Vowel purity and rhyme evidence in Old Chinese reconstruction

Rhyme patterns in Old Chinese poems are important for the reconstruction of Old Chinese pronunciation, as they provide evidence for groups of words which formerly had similar pronunciation. Rhyme patterns can also be used to test Old Chinese reconstruction systems for consistency and plausibility, as reconstruction systems should minimize the conflict with attested rhyme patterns. Here, we build on the idea that rhyming in Old Chinese followed the principle of vowel purity, a tendency to disallow rhymes of words with different vowels, to develop a quantitative test for reconstruction systems of Old Chinese. The test is illustrated by comparing seven different Old Chinese reconstruction systems and by showing that, although the systems differ regarding their degree of vowel purity, the principle seems to hold for Old Chinese rhyme data

Metabolomic Shifts Associated with Heat Stress in Coral Holobionts

Understanding the response of the coral holobiont to environmental change is crucial to inform conservation efforts. The most pressing problem is “coral bleaching,” usually precipitated by prolonged thermal stress. We used untargeted, polar metabolite profiling to investigate the physiological response of the coral species Montipora capitata and Pocillopora acuta to heat stress. Our goal was to identify diagnostic markers present early in the bleaching response. From the untargeted UHPLC-MS data, a variety of co-regulated dipeptides were found that have the highest differential accumulation in both species. The structures of four dipeptides were determined and showed differential accumulation in symbiotic and aposymbiotic (alga-free) populations of the sea anemone Aiptasia (Exaiptasia pallida), suggesting the deep evolutionary origins of these dipeptides and their involvement in symbiosis. These and other metabolites may be used as diagnostic markers for thermal stress in wild coral

Introducing Trait Networks to Elucidate the Fluidity of Organismal Evolution Using Palaeontological Data

International audienceExplaining the evolution of animals requires ecological, developmental, paleontological, and phylogenetic considerations because organismal traits are affected by complex evolutionary processes. Modeling a plurality of processes, operating at distinct timescales on potentially interdependent traits, can benefit from approaches that are complementary treatments to phylogenetics. Here, we developed an inclusive network approach, implemented in the command line software ComponentGrapher, and analyzed trait co-occurrence of rhinocerotoid mammals. We identified stable, unstable, and pivotal traits, as well as traits contributing to complexes, that may follow to a common developmental regulation, that point to an early implementation of the postcranial Bauplan among rhinocerotoids. Strikingly, most identified traits are highly dissociable, used repeatedly in distinct combinations and in different taxa, which usually do not form clades. Therefore, the genes encoding these traits are likely recruited into novel gene regulation networks during the course of evolution. Our evo-systemic framework, generalizable to other evolved organizations, supports a pluralistic modeling of organismal evolution, including trees and networks

Divergent genomic trajectories predate the origin of animals and fungi

22 pages, 4 figures, supplementary information https://doi.org/10.1038/s41586-022-05110-4.-- Data availability: The raw sequence data and assembled genomes generated in this study have been deposited in the European Nucleotide Archive (ENA) at EMBL-EBI under accession number PRJEB52884 (https://www.ebi.ac.uk/ena/browser/view/PRJEB52884). The genome assemblies are also available in figshare (https://doi.org/10.6084/m9.figshare.19895962.v1). Protein sequences of the species used in this study were downloaded from the GenBank public databases (https://www.ncbi.nlm.nih.gov/protein/), Uniprot (https://www.uniprot.org/), JGI genome database (https://genome.jgi.doe.gov/portal/) and Ensembl genomes (https://www.ensembl.org). The following specific databases were also used in this study: Pfam A v29 (https://pfam.xfam.org/), EggNOG emapperdb-4.5.1 (http://eggnog5.embl.de) and UniProt reference proteomes release 2016_02 (https://www.uniprot.org/). The supporting data files of this study are available in the following repository: https://doi.org/10.6084/m9.figshare.13140191.v1.-- Code availability: The most relevant custom code developed for this study (the MAPBOS pipeline and the machine learning classifiers) is available at https://doi.org/10.5281/zenodo.6586559Animals and fungi have radically distinct morphologies, yet both evolved within the same eukaryotic supergroup: Opisthokonta1,2. Here we reconstructed the trajectory of genetic changes that accompanied the origin of Metazoa and Fungi since the divergence of Opisthokonta with a dataset that includes four novel genomes from crucial positions in the Opisthokonta phylogeny. We show that animals arose only after the accumulation of genes functionally important for their multicellularity, a tendency that began in the pre-metazoan ancestors and later accelerated in the metazoan root. By contrast, the pre-fungal ancestors experienced net losses of most functional categories, including those gained in the path to Metazoa. On a broad-scale functional level, fungal genomes contain a higher proportion of metabolic genes and diverged less from the last common ancestor of Opisthokonta than did the gene repertoires of Metazoa. Metazoa and Fungi also show differences regarding gene gain mechanisms. Gene fusions are more prevalent in Metazoa, whereas a larger fraction of gene gains were detected as horizontal gene transfers in Fungi and protists, in agreement with the long-standing idea that transfers would be less relevant in Metazoa due to germline isolation3,4,5. Together, our results indicate that animals and fungi evolved under two contrasting trajectories of genetic change that predated the origin of both groups. The gradual establishment of two clearly differentiated genomic contexts thus set the stage for the emergence of Metazoa and FungiE.O.-P. was supported by a predoctoral FPI grant from MINECO (BES-2015-072241) and by ESF Investing in your future. E.O.-P., D.L-E., A.S.A. and I.R.-T. received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7-2007-2013) (Grant agreement No. 616960) and also from grants (BFU2014-57779-P and PID2020-120609GB-I00) by MCIN/AEI/10.13039/501100011033 and ‘ERDF A way of making Europe’. E.O.-P. and G.J.Sz. received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 714774). T.A.W. was supported by a Royal Society University Research Fellowship (URF\R\201024) and NERC standard grant NE/P00251X/1. This work was supported by the Gordon and Betty Moore Foundation through grant GBMF9741 to T.A.W. and G.J.Sz. J.S.P. and E.B. received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7-2007-2013) (Grant agreement No. 615274). D.V.T. and cell culturing were supported by the Russian Science Foundation grant no. 18-14-00239, https://rscf.ru/project/18-14-00239/. Culture of P. vietnamica was obtained as the result of field work in Vietnam as part of the project ‘Ecolan 3.2’ of the Russian–Vietnam Tropical Center. P.J.K. is supported by an Investigator Award from the Gordon and Betty Moore Foundation (https://doi.org/10.37807/GBMF9201)With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)Peer reviewe

Capture of complete ciliate chromosomes in single sequencing reads reveals widespread chromosome isoforms

Background Whole-genome shotgun sequencing, which stitches together millions of short sequencing reads into a single genome, ushered in the era of modern genomics and led to a rapid expansion of the number of genome sequences available. Nevertheless, assembly of short reads remains difficult, resulting in fragmented genome sequences. Ultimately, only a sequencing technology capable of capturing complete chromosomes in a single run could resolve all ambiguities. Even “third generation” sequencing technologies produce reads far shorter than most eukaryotic chromosomes. However, the ciliate Oxytricha trifallax has a somatic genome with thousands of chromosomes averaging only 3.2 kbp, making it an ideal candidate for exploring the benefits of sequencing whole chromosomes without assembly. Results We used single-molecule real-time sequencing to capture thousands of complete chromosomes in single reads and to update the published Oxytricha trifallax JRB310 genome assembly. In this version, over 50% of the completed chromosomes with two telomeres derive from single reads. The improved assembly includes over 12,000 new chromosome isoforms, and demonstrates that somatic chromosomes derive from variable rearrangements between somatic segments encoded up to 191,000 base pairs away. However, while long reads reduce the need for assembly, a hybrid approach that supplements long-read sequencing with short reads for error correction produced the most complete and accurate assembly, overall. Conclusions This assembly provides the first example of complete eukaryotic chromosomes captured by single sequencing reads and demonstrates that traditional approaches to genome assembly can mask considerable structural variation

Etude de la modularité en évolution moléculaire, morphologique et linguistique par des méthodes de réseaux

Molecular evolution proceeds not only by divergence from a common ancestor, but also by combining parts from evolving objects of different origins, through processes that are called introgressive. Lateral gene transfers are probably the most well-known of these processes, but introgression has been shown to also happen at various levels of biological organization. As a result, most biological evolving objects (genes, genomes, communities) can be composed of parts from different phylogenetic origins and can be described as composites. Such modular evolution is inadequately modeled by trees, since composite objects are not merely the result of divergence from a common ancestor only. Networks on the other hand are much more suited for handling modularity, and graph theory can be used to search networks for patterns that are characteristic of such reticulate evolution. During this PhD, I developed a piece of software, CompositeSearch, that can efficiently detect composite genes in massive sequence dataset, comprising up to millions of sequences. This algorithm was used to identify and quantify the abundance of composite genes in polluted soil environments, and in prokaryotic plasmids. These studies show that important biological novelties and adaptations can result from processes acting at subgenic levels. However, as shown in this manuscript, networks provide a framework that goes well beyond the boundaries of molecular evolution and I have applied them to other evolving entities, such as animals (trait networks) morphology and languages (word networks). In both cases, modularity appears to be a major evolutionary outcome, following rules that remain to be investigated.L'évolution moléculaire procède par divergence depuis un ancêtre commun et en combinant des fragments d'objets évoluant d'origines différentes, par des processus introgressifs. Les transferts horizontaux de gènes sont probablement les plus connus de ces processus, mais l'introgression affecte aussi d'autres niveaux d'organisation biologique. Ainsi, la plupart des objets biologiques évoluant peuvent être composés de parties d'origines phylogénétiques différentes et décrits comme composites. Cette évolution modulaire se modélise mal par des arbres, puisque les objets composites ne sont pas seulement le résultat d'une divergence depuis un ancêtre. Les réseaux sont bien plus aptes à modéliser la modularité, et la théorie des graphes peut être utilisée pour chercher dans ces réseaux des patrons caractéristiques d'une évolution réticulée. Pendant cette thèse, j'ai développé le logiciel CompositeSearch qui détecte les gènes composites dans des jeux de données de séquences massifs, jusqu'à plusieurs millions de séquences. Cet algorithme a été utilisé pour identifier et quantifier l'abondance des gènes composites dans des environnements de sols pollués ainsi que dans les plasmides. Les résultats montrent que d'importantes adaptations et nouveautés biologiques découlent de processus œuvrant au niveau subgénique. De plus, les réseaux fournissent un cadre conceptuel dont l'utilité va bien au-delà de l'évolution moléculaire et je les ai appliqués à d'autres objets évoluant, comme les animaux (réseaux de traits morphologiques) et les langues (réseaux de mots). Dans les deux cas, la modularité se révèle être une conséquence évolutive majeure, et obéit à des règles encore à préciser

CompositeSearch: A Generalized Network Approach for Composite Gene Families Detection

International audienceGenes evolve by point mutations, but also by shuffling, fusion, and fission of genetic fragments. Therefore, similarity between two sequences can be due to common ancestry producing homology, and/or partial sharing of component fragments. Disentangling these processes is especially challenging in large molecular data sets, because of computational time. In this article, we present CompositeSearch, a memory-efficient, fast, and scalable method to detect composite gene families in large data sets (typically in the range of several million sequences). CompositeSearch generalizes the use of similarity networks to detect composite and component gene families with a greater recall, accuracy, and precision than recent programs (FusedTriplets and MosaicFinder). Moreover, CompositeSearch provides user-friendly quality descriptions regarding the distribution and primary sequence conservation of these gene families allowing critical biological analyses of these data

TEF 2.0: a graph-based method for decomposing protein structures into closed loops

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Microbial Dark Matter Investigations: How Microbial Studies Transform Biological Knowledge and Empirically Sketch a Logic of Scientific Discovery

International audienceMicrobes are the oldest and most widespread, phylogenetically and metabolically diverse life forms on Earth. However, they have been discovered only 334 years ago, and their diversity started to become seriously investigated even later. For these reasons, microbial studies that unveil novel microbial lineages and processes affecting or involving microbes deeply (and repeatedly) transform knowledge in biology. Considering the quantitative prevalence of taxonomically and functionally unassigned sequences in environmental genomics data sets, and that of uncultured microbes on the planet, we propose that unraveling the microbial dark matter should be identified as a central priority for biologists. Based on former empirical findings of microbial studies, we sketch a logic of discovery with the potential to further highlight the microbial unknowns

Formation of chimeric genes with essential functions at the origin of eukaryotes

Abstract Background Eukaryotes evolved from the symbiotic association of at least two prokaryotic partners, and a good deal is known about the timings, mechanisms, and dynamics of these evolutionary steps. Recently, it was shown that a new class of nuclear genes, symbiogenetic genes (S-genes), was formed concomitant with endosymbiosis and the subsequent evolution of eukaryotic photosynthetic lineages. Understanding their origins and contributions to eukaryogenesis would provide insights into the ways in which cellular complexity has evolved. Results Here, we show that chimeric nuclear genes (S-genes), built from prokaryotic domains, are critical for explaining the leap forward in cellular complexity achieved during eukaryogenesis. A total of 282 S-gene families contributed solutions to many of the challenges faced by early eukaryotes, including enhancing the informational machinery, processing spliceosomal introns, tackling genotoxicity within the cell, and ensuring functional protein interactions in a larger, more compartmentalized cell. For hundreds of S-genes, we confirmed the origins of their components (bacterial, archaeal, or generally prokaryotic) by maximum likelihood phylogenies. Remarkably, Bacteria contributed nine-fold more S-genes than Archaea, including a two-fold greater contribution to informational functions. Therefore, there is an additional, large bacterial contribution to the evolution of eukaryotes, implying that fundamental eukaryotic properties do not strictly follow the traditional informational/operational divide for archaeal/bacterial contributions to eukaryogenesis. Conclusion This study demonstrates the extent and process through which prokaryotic fragments from bacterial and archaeal genes inherited during eukaryogenesis underly the creation of novel chimeric genes with important functions