RESUMO
Lake Baikal is inhabited by a relatively large number of cyclopid species, many of which are endemics. Two genera, Diacyclops Kiefer, 1927 and Acanthocyclops Kiefer, 1927, are the most specious in the lake. Taxonomic discrimination of the majority of representatives of these genera is difficult owing to their high morphological similarities and poor standard description. In this study, a molecular phylogenetic analysis of Lake Baikal members of the Diacyclops/Acanthocyclops group is performed on the basis of mitochondrial cytochrome c oxidase subunit I (COI) gene. It is shown that a fragment of COI 1000 bp long is sufficient for intragenus discrimination of the cyclopids of Lake Baikal. The issues of Diacyclops/Acanthocyclops taxonomy are reflected in the obtained molecular data. Two distinct phylogenetic groups of Diacyclops genus with uncertain taxonomic status are revealed.
Assuntos
Proteínas de Artrópodes/genética , Copépodes/genética , DNA Mitocondrial/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Filogenia , Animais , Lagos , SibériaRESUMO
The value of chromatin diminution (CD) in different species of freshwater cyclopoid copepods can differ significantly. The biological and evolutionary roles of these differences remain unclear. To expand the knowledge on CD distribution and magnitude in this group of copepods, a quick method for its evaluation was required. This study proposes a simple approach for CD assessment in copepods using quantitative realtime PCR (qPCR). The magnitude of changes in the genome size was assessed by comparing fluorescence curves of qPCR fragments of target genes for pre- and post-diminution materials. The method was tested on four cyclopoid copepods species. In Cyclops kolensis, CD was assessed as 95.3 ± 1.2; in Acanthocyclops vernalis it was assessed at 94.6 ± 0.8%; at C. insignis, it was 82.3 ± 5.2%; and for the first time, CD was found in Megacyclops viridis at 91.1 ± 2.6%. The advantages of our approach are its rapidity, simplicity and minimal requirements of materials studied.
Assuntos
Cromatina/genética , Copépodes/genética , Reação em Cadeia da Polimerase em Tempo Real/métodos , Animais , Cromatina/metabolismo , Copépodes/metabolismoRESUMO
The population structure of Epischura baicalensis Sars (Copepoda, Calanoida), one of the key endemic species of the plankton community of Lake Baikal was studied. An analysis of mitochondrial DNA polymorphism revealed no genetic differences between Epischura sampled in the different basins of the lake or in the winter-spring/summer generations. Baikal Epischura is represented by a single panmictic population with a high level of mtDNA haplotype diversity.
Assuntos
Copépodes/genética , DNA Mitocondrial/genética , Polimorfismo Genético , Zooplâncton/genética , Animais , Lagos , SibériaRESUMO
Baikalian cyclopoids represent one of the richest endemic faunas of freshwater cyclopoid copepods. The genus Diacyclops Kiefer, 1927 is the most numerous by species number in the lake. In this work, molecular-phylogenetic analysis of 14 species and 1 sub-species from Lake Baikal and its water catchment basin is performed. The regions of mitochondrial cytochrom-oxydase I (COI) and of nuclear small-subunit 18S rRNA were used as evolution markers. In the obtained set of nucleotide sequences of COT gene, an effect of synonymous substitution saturation is revealed. Baikalian representatives of the genus Diacyclops form at phylogenetic schemes by two markers a monophyletic griup, it suggest their origin from a common ancestral form. Preliminary estimate of the age of this group is 20-25 My.
Assuntos
Copépodes/genética , Animais , Complexo IV da Cadeia de Transporte de Elétrons/genética , Evolução Molecular , Água Doce , Genes Mitocondriais , Filogenia , Subunidades Proteicas/genética , RNA Ribossômico 18S/genética , SibériaRESUMO
Two members of the Baikal sig family, a lake sig (Coregonus lavaretus baicalensis Dybovsky) and omul (C. autumnalis migratorius Georgi), are close relatives that diverged from the same ancestor 10-20 thousand years ago. In this work, we studied genomic polymorphism of these two fish species. The method of subtraction hybridization (SH) did not reveal the presence of extended sequences in the sig genome and their absence in the omul genome. All the fragments found by SH corresponded to polymorphous noncoding genome regions varying in mononucleotide substitutions and short deletions. Many of them are mapped close to genes of the immune system and have regions identical to the Tc-1-like transposons abundant among fish, whose transcription activity may affect the expression of adjacent genes. Thus, we showed for the first time that genetic differences between Baikal sig family members are extremely small and cannot be revealed by the SH method. This is another endorsement of the hypothesis on the close relationship between Baikal sig and omul and their evolutionarily recent divergence from a common ancestor.
Assuntos
Evolução Biológica , Genoma , Salmonidae/genética , Animais , Elementos de DNA Transponíveis , Dosagem de GenesRESUMO
Two representatives of Baikal ciscoes - lake cisco and omul - diverged from a common ancestor as recently as 10-20 thousand years ago. We have found an increasing expression level of DTSsa4 Tc1-like DNA transposons in cisco and omul brains. The mapping of the sequences of these transposons from Salmo salar and Danio rerio genomes has shown that in some cases, these transposons are located in the 5' and 3' regions, as well as in the promoter regions of various genes. Probably, Tc1-like transposons affect the activity of neighboring genes, providing the adaptive divergence of the cisco population.
Assuntos
Elementos de DNA Transponíveis/fisiologia , Evolução Molecular , Peixes/fisiologia , Regulação da Expressão Gênica/fisiologia , Filogenia , Regiões Promotoras Genéticas/fisiologia , Animais , Encéfalo/metabolismo , SibériaRESUMO
Three new microsatellite loci found for the Baikal omul Coregonus migratorius (Georgi) are described.
Assuntos
Salmonidae/genética , Animais , Repetições de MicrossatélitesRESUMO
Intraspecific genetic polymorphism of a Baikal Lake endemic, little Baikal oilfish (Comephorus dybowski Korotneff, 1905), was evaluated based on microsatellite analysis. Six microsatellite loci designed for the European sculpin, Cottus gobio, were used. Each locus was typed using 25 to 35 individuals from each of the Baikal trenches (southern, middle, and northern). Analysis of genetic differentiation (F(ST) and R(ST)) revealed no statistical significant differences between the samples. The data showed that the target species was represented by a single panmictic stable population.
