[Genetic and cytogenetic predictors of human chromosomal radiosensitivity].

We studied association between the frequencies of gamma-induced (1 Gy in vitro) chromosome aberrations in blood lymphocytes and polymorphism of 45 repair candidate genes, detoxification and oxidative stress genes (53 sites) for 99 healthy volunteers. The levels of chromosome-type aberrations correlated with carriage of the minor alleles of the genes OGG1 Ser326Cys, ABCB1 Ile1145 = and NQO1 Pro187Ser (p = 0.0002). We have shown that all the revealed genetic associations were less effective in predicting chromosomal radiosensitivity as compared to the correlations between spontaneous and gamma-induced aberrations (p = 1.0 x 10(-6)). The addition of genetic markers to cytogenetic predictors improved the predictive accuracy for chromosomal radiosensitivity with the multiple correlation coefficient reaching R = 0.58 (p = 3.1 x 10(-8)). Thereby we were able to explain more than 30% of the population variability in chromosomal radiosensitivity.

[Allelic variants of polymorphic genes associated with a higher frequency of chromosome aberrations].

Genotypic associations were studied for the frequency of chromosome aberrations in human peripheral blood lymphocytes. Cytogenetic analysis (1000 metaphase plate per individual) and genotyping at 19 sites of genes involved in detoxification and DNA repair were performed in a sample of 83 Chernobyl liquidators and a matched control sample of 96 volunteers. In either sample, the frequency of chromosome aberrations was higher in carriers of the minor alleles of the XPD gene (sites 2251T > G and 862G > A) and the positive genotypes of the GSTM1-GSTT1 genes. The highest frequency of chromosome aberrations was observed in carriers of a combined genotype including at least one minor allele of the XPD sites + at least one insertion in the GSTM1-GSTT1 genes. The high-risk genotype, which had a prevalence of 64%, was strongly associated with a higher frequency of chromosome aberrations in both volunteers (OR = 6.9, P = 0.008) and Chernobyl liquidators (OR = 5.6, P = 0.002).

[The relationship between genotypes and frequencies of chromosome aberrations in human lymphocytes under irradiation in vivo and in vitro].

The data on the variability of an elevated level of the frequencies of chromosome aberrations for a group of liquidators of the Chernobyl Nuclear Station accident depending on genotypes by candidate loci are presented. The genotyping was carried out by sites, which previously showed the associations with the cytogenetic variability in control experiments. It was shown that, for a group of liquidators heterozygote by site SOD2 C47T, the control level of the frequency of chromosome aberrations is not exceeded significantly. At the tendency level, the frequency of aberrations for liquidators was reduced for double homozygotes by deletions of genes GSTM1-GSTT1 and for homozygotes by the minor allele of site CYP1A1 T606G that is in an accordance with the results of experiments with the control sampling. The elevated level of chromosome aberrations for liquidators, as a whole, is observed for genotypes, which are characteristic of an elevated level of spontaneous aberrations, and it does not completely correspond to genotypes with the elevated radiosensitivity of chromosomes.

[Polymorphism of repair genes and cytogenetic radiation effects].

For 99 healthy volunteers, the frequencies of spontaneous and y-induced (1 Gy in vitro) chromosome aberrations in blood lymphocytes were compared with the results of PCR-genotyping by 8 repair genes: XRCC1, XPD, ERCC1, APEXI, RAD23B, OGG1, ATM, Tp53 (in all, 10 polymorphic sites). The frequency of spontaneous aberrations of chromosome type increased additively with the number of copies of minor allele of excision repair gene XPD variant *2251G and *862A D (p = 0.025). The frequency of gamma-induced chromosome aberrations proved to be elevated for the carriers of a minor allele OGG1*977G (p = 0.011). The significantly elevated number of gamma-induced chromosome aberrations was also observed for the carriers of major alleles XRCC1*G1996 and XRCC1*C589 (p = 0.002).

[Somatic mutagenesis in human lymphocytes depending on genotypes for detoxification and oxidative response loci].

Associations of polymorphism of seven detoxification genes and three genes of oxidative response with the frequency of chromosome aberrations in human peripheral blood lymphocytes were studied. The genotyping data were correlated with the frequencies of spontaneous and gamma-induced (1 Gy in vitro) chromosome aberrations estimated for a group of healthy donors (97 males under 25 years of age) by analyzing 500-1000 metaphase cells per individual. The spontaneous level of aberrations of the chromosomal type was reduced in homozygotes for the GSTM1 locus deletion, and especially in double homozygotes for deletions of the GSTM1 and GSTT1 genes. The frequency of gamma-induced chromosome aberrations was reduced in G/G homozygotes for the minor allele of the poorly studied CYP1A1 T606G site: 0.094 +/- 0.006 against 0.112 +/- 0.002 for T allele carriers (P = 0.004). Linkage of the T606G site with well known and functionally important sites of the CYP1A1 gene (A4889G, T3801C) was analyzed.

[The effect of polymorphism of genes of xenobiotics detoxication on the frequencies of spontaneous and induced chromosome aberrations in human lymphocytes].

Here presented the data on the frequencies of chromosome aberrations in lymphocytes of peripheral blood of 97 volunteers depending on genotypes by genes of xenobiotics detoxication before and after gamma-irradiation with dose of 1 Gy in vitro. The frequencies of aberrations were estimated by analyzing not less than 500-1000 metaphases per person. The data of cytogenetic analysis were compared with the results of PCR-genotyping of loci GSTM1, GSTT1, GSTP1, CYP1A1, CYP2D6, NAT2, and MTHFR. The significant differences by the frequencies of aberrations between "single-locus" genotypes were not found except for GSTM1 locus, for which the enhanced frequency of spontaneous aberrations of chromosome type in "positive" genotypes compared to "zero" ones, i.e., homozygotes by deletion (p = 0.04) was observed. The minimum frequency of spontaneous aberrations of chromosome type was recorded for carriers of double homozygotes by deletion of GSTM1-GSTT1: 0.0006 +/- 0.0003 against 0.0027 +/- 0.0003 for the rest of genotypes (p = 0.016 by the Mann-Witney test). The frequency of gamma-induced chromosome aberrations was correlated with the total amount of minor alleles in loci GSTP1, NAT2, and MTHFR (r = 0.25 at p = 0.0065).

[The association of TCR-mutant cells with DNA polymorphism in women residing in radiation polluted regions of the Russian Federation].

Using flow-cytometric method the frequency of lymphocytes beaming mutations at T-cell receptor (TCR) locus was assessed in women residing in radiation polluted regions of Bryansk and Tula Districts. Simultaneously genotyping of the 8 polymorph loci for genes involved in detoxication of xenobiotics and oestrogen metabolism was carried out. The increased TCR-mutant cell frequency was found to be characteristic of homozygotes of the low activity appropriated enzymes for 3 loci (HFE187, GSTM1 and MTHFR) at least. This tendency was statistically significant in case of deletion polymorphism of the GSTM1 gene: TCR-mutant cell frequency of the homozygous carriers of a deletion at the GSTM1 locus was (4.63 +/- 0.18) x 10(-4) while it was (4.05 +/- 0.15) x 10(-4) in other groups of persons. The greatest mutant cell frequency was observed in carriers of the minor allele 4889G of the locus CYP1A. More often the increased values of the TCR-mutant cells (outside range "3sigma") were determined in women with genotypes A/G or G/G of the locus CYP1A1 (25%) than in carries of the normal genotype A/A (1.6%) (OR = 20.6; p = 0.0002). The comparison of the groups of women with reproductive system diseases reveals significant elevation in the mean TCR-mutant cell frequency in inhabitants of the most radiation polluted region among others.

[The alterations in profiles of RAPD- and of ISSR-markers in progeny of the single gamma-irradiated mice of BALB/c strain].

Molecular-genetic effects in the offspring of BALB/c male mice exposed to single radiation doses of 1, 2 and 3 Gy were studied. Induced genetic variability was studied using such methods as assessment of variation RAPD- and ISSR-profiles. Comparative analysis of genetic radiosensitivity of stem spermatogonia and of spermatids is presented in the work. The frequency of changes in the patterns of the offsprings of irradiated mice was significantly different from the analogous parameters in the offsprings of the control group already at a dose of 1 Gy. Comparative analysis of genetic radiosensitivity at different stages of spermatogenesis revealed the similar sensitivity of spermatogonia and of spermatids at 1 and 3 Gy and a higer sensitivity of spematogonia at 2 Gy.

Characterization of a new densovirus infecting the German cockroach, Blattella germanica.

A new DNA virus (Parvoviridae: Densovirinae, Densovirus) was isolated and purified from descendants of field-collected German cockroaches, Blattella germanica. Viral DNA and cockroach tissues infected with B. germanica densovirus (BgDNV) were examined by electron microscopy. Virus particles, about 20 nm in diameter, were observed both in the nucleus and in the cytoplasm of infected cells. Virus DNA proved to be a linear molecule of about 1.2 microm in length. BgDNV isolated from infected cockroaches infected successfully and could be maintained in BGE-2, a B. germanica cell line. The complete BgDNV genome was sequenced and analysed. Five open reading frames (ORFs) were detected in the 5335 nt sequence: two ORFS that were on one DNA strand encoded structural capsid proteins (69.7 and 24.8 kDa) and three ORFs that were on the other strand encoded non-structural proteins (60.2, 30.3 and 25.9 kDa). Three putative promoters and polyadenylation signals were identified. Structural analysis of the inverted terminal repeats revealed the presence of extended palindromes. The genome structure of BgDNV was compared with that of other members of the family Parvoviridae; the predicted amino acid sequences were aligned and subjected to phylogenetic analyses.