Ecological Forms of Black Sea Brown Trout (<Emphasis Type="Italic">Salmo trutta labrax</Emphasis>) in the Mzymta River as Manifestation of Ontogenetic Plasticity

Populations of brown trout in the Mzymta River and its tributaries include anadromous (mainly female) and resident (mainly males) fish. Some resident males in the basin of the Mzymty River attain sexual maturity at the age 1+, and resident females mature at the age 2+ or 3+. The maximum age of resident fish is 4+ in the samples studied. Migrations of anadromous brown trout to the sea occur at the ages 1+, 2+, or 3+. Future spawners spend from 1 to 4 years at feeding grounds in the sea. Smolts of the population are characterized by performing not only spring but also autumn migrations to the sea. One smolt specimen has been detected upstream from the dam in the river where spawners of anadromous brown trout do not migrate; this means that the capability for sea migrations persists long in the population represented only by resident specimens of brown trout. The diversity of life cycles and ecological forms in populations of brown trout is not lower than in populations of brown trout in Northern and Western Europe. The comparison of the data obtained with published data makes it possible to come to the conclusion about the high plasticity of ontogenesis of Black Sea brown trout.     

Genes of NAD+-Dependent Formate Dehydrogenases in Taxonomy of Aerobic Methylotrophic Bacteria of the Genus Ancylobacter

Microbiology - Comparative phylogenetic analysis of NAD+-dependent formate dehydrogenases (NAD+-FDH) genes, which have been detected in all available genomes of methylotrophs of the genera...     

Characterization of recombinant fructose-1,6-bisphosphate aldolase from <Emphasis Type="Italic">Methylococcus capsulatus</Emphasis> Bath

The gene fba from the thermotolerant obligate methanotroph Methylococcus capsulatus Bath was cloned and expressed in Escherichia coli BL21(DE3). The fructose-1,6-bisphosphate aldolase (FBA) carrying six His on the C-end was purified by affinity metal chelating chromatography. The Mc. capsulatus FBA is a hexameric enzyme (240 kDa) that is activated by Co²⁺ and inhibited by EDTA. The enzyme displays low K _m to fructose-1,6-bisphosphate (FBP) and higher K _m to the substrates of aldol condensation, dihydroxyacetone phosphate and glyceraldehyde-3-phosphate. The FBA also catalyzes sedoheptulose-1,7-bisphosphate cleavage. The presence of Co²⁺ in the reaction mixture changes the kinetics of FBP hydrolysis and is accompanied by inhibition of the reaction by 2 mM FBP. Phylogenetically, the Mc. capsulatus enzyme belongs to the type B of class II FBAs showing high identity of translated amino acid sequence with FBAs from autotrophic bacteria. The role of the FBA in metabolism of Mc. capsulatus Bath, which realizes simultaneously three C₁ assimilating pathways (the ribulose monophosphate, the ribulose bisphosphate, and the serine cycles), is discussed.     

Structural and functional features of methanotrophs from hypersaline and alkaline lakes

Ten strains of aerobic methanotrophic bacteria represented by halophilic neutrophiles or halotolerant alkaliphiles were isolated from saline and alkaline lakes of southeast Siberia, Mongolia, Africa, and North America. Based on analysis of the nucleotide sequences of 16S rRNA gene and the pmoA gene encoding particulate methane monooxygenase, the isolates were classified as Methylomicrobium alcaliphilum, Methylomicrobium buryatense, and Methylobacter marinus. All strains of the genus Methylomicrobium were shown to synthesize glycoprotein S-layers located on the cell surface with hexagonal symmetry (p6) as a monolayer of cup-shaped structures or fine “inverted” conical structures and as plates consisting of protein subunits with inclined (p2) symmetry. During adaptation to the high salinity of the medium, isolated methanotrophs synthesize osmoprotectants: ectoine, sucrose, and glutamate. The ectC gene encoding ectoine synthase (EctC) was identified in six methanotrophic strains. Phylogenetic analysis of translated amino acid sequence of the ectC gene fragment suggests lateral transfer of the genes of ectoine synthesis as the most probable way for methanotrophs to acquire resistance to high external salinity.     

Ontogenetic niche shifts and resource partitioning in a subarctic piscivore fish guild

The feeding ecology of three piscivorous fish species (perch (Perca fluviatilis), pike (Esox lucius) and burbot (Lota lota)), was studied in the subarctic Pasvik watercourse (69 °N), northern Norway and Russia. All three species primarily occupied the benthic habitats in the watercourse. Perch and burbot exhibited distinct ontogenetic niche shifts in food resource use, perch changing from a dominance of zooplankton to zoobenthos to fish, and burbot from zoobenthos to fish. Fish prey dominated the diet of all the investigated size-classes of pike, but small-sized pike (<20 cm) were not represented in the sample. Fish prey size was positively related to predator size in all three species. Whitefish (Coregonus lavaretus) was the dominant prey of pike and large-sized burbot and perch. Nine-spined sticklebacks (Pungitius pungitius) was also an important prey and appeared to be a dietary stepping-stone enhancing the transition from invertebrate feeding to consumption of large-sized whitefish prey for all three predators. A cluster analysis separated the different size groups of the three predator species into five functional feeding groups, most of them containing two or all three species. Within these feeding groups, and especially among the piscivorous size-classes, there was a strong and significant interspecific overlap in prey selection, and the dietary similarities between the species were in general much larger than the intraspecific similarities between ontogenetic stages. All three piscivorous species are important top predators in the aquatic food web of the watercourse, and their ontogenetic diet shifts and resource partitioning patterns generate a substantial food web complexity in this subarctic ecosystem.     

Analysis of Some Physiological and Biochemical Indices in Patients with Covid-19 Pneumonia Using Mathematical Methods

Journal of Evolutionary Biochemistry and Physiology - The aim of the work was to conduct a retrospective analysis of the clinical data of patients with pneumonia caused by the SARS-CoV-2 virus, and...