Complete mitochondrial genome of Brachionus rubens from wuhu, China (Rotifera, Brachionidae).
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ABSTRACT:
SUBMITTER: Zhang Y
PROVIDER: S-EPMC8008871 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The two complete mitochondrial genomes were sequenced from the freshwater monogonont rotifer Brachionus rubens. The genome sequences were 12,041 bp and 13,793 bp in size, and the gene order and contents were identical to those of the freshwater rotifer B. rubens China, but were different in three tRNA-Arg, tRNA-Ile, and tRNA-Leu between both B. rubens mitochondrial genomes, while B. calyciflorus had peculiar gene order in mitochondrial DNA I. Of 12 protein-coding genes (PCGs), one gene (ND5) had incomplete stop codons. Furthermore, the start codon of ND4 and CO2 gene was ATT, while the start codon of other PCGs was ATG. The base composition of 12 PCGs in B. rubens mitogenome showed 22.5% for A, 46.5% for T, 16.3% for C, and 14.7% for G, respectively.
| S-EPMC7721018 | biostudies-literature
Project description:The two complete mitochondrial genomes were sequenced from the monogonont rotifer Brachionus rotundiformis. The genome sequences were 10,268 bp and 11,703 bp in size, and the gene order and contents were identical with those of B. koreanus but were different in tRNA-Cys with B. plicatilis mitochondrial genomes. Of the 12 protein-coding genes (PCGs), five genes (ND1, ATP6, ND5, CO3, ND3) had incomplete stop codons. Furthermore, the start codon of ND4 and CO3 gene was ATA, while the start codon of other PCGs was ATG. The base composition of B. rotundiformis mitogenome shows an anti-G bias (12.05% and 10.24%) on the second and third position of the PCGs, respectively.
| S-EPMC7799997 | biostudies-literature
Project description:The two complete mitochondrial genomes were sequenced from the Netherlands strain of the freshwater monogonont rotifer Brachionus calyciflorus. The mitochondrial genome sequences were 27,698?bp and 9,906?bp in size, respectively. The gene order and contents of the two B. calyciflorus strains were mostly identical to one another, except for the additional identification and translocation of several tRNAs in mitochondrial DNA I and II. Of 13 protein-coding genes (PCGs), three genes (ND1, ND5, and ND3) had incomplete stop codons. Furthermore, the start codon of ND2, CO2, and CO3 and ND4 genes was ATT, GTG, and ATA, respectively, while the start codon of other PCGs was ATG. The base composition of 13 PCGs of B. calyciflorus (the Netherlands strain) mitogenome showed 31.1% for A, 37.6% for T, 16.5% for C, and 14.8% for G, respectively.
| S-EPMC7707316 | biostudies-literature
Project description:The two complete mitochondrial genomes were sequenced from the freshwater monogonont rotifer Brachionus angularis. The mitochondrial genome sequences were 10,764 bp (mitochondrial DNA I) and 12,238 bp (mitochondrial DNA II) in size, respectively. The gene structure and its orientation of 12 protein-coding genes (PCGs) of complete mitochondrial genomes of B. angularis was identical to those shown in other marine rotifers and the freshwater rotifer Brachionus rubens, but was different from the freshwater rotifer Brachionus calyciflorus. Of 12 PCGs, one gene (ND5) had incomplete stop codon. Furthermore, the start codon for CO1, ND4L, ND5, and CO2 was GTG, while the start codon for ND3 and other PCGs was ATA and ATG, respectively. The base composition of 12 PCGs in B. angularis mitogenome showed 20.4% for A, 47.3% for T, 17.5% for C, and 14.8% for G, respectively. The mitochondrial genome A + T base composition (67.7%) of 12 PCGs was higher than G + C (32.3%), while the complete mitochondrial genome A + T base composition (66.3%) was higher than G + C (33.7%).
| S-EPMC7671714 | biostudies-literature
Project description:The two complete mitochondrial genomes were sequenced from the euryhaline monogonont rotifer Brachionus paranguensis. The mitochondrial genome sequences were 11,603 bp and 12,901 bp in size, and the gene order of 12 protein-coding genes (PCGs) were identical to those of the marine rotifer Brachionus plicatilis, but the positions of some tRNAs (e.g. tRNA-Ile, tRNA-Leu[TTA], tRNA-Phe, and tRNA-Leu[CTC]) of mitochondrial DNA I were different between B. paranguensis and B. plicatilis mitochondrial genomes. Of 12 PCGs, four genes (ND1, ATPase 6, ND5, and ND3) had incomplete stop codons. Furthermore, the start codon of ND4, ND5, and CO3 genes was ATT, while the start codon of other PCGs was ATG. The base composition of 12 PCGs in B. paranguensis mitochondrial genomes was 26.6% for A, 43.0% for T, 17.65% for C, and 12.75% for G, respectively.
| S-EPMC7748681 | biostudies-literature
Project description:BACKGROUND:Studies on genome size variation in animals are rarely done at lower taxonomic levels, e.g., slightly above/below the species level. Yet, such variation might provide important clues on the tempo and mode of genome size evolution. In this study we used the flow-cytometry method to study the evolution of genome size in the rotifer Brachionus plicatilis, a cryptic species complex consisting of at least 14 closely related species. RESULTS:We found an unexpectedly high variation in this species complex, with genome sizes ranging approximately seven-fold (haploid '1C' genome sizes: 0.056-0.416 pg). Most of this variation (67%) could be ascribed to the major clades of the species complex, i.e. clades that are well separated according to most species definitions. However, we also found substantial variation (32%) at lower taxonomic levels--within and among genealogical species--and, interestingly, among species pairs that are not completely reproductively isolated. In one genealogical species, called B. 'Austria', we found greatly enlarged genome sizes that could roughly be approximated as multiples of the genomes of its closest relatives, which suggests that whole-genome duplications have occurred early during separation of this lineage. Overall, genome size was significantly correlated to egg size and body size, even though the latter became non-significant after controlling for phylogenetic non-independence. CONCLUSIONS:Our study suggests that substantial genome size variation can build up early during speciation, potentially even among isolated populations. An alternative, but not mutually exclusive interpretation might be that reproductive isolation tends to build up unusually slow in this species complex.
| S-EPMC3087684 | biostudies-literature
Project description:BackgroundMate choice is of central importance to most animals, influencing population structure, speciation, and ultimately the survival of a species. Mating behavior of male brachionid rotifers is triggered by the product of a chemosensory gene, a glycoprotein on the body surface of females called the mate recognition pheromone. The mate recognition pheromone has been biochemically characterized, but little was known about the gene(s). We describe the isolation and characterization of the mate recognition pheromone gene through protein purification, N-terminal amino acid sequence determination, identification of the mate recognition pheromone gene from a cDNA library, sequencing, and RNAi knockdown to confirm the functional role of the mate recognition pheromone gene in rotifer mating.ResultsA 29 kD protein capable of eliciting rotifer male circling was isolated by high-performance liquid chromatography. Two transcript types containing the N-terminal sequence were identified in a cDNA library; further characterization by screening a genomic library and by polymerase chain reaction revealed two genes belonging to each type. Each gene begins with a signal peptide region followed by nearly perfect repeats of an 87 to 92 codon motif with no codons between repeats and the final motif prematurely terminated by the stop codon. The two Type A genes contain four and seven repeats and the two Type B genes contain three and five repeats, respectively. Only the Type B gene with three repeats encodes a peptide with a molecular weight of 29 kD. Each repeat of the Type B gene products contains three asparagines as potential sites for N-glycosylation; there are no asparagines in the Type A genes. RNAi with Type A double-stranded RNA did not result in less circling than in the phosphate-buffered saline control, but transfection with Type B double-stranded RNA significantly reduced male circling by 17%. The very low divergence between repeat units, even at synonymous positions, suggests that the repeats are kept nearly identical through a process of concerted evolution. Information-rich molecules like surface glycoproteins are well adapted for chemical communication and aquatic animals may have evolved signaling systems based on these compounds, whereas insects use cuticular hydrocarbons.ConclusionOwing to its critical role in mating, the mate recognition pheromone gene will be a useful molecular marker for exploring the mechanisms and rates of selection and the evolution of reproductive isolation and speciation using rotifers as a model system. The phylogenetic variation in the mate recognition pheromone gene can now be studied in conjunction with the large amount of ecological and population genetic data being gathered for the Brachionus plicatilis species complex to understand better the evolutionary drivers of cryptic speciation.
| S-EPMC2746195 | biostudies-literature
Project description:Genome size in the rotifer Brachionus asplanchnoidis, which belongs to the B. plicatilis species complex, is greatly enlarged and extremely variable (205–407 Mbp). Such variation raises the question whether large genome size differences among individuals might cause reproductive barriers, which could trigger speciation within this group by restricting gene flow across populations. To test this hypothesis, we used B. asplanchnoidis clones from three geographic populations and conducted assays to quantify reproductive isolation among clones differing in genome size, and we examined the population structure of all three populations using amplified fragment length polymorphisms (AFLPs). AFLPs indicated that these populations were genetically separated, but we also found hints of natural gene flow. Clones from different populations with genome size differences of up to 1.7-fold could interbred successfully in the laboratory and give rise to viable, fertile ‘hybrid’ offspring. Genome sizes of these ‘hybrids’ were intermediate between those of their parents, and fitness in terms of male production, population growth, and egg development time was not negatively affected. Thus, we found no evidence for reproductive isolation or nascent speciation within B. asplanchnoidis. Instead, our results suggest that gene flow within this species can occur despite a remarkably large range of genome sizes.
| S-EPMC7611973 | biostudies-literature
Project description:The Brachionus plicatilis complex represents the most studied group of rotifers, although the systematics of the species complex has not been completely clarified. Many studies have been conducted trying to explore the diversity within the complex, leading to the recognition of three major morphotypes: large (L), small-medium (SM), and small (SS). Currently six species have been described and classified under these types and another nine taxa have been identified but not formally described. Within the L group, three species have been officially described [B. plicatilis s.s. (L1), B. manjavacas (L2), and B. asplanchnoidis (L3)], while a formal description of L4, unofficially known as B. 'Nevada', is still lacking. In the present study, a new species, Brachionus paranguensis sp. nov., is formally described and presented as a representative of the L4 clade. The species has been named after a high altitude saline crater lake from Central Mexico, where the specimens were collected. An integrated approach using DNA taxonomy through COI and ITS1 markers, morphology, and ecology was used to confirm the identity of the new species.
| S-EPMC6803355 | biostudies-literature
Project description:BackgroundThe Syndermata (Rotifera+Acanthocephala) is one of the best model systems for studying the evolutionary origins and persistence of different life styles because it contains a series of lineage-specific life histories: Monogononta (cyclic parthenogenetic and free-living), Bdelloidea (entirely parthenogenetic and mostly benthic dweller), Seisonidea (exclusively bisexual and epizoic or ectoparasitic), and Acanthocephala (sexual and obligatory endoparasitic). Providing phylogenetic resolution to the question of Eurotatoria (Monogononta and Bdelloidea) monophyly versus paraphyly is a key factor for better understanding the evolution of different life styles, yet this matter is not clearly resolved. In this study, we revisited this issue based on comparative analysis of complete mitochondrial genome information for major groups of the Syndermata.ResultsWe determined the first complete mitochondrial genome sequences (15,319 bp) of a bdelloid rotifer, Rotaria rotatoria. In order to examine the validity of Eurotatoria (Monogononta and Bdelloidea) monophyly/paraphyly, we performed phylogenetic analysis of amino acid sequences for eleven protein-coding genes sampled from a wide variety of bilaterian representatives. The resulting mitochondrial genome trees, inferred using different algorithms, consistently failed to recover Monogononta and Bdelloidea as monophyletic, but instead identified them as a paraphyletic assemblage. Bdelloidea (as represented by R. rotatoria) shares most common ancestry with Acanthocephala (as represented by L. thecatus) rather than with monogonont B. plicatilis, the other representative of Eurotatoria.ConclusionComparisons of inferred amino acid sequence and gene arrangement patterns with those of other metazoan mtDNAs (including those of acanthocephalan L. thecatus and monogonont B. plicatilis) support the hypothesis that Bdelloidea shares most common ancestry with Acanthocephala rather than with Monogononta. From this finding, we suggest that the obligatory asexuality of bdelloideans may have secondarily derived from some other preexisting condition in earlier lineage of rotifers. Providing a more complete assessment of phylogenetic relationships and inferring patterns of evolution of different types of life styles among Syndermata awaits comparisons requiring mitochondrial genome sequencing of Seisonidea.
| S-EPMC2784805 | biostudies-literature