[Phenotypic and genetic changes of entomopathogenic ascomycete Beauveria Bassiana under passaging through various hosts].

Phenotypic and genetic estimations of entomopathogenic ascomycete B.bassiana (strain Sar-31) after 6-passaging through four hosts were shown. Increasing of virulence, changes in morpho-cultural characteristics and variations in Inter Simple Sequence Repeats (ISSR) assay between initial and reisolated cultures were registered. Six passages of entomopathogenic ascomycete Beauveria bassiana (strain Sar-31) through four hosts (Galleria mellonella, Tenebrio molitor, Leptinotarsa decemlineata, Locusta migratoria) and following estimation of phenotypic and genetic differences of the initial strain and reisolated cultures were conducted. The passaging of strain through certain host led to increasing of virulence for both this host and other test-insects. Unidirectional changes of morpho-cultural characteristics: colonies pigmentation and relief strengthening, increasing of conidia production and lipolytic activity were registered in all passaged cultures. Genetic analysis with 6 ISSR markers revealed variations between initial and reisolated cultures in 3 markers. Taken together, the results of this study help us understand potential ways of fungi strains changes during epizootic process and possibilities of ISSR assay applying for investigation of pathogen transmission.

[COMPARATIVE ANALYSIS OF THE IMMUNE REACTIONS IN COLORADO POTATO BEETLE LARVAE UNDER DEVELOPMENT OF MYCOSES CAUSED BY METARHIZIUM ROBERTSII, M. BRUNNEUM AND M. PEMPHIGI].

A comparative investigation of humoral and cellular immune response in larvae of Colorado potato beetle Leptinotarsa decemlineata was conducted under development of mycoses caused by entomopatho- genic fungi Metarhizium robertsii, M. brunneum and M. pemphigi. The larvae were found highly suscep- tible to M. robertsii, M. brunneum and less susceptible to M. pemphigi. The susceptibility to the fungi was not correlated with the rate of conidia germination in epicuticular extracts of larvae. A non-specific for Colorado beetle pathogen M. pemphigi did not cause significant changes in the immune response and did not result in colonization of larvae hemocoel. Infection with M. robertsi and M. brunneum led to an increase in total hemocyte count at the initial stages of mycoses (day 2) followed by a sharp decrease on day 3. The strongest decrease was observed for the immunocompetent cells - plasmatocytes and granu- locytes. Enhanced phenoloxidase activity in hemolymph and cuticle was found on days 2 and 3 after in- fection. These changes in immune reactions correlated with the level of virulence of the strains. Thus, the immune response in Colorado potato beetle larvae is an important factor determining differences in the development of mycoses caused by different Metarhizium species.

[Microrna, evolution and cancer].

MicroRNAs are known as a posttranscriptional negative regulators of gene expression by binding to the 3'UTP of target mRNAs in cytoplasm. More than 1600 microRNAs expressed in human cells, are involved in the regulation of embryogenesis, differentiation, cell cycle, apoptosis, senescence, thus determining cell fate. Up to 60 % of protein coding genes are under their control. Various sets of microRNAs found in different human tissues under normal and pathological conditions, including cancer, suggest that miRNAs are involved in most cellular pathways. To date, there is no doubt that regulatory potential of the genome is largely determined by miRNAs. In our study, we performed a comparative phylogenetic analysis of the origin and evolution of the total set of 1048 miRNAs in the human genome and investigated the role of certain miRNAs in carcinogenesis of thyroid and mammary glands, as potential diagnostic and prognostic biomarkers of malignancy. Analysis of phylogenetic distribution of miRNAs in the human genome has shown four peaks of appearance of new miRNA genes in the evolution from Methazoa to H. sapiens. The highest amount of new miRNA genes appeared after divergence of H. s. from common ancestor with P. t. Expansion of transposable elements in genome was accompanied by the origin of new miRNA genes on the basis of their sequences. More than 14 % from 1600 miRNAs of human genome originated from mobile elements and still remain. Profiles of expression of 5 miRNAs, pertaining to oncomicroRNAs - miR-21, -221, -222, -155 and -205 - allow distinguishing ductal invasive carcinoma of mammary gland and thyroid papillary carcinoma. The data obtained suggest different ways and roles of participation of the same miRNAs in carcinogenesis of thyroid and mammary glands. So, these miRNAs and profiles of their expression might be used in the diagnosis and prognosis of cancer.

Repetitive DNA sequences in the common vole: cloning, characterization and chromosome localization of two novel complex repeats MS3 and MS4 from the genome of the East European vole Microtus rossiaemeridionalis.

We have characterized two novel, complex, heterochromatic repeat sequences, MS3 and MS4, isolated from Microtus rossiaemeridionalis genomic DNA. Sequence analysis indicates that both repeats consist of unique sequences interrupted by repeat elements of different origin and can be classified as long complex repeat units (LCRUs). A unique feature of both repeat units is the presence of short interspersed repeat elements (SINEs), which are usually characteristic of the euchromatic part of the genome. Comparative analysis revealed no significant stretches of homology in the nucleotide sequences between the two repeats, suggesting that the repeats originated independently during the course of vole genome evolution. Fluorescence in situ hybridization analysis demonstrates that MS3 and MS4 occupy distinct domains in the heterochromatic regions of the sex chromosomes in M. transcaspicus and M. arvalis but collocalize in M. rossiaemeridionalis and M. kirgisorum heterochromatic blocks. The localization pattern of the repeats on the vole chromosomes confirms the independent origin of the two repeats and suggests that expansion of the heterochromatic blocks has occurred subsequent to speciation.

Characterization of the genomic Xist locus in rodents reveals conservation of overall gene structure and tandem repeats but rapid evolution of unique sequence.

The Xist locus plays a central role in the regulation of X chromosome inactivation in mammals, although its exact mode of action remains to be elucidated. Evolutionary studies are important in identifying conserved genomic regions and defining their possible function. Here we report cloning, sequence analysis, and detailed characterization of the Xist gene from four closely related species of common vole (field mouse), Microtus arvalis. Our analysis reveals that there is overall conservation of Xist gene structure both between different vole species and relative to mouse and human Xist/XIST. Within transcribed sequence, there is significant conservation over five short regions of unique sequence and also over Xist-specific tandem repeats. The majority of unique sequences, however, are evolving at an unexpectedly high rate. This is also evident from analysis of flanking sequences, which reveals a very high rate of rearrangement and invasion of dispersed repeats. We discuss these results in the context of Xist gene function and evolution.