Microsatellite variation in white-spotted char Salvelinus leucomaenis from Sakhalin oblast

Russian Journal of Genetics - A panel of 12 polymorphic microsatellite markers was developed for the population genetic studies of white-spotted char Salvelinus leucomaensis. The four population...     

Genetic divergence of chars of the genus Salvelinus from Kronotsky Lake (Kamchatka Peninsula)

Chars from the genus Salvelinus, inhabiting lakes and lake-river systems, belong to morphologically and ecologically different forms whose taxonomic status is under dispute. In the present work, we have examined genetic variation and divergence in various chars from the Kronotsky lake basin: the lacustrine chars (white, nose, and long-head) and Dolly Varden char Salvelinus malma. The study was conducted using analysis of allozyme and microsatellite loci, myogens, RAPD, and restriction analysis of two mtDNA segments. The estimates of heterozygoisty at allozyme and microsatellite loci were similar to the corresponding parameters in populations of northern Dolly Varden and Arctic char. Heterozygote deficit was recorded in both samples of individual forms, and in the combined sample of all chars from Kronotsky Lake. For both markers, appreciable genetic differentiation among the samples of different char forms was found, which was comparable to that among the spatially isolated populations of northern Dolly Varden. This result indicates reproductive isolation among the char forms examined. However, this isolation is not complete, because no fixed differences between the forms by any of the genetic systems analyzed was found. The genetic differentiation among different forms of lacustrine chars, which corresponds to the interpopulation rather than interspecies level, is thought to be explained by their comparatively recent divergence.     

The auxins centrophenoxine and 2,4-D differ in their effects on non-directly induced chromosome doubling in anther culture of wheat (T. aestivum L.)

Doubled haploid technologies have become key tools for plant breeding. Using these techniques, the speed and efficiency of plant improvement processes can be significantly enhanced. Anther culture-based technologies have the potential to regenerate large numbers of doubled haploid plants without colchicine treatment. In an attempt to elucidate the influence of phytohormones on non-directly induced chromosome doubling, two synthetic auxins, 2,4-D and centrophenoxine, were tested in a wheat anther culture approach. Whereas the induction of androgenic embryo-like structures (ELSs) was efficient for both auxins, we observed a significantly higher frequency of chromosome doubling when using 2,4-D than when using centrophenoxine. When 2,4-D was added to the induction medium, a positive correlation between the size of ELSs and their ploidy level was detected by flow cytometry. The morphological selection of ELSs, a process that was included in routine operations of the method without significantly extending the input of time and effort, facilitates the production of fertile DH plants with a frequency of 60 %. Our findings may contribute to a more efficient production of doubled haploid wheat plants using a colchicine-free anther culture approach.     

Novel enzyme preparations with high pectinase and hemicellulase activity based on Penicillium canescens strains

Applied Biochemistry and Microbiology - Recombinant strains of Penicillium canescens producing homologous pectin lyase A and heterologous endo-1,5-α-arabinase A and...     

Mechanisms of the adaptation of the Kildin cod <Emphasis Type=Italic>Gadus morhua kildinensis</Emphasis> Derjugin, 1920 (Pisces: Gadidae) to the specific conditions of Lake Mogilnoye

The mechanisms of the adaptation of the Kildin cod to the conditions of a meromictic lake were analyzed based on the study of morphological, biological, and genetic characteristics. Significant differences between the Kildin cod and Atlantic cod have been found in their morphological and genetic characteristics. The results of an X-ray microanalysis of otoliths, which were conducted for the first time, confirm that the distribution range of the Kildin cod in Lake Mogilnoye also extends to brackish waters. It has been shown that the formation of the reproductively isolated lacustrine population of Kildin cod is accompanied by specialization in a number of characteristics (body color, feeding strategy, behavior, etc.) and by a decrease in genetic diversity.     

phiC31 Integrase-Mediated Site-Specific Recombination in Barley

The Streptomyces phage phiC31 integrase was tested for its feasibility in excising transgenes from the barley genome through site-specific recombination. We produced transgenic barley plants expressing an active phiC31 integrase and crossed them with transgenic barley plants carrying a target locus for recombination. The target sequence involves a reporter gene encoding green fluorescent protein (GFP), which is flanked by the attB and attP recognition sites for the phiC31 integrase. This sequence disruptively separates a gusA coding sequence from an upstream rice actin promoter. We succeeded in producing site-specific recombination events in the hybrid progeny of 11 independent barley plants carrying the above target sequence after crossing with plants carrying a phiC31 expression cassette. Some of the hybrids displayed fully executed recombination. Excision of the GFP gene fostered activation of the gusA gene, as visualized in tissue of hybrid plants by histochemical staining. The recombinant loci were detected in progeny of selfed F₁, even in individuals lacking the phiC31 transgene, which provides evidence of stability and generative transmission of the recombination events. In several plants that displayed incomplete recombination, extrachromosomal excision circles were identified. Besides the technical advance achieved in this study, the generated phiC31 integrase-expressing barley plants provide foundational stock material for use in future approaches to barley genetic improvement, such as the production of marker-free transgenic plants or switching transgene activity.     

Telomerase RNA biosynthesis and processing

Telomerase synthesizes repetitive G-rich sequences (telomeric repeats) at the ends of eukaryotic chromosomes. This mechanism maintains the integrity of the genome, as telomere shortening leads to degradation and fusion of chromosomes. The core components of telomerase are the telomerase catalytic subunit and telomerase RNA, which possesses a small template region serving for the synthesis of a telomeric repeat. Mutations in the telomerase RNA are associated with some cases of aplastic anemia and also cause dyskeratosis congenita, myelodysplasia, and pulmonary fibrosis. Telomerase is active in 85% of cancers, and telomerase activation is one of the first steps in cell transformation. The study of telomerase and pathways where this enzyme is involved will help to understand the mechanism of the mentioned diseases and to develop new approaches for their treatment. In this review we describe the modern conception of telomerase RNA biosynthesis, processing, and functioning in the three most studied systems — yeast, vertebrates, and ciliates.     

Preliminary data on variation of four microsatellite loci in Pacific herring Clupea pallasii

Variation of microsatellite loci Cpa 10, Cpa 113, Cpa4, and Cpa7 was for the first time examined in Pacific-type herring Clupea pallasii from the White Sea (CI. pallasii marisalbi), the Kara Sea (CI. pallasii suworowi), the Sea of Okhotsk, and Lake Nerpich'e, Kamchatka Bay, northwestern Pacific (CI. pallasiipallasii). All loci exhibitedhigh genetic diversity. The estimates of expected heterozygosity varied from 41.5 to 95.6% (mean, 82%). The level of pairwise genetic differentiation Fst at all microsatellite loci varied from 0.005 to 0.076 (0.019, on average) and t was statistically significant (P < 0.05) in most of the pairs of herring samples. Estimates of genetic differentiation among the herring of one subspecies were lower than between the groups belonging to different subspecies.     

Influence of the spacer region between the Shine–Dalgarno box and the start codon for fine-tuning of the translation efficiency in Escherichia coli

Translation efficiency contributes several orders of magnitude difference in the overall yield of exogenous gene expression in bacteria. In diverse bacteria, the translation initiation site, whose sequence is the primary determinant of the translation performance, is comprised of the start codon and the Shine–Dalgarno box located upstream. Here, we have examined how the sequence of a spacer between these main components of the translation initiation site contributes to the yield of synthesized protein. We have created a library of reporter constructs with the randomized spacer region, performed fluorescently activated cell sorting and applied next-generation sequencing analysis (the FlowSeq protocol). As a result, we have identified sequence motifs for the spacer region between the Shine–Dalgarno box and AUG start codon that may modulate the translation efficiency in a 100-fold range.