Biology subjects

Neretina, T. V.

Publications and source records attributed to Neretina, T. V..

10 recordsLinked to original sources

bioRxiv2025

Rapid divergence of male and female mitochondrial genomes in a basal protobranch bivalve Yoldia hyperborea

Doubly uniparental inheritance (DUI) of mitochondrial DNA (mtDNA) is a mode of mtDNA transmission whereby the male mitogenome is inherited predominately by males and the female mitogenome is inherited by females. DUI is unique to bivalve mollusks and has been identified in all major bivalve clades, including Protobranchia, the most basal bivalve subclade. Meanwhile, the mechanisms underlying the emergence and evolution of DUI remain poorly understood. Here, we focus on the early stages of divergence of male and female mitochondrial genomes by sequencing them in a basal Protobranchia species Yoldia hyperborea where they are characterized by low level of divergence, suggesting a recent origin of this system. Despite the relatively high relatedness of female and male genomes, we find that they have undergone rapid divergence both on the sequence and the structural level, including an origin of a novel gene, the ORFan, in the male genome. This novel gene is functional, as evidenced by the fact that it is transcribed and is subject to purifying selection. We show that this gene is a result of duplication and rapid evolution of another mitochondrial gene, NAD2. Additionally, the female mitogenome carries a duplicated cassette containing the cytochrome b gene, resulting in two different transcripts in female gonads both of which are subject to purifying selection, although their transcription levels differ by two orders of magnitude. These results showcase the rapid evolution of mitochondrial genes following their duplication, which occurred near the time of divergence of M- and F- mitochondrial genomes within a doubly uniparental inheritance system.

evolutionary biology↗

bioRxiv2024

The White Sea littoral oligochaete Lumbricillus sp. as a model for annelid development studies

Oligochaetes play a significant role in aquatic ecosystems, and studying their development can contribute to a deeper understanding of the evolutionary features of embryonic development in the phylum Annelida. In this paper, we initially explored a littoral oligochaete species from the White Sea, which is abundant in the vicinity of the White Sea Biological Station MSU and reproduces in the early summer. A molecular phylogenetic analysis utilizing COI and 18S markers confirmed that the species under investigation belongs to the genus Lumbricillus, family Enchytridae. The early stages of embryonic development were described in detail, and the timing of the onset of key stages was established. The specifics of the cellular patterns observed in the early embryo were elucidated using the fluorescence staining and confocal microscopy. The embryonic development of Lumbricillus sp. exhibits characteristics that are consistent with the typical development of oligochaetes. Additionally, it displays specific characteristics that are typical of representatives of the Enchytriidae family, including equal size of the 2nd and 2D blastomeres and a small size of the 4D blastomere in comparison to the large 4D blastomere. The combination of synchrony and low developmental variability, coupled with the accessibility of the object, ease of maintenance and manipulation, makes Lumbricillus sp. a highly promising object for the study of embryonic development in Annelides.

developmental biology↗

bioRxiv2023

ORFanes in mitochondrial genomes of marine polychaete Polydora

Most characterised metazoan mitochondrial genomes are compact and encode a small set of proteins that are essential for oxidative phosphorylation. However, in rare cases, invertebrate taxa have additional open reading frames (ORFs) in their mtDNA sequences. Here, we sequenced and analysed the mitochondrial genome of a polychaete worm, Polydora cf. ciliata, part of whose life cycle takes place in low-oxygen conditions. In the mitogenome, we found three "ORFane" regions (1063, 427, and 519 bp) that have no resemblance to any standard metazoan mtDNA gene but lack stop codons in one of the reading frames. Similar regions are found in the mitochondrial genomes of three other Polydora species and Bocardiella hamata. All five species share the same gene order in their mitogenomes, which differ from that of other known spionidae mitogenomes. By analysing the ORFane sequences, we found that they are under negative selection pressure, contain conservative regions, and harbour predicted transmembrane domains.The codon adaptation indices (CAIs) of the ORFan genes were in the same range of values as the CAI of conventional protein-coding genes in corresponding mitochondrial genomes. Together, this suggests that ORFanes encode functional proteins. We speculate that the ORFanes originated from the conventional mitochondrial protein-coding genes which were duplicated when the Polydora/Bocardiella species complex separated from the rest of the Spionidae. Significance statementMetazoan mitochondrial genomes usually contain a conservative set of genes and features. However, mitogenomes of some species contain ORFanes - putative protein-coding genes without clear homology with other known sequences. In this study, we analysed three ORFanes in mitochondria of species of the genera Polydora and Bocardiella, which were absent in all other representatives of Spionidae. To the best of our knowledge, ORFanes havent been described in Annelida before. Sequence analysis of the ORFanes suggests they contain conservative regions and are likely translated into functional proteins. Our study features an uncommon case where new protein-coding genes emerged in the mitochondrial genomes of metazoa.

evolutionary biology↗

bioRxiv2021

Complex fitness landscape shapes variation in a hyperpolymorphic species

It is natural to assume that patterns of genetic variation in hyperpolymorphic species can reveal large-scale properties of the fitness landscape that are hard to detect by studying species with ordinary levels of genetic variation1,2. Here, we study such patterns in a fungus Schizophyllum commune, the most polymorphic species known3. Throughout the genome, short-range linkage disequilibrium caused by attraction of rare alleles is higher between pairs of nonsynonymous than of synonymous sites. This effect is especially pronounced for pairs of sites that are located within the same gene, especially if a large fraction of the gene is covered by haploblocks, genome segments where the gene pool consists of two highly divergent haplotypes, which is a signature of balancing selection. Haploblocks are usually shorter than 1000 nucleotides, and collectively cover about 10% of the S. commune genome. LD tends to be substantially higher for pairs of nonsynonymous sites encoding amino acids that interact within the protein. There is a substantial correlation between LDs at the same pairs of nonsynonymous sites in the USA and the Russian populations. These patterns indicate that selection in S. commune involves positive epistasis due to compensatory interactions between nonsynonymous alleles. When less polymorphic species are studied, analogous patterns can be detected only through interspecific comparisons.

evolutionary biology↗

bioRxiv2019

Rapid accumulation of mutations in growing mycelia of a hypervariable fungus Schizophyllum commune

The number of mutations that occur per nucleotide per generation varies between species by several orders of magnitude. In multicellular eukaryotes, the per generation mutation rate depends both on the per cell division mutation rate and on the number of germline cell divisions per generation. In a range of species, from fungi to humans, the number of germline cell divisions is lower than that of somatic cells, reducing the mutation burden on the offspring. The basidiomycete Schizophyllum commune has the highest level of genetic polymorphism known among eukaryotes. In a previous study, it was also found to have a high per generation mutation rate, probably contributing to its high polymorphism. However, this rate has been measured only in a breeding experiment on Petri dishes, and it is unclear how this result translates to natural populations. Here, we used an experimental design that measures the rate of accumulation of de novo mutations in a linearly growing mycelium. We show that S. commune accumulates mutations at a uniform rate of 1.4{middle dot}10-7 substitutions per nucleotide per meter of growth, which is 3 orders of magnitude higher than the corresponding rates in the oak Quercus robur and the fungus Armillaria gallica. This figure is consistent with the estimate obtained before, and suggests the lack of a dedicated germline in this system. If so, even a low per cell division mutation rate can translate into a very high per generation mutation rate when the number of cell divisions between consecutive meioses is large.

evolutionary biology↗

bioRxiv2019

Accurate Fetal Variant Calling in the Presence of Maternal Cell Contamination

High-throughput sequencing of fetal DNA is a promising and increasingly common method for the discovery of all (or all coding) genetic variants in the fetus, either as part of prenatal screening or diagnosis, or for genetic diagnosis of spontaneous abortions. In many cases, the fetal DNA (from chorionic villi, amniotic fluid, or abortive tissue) can be contaminated with maternal cells, resulting in the mixture of fetal and maternal DNA. This maternal cell contamination (MCC) undermines the assumption, made by traditional variant callers, that each allele in a heterozygous site is covered, on average, by 50% of the reads, and therefore can lead to erroneous genotype calls. We present a panel of methods for reducing the genotyping error in the presence of MCC. All methods start with the output of GATK HaplotypeCaller on the sequencing data for the (contaminated) fetal sample and both of its parents, and additionally rely on information about the MCC fraction (which itself is readily estimated from the high-throughput sequencing data). The first of these methods uses a Bayesian probabilistic model to correct the fetal genotype calls produced by MCC-unaware HaplotypeCaller. The other two methods “learn” the genotype-correction model from examples. We use simulated contaminated fetal data to train and test the models. Using the test sets, we show that all three methods lead to substantially improved accuracy when compared with the original MCC-unaware HaplotypeCaller calls. We then apply the best-performing method to three chorionic villus samples from spontaneously terminated pregnancies.Code and training data availability https://github.com/bazykinlab/ML-maternal-cell-contaminationCompeting Interest StatementThe authors have declared no competing interest.View Full Text

bioinformatics↗

bioRxiv2018

Recombination in a natural population of the bdelloid rotifer Adineta vaga

Sexual reproduction which involves alternation of meiosis and syngamy is the ancestral condition of extant eukaryotes. Transitions to asexual reproduction were numerous, but most of the resulting eukaryotic lineages are rather short-lived. Still, there are several exceptions to this rule including darwinulid ostracods1,2 and timema stick insects3. The most striking of them is bdelloid rotifers4-6, microscopic freshwater invertebrates which underwent an extensive adaptive radiation after apparently losing meiosis over 10 Mya. Indeed, both the lack of males in numerous bdelloid species and the lack of proper homology between chromosomes6 rule out ordinary sex. However, this does not exclude the possibility of some other mode of interindividual genetic exchange and recombination in their populations7. Recent analyses based on a few loci suggested genetic exchanges in this group8,9, although this has been controversial10. Here, we compare complete genomes of 11 individuals from the wild population of the bdelloid rotifer Adineta vaga, and show that its genetic structure, which involves Hardy-Weinberg proportions of genotypes within loci and lack of linkage disequilibrium between distant loci, is incompatible with strictly clonal reproduction. Instead, it can emerge only under ongoing recombination between different individuals within this species, possibly through transformation. Such a genetic structure makes the population immune to negative long-term consequences of the loss of conventional meiosis11, although this does not necessarily imply that interindividual genetic exchanges in A. vaga are directly maintained by natural selection.

evolutionary biology↗

bioRxiv2018

Genetics of adaptation of the ascomycetous fungus Podospora anserina to submerged cultivation

Podospora anserina is a model ascomycetous fungus which shows pronounced phenotypic senescence when grown on solid medium but possesses unlimited lifespan under submerged cultivation. In order to study the genetic aspects of adaptation of P. anserina to submerged cultivation, we initiated a long-term evolution experiment. In the course of the first four years of the experiment, 125 single-nucleotide substitutions and 23 short indels were fixed in eight independently evolving populations. Six proteins that affect fungal growth and development evolved in more than one population; in particular, the G-protein alpha subunit FadA evolved in seven out of eight experimental populations. Parallel evolution at the level of genes and pathways, an excess of nonsense and missense substitutions, and an elevated conservation of proteins and their sites where the changes occurred suggest that many of the observed allele replacements were adaptive and driven by positive selection.\n\nAuthor summaryLiving beings adapt to novel conditions that are far from their original environments in different ways. Studying mechanisms of adaptation is crucial for our understanding of evolution. The object of our interest is a multicellular fungus Podospora anserina. This fungus is known for its pronounced senescence and a definite lifespan, but it demonstrates an unlimited lifespan and no signs of senescence when grown under submerged conditions. Soon after transition to submerged cultivation, the rate of growth of P. anserina increases and its pigmentation changes. We wanted to find out whether there are any genetic changes that contribute to adaptation of P. anserina to these novel conditions and initiated a long-term evolutionary experiment on eight independent populations. Over the first four years of the experiment, 148 mutations were fixed in these populations. Many of these mutations lead to inactivation of the part of the developmental pathway in P. anserina, probably reallocating resources to vegetative proliferation in liquid medium. Our observations imply that strong positive selection drives changes in at least some of the affected protein-coding genes.\n\nData AvailabilityGenome sequence data have been deposited at DDBJ/ENA/GenBank under accessions QHKV00000000 (founder genotype A; version QHKV01000000) and QHKU00000000 (founder genotype B; version QHKU01000000), with the respective BioSample accessions SAMN09270751 and SAMN09270757, under BioProject PRJNA473312. Sequencing data have been deposited at the SRA with accession numbers SRR7233712-SRR7233727, under the same BioProject.\n\nFundingExperimental work and sequencing were supported by the Russian Foundation for Basic Research (grants no. 16-04-01845a and 18-04-01349a). Bioinformatic analysis was supported by the Russian Science Foundation (grant no. 16-14-10173). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

evolutionary biology↗

bioRxiv2018

The comparative and genetic methods for East European Unionidae taxonomy

Taxonomy of freshwater mussels from family Unionidae has been ambiguous for a long time. A number of methods used for their identification, including the so-called comparative method, are based on shell morphology. However, this morphology turned out to have a high level of within-species variation, and the shape of the shell of a specimen depends strongly on its environment and conditions of growth. For these reasons, the number of species recognized by the comparative method kept increasing. We applied both the comparative morphological method and methods of molecular genetics to address the taxonomy of Unionidae. We performed the comprehensive study of 70 specimens of Unionidae mussels collected from the River Ivitza, Volga basin. The specimens represented 14 comparative species, belonging to 4 comparative genera of Unionidae: Colletopterum, Pseudanodonta, Unio and Crassiana. Sequencing of the nuclear (ITS1) and mitochondrial (COI, 16S rDNA) genetic regions revealed 5 groups with high within-group genetic homogeneity separated from each other by long genetic distances. According to the comparison with the available sequences, these groups correspond to 3 Eastern European genera and 5 species: Anodonta anatina, Pseudanodonta complanata, Unio pictorum, Unio tumidus and Unio crassus. The results obtained indicate that the comparative method is inappropriate for the taxonomic analysis of East European Unionidae.

zoology↗

bioRxiv2017

Bursts of amino acid replacements in protein evolution

Evolution can occur both gradually and through alternating episodes of stasis and rapid changes. However, the prevalence and magnitude of fluctuations of the rate of evolution remains obscure. Detecting a rapid burst of changes requires a detailed record of past evolution, so that events that occurred within a short time interval can be identified. Here, we use the phylogenies of the Baikal Lake amphipods and of Catarrhini, which contain very short internal edges facilitating this task. We detect 6 radical bursts of evolution of individual proteins during such short time periods, each involving between 6 and 38 amino acid substitutions. These bursts were extremely unlikely to have occurred neutrally, and were apparently caused by positive selection. On average, in the course of a time interval required for one synonymous substitution per site, a protein undergoes a strong burst of rapid evolution with probability at least ~0.01.

evolutionary biology↗