Vol 53, No 8 (2017)

The European water frog (Pelophylax esculentus) complex represents a unique and adequate model system for the study of interspecific hybridization and the mechanisms enabling interspecific hybrids to overcome the reproductive barriers. The difficulties in the study of individuals from the P. esculentus complex are associated with high polymorphism of morphological characters in parental species and interspecific hybrids, as well as with the presence of polyploid hybrid forms. From the discovery of the phenomenon of interspecific hybridization and the demonstration of successful reproduction of interspecific hybrids, researchers constantly searched for the methods necessary for the most accurate identification of parental species and various hybrid forms. This review describes biochemical, cytogenetic, and molecular methods and approaches used to identify individuals from the European water frog complex, as well as to analyze the genomes transferred with the gametes of hybrids. The advantages and disadvantages of these approaches are discussed. The presented methods can be used for studying other hybrid complexes of fish, amphibians, and reptiles.

The genetic diversity and population structure of Taxus cuspidata Sieb. et Zucc. ex Endl. on the Russian part of its range was studied for the first time on the basis of the nucleotide polymorphism of intergenic spacers psbA–trnH, trnL–trnF, and trnS–trnfM of chloroplast DNA. A high level of gene (h = 0.807) and nucleotide (π = 0.0227) diversity was revealed. The data of AMOVA showed that the interpopulation component accounted for 12% of genetic variability (F_ST = 0.12044, P = 0.0000). We revealed 15 haplotypes, four of which were shown to be unique. The presence of common haplotypes in the majority of populations, the absence of phylogenetic structure, and low values or even the absence of nucleotide divergence show that the T. cuspidata populations studied are fragments of the once common ancestor population. Geographical isolation, which resulted from climatic changes in the Pleistocene–Holocene, as well as from human activities, did not produce a significant effect on the genetic structure of the species.

Molecular genetic analysis of some ecological forms of whitefish belonging to the Coregonus lavaretus (L.) complex from different water bodies of Siberia revealed a high degree of differentiation between them. On the basis of the analysis of the mitochondrial DNA protein-coding ND1 gene, it was demonstrated that the previously described ecological forms of C. anaulorum, Yenisei River whitefish, or Issatschenko’s whitefish (C. fluviatilis), and cisco-like whitefish from Lake Baunt were good biological species. Moreover, each ecological form was represented by a number of phylogenetic lineages, one of which was species-specific. The remaining lineages were characterized by the mitochondrial DNA of another whitefish species, usually, the most common in each geographic region. The results of genetic analysis demonstrated that the formation of modern ecological forms of Siberian pidschian-like whitefish was accompanied by natural introgressive hybridization. It is suggested that most of the modern pidschian-like whitefish species originated as a result of reticulate evolution.

We analyzed the polymorphic loci in the genes of the antioxidant system enzymes, such as GSTP1 (313A>G and 341C>T), MnSOD (47С>Т), GPx1 (599C>T), and CAT (–262C>>T), among 497 residents of Kemerovo oblast (Western Siberia, Russia). The analysis of the single-locus effects demonstrated a significant protective effect of the major C allele in the GPx1 (599C>T) locus. The MDR analysis of the gene-gene interactions showed that the GPx1 and the CAT genes work in close cooperation and mutually reinforce the risk of development of squamous cell lung cancer among the inhabitants of the industrial region.

The genetic structure of susceptibility to type 1 diabetes (T1D) in the population of Tomsk was studied. We had a group of T1D patients (N = 285) and a population sample (N = 300) and we studied 58 SNPs localized in the 47 genes which products are involved in various metabolic pathways and processes as fibrogenesis, endothelial dysfunction, and inflammation. Genotyping was performed by mass spectrometry using the Sequenom MassARRAY system (United States). We compared the group of T1D patients and the population sample and found an association with the predisposition to disease for seven markers: rs3765124 of the ADAMDEC1 gene, genotype AA (p = 0.004), allele A (p = 0.033); rs1007856 of the ITGB5 gene, genotype TT (p = 0.015), allele T (p = 0.036); rs20579 of the LIG1 gene, genotype CC (p = 0.004), allele C (p = 0.002); rs12980602 of the IFNL2 gene, allele C (p = 0.029); rs4986819 of the PARP4 gene, allele C (p = 0.044); rs1143674 of the ITGA4 gene genotype GG (p = 0.002); rs679620 of the MMP3 gene, genotype AA (p = 0.008). Thus, the products of genes associated with T1D belong to different molecular classes: metalloproteases (ADAMDEC1, MMP3), cytokines (IL28A), cell surface receptors (ITGA4), adhesion molecules (ITGB5), DNA ligases (LIG1), and ribosyltransferase enzymes (PARP4). The ADAMDEC1, ITGA4, and ITGB5 genes belong to two biological processes: cell communication and signal transduction. The LIG1 and PARP4 genes regulate the metabolism of nucleic acids, MMP3 is involved in the regulation of protein metabolism, and the IFNL2 is involved in the immune response.

The c.-23+1G>A splice site mutation is one of the most frequent mutations of gene GJB2 (Cx26, 13q11-q12) associated with congenital non-syndromic autosomal recessive deafness. This mutation is characterized by a wide spread from Eastern Siberia and Central Asia to Eastern Europe, the Middle East, and South Asia. It is currently unknown whether this mutation spread over such a vast territory as a result of the founder effect or there were several local centers of origin of this mutation. For the first time, on the basis of the analysis of variability of nine SNP markers, five different haplotypes in deaf patients homozygous for mutation c.-23+1G>A from six Eurasian populations were reconstructed. The structure of the haplotypes revealed in Yakuts, Russians, Evenks, Tuvinians, Mongols, and Turks makes it possible to assume that mutation c.-23+1G>A (GJB2) could have spread across Eurasia as a result of the founder effect. The greatest diversity of haplotypes with c.-23+1G>A was found in patients from Mongolia, which probably refers to the earlier period of expansion of haplotypes carrying this mutation on the territory of Central Asia.