No 2 (2021)
Articles
Modelling of transparency of Lake Baikal inferred from the Sentinel-2 data
Abstract
The remote sensing methods usage makes it possible to increase the accuracy and efficiency of data on the state of water bodies. Among the many satellite systems, Sentinel-2 is the most suitable for inland water assessment. One of the abiotic factors in assessing the trophicity of water bodies is the transparency along the Secchi disk. Models for calculating water transparency have been developed for individual water bodies. The analysis showed that these models don’t adequately describe the transparency for Lake Baikal. Based on the correlation-regression analysis, the parameters of the exponential function were estimated for calculating the transparency of the surface waters of Lake Baikal using the values of the Sentinel-2 spectral channels. Despite the inaccuracy of the model for assessing the transparency in the coastal zone, it can be used to assess the seasonal and interannual transparency of the surface waters of Lake Baikal.
1126-1129
Variability and problem of species identification of sculpins of the genus Cyphocottus (Pisces: Cottidae)
Abstract
Based on the material collected during the fieldwork seasons from 1996 to 2007 in the amount of 223 specimens, we studied phenetic relationships and taxonomic structure of the genus Cyphocottus. Two valid species, C. megalops and C. eurystomus, within the taxonomic boundaries established by D.N. Taliev (1955) were confirmed in the genus Cyphocottus. Interspecific differences in C. eurystomus are manifested in greater values of interorbital distance, the height of the head, body and caudal peduncle, as well as in smaller values of eye diameter and caudal peduncle length. Polymorphism in the definitive sizes, colour and the number of neuromasts in the lateral line is typical of C. eurystomus. At the same time, all populations have specific characters of C. eurystomus different from C. megalops. We found no intraspecific variability in C. megalops.
1130-1136
PCR screening of bacterial strains isolated from the microbiome of the Lubomirskia baicalensis sponge for the presence of secondary metabolite synthesis genes
Abstract
The microbial communities of sponges (Porifera) are often a source of natural bioactive metabolites. From the microbiome of the endemic Lubomirskia baicalensis sponge, 35 bacterial strains were isolated and identified using molecular methods. The strains belonged to the phyla Actinobacteria, Firmicutes, and Proteobacteria (classes Alpha- and Betapriteobacteria). To analyze the strains for the presence of genes in the synthesis of secondary metabolites, polyketide synthases (PKS), PCR screening was applied using degenerate primers. Overall, 15 out of 35 strains contained PCR products corresponding in size to a fragment of the ketosynthase domain of the PKS gene cluster. Thus, the proposed method is applicable for rapid screening of the potential ability of microorganisms of different taxonomic groups to produce secondary metabolites. The work contributes to the study of the taxonomic diversity of cultured microorganisms, potential producers of biologically active substances, isolated from the microbiomes of Baikal sponges.
1137-1142