The article presents data on the mercury content in the muscles of perch Perca fluviatilis (L.) in four large reservoirs of the Vologda region (Kubenskoe and Vozhe lakes, river and lake (Lake Beloe) parts of the Sheksna reservoir) collected during the period 2007–2018. The metal concentration varied widely: from 0,01 mg/kg for perch from Lake Vozhe to 1,51 mg/kg for perch from Lake Kubenskoe. The highest percentage of fish with mercury content exceeding the established SanPiN 2.3.2.1078-01 norms (29,4%) was recorded in perch from Lake Kubenskoe, while the smallest – in fish from Lake Vozhe (5,4%). In fish from the Sheksna reservoir the content of the toxicant in muscles did not go beyond the accepted SanPiN 2.3.2.1078-01 norms. For all perch samples, a statistically significant positive correlation between mercury content and linear-weight characteristics, as well as fish age, was established.
The purpose of this article is analysis of the relevance of whitefish commercial fisheries regulation in Kubenskoye Lake and development of measures to preserve the endemic whitefish population, increase its commercial stocks and catches.The material for the study is the statistics of whitefish-nelmushka catches in Kubenskoye Lake and the longterm dynamics of the size and age characteristics, terms of puberty.The research methods: field ichthyological materials were collected and processed according to standard methods; the fishing stocks were estimated based on the results of the analysis of non-water fishing catches, as well as taking into account the volume of water filtered by fixed fishing nets per unit of time.Results: the long-term dynamics of whitefish-nelmushka catches are described in the article. The effectiveness of its fisheries regulation has been studied. Fishing does not have a significant impact on the whitefish abundance dynamics. The exclusion of whitefish from the category of aquatic biological resources, in respect of which the total allowable catch is established, is justified in the article. The size and age population characteristics of the whitefish, age of puberty last years have been summarized in the article.Practical significance: artificial reproduction of the Kubenskoye Lake whitefish is recommended to be carried out to restore the population abundance, which is significant for the preservation of the gene pool of the polymorphic species Coregonus lavaretus. Recommendations on changing the Fishing Rules for the Northern Fishery Basin to reduce the legal size for whitefish-nelmushka were developed for the implementation of commercial and recreation fisheries.
The article presents information about the mercury content in the muscle tissue of the European grayling Thymallus thymallus (L.) in 11 rivers of the Vologda region (Tagazhma, Vozhega, Votcha, Kostyuga, Tiksna, Sheben’ga, Pyrnug, Zemtsovka, Yurmanga, Bol’shaya Rechka and Yontala) for the period of 2011–2015. The average content of toxicant ranged from 0,04 mg/kg in individuals of the river Sheben’ga up to 0,21 mg/kg in the rivers Yurmanga and Bol’shaya Rechka. Four fish noted an excess of the permissible level of sanitary and hygienic standards (SanPiN 2.3.2.1078-01. 2.3.2.) for non-predatory fish species (0,3 mg/kg). Young grayling contains an average of 0,06–0,10 mg/kg mercury in muscle tissue, individuals five to six years old contain 0,26 and 0,27 mg/kg, respectively. A comparison of the level of mercury concentration in the muscle tissue of European grayling with that of other fish species showed that the Hg content does not go beyond the revealed background values for water bodies of the Vologda region.
This paper presents results of the experiments performed on a nonconventional and extremely interesting in regard to evolution, creature, the European river lamprey Lampetra fluviatilis (Petromyzontiformes, Cyclostomata), one of the oldest taxa of vertebrates. We present detailed immunocytochemical and electron microscopy analyses of chromosome synapsis, the transcription process, and chromatin dynamics in lamprey prophase I, which is the first time for science. We found that not all chromosomes complete synapsis. Rounded structures were detected in chromatin and in some synaptonemal complexes but their nature could not be determined conclusively. An analysis of RNA polymerase II distribution led to the conclusion that transcriptional reactivation in lamprey prophase I is not associated with the completion of chromosome synapsis. Monomethylated histone H3K4 is localized to meiotic chromatin throughout prophase I, and this pattern has not been previously detected in the animals. Thus, the findings made it possible to identify synaptic and epigenetic patterns specific for this group, and to add new pieces of the puzzle to the discussions of the scientific issues under study. The research on lamprey meiotic chromatin and chromosomal dynamics raises many questions leading to new discoveries.
Transcription is known to be substage-specific in meiotic prophase I. If transcription is reactivated in the mid pachytene stage in mammals when synapsis is completed, then this process is observed in the zygotene stage in insects. The process of transcriptional reactivation has been studied in a small number of different taxa of invertebrates and vertebrates. Here, for the first time, we investigate synapsis and transcription in prophase I in the European river lamprey Lampetra fluviatilis (Petromyzontiformes, Cyclostomata), which is representative of jawless vertebrates that diverged from the main branch of vertebrates between 535 and 462 million years ago. We found that not all chromosomes complete synapsis in telomeric regions. Rounded structures were detected in chromatin and in some synaptonemal complexes, but their nature could not be determined conclusively. An analysis of RNA polymerase II distribution led to the conclusion that transcriptional reactivation in lamprey prophase I is not associated with the completion of chromosome synapsis. Monomethylated histone H3K4 is localized in meiotic chromatin throughout prophase I, and this pattern has not been previously detected in animals. Thus, the findings made it possible to identify synaptic and epigenetic patterns specific to this group and to expand knowledge about chromatin epigenetics in prophase I.
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