Identification of proteins determining the virulence of Listeria monocytogenes using the bioinformation analysis]

The postgenomic stage of biotechnology allows the bioinformation approaches to be used for revealing previously unknown factors involved in different processes. In this work, bioinformation approaches were applied to analysis of factors involved in the L. monocytogenes virulence. Several open reading frames (ORFs) were identified in L. monocytogenes genome, which encode proteins with high level homology to bacterial peptidases and which meets the developed criteria. The influence of the ORFs on virulence was demonstrated by infection of mice with L. monocytogenes strains mutated in the studied genes. Growth rates, morphology, and production of surface proteins characterized the obtained strains.     

Interindividual hyperpolymorphism of autosomal satellites III of human DNA

Hypervariability of DNA restriction fragments from pericentromeric heterochromatin detected by autosomal "classic" DNA of satellite III has been demonstrated in this work. Using hybridization probe of satellite III DNA localized predominantly on the chromosome 9 strong interindividual differences in the sets of polymorphic DNA restriction fragments inherited from both paternal and maternal sides as well as intraspecies amplifications of some variants of the satellite III were observed. The number and intensity of restriction bands are identical in both sexes. It is suggested that strong interindividual DNA variability may be largely specified by high level of DNA spot mutability in satellites III. Pericentromeric "classic" satellites III may serve as efficient markers for identification of individuals and for molecular-genetic mapping of human genome pericentromeric regions.     

Molecular cytogenetic research on the polymorphism of segments of the constitutive heterochromatin in human chromosomes

Cloned alpha-satellite DNA sequences were used to evaluate the specificity and possible variability of repetitive DNA in constitutive heterochromatin of human chromosomes. Five probes of high specificity to individual chromosomes (chromosomes 3, 11, 17, 18 and X) were hybridized in situ to metaphase chromosomes of different individuals. The stable position of alpha-satellite DNA sequences in definite heterochromatic regions of particular chromosomes was found. Therefore, the chromosome-specific alpha-satellite DNA sequences may be used as molecular markers for heterochromatic regions of certain human chromosomes. The significant interindividual differences in relative copy number of alpha-satellite DNA have been detected. The homologous chromosomes of many individuals were characterized by cytologically visible heteromorphisms, as shown by intensity of hybridization with chromosome-specific alpha-satellite DNA sequences. A special analysis of hybridization between homologues with morphological differences gives evidence for a high resolution power of in situ hybridization technique for evaluation of chromosome heteromorphisms. The approaches for detection of heteromorphisms in cases without morphological differences between homologues are discussed. The results obtained indicate that constitutive heterochromatin of human chromosomes is variable for amount of alpha-satellite DNA sequences. In situ hybridization of cloned satellite DNA sequences may be used as novel general approach to analysis of chromosome heteromorphisms in man.     

Cloned fragment of human alphoid DNA--a molecular marker of the pericentromeric region of chromosome 18

From the library of cloned fragments of human DNA we have isolated two recombinant plasmids containing alphoid DNA sequences pBRHS13, pBRHS65. Both cloned sequences hybridized in situ predominantly to pericentromeric regions of chromosome 18 and with less intensity to pericentromeric regions of chromosomes 2, 9, 20, and were characterized by populational copy number polymorphism in homologous chromosomes. These sequences may appear very useful in the diagnostics and cytogenetic analysis of chromosomal aberrations and in studies of polymorphisms of heterochromatic regions of human chromosomes.     

Species specific variant of human centromeric DNA repeats: localization on chromosome 18 and recent amplification in human ancestral line

Plasmid library of rapidly renaturating fraction of human DNA was constructed. The library was used for isolation of primate-specific DNA repeats. A clone (1hsp-4) which was intensively hybridizable with human DNA exclusively and produced no signals when hybridized with animal DNAs including the ones from orangoutan and chimpanzee was isolated. The cloned sequences 1hsp-4 have been found to be highly specific to centromeric heterochromatin of the 18 chromosome. Primary structure of a short 1hsp-4 fragment has been determined. The obtained data suggest the emergence of a DNA family homologous to the 1hsp-4 probe to be due to the thousandfold leapwise amplification occuring less than 5-8 millions years ago.     

Haemodynamic structure of the venous return changes in action of pressor neurogenic and humoral stimuli upon the circulation system

In cats, constancy of blood flow changes was found in the anterior vena cava under the effect of pressor neurogenic and humoral stimuli. The latter proved to be more efficient in their effect. In the pressor systemic responses, changes of the blood flow in the anterior vena cava yielded the greates contribution.     

X chromosome inactivation pattern in elderly women over 70 years of age

In the present study we have analyzed X chromosome inactivation patterns in 40 women aged from 74 to 85 years (mean age 78 years). The control group was 36 women (mean age 30 years). The most common AR-assay was used to determine X-inactivation patterns (the study of methylation patterns of HpaII site in human androgen receptor gene (HUMARA) by quantative PCR). The age dependence of X-inactivation was not observed. We have detected skewed X-inactivation in three women among 40 (7.5%) elderly women comparing to two women among 36 (5.5%) women from control group. The difference was not found to be statistically significant. We made a suggestion that higher incidence of skewed X-inactivation in elderly women revealed by previous studies could occur due to some experimental ambiguities as heterogeneity of the group studied; inclusion of women having relatives with genetic abnormalities associated with skewed X-inactivation patterns; the difference of X chromosome inactivation skewing determination. We conclude that present study does not show X chromosome inactivation to be age dependent.