functional and evolutionary studies of miRNAs.

RevDate: 2018-09-20

Herron MD, Ratcliff WC, Boswell J, et al (2018)

Genetics of a de novo origin of undifferentiated multicellularity.

Royal Society open science, 5(8):180912 pii:rsos180912.

The evolution of multicellularity was a major transition in evolution and set the stage for unprecedented increases in complexity, especially in land plants and animals. Here, we explore the genetics underlying a de novo origin of multicellularity in a microbial evolution experiment carried out on the green alga Chlamydomonas reinhardtii. We show that large-scale changes in gene expression underlie the transition to a multicellular life cycle. Among these, changes to genes involved in cell cycle and reproductive processes were overrepresented, as were changes to C. reinhardtii-specific and volvocine-specific genes. These results suggest that the genetic basis for the experimental evolution of multicellularity in C. reinhardtii has both lineage-specific and shared features, and that the shared features have more in common with C. reinhardtii's relatives among the volvocine algae than with other multicellular green algae or land plants.

RevDate: 2018-09-25

De Clerck O, Kao SM, Bogaert KA, et al (2018)

Insights into the Evolution of Multicellularity from the Sea Lettuce Genome.

Current biology : CB, 28(18):2921-2933.e5.

We report here the 98.5 Mbp haploid genome (12,924 protein coding genes) of Ulva mutabilis, a ubiquitous and iconic representative of the Ulvophyceae or green seaweeds. Ulva's rapid and abundant growth makes it a key contributor to coastal biogeochemical cycles; its role in marine sulfur cycles is particularly important because it produces high levels of dimethylsulfoniopropionate (DMSP), the main precursor of volatile dimethyl sulfide (DMS). Rapid growth makes Ulva attractive biomass feedstock but also increasingly a driver of nuisance "green tides." Ulvophytes are key to understanding the evolution of multicellularity in the green lineage, and Ulva morphogenesis is dependent on bacterial signals, making it an important species with which to study cross-kingdom communication. Our sequenced genome informs these aspects of ulvophyte cell biology, physiology, and ecology. Gene family expansions associated with multicellularity are distinct from those of freshwater algae. Candidate genes, including some that arose following horizontal gene transfer from chromalveolates, are present for the transport and metabolism of DMSP. The Ulva genome offers, therefore, new opportunities to understand coastal and marine ecosystems and the fundamental evolution of the green lineage.

RevDate: 2018-10-25

Kulkarni P, VN Uversky (2018)

Intrinsically Disordered Proteins: The Dark Horse of the Dark Proteome.

Proteomics [Epub ahead of print].

A good portion of the 'protein universe' embodies the 'dark proteome'. The latter comprises proteins not amenable to experimental structure determination by existing means and inaccessible to homology modeling. Hence, the dark proteome has remained largely unappreciated. Intrinsically disordered proteins (IDPs) that lack rigid 3D structure are a major component of this dark proteome across all three kingdoms of life. Despite lack of structure, IDPs play critical roles in numerous important biological processes. Furthermore, IDPs serve as crucial constituents of proteinaceous membrane-less organelles (PMLOs), where they often serve as drivers and controllers of biological liquid-liquid phase transitions responsible for the PMLO biogenesis. In this perspective, the role of IDPs is discussed in i) the origin of prebiotic life and the evolution of the first independent primordial living unit akin to Tibor Gánti's chemoton, which preceded the Last Universal Common Ancestor (LUCA), ii) role in multicellularity and hence, in major evolutionary transitions, and iii), their role in phenotypic switching, and the emergence of new traits and adaptive opportunities via non-genetic, protein-based mechanisms. The emerging picture suggests that despite being major constituents of the dark matter, IDPs may be the dark horse in the protein universe.

RevDate: 2018-09-16

Baluška F, WB Miller (Jr) (2018)

Senomic view of the cell: Senome versus Genome.

Communicative & integrative biology, 11(3):1-9 pii:1489184.

In the legacy of Thomas Henry Huxley, and his 'epigenetic' philosophy of biology, cells are proposed to represent a trinity of three memory-storing media: Senome, Epigenome, and Genome that together comprise a cell-wide informational architecture. Our current preferential focus on the Genome needs to be complemented by a similar focus on the Epigenome and a here proposed Senome, representing the sum of all the sensory experiences of the cognitive cell and its sensing apparatus. Only then will biology be in a position to embrace the whole complexity of the eukaryotic cell, understanding its true nature which allows the communicative assembly of cells in the form of sentient multicellular organisms.

RevDate: 2018-09-13

Zhang L, J Vijg (2018)

Somatic Mutagenesis in Mammals and Its Implications for Human Disease and Aging.

Annual review of genetics [Epub ahead of print].

DNA mutations as a consequence of errors during DNA damage repair, replication, or mitosis are the substrate for evolution. In multicellular organisms, mutations can occur in the germline and also in somatic tissues, where they are associated with cancer and other chronic diseases and possibly with aging. Recent advances in high-throughput sequencing have made it relatively easy to study germline de novo mutations, but in somatic cells, the vast majority of mutations are low-abundant and can be detected only in clonal lineages, such as tumors, or single cells. Here we review recent results on somatic mutations in normal human and animal tissues with a focus on their possible functional consequences. Expected final online publication date for the Annual Review of Genetics Volume 52 is November 23, 2018. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

RevDate: 2018-09-06

Yruela I, Contreras-Moreira B, Dunker AK, et al (2018)

Evolution of Protein Ductility in Duplicated Genes of Plants.

Frontiers in plant science, 9:1216.

Previous work has shown that ductile/intrinsically disordered proteins (IDPs) and residues (IDRs) are found in all unicellular and multicellular organisms, wherein they are essential for basic cellular functions and complement the function of rigid proteins. In addition, computational studies of diverse phylogenetic lineages have revealed: (1) that protein ductility increases in concert with organismic complexity, and (2) that distributions of IDPs and IDRs along the chromosomes of plant species are non-random and correlate with variations in the rates of the genetic recombination and chromosomal rearrangement. Here, we show that approximately 50% of aligned residues in paralogs across a spectrum of algae, bryophytes, monocots, and eudicots are IDRs and that a high proportion (ca. 60%) are in disordered segments greater than 30 residues. When three types of IDRs are distinguished (i.e., identical, similar and variable IDRs) we find that species with large numbers of chromosome and endoduplicated genes exhibit paralogous sequences with a higher frequency of identical IDRs, whereas species with small chromosomes numbers exhibit paralogous sequences with a higher frequency of similar and variable IDRs. These results are interpreted to indicate that genome duplication events influence the distribution of IDRs along protein sequences and likely favor the presence of identical IDRs (compared to similar IDRs or variable IDRs). We discuss the evolutionary implications of gene duplication events in the context of ductile/disordered residues and segments, their conservation, and their effects on functionality.

RevDate: 2018-10-06

Olejarz J, Kaveh K, Veller C, et al (2018)

Selection for synchronized cell division in simple multicellular organisms.

Journal of theoretical biology, 457:170-179.

The evolution of multicellularity was a major transition in the history of life on earth. Conditions under which multicellularity is favored have been studied theoretically and experimentally. But since the construction of a multicellular organism requires multiple rounds of cell division, a natural question is whether these cell divisions should be synchronous or not. We study a population model in which there compete simple multicellular organisms that grow by either synchronous or asynchronous cell divisions. We demonstrate that natural selection can act differently on synchronous and asynchronous cell division, and we offer intuition for why these phenotypes are generally not neutral variants of each other.

RevDate: 2018-10-04
CmpDate: 2018-10-02

Liu Y, Liu D, Khan AR, et al (2018)

NbGIS regulates glandular trichome initiation through GA signaling in tobacco.

Plant molecular biology, 98(1-2):153-167.

KEY MESSAGE: A novel gene NbGIS positively regulates glandular trichome initiation through GA Signaling in tobacco. NbMYB123-like regulates glandular trichome initiation by acting downstream of NbGIS in tobacco. Glandular trichome is a specialized multicellular structure which has capability to synthesize and secrete secondary metabolites and protects plants from biotic and abiotic stresses. Our previous results revealed that a C2H2 zinc-finger transcription factor GIS and its sub-family genes act upstream of GL3/EGL3-GL1-TTG1 transcriptional activator complex to regulate trichome initiation in Arabidopsis. In this present study, we found that NbGIS could positively regulate glandular trichome development in Nicotiana benthamiana (tobacco). Our result demonstrated that 35S:NbGIS lines exhibited much higher densities of trichome on leaves, main stems, lateral branches and sepals than WT plants, while NbGIS:RNAi lines had the opposite phenotypes. Furthermore, our results also showed that NbGIS was required in response to GA signal to control glandular trichome initiation in Nicotiana benthamiana. In addition, our results also showed that NbGIS significantly influenced GA accumulation and expressions of marker genes of the GA biosynthesis, might result in the changes of growth and maturation in tobacco. Lastly, our results also showed that NbMYB123-like regulated glandular trichome initiation in tobacco by acting downstream of NbGIS. These findings provide new insights to discover the molecular mechanism by which C2H2 transcriptional factors regulates glandular trichome initiation through GA signaling pathway in tobacco.

RevDate: 2018-10-25
CmpDate: 2018-10-25

Atkinson SD, Bartholomew JL, T Lotan (2018)

Myxozoans: Ancient metazoan parasites find a home in phylum Cnidaria.

Zoology (Jena, Germany), 129:66-68.

Myxozoans are endoparasites with complex life cycles that alternate between invertebrate and vertebrate hosts. Though considered protozoans for over 150 years, they are now recognized as metazoans, given their multicellularity and ultrastructural features. In recognition of synapomorphies and cnidarian-specific genes, myxozoans were placed recently within the phylum Cnidaria. Although they have lost genetic and structural complexity on the path to parasitism, myxozoans have retained characteristic cnidarian cnidocysts, but use them for initiating host infection. Myxozoans represent at least 20% of phylum Cnidaria, but as a result of rapid evolution, extensive diversification and host specialization, they are probably at least as diverse as their free-living relatives. The ability of myxozoans to infect freshwater, marine and terrestrial hosts implies that Cnidaria are no longer constrained to the aquatic environment.

RevDate: 2018-09-23

Chi C, Wang L, Lan W, et al (2018)

PpV, acting via the JNK pathway, represses apoptosis during normal development of Drosophila wing.

Apoptosis : an international journal on programmed cell death, 23(9-10):554-562.

Apoptosis is one of the main fundamental biological processes required for development of multicellular organisms. Inappropriate regulation of apoptosis can lead to severe developmental abnormalities and diseases. Therefore, the control of apoptosis, not only for its activation but also for its inhibition, is critically important during development. In contrast to the extensive studies of apoptosis induction, its inhibitory mechanisms that are even more vital in certain populations of cells actually are very far from being well understood. Here we report an inhibitory role of protein phosphatase V (PpV), a serine/threonine protein phosphatase, in controlling the apoptosis during Drosophila wing development. We observed that inhibition of ppv by RNAi in wing imaginal discs induced ectopic cell death and caspase activation, thus, resulted in a defective adult wing. Moreover, knocking-down ppv triggered the activation of c-Jun N-terminal kinase (JNK) signal, an evolutionarily conserved intracellular signaling that has been implicated to modulate the apoptotic machinery in many biological and experimental systems. Disrupting the JNK signal transduction was adequate to suppress the ppv effects for wing development. Together, we provided the evidence to demonstrate that ppv is required for normal wing development in maintaining the silence of apoptotic signal possibly through JNK pathway.

RevDate: 2018-08-28

Strauss J, Wilkinson C, Vidilaseris K, et al (2018)

A Simple Strategy to Determine the Dependence of Membrane-Bound Pyrophosphatases on K+ as a Cofactor.

Methods in enzymology, 607:131-156.

Membrane-bound pyrophosphatases (mPPases) couple pyrophosphate hydrolysis to H+ and/or Na+ pumping across membranes and are found in all domains of life except for multicellular animals including humans. They are important for development and stress resistance in plants. Furthermore, mPPases play a role in virulence of human pathogens that cause severe diseases such as malaria and African sleeping sickness. Sequence analysis, functional studies, and recently solved crystal structures have contributed to the understanding of the mPPase catalytic cycle. However, several key mechanistic features remain unknown. During evolution, several subgroups of mPPases differing in their pumping specificity and cofactor dependency arose. mPPases are classified into one of five subgroups, usually by sequence analysis. However, classification based solely on sequence has been inaccurate in several instances due to our limited understanding of the molecular mechanism of mPPases. Thus, pumping specificity and cofactor dependency of mPPases require experimental confirmation. Here, we describe a simple method for the determination of K+ dependency in mPPases using a hydrolytic activity assay. By coupling these dependency studies with site-directed mutagenesis, we have begun to build a better understanding of the molecular mechanisms of mPPases. We optimized the assay for thermostable mPPases that are commonly used as model systems in our lab, but the method is equally applicable to mesophilic mPPases with minor modifications.

RevDate: 2018-09-08

Stone R, Portegys T, Mikhailovsky G, et al (2018)

Origins of the Embryo: Self-organization through cybernetic regulation.

Bio Systems pii:S0303-2647(18)30206-5 [Epub ahead of print].

The construction of an embryo from a single cell precursor is a highly complex process. Evolutionary emergence of the first embryos is even more complex, and involves both a transition to multicellularity along with the establishment of developmental mechanisms. We propose that embryogenesis relies on a community of cells conforming to a regulatory model of emergent multicellularity. This model draws together multiple threads in the scientific literature, from complexity theory to cybernetics, and from thermodynamic entropy to artificial life. All of these strands come together to inform a model of goal-oriented regulation for emergent structures in early life. This is an important step in the evolution of early life, as well as the emergence of complex life in the earliest habitats. Our model, called the cybernetic embryo, allows for a systems-level view of the embryogenetic process.

RevDate: 2018-08-20

Hanschen ER, Herron MD, Wiens JJ, et al (2018)

Multicellularity Drives the Evolution of Sexual Traits.

The American naturalist, 192(3):E93-E105.

From the male peacock's tail plumage to the floral displays of flowering plants, traits related to sexual reproduction are often complex and exaggerated. Why has sexual reproduction become so complicated? Why have such exaggerated sexual traits evolved? Early work posited a connection between multicellularity and sexual traits such as anisogamy (i.e., the evolution of small sperm and large eggs). Anisogamy then drives the evolution of other forms of sexual dimorphism. Yet the relationship between multicellularity and the evolution of sexual traits has not been empirically tested. Given their extensive variation in both multicellular complexity and sexual systems, the volvocine green algae offer a tractable system for understanding the interrelationship of multicellular complexity and sex. Here we show that species with greater multicellular complexity have a significantly larger number of derived sexual traits, including anisogamy, internal fertilization, and secondary sexual dimorphism. Our results demonstrate that anisogamy repeatedly evolved from isogamous multicellular ancestors and that anisogamous species are larger and produce larger zygotes than isogamous species. In the volvocine algae, the evolution of multicellularity likely drives the evolution of anisogamy, and anisogamy subsequently drives secondary sexual dimorphism. Multicellularity may set the stage for the overall diversity of sexual complexity throughout the Tree of Life.

RevDate: 2018-08-18

Wang X, Zhu W, Chang P, et al (2018)

Merge and separation of NuA4 and SWR1 complexes control cell fate plasticity in Candida albicans.

Cell discovery, 4:45 pii:43.

Phenotypic plasticity is common in development. Candida albicans, a polymorphic fungal pathogen of humans, possesses the unique ability to achieve rapid and reversible cell fate between unicellular form (yeast) and multicellular form (hypha) in response to environmental cues. The NuA4 histone acetyltransferase activity and Hda1 histone deacetylase activity have been reported to be required for hyphal initiation and maintenance. However, how Hda1 and NuA4 regulate hyphal elongation is not clear. NuA4 histone acetyltransferase and SWR1 chromatin remodeling complexes are conserved from yeast to human, which may have merged together to form a larger TIP60 complex since the origin of metazoan. In this study, we show a dynamic merge and separation of NuA4 and SWR1 complexes in C. albicans. NuA4 and SWR1 merge together in yeast state and separate into two distinct complexes in hyphal state. We demonstrate that acetylation of Eaf1 K173 controls the interaction between the two complexes. The YEATS domain of Yaf9 in C. albicans can recognize an acetyl-lysine of the Eaf1 and mediate the Yaf9-Eaf1 interaction. The reversible acetylation and deacetylation of Eaf1 by Esa1 and Hda1 control the merge and separation of NuA4 and SWR1, and this regulation is triggered by Brg1 recruitment of Hda1 to chromatin in response nutritional signals that sustain hyphal elongation. We have also observed an orchestrated promoter association of Esa1, Hda1, Swr1, and H2A.Z during the reversible yeast-hyphae transitions. This is the first discovery of a regulated merge of the NuA4 and SWR1 complexes that controls cell fate determination and this regulation may be conserved in polymorphic fungi.

RevDate: 2018-10-10

Mattick JS (2018)

The State of Long Non-Coding RNA Biology.

Non-coding RNA, 4(3): pii:ncrna4030017.

Transcriptomic studies have demonstrated that the vast majority of the genomes of mammals and other complex organisms is expressed in highly dynamic and cell-specific patterns to produce large numbers of intergenic, antisense and intronic long non-protein-coding RNAs (lncRNAs). Despite well characterized examples, their scaling with developmental complexity, and many demonstrations of their association with cellular processes, development and diseases, lncRNAs are still to be widely accepted as major players in gene regulation. This may reflect an underappreciation of the extent and precision of the epigenetic control of differentiation and development, where lncRNAs appear to have a central role, likely as organizational and guide molecules: most lncRNAs are nuclear-localized and chromatin-associated, with some involved in the formation of specialized subcellular domains. I suggest that a reassessment of the conceptual framework of genetic information and gene expression in the 4-dimensional ontogeny of spatially organized multicellular organisms is required. Together with this and further studies on their biology, the key challenges now are to determine the structure⁻function relationships of lncRNAs, which may be aided by emerging evidence of their modular structure, the role of RNA editing and modification in enabling epigenetic plasticity, and the role of RNA signaling in transgenerational inheritance of experience.

RevDate: 2018-09-14

Gaouda H, Hamaji T, Yamamoto K, et al (2018)

Exploring the Limits and Causes of Plastid Genome Expansion in Volvocine Green Algae.

Genome biology and evolution, 10(9):2248-2254 pii:5068482.

Plastid genomes are not normally celebrated for being large. But researchers are steadily uncovering algal lineages with big and, in rare cases, enormous plastid DNAs (ptDNAs), such as volvocine green algae. Plastome sequencing of five different volvocine species has revealed some of the largest, most repeat-dense plastomes on record, including that of Volvox carteri (∼525 kb). Volvocine algae have also been used as models for testing leading hypotheses on organelle genome evolution (e.g., the mutational hazard hypothesis), and it has been suggested that ptDNA inflation within this group might be a consequence of low mutation rates and/or the transition from a unicellular to multicellular existence. Here, we further our understanding of plastome size variation in the volvocine line by examining the ptDNA sequences of the colonial species Yamagishiella unicocca and Eudorina sp. NIES-3984 and the multicellular Volvox africanus, which are phylogenetically situated between species with known ptDNA sizes. Although V. africanus is closely related and similar in multicellular organization to V. carteri, its ptDNA was much less inflated than that of V. carteri. Synonymous- and noncoding-site nucleotide substitution rate analyses of these two Volvox ptDNAs suggest that there are drastically different plastid mutation rates operating in the coding versus intergenic regions, supporting the idea that error-prone DNA repair in repeat-rich intergenic spacers is contributing to genome expansion. Our results reinforce the idea that the volvocine line harbors extremes in plastome size but ultimately shed doubt on some of the previously proposed hypotheses for ptDNA inflation within the lineage.

RevDate: 2018-09-10

Lazzari G, Nicolas V, Matsusaki M, et al (2018)

Multicellular spheroid based on a triple co-culture: A novel 3D model to mimic pancreatic tumor complexity.

Acta biomaterialia, 78:296-307.

The preclinical drug screening of pancreatic cancer treatments suffers from the absence of appropriate models capable to reproduce in vitro the heterogeneous tumor microenvironment and its stiff desmoplasia. Driven by this pressing need, we describe in this paper the conception and the characterization of a novel 3D tumor model consisting of a triple co-culture of pancreatic cancer cells (PANC-1), fibroblasts (MRC-5) and endothelial cells (HUVEC), which assembled to form a hetero-type multicellular tumor spheroid (MCTS). By histological analyses and Selective Plain Illumination Microscopy (SPIM) we have monitored the spatial distribution of each cell type and the evolution of the spheroid composition. Results revealed the presence of a core rich in fibroblasts and fibronectin in which endothelial cells were homogeneously distributed. The integration of the three cell types enabled to reproduce in vitro with fidelity the influence of the surrounding environment on the sensitivity of cancer cells to chemotherapy. To our knowledge, this is the first time that a scaffold-free pancreatic cancer spheroid model combining both tumor and multiple stromal components has been designed. It holds the possibility to become an advantageous tool for a pertinent assessment of the efficacy of various therapeutic strategies.

STATEMENT OF SIGNIFICANCE: Pancreatic tumor microenvironment is characterized by abundant fibrosis and aberrant vasculature. Aiming to reproduce in vitro these features, cancer cells have been already co-cultured with fibroblasts or endothelial cells separately but the integration of both these essential components of the pancreatic tumor microenvironment in a unique system, although urgently needed, was still missing. In this study, we successfully integrated cellular and acellular microenvironment components (i.e., fibroblasts, endothelial cells, fibronectin) in a hetero-type scaffold-free multicellular tumor spheroid. This new 3D triple co-culture model closely mimicked the resistance to treatments observed in vivo, resulting in a reduction of cancer cell sensitivity to the anticancer treatment.

RevDate: 2018-08-29

Tverskoi D, Makarenkov V, F Aleskerov (2018)

Modeling functional specialization of a cell colony under different fecundity and viability rates and resource constraint.

PloS one, 13(8):e0201446 pii:PONE-D-17-26391.

The emergence of functional specialization is a core problem in biology. In this work we focus on the emergence of reproductive (germ) and vegetative viability-enhancing (soma) cell functions (or germ-soma specialization). We consider a group of cells and assume that they contribute to two different evolutionary tasks, fecundity and viability. The potential of cells to contribute to fitness components is traded off. As embodied in current models, the curvature of the trade-off between fecundity and viability is concave in small-sized organisms and convex in large-sized multicellular organisms. We present a general mathematical model that explores how the division of labor in a cell colony depends on the trade-off curvatures, a resource constraint and different fecundity and viability rates. Moreover, we consider the case of different trade-off functions for different cells. We describe the set of all possible solutions of the formulated mathematical programming problem and show some interesting examples of optimal specialization strategies found for our objective fitness function. Our results suggest that the transition to specialized organisms can be achieved in several ways. The evolution of Volvocalean green algae is considered to illustrate the application of our model. The proposed model can be generalized to address a number of important biological issues, including the evolution of specialized enzymes and the emergence of complex organs.

RevDate: 2018-08-07

Furumizu C, Hirakawa Y, Bowman JL, et al (2018)

3D Body Evolution: Adding a New Dimension to Colonize the Land.

Current biology : CB, 28(15):R838-R840.

Complex multicellular plant bodies evolved in both generations of land plants. A new study demonstrates that CLAVATA3-like peptides function via conserved receptors in Physcomitrella patens as key molecules for morphological innovation of 3D growth in land plants.

RevDate: 2018-08-31

Li Z, Fu X, Wang Y, et al (2018)

Polycomb-mediated gene silencing by the BAH-EMF1 complex in plants.

Nature genetics, 50(9):1254-1261.

Polycomb proteins implement genome-wide transcriptional repression in multicellular organisms. The evolutionarily conserved Polycomb repressive complex 2 (PRC2) catalyzes histone H3 Lys27 trimethylation (H3K27me3) that is read and effected by Polycomb repressive complex 1 (PRC1) in animals, but the interpretation of this mark remains unclear in plants. Here we report that in the eudicot Arabidopsis thaliana two homologous BAH (Bromo adjacent homology) domain-containing proteins form a plant-specific complex with EMBRYONIC FLOWER 1 (EMF1), and that the BAH-EMF1 complex (BAH-EMF1c) reads and effects the H3K27me3 mark and mediates genome-wide transcriptional repression. Furthermore, in the monocot rice a homolog of the Arabidopsis BAH-domain proteins also binds methylated H3K27 and forms a complex with the rice homolog of EMF1, suggesting that BAH-EMF1c is conserved in flowering plants. Therefore, our results show that the plant-specific BAH-EMF1c fulfills PRC1-like functions in higher plants, suggesting a convergent evolution of PRC1 activity in plants and animals.

RevDate: 2018-10-19
CmpDate: 2018-10-19

Oka M, Y Yoneda (2018)

Importin α: functions as a nuclear transport factor and beyond.

Proceedings of the Japan Academy. Series B, Physical and biological sciences, 94(7):259-274.

Nucleocytoplasmic transport is an essential process in eukaryotes. The molecular mechanisms underlying nuclear transport that involve the nuclear transport receptor, small GTPase Ran, and the nuclear pore complex are highly conserved from yeast to humans. On the other hand, it has become clear that the nuclear transport system diverged during evolution to achieve various physiological functions in multicellular eukaryotes. In this review, we first summarize the molecular mechanisms of nuclear transport and how these were elucidated. Then, we focus on the diverse functions of importin α, which acts not merely an import factor but also as a multi-functional protein contributing to a variety of cellular functions in higher eukaryotes.

RevDate: 2018-08-05

Sharma G, Burrows LL, M Singer (2018)

Diversity and Evolution of Myxobacterial Type IV Pilus Systems.

Frontiers in microbiology, 9:1630.

Type IV pili (T4P) are surface-exposed protein fibers that play key roles in the bacterial life cycle via surface attachment/adhesion, biofilm formation, motility, and development. The order Myxococcales (myxobacteria) are members of the class Deltaproteobacteria and known for their large genome size and complex social behaviors, including gliding motility, fruiting body formation, biofilm production, and prey hunting. Myxococcus xanthus, the best-characterized member of the order, relies on the appropriate expression of 17 type IVa (T4aP) genes organized in a single cluster plus additional genes (distributed throughout the genome) for social motility and development. Here, we compared T4aP genes organization within the myxobacteria to understand their evolutionary origins and diversity. We found that T4aP genes are organized as large clusters in suborder Cystobacterineae, whereas in other two suborders Sorangiineae and Nannocystineae, these genes are dispersed throughout the genome. Based on the genomic organization, the phylogeny of conserved proteins, and synteny studies among 28 myxobacterial and 66 Proteobacterial genomes, we propose an evolutionary model for the origin of myxobacterial T4aP genes independently from other orders in class Deltaproteobacteria. Considering a major role for T4P, this study further proposes the origins and evolution of social motility in myxobacteria and provides a foundation for understanding how complex-behavioral traits, such as gliding motility, multicellular development, etc., might have evolved in this diverse group of complex organisms.

RevDate: 2018-09-07

Bornens M (2018)

Cell polarity: having and making sense of direction-on the evolutionary significance of the primary cilium/centrosome organ in Metazoa.

Open biology, 8(8):.

Cell-autonomous polarity in Metazoans is evolutionarily conserved. I assume that permanent polarity in unicellular eukaryotes is required for cell motion and sensory reception, integration of these two activities being an evolutionarily constrained function. Metazoans are unique in making cohesive multicellular organisms through complete cell divisions. They evolved a primary cilium/centrosome (PC/C) organ, ensuring similar functions to the basal body/flagellum of unicellular eukaryotes, but in different cells, or in the same cell at different moments. The possibility that this innovation contributed to the evolution of individuality, in being instrumental in the early specification of the germ line during development, is further discussed. Then, using the example of highly regenerative organisms like planarians, which have lost PC/C organ in dividing cells, I discuss the possibility that part of the remodelling necessary to reach a new higher-level unit of selection in multi-cellular organisms has been triggered by conflicts among individual cell polarities to reach an organismic polarity. Finally, I briefly consider organisms with a sensorimotor organ like the brain that requires exceedingly elongated polarized cells for its activity. I conclude that beyond critical consequences for embryo development, the conservation of cell-autonomous polarity in Metazoans had far-reaching implications for the evolution of individuality.

RevDate: 2018-09-21

Stencel A, DM Wloch-Salamon (2018)

Some theoretical insights into the hologenome theory of evolution and the role of microbes in speciation.

Theory in biosciences = Theorie in den Biowissenschaften pii:10.1007/s12064-018-0268-3 [Epub ahead of print].

Research on symbiotic communities (microbiomes) of multicellular organisms seems to be changing our understanding of how species of plants and animals have evolved over millions of years. The quintessence of these discoveries is the emergence of the hologenome theory of evolution, founded on the concept that a holobiont (a host along with all of its associated symbiotic microorganisms) acts a single unit of selection in the process of evolution. Although the hologenome theory has become very popular among certain scientific circles, its principles are still being debated. In this paper, we argue, firstly, that only a very small number of symbiotic microorganisms are sufficiently integrated into multicellular organisms to act in concert with them as units of selection, thus rendering claims that holobionts are units of selection invalid. Secondly, even though holobionts are not units of selection, they can still constitute genuine units from an evolutionary perspective, provided we accept certain constraints: mainly, they should be considered units of co-operation. Thirdly, we propose a reconciliation of the role of symbiotic microorganisms with the theory of speciation through the use of a developed framework. Mainly, we will argue that, in order to understand the role of microorganisms in the speciation of multicellular organisms, it is not necessary to consider holobionts units of selection; it is sufficient to consider them units of co-operation.

RevDate: 2018-08-03

Chen H, Zhang SD, Chen L, et al (2018)

Efficient Genome Editing of Magnetospirillum magneticum AMB-1 by CRISPR-Cas9 System for Analyzing Magnetotactic Behavior.

Frontiers in microbiology, 9:1569.

Magnetotactic bacteria (MTB) are a diverse group of microorganisms capable of using geomagnetic fields for navigation. This magnetotactic behavior can help microorganisms move toward favorable habitats for optimal growth and reproduction. A comprehensive understanding of the magnetotactic mechanism at molecular levels requires highly efficient genomic editing tools, which remain underdeveloped in MTB. Here, we adapted an engineered CRISPR-Cas9 system for efficient inactivation of genes in a widely used MTB model strain, Magnetospirillum magneticum AMB-1. By combining a nuclease-deficient Cas9 (dCas9) and single-guide RNA (sgRNA), a CRISPR interference system was successfully developed to repress amb0994 expression. Furthermore, we constructed an in-frame deletion mutant of amb0994 by developing a CRISPR-Cas9 system. This mutant produces normal magnetosomes; however, its response to abrupt magnetic field reversals is faster than wild-type strain. This behavioral difference is probably a consequence of altered flagella function, as suggested with our dynamics simulation study by modeling M. magneticum AMB-1 cell as an ellipsoid. These data indicate that, Amb0994 is involved in the cellular response to magnetic torque changes via controlling flagella. In summary, this study, besides contributing to a better understanding of magnetotaxis mechanism, demonstrated the CRISPR-(d)Cas9 system as a useful genetic tool for efficient genome editing in MTB.

RevDate: 2018-08-02

Benítez M, Hernández-Hernández V, Newman SA, et al (2018)

Dynamical Patterning Modules, Biogeneric Materials, and the Evolution of Multicellular Plants.

Frontiers in plant science, 9:871.

Comparative analyses of developmental processes across a broad spectrum of organisms are required to fully understand the mechanisms responsible for the major evolutionary transitions among eukaryotic photosynthetic lineages (defined here as the polyphyletic algae and the monophyletic land plants). The concepts of dynamical patterning modules (DPMs) and biogeneric materials provide a framework for studying developmental processes in the context of such comparative analyses. In the context of multicellularity, DPMs are defined as sets of conserved gene products and molecular networks, in conjunction with the physical morphogenetic and patterning processes they mobilize. A biogeneric material is defined as mesoscale matter with predictable morphogenetic capabilities that arise from complex cellular conglomerates. Using these concepts, we outline some of the main events and transitions in plant evolution, and describe the DPMs and biogeneric properties associated with and responsible for these transitions. We identify four primary DPMs that played critical roles in the evolution of multicellularity (i.e., the DPMs responsible for cell-to-cell adhesion, identifying the future cell wall, cell differentiation, and cell polarity). Three important conclusions emerge from a broad phyletic comparison: (1) DPMs have been achieved in different ways, even within the same clade (e.g., phycoplastic cell division in the Chlorophyta and phragmoplastic cell division in the Streptophyta), (2) DPMs had their origins in the co-option of molecular species present in the unicellular ancestors of multicellular plants, and (3) symplastic transport mediated by intercellular connections, particularly plasmodesmata, was critical for the evolution of complex multicellularity in plants.

RevDate: 2018-08-23

Stewart AD, WR Rice (2018)

Arrest of sex-specific adaptation during the evolution of sexual dimorphism in Drosophila.

Nature ecology & evolution, 2(9):1507-1513.

Sexually antagonistic selection arises when a trait expressed in both sexes (a shared trait) is selected towards different, sex-specific optima. Sex-discordant selection causes different alleles to be favoured in each sex (intralocus sexual conflict). A key parameter responsible for generating this conflict is the intersexual genetic correlation (rMF), which determines the degree to which heritable genetic variation for the shared trait produces a similar phenotype in both sexes. A strong, positive rMF interferes with adaptation when there is sex-discordant selection. In principle, the rMF can evolve in response to sex-discordant selection: the faster it declines, the faster the resolution of intralocus sexual conflict. Here, we use Drosophila melanogaster to quantify the time scale over which a strong, positive rMF impedes a response to sex-discordant selection for a canonical quantitative trait (body size) with an exceptionally long (250 generations) selection experiment for a complex multicellular organism. We found that, compared with rapid and substantial evolution under sex-concordant selection, a high rMF arrested sex-specific adaptation for 100 generations in females and a minimum of 250 generations in males. Our study demonstrates that a high rMF can lead to a protracted period of adaptive stalemate during the evolution of sexual dimorphism.

RevDate: 2018-08-19

Waldron FM, Stone GN, DJ Obbard (2018)

Metagenomic sequencing suggests a diversity of RNA interference-like responses to viruses across multicellular eukaryotes.

PLoS genetics, 14(7):e1007533 pii:PGENETICS-D-18-00517.

RNA interference (RNAi)-related pathways target viruses and transposable element (TE) transcripts in plants, fungi, and ecdysozoans (nematodes and arthropods), giving protection against infection and transmission. In each case, this produces abundant TE and virus-derived 20-30nt small RNAs, which provide a characteristic signature of RNAi-mediated defence. The broad phylogenetic distribution of the Argonaute and Dicer-family genes that mediate these pathways suggests that defensive RNAi is ancient, and probably shared by most animal (metazoan) phyla. Indeed, while vertebrates had been thought an exception, it has recently been argued that mammals also possess an antiviral RNAi pathway, although its immunological relevance is currently uncertain and the viral small RNAs (viRNAs) are not easily detectable. Here we use a metagenomic approach to test for the presence of viRNAs in five species from divergent animal phyla (Porifera, Cnidaria, Echinodermata, Mollusca, and Annelida), and in a brown alga-which represents an independent origin of multicellularity from plants, fungi, and animals. We use metagenomic RNA sequencing to identify around 80 virus-like contigs in these lineages, and small RNA sequencing to identify viRNAs derived from those viruses. We identified 21U small RNAs derived from an RNA virus in the brown alga, reminiscent of plant and fungal viRNAs, despite the deep divergence between these lineages. However, contrary to our expectations, we were unable to identify canonical (i.e. Drosophila- or nematode-like) viRNAs in any of the animals, despite the widespread presence of abundant micro-RNAs, and somatic transposon-derived piwi-interacting RNAs. We did identify a distinctive group of small RNAs derived from RNA viruses in the mollusc. However, unlike ecdysozoan viRNAs, these had a piRNA-like length distribution but lacked key signatures of piRNA biogenesis. We also identified primary piRNAs derived from putatively endogenous copies of DNA viruses in the cnidarian and the echinoderm, and an endogenous RNA virus in the mollusc. The absence of canonical virus-derived small RNAs from our samples may suggest that the majority of animal phyla lack an antiviral RNAi response. Alternatively, these phyla could possess an antiviral RNAi response resembling that reported for vertebrates, with cryptic viRNAs not detectable through simple metagenomic sequencing of wild-type individuals. In either case, our findings show that the antiviral RNAi responses of arthropods and nematodes, which are highly divergent from each other and from that of plants and fungi, are also highly diverged from the most likely ancestral metazoan state.

RevDate: 2018-08-20

Campbell FC, Loughrey MB, McClements J, et al (2018)

Mechanistic Insights into Colorectal Cancer Phenomics from Fundamental and Organotypic Model Studies.

The American journal of pathology, 188(9):1936-1948.

Colorectal cancer (CRC) diagnosis and prognostic stratification are based on histopathologic assessment of cell or nuclear pleomorphism, aberrant mitotic figures, altered glandular architecture, and other phenomic abnormalities. This complexity is driven by oncogenic perturbation of tightly coordinated spatiotemporal signaling to disrupt multiple scales of tissue organization. This review clarifies molecular and cellular mechanisms underlying common CRC histologic features and helps understand how the CRC genome controls core aspects of tumor aggressiveness. It further explores a spatiotemporal framework for CRC phenomics based on regulation of living cells in fundamental and organotypic model systems. The review also discusses tissue homeostasis, considers distinct classes of oncogenic perturbations, and evolution of cellular or multicellular cancer phenotypes. It further explores the molecular controls of cribriform, micropapillary, and high-grade CRC morphology in organotypic culture models and assesses relevant translational studies. In addition, the review delves into complexities of morphologic plasticity whereby a single molecular signature generates heterogeneous cancer phenotypes, and, conversely, morphologically homogeneous tumors show substantive molecular diversity. Principles outlined may aid mechanistic interpretation of omics data in a setting of cancer pathology, provide insight into CRC consensus molecular subtypes, and better define principles for CRC prognostic stratification.

RevDate: 2018-10-28

Leong SP, Aktipis A, C Maley (2018)

Cancer initiation and progression within the cancer microenvironment.

Clinical & experimental metastasis pii:10.1007/s10585-018-9921-y [Epub ahead of print].

Within the cancer microenvironment, the growth and proliferation of cancer cells in the primary site as well as in the metastatic site represent a global biological phenomenon. To understand the growth, proliferation and progression of cancer either by local expansion and/or metastasis, it is important to understand the cancer microenvironment and host response to cancer growth. Melanoma is an excellent model to study the interaction of cancer initiation and growth in relationship to its microenvironment. Social evolution with cooperative cellular groups within an organism is what gives rise to multicellularity in the first place. Cancer cells evolve to exploit their cellular environment. The foundations of multicellular cooperation break down in cancer because those cells that misbehave have an evolutionary advantage over their normally behaving neighbors. It is important to classify evolutionary and ecological aspects of cancer growth, thus, data for cancer growth and outcomes need to be collected to define these parameters so that accurate predictions of how cancer cells may proliferate and metastasize can be developed.

RevDate: 2018-10-10

Liao Z, Kjellin J, Hoeppner MP, et al (2018)

Global characterization of the Dicer-like protein DrnB roles in miRNA biogenesis in the social amoeba Dictyostelium discoideum.

RNA biology, 15(7):937-954.

Micro (mi)RNAs regulate gene expression in many eukaryotic organisms where they control diverse biological processes. Their biogenesis, from primary transcripts to mature miRNAs, have been extensively characterized in animals and plants, showing distinct differences between these phylogenetically distant groups of organisms. However, comparably little is known about miRNA biogenesis in organisms whose evolutionary position is placed in between plants and animals and/or in unicellular organisms. Here, we investigate miRNA maturation in the unicellular amoeba Dictyostelium discoideum, belonging to Amoebozoa, which branched out after plants but before animals. High-throughput sequencing of small RNAs and poly(A)-selected RNAs demonstrated that the Dicer-like protein DrnB is required, and essentially specific, for global miRNA maturation in D. discoideum. Our RNA-seq data also showed that longer miRNA transcripts, generally preceded by a T-rich putative promoter motif, accumulate in a drnB knock-out strain. For two model miRNAs we defined the transcriptional start sites (TSSs) of primary (pri)-miRNAs and showed that they carry the RNA polymerase II specific m7G-cap. The generation of the 3'-ends of these pri-miRNAs differs, with pri-mir-1177 reading into the downstream gene, and pri-mir-1176 displaying a distinct end. This 3´-end is processed to shorter intermediates, stabilized in DrnB-depleted cells, of which some carry a short oligo(A)-tail. Furthermore, we identified 10 new miRNAs, all DrnB dependent and developmentally regulated. Thus, the miRNA machinery in D. discoideum shares features with both plants and animals, which is in agreement with its evolutionary position and perhaps also an adaptation to its complex lifestyle: unicellular growth and multicellular development.

RevDate: 2018-07-16

Zhao J, Yuan S, Gao B, et al (2018)

Molecular diversity of fungal inhibitor cystine knot peptides evolved by domain repeat and fusion.

FEMS microbiology letters, 365(15):.

Peptides with the inhibitor cystine knot (ICK) motif are extensively present in animals and plants where they exert a diversity of biological functions. However, few studies have been undertaken on this class of peptides in fungi. In this work, we identify a total of 386 fungal ICK peptides and proteins containing this motif by computational data mining of fungal genome databases, which exhibit 14 different exon-intron structures. According to their domain architectures, these proteins are classified into three distinct structural types, including single domains, tandem repeat domains and fusion domains, in which six families belonging to single or tandem repeat domains show remarkable sequence similarity to those from animals and plants, suggesting their orthologous relationship. Extremely high molecular diversity in fungal ICKs might be attributable to different genetic mechanisms, such as gene/domain duplication and fusion. This work not only enlarges the number of ICK peptides in multicellular organisms, but also uncovers their complex evolutionary history in a specific lineage.

RevDate: 2018-08-23
CmpDate: 2018-08-23

Pennisi E (2018)

Is cancer a breakdown of multicellularity?.

Science (New York, N.Y.), 360(6396):1391.

RevDate: 2018-07-18

Sebé-Pedrós A, Chomsky E, Pang K, et al (2018)

Early metazoan cell type diversity and the evolution of multicellular gene regulation.

Nature ecology & evolution, 2(7):1176-1188.

A hallmark of metazoan evolution is the emergence of genomic mechanisms that implement cell-type-specific functions. However, the evolution of metazoan cell types and their underlying gene regulatory programmes remains largely uncharacterized. Here, we use whole-organism single-cell RNA sequencing to map cell-type-specific transcription in Porifera (sponges), Ctenophora (comb jellies) and Placozoa species. We describe the repertoires of cell types in these non-bilaterian animals, uncovering diverse instances of previously unknown molecular signatures, such as multiple types of peptidergic cells in Placozoa. Analysis of the regulatory programmes of these cell types reveals variable levels of complexity. In placozoans and poriferans, sequence motifs in the promoters are predictive of cell-type-specific programmes. By contrast, the generation of a higher diversity of cell types in ctenophores is associated with lower specificity of promoter sequences and the existence of distal regulatory elements. Our findings demonstrate that metazoan cell types can be defined by networks of transcription factors and proximal promoters, and indicate that further genome regulatory complexity may be required for more diverse cell type repertoires.

RevDate: 2018-10-10
CmpDate: 2018-10-10

Pashov A, Hernandez Puente CV, Ibrahim SM, et al (2018)

Thinking Cancer.

Monoclonal antibodies in immunodiagnosis and immunotherapy, 37(3):117-125.

Evolutionary theories are necessarily invoked for understanding cancer development at the level of species, at the level of cells and tissues, and for developing effective therapies. It is crucial to view cancer in a Darwinian light, where the differential survival of individual cells is based on heritable variations. In the process of this somatic evolution, multicellularity controls are overridden by cancer cells, which become increasingly autonomous. Ecological epigenetics also helps understand how rogue cells that have basically the same DNA as their normal cell counterpart overcome the tissue homeostasis. As we struggle to wrap our minds around the complexity of these phenomena, we apply often times anthropomorphic terms, such as subversion, hijacking, or hacking, to describe especially the most complex among them-the interaction of tumors with the immune system. In this commentary we highlight examples of the anthropomorphic thinking of cancer and try to put into context the relative meaning of terms and the mechanisms that are oftentimes invoked to justify those terms.

RevDate: 2018-06-25

Funayama N (2018)

The cellular and molecular bases of the sponge stem cell systems underlying reproduction, homeostasis and regeneration.

The International journal of developmental biology, 62(6-7-8):513-525.

The evolution of multicellular organisms is generally thought (and seems likely) to have been accompanied by the evolution of a stem cell system. Sponges, some of the early-evolved metazoans, have totipotent/pluripotent stem cells. Thus, uncovering the cellular and molecular bases of the sponge stem cells will not only be crucial for understanding the ancestral gene repertoire of animal stem cells, but will also give us clues to understanding the evolution of molecular mechanisms for maintaining multipotency (pluripotency) and differentiation ability during animal evolution. Sponges (Porifera) are a large phylum that includes an enormous number of species, whose cellular compositions and life cycles show striking variations. In the last decade, methodologies for molecular studies and sequencing resources have dramatically advanced and made it possible to clearly define stem cells in sponges in cellular and molecular terms. In this review, together with recent studies of sponges in various classes, the following issues will be discussed: i) recent findings that revealed that the previously proposed model that "archeocytes and choanocytes are the two types of stem cells" originally based on work in demosponges can be applied as a unified view of the stem cell system in sponges that have various cellular organizations, ii) the fact that sponge cells are more plastic than previously thought, as shown by recent studies of sponge regeneration both from dissociated cells and upon injury, and iii) the importance of transdifferentiation in sponge stem cell systems and regeneration.

RevDate: 2018-06-24

Fiore APZP, Ribeiro PF, A Bruni-Cardoso (2018)

Sleeping Beauty and the Microenvironment Enchantment: Microenvironmental Regulation of the Proliferation-Quiescence Decision in Normal Tissues and in Cancer Development.

Frontiers in cell and developmental biology, 6:59.

Cells from prokaryota to the more complex metazoans cease proliferating at some point in their lives and enter a reversible, proliferative-dormant state termed quiescence. The appearance of quiescence in the course of evolution was essential to the acquisition of multicellular specialization and compartmentalization and is also a central aspect of tissue function and homeostasis. But what makes a cell cease proliferating even in the presence of nutrients, growth factors, and mitogens? And what makes some cells "wake up" when they should not, as is the case in cancer? Here, we summarize and discuss evidence showing how microenvironmental cues such as those originating from metabolism, extracellular matrix (ECM) composition and arrangement, neighboring cells and tissue architecture control the cellular proliferation-quiescence decision, and how this complex regulation is corrupted in cancer.

RevDate: 2018-09-28

Dunning Hotopp JC (2018)

Grafting or pruning in the animal tree: lateral gene transfer and gene loss?.

BMC genomics, 19(1):470 pii:10.1186/s12864-018-4832-5.

BACKGROUND: Lateral gene transfer (LGT), also known as horizontal gene transfer, into multicellular eukaryotes with differentiated tissues, particularly gonads, continues to be met with skepticism by many prominent evolutionary and genomic biologists. A detailed examination of 26 animal genomes identified putative LGTs in invertebrate and vertebrate genomes, concluding that there are fewer predicted LGTs in vertebrates/chordates than invertebrates, but there is still evidence of LGT into chordates, including humans. More recently, a reanalysis of a subset of these putative LGTs into vertebrates concluded that there is not horizontal gene transfer in the human genome. One of the genes in dispute is an N-acyl-aromatic-L-amino acid amidohydrolase (ENSG00000132744), which encodes ACY3. This gene was initially identified as a putative bacteria-chordate LGT but was later debunked as it has a significant BLAST match to a more recently deposited genome of Saccoglossus kowalevskii, a flatworm, Metazoan, and hemichordate.

RESULTS: Using BLAST searches, HMM searches, and phylogenetics to assess the evidence for LGT, gene loss, and rate variation in ACY3/ASPA homologues, the most parsimonious explanation for the distribution of ACY3/ASPA genes in eukaryotes involves both gene loss and bacteria-animal LGT, albeit LGT that occurred hundreds of millions of years ago prior to the divergence of gnathostomes.

CONCLUSIONS: ACY3/ASPA is most likely a bacteria-animal LGT. LGTs at these time scales in the ancestors of humans are not unexpected given the many known, well-characterized, and adaptive LGTs from bacteria to insects and nematodes.

RevDate: 2018-10-09
CmpDate: 2018-10-09

Kang C, Aguilar B, I Shmulevich (2018)

Emergence of diversity in homogeneous coupled Boolean networks.

Physical review. E, 97(5-1):052415.

The origin of multicellularity in metazoa is one of the fundamental questions of evolutionary biology. We have modeled the generic behaviors of gene regulatory networks in isogenic cells as stochastic nonlinear dynamical systems-coupled Boolean networks with perturbation. Model simulations under a variety of dynamical regimes suggest that the central characteristic of multicellularity, permanent spatial differentiation (diversification), indeed can arise. Additionally, we observe that diversification is more likely to occur near the critical regime of Lyapunov stability.

RevDate: 2018-07-10
CmpDate: 2018-07-10

Jacobeen S, Graba EC, Brandys CG, et al (2018)

Geometry, packing, and evolutionary paths to increased multicellular size.

Physical review. E, 97(5-1):050401.

The evolutionary transition to multicellularity transformed life on earth, heralding the evolution of large, complex organisms. Recent experiments demonstrated that laboratory-evolved multicellular "snowflake yeast" readily overcome the physical barriers that limit cluster size by modifying cellular geometry [Jacobeen et al., Nat. Phys. 14, 286 (2018)10.1038/s41567-017-0002-y]. However, it is unclear why this route to large size is observed, rather than an evolved increase in intercellular bond strength. Here, we use a geometric model of the snowflake yeast growth form to examine the geometric efficiency of increasing size by modifying geometry and bond strength. We find that changing geometry is a far more efficient route to large size than evolving increased intercellular adhesion. In fact, increasing cellular aspect ratio is on average ∼13 times more effective than increasing bond strength at increasing the number of cells in a cluster. Modifying other geometric parameters, such as the geometric arrangement of mother and daughter cells, also had larger effects on cluster size than increasing bond strength. Simulations reveal that as cells reproduce, internal stress in the cluster increases rapidly; thus, increasing bond strength provides diminishing returns in cluster size. Conversely, as cells become more elongated, cellular packing density within the cluster decreases, which substantially decreases the rate of internal stress accumulation. This suggests that geometrically imposed physical constraints may have been a key early selective force guiding the emergence of multicellular complexity.

RevDate: 2018-09-07
CmpDate: 2018-09-07

Smith CCR, Tittes S, Mendieta JP, et al (2018)

Genetics of alternative splicing evolution during sunflower domestication.

Proceedings of the National Academy of Sciences of the United States of America, 115(26):6768-6773.

Alternative splicing enables organisms to produce the diversity of proteins necessary for multicellular life by using relatively few protein-coding genes. Although differences in splicing have been identified among divergent taxa, the shorter-term evolution of splicing is understudied. The origins of novel splice forms, and the contributions of alternative splicing to major evolutionary transitions, are largely unknown. This study used transcriptomes of wild and domesticated sunflowers to examine splice differentiation and regulation during domestication. We identified substantial splicing divergence between wild and domesticated sunflowers, mainly in the form of intron retention. Transcripts with divergent splicing were enriched for seed-development functions, suggesting that artificial selection impacted splicing patterns. Mapping of quantitative trait loci (QTLs) associated with 144 differential splicing cases revealed primarily trans-acting variation affecting splicing patterns. A large proportion of identified QTLs contain known spliceosome proteins and are associated with splicing variation in multiple genes. Examining a broader set of wild and domesticated sunflower genotypes revealed that most differential splicing patterns in domesticated sunflowers likely arose from standing variation in wild Helianthus annuus and gained frequency during the domestication process. However, several domesticate-associated splicing patterns appear to be introgressed from other Helianthus species. These results suggest that sunflower domestication involved selection on pleiotropic regulatory alleles. More generally, our findings indicate that substantial differences in isoform abundances arose rapidly during a recent evolutionary transition and appear to contribute to adaptation and population divergence.

RevDate: 2018-10-08

Leys SP, AS Kahn (2018)

Oxygen and the Energetic Requirements of the First Multicellular Animals.

Integrative and comparative biology, 58(4):666-676.

The appearance of multicellular animals during the Neoproterozoic Era is thought to have coincided with oxygenation of the oceans; however, we know little about the physiological needs of early animals or about the environment they lived in. Approaches using biomarkers, fossils, and phylogenomics have provided some hints of the types of animals that may have been present during the Neoproterozoic, but extant animals are our best modern links to the theoretical ancestors of animals. Neoproterozoic oceans were low energy habitats, with low oxygen concentrations and sparse food availability for the first animals. We examined tolerance of extant ctenophores and sponges-as representatives of extant lineages of the earliest known metazoan groups-to feeding and oxygen use. A review of respiration rates in species across several phyla suggests that suspension feeders in general have a wide range of metabolic rates, but sponges have some of the highest of invertebrates and ctenophores some of the lowest. Our own studies on the metabolism of two groups of deep water sponges show that sponges have different approaches to deal with the cost of filtration and low food availability. We also confirmed that deep water sponges tolerate periods of hypoxia, but at the cost of filtration, indicating that normal feeding is energetically expensive. Predictions of oxygen levels in the Neoproterozoic suggest the last common ancestor of multicellular animals was unlikely to have filtered like modern sponges. Getting enough food at low oxygen would have been a more important driver of the evolution of early body plans.

RevDate: 2018-08-02

Miller PW, Pokutta S, Mitchell JM, et al (2018)

Analysis of a vinculin homolog in a sponge (phylum Porifera) reveals that vertebrate-like cell adhesions emerged early in animal evolution.

The Journal of biological chemistry, 293(30):11674-11686.

The evolution of cell-adhesion mechanisms in animals facilitated the assembly of organized multicellular tissues. Studies in traditional animal models have revealed two predominant adhesion structures, the adherens junction (AJ) and focal adhesions (FAs), which are involved in the attachment of neighboring cells to each other and to the secreted extracellular matrix (ECM), respectively. The AJ (containing cadherins and catenins) and FAs (comprising integrins, talin, and paxillin) differ in protein composition, but both junctions contain the actin-binding protein vinculin. The near ubiquity of these structures in animals suggests that AJ and FAs evolved early, possibly coincident with multicellularity. However, a challenge to this perspective is that previous studies of sponges-a divergent animal lineage-indicate that their tissues are organized primarily by an alternative, sponge-specific cell-adhesion mechanism called "aggregation factor." In this study, we examined the structure, biochemical properties, and tissue localization of a vinculin ortholog in the sponge Oscarella pearsei (Op). Our results indicate that Op vinculin localizes to both cell-cell and cell-ECM contacts and has biochemical and structural properties similar to those of vertebrate vinculin. We propose that Op vinculin played a role in cell adhesion and tissue organization in the last common ancestor of sponges and other animals. These findings provide compelling evidence that sponge tissues are indeed organized like epithelia in other animals and support the notion that AJ- and FA-like structures extend to the earliest periods of animal evolution.

RevDate: 2018-10-24
CmpDate: 2018-10-24

Ye AY, Dou Y, Yang X, et al (2018)

A model for postzygotic mosaicisms quantifies the allele fraction drift, mutation rate, and contribution to de novo mutations.

Genome research, 28(7):943-951.

The allele fraction (AF) distribution, occurrence rate, and evolutionary contribution of postzygotic single-nucleotide mosaicisms (pSNMs) remain largely unknown. In this study, we developed a mathematical model to describe the accumulation and AF drift of pSNMs during the development of multicellular organisms. By applying the model, we quantitatively analyzed two large-scale data sets of pSNMs identified from human genomes. We found that the postzygotic mutation rate per cell division during early embryogenesis, especially during the first cell division, was higher than the average mutation rate in either male or female gametes. We estimated that the stochastic cell death rate per cell cleavage during human embryogenesis was ∼5%, and parental pSNMs occurring during the first three cell divisions contributed to ∼10% of the de novo mutations observed in children. We further demonstrated that the genomic profiles of pSNMs could be used to measure the divergence distance between tissues. Our results highlight the importance of pSNMs in estimating recurrence risk and clarified the quantitative relationship between postzygotic and de novo mutations.

RevDate: 2018-06-17

Grüter C, Jongepier E, S Foitzik (2018)

Insect societies fight back: the evolution of defensive traits against social parasites.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 373(1751):.

Insect societies face many social parasites that exploit their altruistic behaviours or their resources. Due to the fitness costs these social parasites incur, hosts have evolved various behavioural, chemical, architectural and morphological defence traits. Similar to bacteria infecting multicellular hosts, social parasites have to successfully go through several steps to exploit their hosts. Here, we review how social insects try to interrupt this sequence of events. They can avoid parasite contact by choosing to nest in parasite-free locales or evade attacks by adapting their colony structure. Once social parasites attack, hosts attempt to detect them, which can be facilitated by adjustments in colony odour. If social parasites enter the nest, hosts can either aggressively defend their colony or take their young and flee. Nest structures are often shaped to prevent social parasite invasion or to safeguard host resources. Finally, if social parasites successfully establish themselves in host nests, hosts can rebel by killing the parasite brood or by reproducing in the parasites' presence. Hosts of social parasites can therefore develop multiple traits, leading to the evolution of complex defence portfolios of co-dependent traits. Social parasites can respond to these multi-level defences with counter-adaptations, potentially leading to geographical mosaics of coevolution.This article is part of the Theo Murphy meeting issue 'Evolution of pathogen and parasite avoidance behaviours'.

RevDate: 2018-06-03

Mustafin RN, EK Khusnutdinova (2018)

[Epigenetic hypothesis of the role of peptides in aging.].

Advances in gerontology = Uspekhi gerontologii, 31(1):10-20.

In regulation of gene expression in the ontogenesis of multicellular eukaryotes, in addition to transcription factors, an important role is played by epigenetic factors that control the release of genetic information in each cell division. Many binding sites for the transcription factors were derived from transposons sequences. Mobile elements are also important sources of non-coding RNA. Due to this, transposons have an indirect effect on gene expression and genome methylation. In evolution, transposons serve as important sources for the origin of new protein and proteins domains. A number of studies have identified that long non-coding RNAs and microRNAs can be translated into functional peptides. At the same time, transposons remain active in the hypothalamus of adult humans, which is consistent with the transcription of non-coding RNAs in these structures, which may be key in aging.

RevDate: 2018-06-01

Sebé-Pedrós A, Saudemont B, Chomsky E, et al (2018)

Cnidarian Cell Type Diversity and Regulation Revealed by Whole-Organism Single-Cell RNA-Seq.

Cell, 173(6):1520-1534.e20.

The emergence and diversification of cell types is a leading factor in animal evolution. So far, systematic characterization of the gene regulatory programs associated with cell type specificity was limited to few cell types and few species. Here, we perform whole-organism single-cell transcriptomics to map adult and larval cell types in the cnidarian Nematostella vectensis, a non-bilaterian animal with complex tissue-level body-plan organization. We uncover eight broad cell classes in Nematostella, including neurons, cnidocytes, and digestive cells. Each class comprises different subtypes defined by the expression of multiple specific markers. In particular, we characterize a surprisingly diverse repertoire of neurons, which comparative analysis suggests are the result of lineage-specific diversification. By integrating transcription factor expression, chromatin profiling, and sequence motif analysis, we identify the regulatory codes that underlie Nematostella cell-specific expression. Our study reveals cnidarian cell type complexity and provides insights into the evolution of animal cell-specific genomic regulation.

RevDate: 2018-09-13
CmpDate: 2018-09-13

Toda S, Blauch LR, Tang SKY, et al (2018)

Programming self-organizing multicellular structures with synthetic cell-cell signaling.

Science (New York, N.Y.), 361(6398):156-162.

A common theme in the self-organization of multicellular tissues is the use of cell-cell signaling networks to induce morphological changes. We used the modular synNotch juxtacrine signaling platform to engineer artificial genetic programs in which specific cell-cell contacts induced changes in cadherin cell adhesion. Despite their simplicity, these minimal intercellular programs were sufficient to yield assemblies with hallmarks of natural developmental systems: robust self-organization into multidomain structures, well-choreographed sequential assembly, cell type divergence, symmetry breaking, and the capacity for regeneration upon injury. The ability of these networks to drive complex structure formation illustrates the power of interlinking cell signaling with cell sorting: Signal-induced spatial reorganization alters the local signals received by each cell, resulting in iterative cycles of cell fate branching. These results provide insights into the evolution of multicellularity and demonstrate the potential to engineer customized self-organizing tissues or materials.

RevDate: 2018-05-31

Schaefke B, Sun W, Li YS, et al (2018)

The evolution of posttranscriptional regulation.

Wiley interdisciplinary reviews. RNA [Epub ahead of print].

"DNA makes RNA makes protein." After transcription, mRNAs undergo a series of intertwining processes to be finally translated into functional proteins. The "posttranscriptional" regulation (PTR) provides cells an extended option to fine-tune their proteomes. To meet the demands of complex organism development and the appropriate response to environmental stimuli, every step in these processes needs to be finely regulated. Moreover, changes in these regulatory processes are important driving forces underlying the evolution of phenotypic differences across different species. The major PTR mechanisms discussed in this review include the regulation of splicing, polyadenylation, decay, and translation. For alternative splicing and polyadenylation, we mainly discuss their evolutionary dynamics and the genetic changes underlying the regulatory differences in cis-elements versus trans-factors. For mRNA decay and translation, which, together with transcription, determine the cellular RNA or protein abundance, we focus our discussion on how their divergence coordinates with transcriptional changes to shape the evolution of gene expression. Then to highlight the importance of PTR in the evolution of higher complexity, we focus on their roles in two major phenomena during eukaryotic evolution: the evolution of multicellularity and the division of labor between different cell types and tissues; and the emergence of diverse, often highly specialized individual phenotypes, especially those concerning behavior in eusocial insects. This article is categorized under: RNA Evolution and Genomics > RNA and Ribonucleoprotein Evolution Translation > Translation Regulation RNA Processing > Splicing Regulation/Alternative Splicing.

RevDate: 2018-10-08

Paps J (2018)

What Makes an Animal? The Molecular Quest for the Origin of the Animal Kingdom.

Integrative and comparative biology, 58(4):654-665.

What makes an animal? To find the answer we need to integrate data from disciplines such as phylogenetics, paleontology, ecology, development, anatomy, and physiology, as well as molecular biology and genomics. Knowledge of which groups branched before and after the origin of animals is essential. Recent advances in molecular phylogenetics, together with the discovery of new eukaryotic lineages, have drawn a new picture of the ancestry of animals. The nature of the early diverging animal lineages and the timing of the transition are in a state of flux. Various factors have been linked to this striking transition to multicellularity, including changes in environmental conditions and the ecological interactions between unicellular eukaryotes. The current wealth of genomic data has also shed new light on this question. The analysis of the genome of various close relatives of animals has revealed the importance that recycling of ancient genes into metazoan biological functions played into animal origins. A recent study reconstructing the genome of the last common ancestor of extant animals has unveiled an unprecedented emergence of new genes, highlighting the role of genomic novelty in the origin of metazoans.

RevDate: 2018-06-01

Pinhal D, Bovolenta LA, Moxon S, et al (2018)

Genome-wide microRNA screening in Nile tilapia reveals pervasive isomiRs' transcription, sex-biased arm switching and increasing complexity of expression throughout development.

Scientific reports, 8(1):8248 pii:10.1038/s41598-018-26607-x.

MicroRNAs (miRNAs) are key regulators of gene expression in multicellular organisms. The elucidation of miRNA function and evolution depends on the identification and characterization of miRNA repertoire of strategic organisms, as the fast-evolving cichlid fishes. Using RNA-seq and comparative genomics we carried out an in-depth report of miRNAs in Nile tilapia (Oreochromis niloticus), an emergent model organism to investigate evo-devo mechanisms. Five hundred known miRNAs and almost one hundred putative novel vertebrate miRNAs have been identified, many of which seem to be teleost-specific, cichlid-specific or tilapia-specific. Abundant miRNA isoforms (isomiRs) were identified with modifications in both 5p and 3p miRNA transcripts. Changes in arm usage (arm switching) of nine miRNAs were detected in early development, adult stage and even between male and female samples. We found an increasing complexity of miRNA expression during ontogenetic development, revealing a remarkable synchronism between the rate of new miRNAs recruitment and morphological changes. Overall, our results enlarge vertebrate miRNA collection and reveal a notable differential ratio of miRNA arms and isoforms influenced by sex and developmental life stage, providing a better picture of the evolutionary and spatiotemporal dynamics of miRNAs.

RevDate: 2018-06-28

Cooper GA, SA West (2018)

Division of labour and the evolution of extreme specialization.

Nature ecology & evolution, 2(7):1161-1167.

Division of labour is a common feature of social groups, from biofilms to complex animal societies. However, we lack a theoretical framework that can explain why division of labour has evolved on certain branches of the tree of life but not others. Here, we model the division of labour over a cooperative behaviour, considering both when it should evolve and the extent to which the different types should become specialized. We found that: (1) division of labour is usually-but not always-favoured by high efficiency benefits to specialization and low within-group conflict; and (2) natural selection favours extreme specialization, where some individuals are completely dependent on the helping behaviour of others. We make a number of predictions, several of which are supported by the existing empirical data, from microbes and animals, while others suggest novel directions for empirical work. More generally, we show how division of labour can lead to mutual dependence between different individuals and hence drive major evolutionary transitions, such as those to multicellularity and eusociality.

RevDate: 2018-05-26

Reeves MQ, Kandyba E, Harris S, et al (2018)

Multicolour lineage tracing reveals clonal dynamics of squamous carcinoma evolution from initiation to metastasis.

Nature cell biology, 20(6):699-709.

Tumour cells are subjected to evolutionary selection pressures during progression from initiation to metastasis. We analysed the clonal evolution of squamous skin carcinomas induced by DMBA/TPA treatment using the K5CreER-Confetti mouse and stage-specific lineage tracing. We show that benign tumours are polyclonal, but only one population contains the Hras driver mutation. Thus, benign papillomas are monoclonal in origin but recruit neighbouring epithelial cells during growth. Papillomas that never progress to malignancy retain several distinct clones, whereas progression to carcinoma is associated with a clonal sweep. Newly generated clones within carcinomas demonstrate intratumoural invasion and clonal intermixing, often giving rise to metastases containing two or more distinct clones derived from the matched primary tumour. These data demonstrate that late-stage tumour progression and dissemination are governed by evolutionary selection pressures that operate at a multicellular level and, therefore, differ from the clonal events that drive initiation and the benign-malignant transition.

RevDate: 2018-10-15
CmpDate: 2018-10-15

Hauser CJ, LE Otterbein (2018)

Danger signals from mitochondrial DAMPS in trauma and post-injury sepsis.

European journal of trauma and emergency surgery : official publication of the European Trauma Society, 44(3):317-324.

In all multicellular organisms, immediate host responses to both sterile and infective threat are initiated by very primitive systems now grouped together under the general term 'danger responses'. Danger signals are generated when primitive 'pattern recognition receptors' (PRR) encounter activating 'alarmins'. These molecular species may be of pathogenic infective origin (pathogen-associated molecular patterns) or of sterile endogenous origin (danger-associated molecular patterns). There are many sterile and infective alarmins and there is considerable overlap in their ability to activate PRR, but in all cases the end result is inflammation. It is the overlap between sterile and infective signals acting via a relatively limited number of PRR that generally underlies the great clinical similarity we see between sterile and infective systemic inflammatory responses. Mitochondria (MT) are evolutionarily derived from bacteria, and thus they sit at the crossroads between sterile and infective danger signal pathways. Many of the molecular species in mitochondria are alarmins, and so the release of MT from injured cells results in a wide variety of inflammatory events. This paper discusses the known participation of MT in inflammation and reviews what is known about how the major.

RevDate: 2018-09-18

Al Habyan S, Kalos C, Szymborski J, et al (2018)

Multicellular detachment generates metastatic spheroids during intra-abdominal dissemination in epithelial ovarian cancer.

Oncogene, 37(37):5127-5135.

Ovarian cancer is the most lethal gynecological cancer, where survival rates have had modest improvement over the last 30 years. Metastasis of cancer cells is a major clinical problem, and patient mortality occurs when ovarian cancer cells spread beyond the confinement of ovaries. Disseminated ovarian cancer cells typically spread within the abdomen, where ascites accumulation aids in their transit. Metastatic ascites contain multicellular spheroids, which promote chemo-resistance and recurrence. However, little is known about the origin and mechanisms through which spheroids arise. Using live-imaging of 3D culture models and animal models, we report that epithelial ovarian cancer (EOC) cells, the most common type of ovarian cancer, can spontaneously detach as either single cells or clusters. We report that clusters are more resistant to anoikis and have a potent survival advantage over single cells. Using in vivo lineage tracing, we found that multicellular spheroids arise preferentially from collective detachment, rather than aggregation in the abdomen. Finally, we report that multicellular spheroids from collective detachment are capable of seeding intra-abdominal metastases that retain intra-tumoral heterogeneity from the primary tumor.

RevDate: 2018-07-13

Tarver JE, Taylor RS, Puttick MN, et al (2018)

Well-Annotated microRNAomes Do Not Evidence Pervasive miRNA Loss.

Genome biology and evolution, 10(6):1457-1470.

microRNAs are conserved noncoding regulatory factors implicated in diverse physiological and developmental processes in multicellular organisms, as causal macroevolutionary agents and for phylogeny inference. However, the conservation and phylogenetic utility of microRNAs has been questioned on evidence of pervasive loss. Here, we show that apparent widespread losses are, largely, an artefact of poorly sampled and annotated microRNAomes. Using a curated data set of animal microRNAomes, we reject the view that miRNA families are never lost, but they are rarely lost (92% are never lost). A small number of families account for a majority of losses (1.7% of families account for >45% losses), and losses are associated with lineages exhibiting phenotypic simplification. Phylogenetic analyses based on the presence/absence of microRNA families among animal lineages, and based on microRNA sequences among Osteichthyes, demonstrate the power of these small data sets in phylogenetic inference. Perceptions of widespread evolutionary loss of microRNA families are due to the uncritical use of public archives corrupted by spurious microRNA annotations, and failure to discriminate false absences that occur because of incomplete microRNAome annotation.

RevDate: 2018-08-13

Dechristé G, Fehrenbach J, Griseti E, et al (2018)

Viscoelastic modeling of the fusion of multicellular tumor spheroids in growth phase.

Journal of theoretical biology, 454:102-109.

BACKGROUND: Since several decades, the experiments have highlighted the analogy of fusing cell aggregates with liquid droplets. The physical macroscopic models have been derived under incompressible assumptions. The aim of this paper is to provide a 3D model of growing spheroids, which is more relevant regarding embryo cell aggregates or tumor cell spheroids.

METHODS: We extend the past approach to a compressible 3D framework in order to account for the tumor spheroid growth. We exhibit the crucial importance of the effective surface tension, and of the inner pressure of the spheroid to describe precisely the fusion. The experimental data were obtained on spheroids of colon carcinoma human cells (HCT116 cell line). After 3 or 6 days of culture, two identical spheroids were transferred in one well and their fusion was monitored by live videomicroscopy acquisition each 2 h during 72 h. From these images the neck radius and the diameter of the assembly of the fusing spheroids are extracted.

RESULTS: The numerical model is fitted with the experiments. It is worth noting that the time evolution of both neck radius and spheroid diameter are quantitatively obtained. The interesting feature lies in the fact that such measurements characterise the macroscopic rheological properties of the tumor spheroids.

CONCLUSIONS: The experimental determination of the kinetics of neck radius and overall diameter during spheroids fusion characterises the rheological properties of the spheroids. The consistency of the model is shown by fitting the model with two different experiments, enhancing the importance of both surface tension and cell proliferation.

GENERAL SIGNIFICANCE: The paper sheds new light on the macroscopic rheological properties of tumor spheroids. It emphasizes the role of the surface tension and the inner pressure in the fusion of growing spheroid. Under geometrical assumptions, the model reduces to a 2-parameter differential equation fit with experimental measurements. The 3-D partial differential system makes it possible to study the fusion of spheroids in non-symmetrical or more general frameworks.

RevDate: 2018-05-17

Quintero-Galvis JF, Paleo-López R, Solano-Iguaran JJ, et al (2018)

Exploring the evolution of multicellularity in Saccharomyces cerevisiae under bacteria environment: An experimental phylogenetics approach.

Ecology and evolution, 8(9):4619-4630 pii:ECE33979.

There have been over 25 independent unicellular to multicellular evolutionary transitions, which have been transformational in the complexity of life. All of these transitions likely occurred in communities numerically dominated by unicellular organisms, mostly bacteria. Hence, it is reasonable to expect that bacteria were involved in generating the ecological conditions that promoted the stability and proliferation of the first multicellular forms as protective units. In this study, we addressed this problem by analyzing the occurrence of multicellularity in an experimental phylogeny of yeasts (Sacharomyces cerevisiae) a model organism that is unicellular but can generate multicellular clusters under some conditions. We exposed a single ancestral population to periodic divergences, coevolving with a cocktail of environmental bacteria that were inoculated to the environment of the ancestor, and compared to a control (no bacteria). We quantified culturable microorganisms to the level of genera, finding up to 20 taxa (all bacteria) that competed with the yeasts during diversification. After 600 generations of coevolution, the yeasts produced two types of multicellular clusters: clonal and aggregative. Whereas clonal clusters were present in both treatments, aggregative clusters were only present under the bacteria treatment and showed significant phylogenetic signal. However, clonal clusters showed different properties if bacteria were present as follows: They were more abundant and significantly smaller than in the control. These results indicate that bacteria are important modulators of the occurrence of multicellularity, providing support to the idea that they generated the ecological conditions-promoting multicellularity.

RevDate: 2018-08-30

Jézéquel P, M Campone (2018)

Comment on "How the evolution of multicellularity set the stage for cancer".

British journal of cancer, 119(1):133-134.

RevDate: 2018-07-10
CmpDate: 2018-07-10

Parra-Acero H, Ros-Rocher N, Perez-Posada A, et al (2018)

Transfection of Capsaspora owczarzaki, a close unicellular relative of animals.

Development (Cambridge, England), 145(10): pii:dev.162107.

How animals emerged from their unicellular ancestor remains a major evolutionary question. New genome data from the closest unicellular relatives of animals have provided important insights into the evolution of animal multicellularity. We know that the unicellular ancestor of animals had an unexpectedly complex genetic repertoire, including many genes that are key to animal development and multicellularity. Thus, assessing the function of these genes among unicellular relatives of animals is key to understanding how they were co-opted at the onset of the Metazoa. However, such analyses have been hampered by the lack of genetic tools. Progress has been made in choanoflagellates and teretosporeans, two of the three lineages closely related to animals, whereas no tools are yet available for functional analysis in the third lineage: the filastereans. Importantly, filastereans have a striking repertoire of genes involved in transcriptional regulation and other developmental processes. Here, we describe a reliable transfection method for the filasterean Capsaspora owczarzaki We also provide a set of constructs for visualising subcellular structures in live cells. These tools convert Capsaspora into a unique experimentally tractable organism to use to investigate the origin and evolution of animal multicellularity.

RevDate: 2018-06-02

Tasic B (2018)

Single cell transcriptomics in neuroscience: cell classification and beyond.

Current opinion in neurobiology, 50:242-249.

Biology has been facing a daunting problem since the cell was understood to be the building block of metazoans: how do we study multicellular systems, when a universal approach to characterize their building blocks and classify them does not exist? Metazoan diversity has not helped: there are many model and non-model organisms, developmental and adult stages, healthy and diseased states. Here, I review the application of single cell transcriptomics to cell classification in neuroscience and its corollaries: the differentially expressed genes discovered in this process are a treasure trove for understanding cell type function and enabling specific access to those types. The advancements and widespread adoption of single-cell transcriptomics are bound to transform our understanding of neural system development, function, pathology and evolution.

RevDate: 2018-09-19
CmpDate: 2018-09-19

Elsner D, Meusemann K, J Korb (2018)

Longevity and transposon defense, the case of termite reproductives.

Proceedings of the National Academy of Sciences of the United States of America, 115(21):5504-5509.

Social insects are promising new models in aging research. Within single colonies, longevity differences of several magnitudes exist that can be found elsewhere only between different species. Reproducing queens (and, in termites, also kings) can live for several decades, whereas sterile workers often have a lifespan of a few weeks only. We studied aging in the wild in a highly social insect, the termite Macrotermes bellicosus, which has one of the most pronounced longevity differences between reproductives and workers. We show that gene-expression patterns differed little between young and old reproductives, implying negligible aging. By contrast, old major workers had many genes up-regulated that are related to transposable elements (TEs), which can cause aging. Strikingly, genes from the PIWI-interacting RNA (piRNA) pathway, which are generally known to silence TEs in the germline of multicellular animals, were down-regulated only in old major workers but not in reproductives. Continued up-regulation of the piRNA defense commonly found in the germline of animals can explain the long life of termite reproductives, implying somatic cooption of germline defense during social evolution. This presents a striking germline/soma analogy as envisioned by the superorganism concept: the reproductives and workers of a colony reflect the germline and soma of multicellular animals, respectively. Our results provide support for the disposable soma theory of aging.

RevDate: 2018-05-22

Maclean AE, Hertle AP, Ligas J, et al (2018)

Absence of Complex I Is Associated with Diminished Respiratory Chain Function in European Mistletoe.

Current biology : CB, 28(10):1614-1619.e3.

Parasitism is a life history strategy found across all domains of life whereby nutrition is obtained from a host. It is often associated with reductive evolution of the genome, including loss of genes from the organellar genomes [1, 2]. In some unicellular parasites, the mitochondrial genome (mitogenome) has been lost entirely, with far-reaching consequences for the physiology of the organism [3, 4]. Recently, mitogenome sequences of several species of the hemiparasitic plant mistletoe (Viscum sp.) have been reported [5, 6], revealing a striking loss of genes not seen in any other multicellular eukaryotes. In particular, the nad genes encoding subunits of respiratory complex I are all absent and other protein-coding genes are also lost or highly diverged in sequence, raising the question what remains of the respiratory complexes and mitochondrial functions. Here we show that oxidative phosphorylation (OXPHOS) in European mistletoe, Viscum album, is highly diminished. Complex I activity and protein subunits of complex I could not be detected. The levels of complex IV and ATP synthase were at least 5-fold lower than in the non-parasitic model plant Arabidopsis thaliana, whereas alternative dehydrogenases and oxidases were higher in abundance. Carbon flux analysis indicates that cytosolic reactions including glycolysis are greater contributors to ATP synthesis than the mitochondrial tricarboxylic acid (TCA) cycle. Our results describe the extreme adjustments in mitochondrial functions of the first reported multicellular eukaryote without complex I.

RevDate: 2018-10-08
CmpDate: 2018-10-08

Vijay K (2018)

Toll-like receptors in immunity and inflammatory diseases: Past, present, and future.

International immunopharmacology, 59:391-412.

The immune system is a very diverse system of the host that evolved during evolution to cope with various pathogens present in the vicinity of environmental surroundings inhabited by multicellular organisms ranging from achordates to chordates (including humans). For example, cells of immune system express various pattern recognition receptors (PRRs) that detect danger via recognizing specific pathogen-associated molecular patterns (PAMPs) and mount a specific immune response. Toll-like receptors (TLRs) are one of these PRRs expressed by various immune cells. However, they were first discovered in the Drosophila melanogaster (common fruit fly) as genes/proteins important in embryonic development and dorso-ventral body patterning/polarity. Till date, 13 different types of TLRs (TLR1-TLR13) have been discovered and described in mammals since the first discovery of TLR4 in humans in late 1997. This discovery of TLR4 in humans revolutionized the field of innate immunity and thus the immunology and host-pathogen interaction. Since then TLRs are found to be expressed on various immune cells and have been targeted for therapeutic drug development for various infectious and inflammatory diseases including cancer. Even, Single nucleotide polymorphisms (SNPs) among various TLR genes have been identified among the different human population and their association with susceptibility/resistance to certain infections and other inflammatory diseases. Thus, in the present review the current and future importance of TLRs in immunity, their pattern of expression among various immune cells along with TLR based therapeutic approach is reviewed.

RevDate: 2018-10-08

Tarhan LG, Droser ML, Cole DB, et al (2018)

Ecological Expansion and Extinction in the Late Ediacaran: Weighing the Evidence for Environmental and Biotic Drivers.

Integrative and comparative biology, 58(4):688-702.

The Ediacara Biota, Earth's earliest communities of complex, macroscopic, multicellular organisms, appeared during the late Ediacaran Period, just prior to the Cambrian Explosion. Ediacara fossil assemblages consist of exceptionally preserved soft-bodied forms of enigmatic morphology and affinity which nonetheless represent a critical stepping-stone in the evolution of complex animal ecosystems. The Ediacara Biota has historically been divided into three successive Assemblages-the Avalon, the White Sea, and the Nama. Although the oldest (Avalon) Assemblage documents the initial appearance of several groups of Ediacara taxa, the two younger (White Sea and Nama) Assemblages record a particularly striking suite of ecological innovations, including the appearance of diverse Ediacara body plans-in tandem with the rise of bilaterian animals-as well as the emergence of novel ecological strategies such as movement, sexual reproduction, biomineralization, and the development of dense, heterogeneous benthic communities. Many of these ecological innovations appear to be linked to adaptations to heterogeneous substrates and shallow and energetic marine settings. In spite of these innovations, the majority of Ediacara taxa disappear by the end of the Ediacaran, with interpretations for this disappearance historically ranging from the closing of preservational windows to environmentally or biotically mediated extinction. However, in spite of the unresolved affinity and eventual extinction of individual Ediacara taxa, these distinctive ecological strategies persist across the Ediacaran-Cambrian boundary and are characteristic of younger animal-dominated communities of the Phanerozoic. The late Ediacaran emergence of these strategies may, therefore, have facilitated subsequent radiations of the Cambrian. In this light, the Ediacaran and Cambrian Periods, although traditionally envisioned as separate worlds, are likely to have been part of an ecological and evolutionary continuum.


RJR Experience and Expertise


Robbins holds BS, MS, and PhD degrees in the life sciences. He served as a tenured faculty member in the Zoology and Biological Science departments at Michigan State University. He is currently exploring the intersection between genomics, microbial ecology, and biodiversity — an area that promises to transform our understanding of the biosphere.


Robbins has extensive experience in college-level education: At MSU he taught introductory biology, genetics, and population genetics. At JHU, he was an instructor for a special course on biological database design. At FHCRC, he team-taught a graduate-level course on the history of genetics. At Bellevue College he taught medical informatics.


Robbins has been involved in science administration at both the federal and the institutional levels. At NSF he was a program officer for database activities in the life sciences, at DOE he was a program officer for information infrastructure in the human genome project. At the Fred Hutchinson Cancer Research Center, he served as a vice president for fifteen years.


Robbins has been involved with information technology since writing his first Fortran program as a college student. At NSF he was the first program officer for database activities in the life sciences. At JHU he held an appointment in the CS department and served as director of the informatics core for the Genome Data Base. At the FHCRC he was VP for Information Technology.


While still at Michigan State, Robbins started his first publishing venture, founding a small company that addressed the short-run publishing needs of instructors in very large undergraduate classes. For more than 20 years, Robbins has been operating The Electronic Scholarly Publishing Project, a web site dedicated to the digital publishing of critical works in science, especially classical genetics.


Robbins is well-known for his speaking abilities and is often called upon to provide keynote or plenary addresses at international meetings. For example, in July, 2012, he gave a well-received keynote address at the Global Biodiversity Informatics Congress, sponsored by GBIF and held in Copenhagen. The slides from that talk can be seen HERE.


Robbins is a skilled meeting facilitator. He prefers a participatory approach, with part of the meeting involving dynamic breakout groups, created by the participants in real time: (1) individuals propose breakout groups; (2) everyone signs up for one (or more) groups; (3) the groups with the most interested parties then meet, with reports from each group presented and discussed in a subsequent plenary session.


Robbins has been engaged with photography and design since the 1960s, when he worked for a professional photography laboratory. He now prefers digital photography and tools for their precision and reproducibility. He designed his first web site more than 20 years ago and he personally designed and implemented this web site. He engages in graphic design as a hobby.

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E-mail: RJR8222@gmail.com

Collection of publications by R J Robbins

Reprints and preprints of publications, slide presentations, instructional materials, and data compilations written or prepared by Robert Robbins. Most papers deal with computational biology, genome informatics, using information technology to support biomedical research, and related matters.

Research Gate page for R J Robbins

ResearchGate is a social networking site for scientists and researchers to share papers, ask and answer questions, and find collaborators. According to a study by Nature and an article in Times Higher Education , it is the largest academic social network in terms of active users.

Curriculum Vitae for R J Robbins

short personal version

Curriculum Vitae for R J Robbins

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RJR Picks from Around the Web (updated 11 MAY 2018 )