Ancient Endogenous Pararetroviruses in Oryza Genomes Provide Insights into the Heterogeneity of Viral Gene Macroevolution.
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ABSTRACT:
SUBMITTER: Chen S
PROVIDER: S-EPMC6179347 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Crocodilians are thought to be hosts to a diverse and divergent complement of endogenous retroviruses (ERVs) but a comprehensive investigation is yet to be performed. The recent sequencing of three crocodilian genomes provides an opportunity for a more detailed and accurate representation of the ERV diversity that is present in these species. Here we investigate the diversity, distribution and evolution of ERVs from the genomes of three key crocodilian species, and outline the key processes driving crocodilian ERV proliferation and evolution.ERVs and ERV related sequences make up less than 2% of crocodilian genomes. We recovered and described 45 ERV groups within the three crocodilian genomes, many of which are species specific. We have also revealed a new class of ERV, ERV4, which appears to be common to crocodilians and turtles, and currently has no characterised exogenous counterpart. For the first time, we formally describe the characteristics of this ERV class and its classification relative to other recognised ERV and retroviral classes. This class shares some sequence similarity and sequence characteristics with ERV3, although it is phylogenetically distinct from the other ERV classes. We have also identified two instances of gene capture by crocodilian ERVs, one of which, the capture of a host KIT-ligand mRNA has occurred without the loss of an ERV domain.This study indicates that crocodilian ERVs comprise a wide variety of lineages, many of which appear to reflect ancient infections. In particular, ERV4 appears to have a limited host range, with current data suggesting that it is confined to crocodilians and some lineages of turtles. Also of interest are two ERV groups that demonstrate evidence of host gene capture. This study provides a framework to facilitate further studies into non-mammalian vertebrates and highlights the need for further studies into such species.
| S-EPMC4299795 | biostudies-literature
Project description:Integration into the nuclear genome of germ line cells can lead to vertical inheritance of retroviral genes as host alleles. For other viruses, germ line integration has only rarely been documented. Nonetheless, we identified endogenous viral elements (EVEs) derived from ten non-retroviral families by systematic in silico screening of animal genomes, including the first endogenous representatives of double-stranded RNA, reverse-transcribing DNA, and segmented RNA viruses, and the first endogenous DNA viruses in mammalian genomes. Phylogenetic and genomic analysis of EVEs across multiple host species revealed novel information about the origin and evolution of diverse virus groups. Furthermore, several of the elements identified here encode intact open reading frames or are expressed as mRNA. For one element in the primate lineage, we provide statistically robust evidence for exaptation. Our findings establish that genetic material derived from all known viral genome types and replication strategies can enter the animal germ line, greatly broadening the scope of paleovirological studies and indicating a more significant evolutionary role for gene flow from virus to animal genomes than has previously been recognized.
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Project description:Many emerging arboviruses are not transmitted by traditional mosquito vectors, but by lesser-studied arthropods such as ticks, midges, and sand flies. Small RNA (sRNA) silencing pathways are the main antiviral defence mechanism for arthropods, which lack adaptive immunity. Non-retroviral integrated RNA virus sequences (NIRVS) are one potential source of sRNAs which comprise these pathways. NIRVS are remnants of past germline RNA viral infections, where viral cDNA integrates into the host genome and is vertically transmitted. In Aedes mosquitoes, NIRVS are widespread and produce PIWI-interacting RNAs (piRNAs). These are hypothesised to target incoming viral transcripts to modulate viral titre, perhaps rendering the organism a more efficient arbovirus vector. To explore the NIRVS landscape in alternative arbovirus vectors, we validated the NIRVS landscape in Aedes spp. and then identified novel NIRVS in six medically relevant arthropods and also in Drosophila melanogaster. We identified novel NIRVS in Phlebotomus papatasi, Culicoides sonorensis, Rhipicephalus microplus, Anopheles gambiae, Culex quinquefasciatus, and Ixodes scapularis. Due to their unexpected abundance, we further characterised NIRVS in the blacklegged tick I. scapularis (n = 143). Interestingly, NIRVS are not enriched in R. microplus, another hard tick, suggesting this is an Ixodes-specific adaptation. I. scapularis NIRVS are enriched in bunya- and orthomyxo-like sequences, reflecting that ticks are a dominant host for these virus groups. Unlike in mosquitoes, I. scapularis NIRVS are more commonly derived from the non-structural region (replicase) of negative-sense viruses, as opposed to structural regions (e.g. glycoprotein). Like other arthropods, I. scapularis NIRVS preferentially integrate into genomic piRNA clusters, and serve as a template for primary piRNA production in the commonly used embryonic I. scapularis ISE6 cell line. Interestingly, we identified a two-fold enrichment of non-long terminal repeat (non-LTR) retrotransposons, in genomic proximity to NIRVS, contrasting with studeis in Ae. aegypti, where LTR retrotransposons are instead associated with NIRVS formation. We characterised NIRVS phylogeny and integration patterns in the important vector, I. scapularis, revealing they are distinct from those in Aedes spp. Future studies will explore the possible antiviral mechanism conferred by NIRVS to I. scapularis,which may help the transmission of pathogenic arboviruses. Finally, this study explored NIRVS as an untapped wealth of viral diversity in arthropods.
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Project description:Cave hyenas (genus Crocuta) are extinct bone-cracking carnivores from the family Hyaenidae and are generally split into two taxa that correspond to a European/Eurasian and an (East) Asian lineage. They are close relatives of the extant African spotted hyenas, the only extant member of the genus Crocuta. Cave hyenas inhabited a wide range across Eurasia during the Pleistocene, but became extinct at the end of the Late Pleistocene. Using genetic and genomic datasets, previous studies have proposed different scenarios about the evolutionary history of Crocuta. However, causes of the extinction of cave hyenas are widely speculative and samples from China are severely understudied. In this study, we assembled near-complete mitochondrial genomes from two cave hyenas from northeastern China dating to 20 240 and 20 253 calBP, representing the youngest directly dated fossils of Crocuta in Asia. Phylogenetic analyses suggest a monophyletic clade of these two samples within a deeply diverging mitochondrial haplogroup of Crocuta. Bayesian analyses suggest that the split of this Asian cave hyena mitochondrial lineage from their European and African relatives occurred approximately 1.85 Ma (95% CI 1.62-2.09 Ma), which is broadly concordant with the earliest Eurasian Crocuta fossil dating to approximately 2 Ma. Comparisons of mean genetic distance indicate that cave hyenas harboured higher genetic diversity than extant spotted hyenas, brown hyenas and aardwolves, but this is probably at least partially due to the fact that their mitochondrial lineages do not represent a monophyletic group, although this is also true for extant spotted hyenas. Moreover, the joint female effective population size of Crocuta (both cave hyenas and extant spotted hyenas) has sustained two declines during the Late Pleistocene. Combining this mitochondrial phylogeny, previous nuclear findings and fossil records, we discuss the possible relationship of fossil Crocuta in China and the extinction of cave hyenas.
| S-EPMC7893252 | biostudies-literature
Project description:Background and aimsBanana genomes harbour numerous copies of viral sequences derived from banana streak viruses (BSVs) - dsDNA viruses belonging to the family Caulimoviridae.These viral integrants (eBSVs) are mostly defective, probably as a result of 'pseudogenization' driven by host genome evolution. However, some can give rise to infection by releasing a functional viral genome following abiotic stresses. These distinct infective eBSVs correspond to the three main widespread BSV species (BSOLV, BSGFV and BSIMV), fully described within the Musa balbisiana B genomes of the seedy diploid 'Pisang Klutuk Wulung' (PKW).MethodsWe characterize eBSV distribution among a Musa sampling including seedy BB diploids and interspecific hybrids with Musa acuminate exhibiting different levels of ploidy for the B genome (ABB, AAB, AB). We used representative samples of the two areas of sympatry between M. acuminate and M. balbisiana species representing the native area of the most widely cultivated AAB cultivars (in India and in East Asia, ranging from the Philippines to New Guinea). Seventy-seven accessions were characterized using eBSV-related PCR markers and Southern hybridization approaches. We coded both sets of results to create a common dissimilarity matrix with which to interpret eBSV distribution.Key resultsWe propose a Musa phylogeny driven by the M. balbisiana genome based on a dendrogram resulting from a joint neighbour-joining analysis of the three BSV species, showing for the first time lineages between BB and ABB/AAB hybrids. eBSVs appear to be relevant phylogenetic markers that can illustrate theM. balbisiana phylogeography story.ConclusionThe theoretical implications of this study for further elucidation of the historical and geographical process of Musa domestication are numerous. Discovery of banana plants with B genome non-infective for eBSV opens the way to the introduction of new genitors in programmes of genetic banana improvement.
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Project description:Twenty-four palaeogenomes from Mokrin, a major Early Bronze Age necropolis in southeastern Europe, were sequenced to analyse kinship between individuals and to better understand prehistoric social organization. 15 investigated individuals were involved in genetic relationships of varying degrees. The Mokrin sample resembles a genetically unstructured population, suggesting that the community's social hierarchies were not accompanied by strict marriage barriers. We find evidence for female exogamy but no indications for strict patrilocality. Individual status differences at Mokrin, as indicated by grave goods, support the inference that females could inherit status, but could not transmit status to all their sons. We further show that sons had the possibility to acquire status during their lifetimes, but not necessarily to inherit it. Taken together, these findings suggest that Southeastern Europe in the Early Bronze Age had a significantly different family and social structure than Late Neolithic and Early Bronze Age societies of Central Europe.
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Project description:BackgroundEuholognatha is a monophyletic group within stoneflies comprised by a superfamily Nemouroidea and a family Scopuridae. Based on morphological data, the family-level phylogenetic relationships within Euholognatha are widely accepted, but there is still controversy among different molecular studies. To better understand the phylogeny of all six extant euholognathan families, we sequenced and analyzed seven euholognathan mitogenomes.ResultsThe sequence heterogeneity analysis observed a low degree of compositional heterogeneity in euholognathan mitogenomes. Meanwhile, leuctrid mitogenomes were more heterogeneous than other euholognathan families, which may affect the phylogenetic reconstruction. Phylogenetic analyses with various datasets generated three topologies. The Leuctridae was recovered as the earliest branching lineage, and the sister relationship of Capniidae and Taeniopterygidae was supported by most tree topologies and FcLM analyses. When separately excluding sparsely sampled Scopuridae or high heterogeneity leuctrid taxa, phylogenetic analyses under the same methods generated more stable and consistent tree topologies. Finally, based on the results of this study, we reconstructed the relationships within Euholognatha as: Leuctridae + (Scopuridae + ((Taeniopterygidae + Capniidae) + (Nemouridae + Notonemouridae))).ConclusionOur research shows the potential of data optimizing strategies in reconstructing phylogeny within Euholognatha and provides new insight into the phylogeny of this group.
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Project description:CRISPR arrays and associated cas genes are widespread in bacteria and archaea and confer acquired resistance to viruses. To examine viral immunity in the context of naturally evolving microbial populations we analyzed genomic data from two thermophilic Synechococcus isolates (Syn OS-A and Syn OS-B') as well as a prokaryotic metagenome and viral metagenome derived from microbial mats in hotsprings at Yellowstone National Park. Two distinct CRISPR types, distinguished by the repeat sequence, are found in both the Syn OS-A and Syn OS-B' genomes. The genome of Syn OS-A contains a third CRISPR type with a distinct repeat sequence, which is not found in Syn OS-B', but appears to be shared with other microorganisms that inhabit the mat. The CRISPR repeats identified in the microbial metagenome are highly conserved, while the spacer sequences (hereafter referred to as "viritopes" to emphasize their critical role in viral immunity) were mostly unique and had no high identity matches when searched against GenBank. Searching the viritopes against the viral metagenome, however, yielded several matches with high similarity some of which were within a gene identified as a likely viral lysozyme/lysin protein. Analysis of viral metagenome sequences corresponding to this lysozyme/lysin protein revealed several mutations all of which translate into silent or conservative mutations which are unlikely to affect protein function, but may help the virus evade the host CRISPR resistance mechanism. These results demonstrate the varied challenges presented by a natural virus population, and support the notion that the CRISPR/viritope system must be able to adapt quickly to provide host immunity. The ability of metagenomics to track population-level variation in viritope sequences allows for a culture-independent method for evaluating the fast co-evolution of host and viral genomes and its consequence on the structuring of complex microbial communities.
| S-EPMC2612747 | biostudies-literature
Project description:As a historical nomadic group in Central Asia, Kazaks have mainly inhabited the steppe zone from the Altay Mountains in the East to the Caspian Sea in the West. Fine scale characterization of the genetic profile and population structure of Kazaks would be invaluable for understanding their population history and modeling prehistoric human expansions across the Eurasian steppes. With this mind, we characterized the maternal lineages of 200 Kazaks from Jetisuu at mitochondrial genome level. Our results reveal that Jetisuu Kazaks have unique mtDNA haplotypes including those belonging to the basal branches of both West Eurasian (R0, H, HV) and East Eurasian (A, B, C, D) lineages. The great diversity observed in their maternal lineages may reflect pivotal geographic location of Kazaks in Eurasia and implies a complex population history. Comparative analyses of mitochondrial genomes of human populations in Central Eurasia reveal a common maternal genetic ancestry for Turko-Mongolian speakers and their expansion being responsible for the presence of East Eurasian maternal lineages in Central Eurasia. In addition, our analyses indicate maternal genetic affinity between the Sherpas from the Tibetan Plateau with the Turko-Mongolian speakers.
2022-11-09 | GSE208402 | GEO
Project description:BACKGROUND:The relative scarcity of Copia retrotransposons has been recently characterized in metazoans in comparison with the other superfamilies of LTR elements. Furthermore, Copia retrotransposons have often a particular dynamics that results in a highly predominant single clade of elements within a large host taxon, such as the GalEa-like retrotransposons in crustaceans. Taking advantage of the skyrocketing amount of genomic data available for fungi, we carried out the first large-scale comparative genomic analysis of the Copia clades in filamentous ascomycetes. RESULTS:Screening 30 completely sequenced genomes allowed us to identify more than 2500 Copia copies with conserved LTR, which are distributed in 138 families. Their characterization revealed that fungal Copia diversity is much broader than previously thought with at least 27 clades, 23 of which likely correspond to new ones. While the Copia copy number is low in most species, the two clades GalEa and FunCo1 are widely distributed and highly dominate Copia content as they both account for 80% of the detected sequences. CONCLUSIONS:In Fungi, GalEa retrotransposons are restricted to Pezizomycotina in which they can make up an outstandingly high proportion of the genome (up to 10% in Cenococcum geophilum). At last, we revealed that fungal GalEa elements structurally differ from all other Copia elements with an absence of Primer Binding Site. These elements however harbor a Conserved Hairpin Site which is probably essential for their transposition.
| S-EPMC5445492 | biostudies-literature