A comparative study of the antimutagenic effects of antioxidants on chemical mutagenesis in Drosophila melanogaster

The 1,4-dihydropyridine derivative 2,6-dimethyl-3,5-diethoxycarbonyl-4-(Na carboxylate)-1,4-dihydropyridine (1,4-DHP) was studied for antimutagenic effects in the dominant lethal test and in the sex-linked recessive lethal test of Drosophila melanogaster. The observed effects were compared with those of the radioprotectors cysteine and cysteamine and with those of the phenolic antioxidant butylated hydroxytoluene (BHT). In a wide range of concentrations, including low ones, 1,4-DHP reduces the frequency of EMS-induced genetic damage (point mutations and chromosome breakage). A reduction of the mutation rate induced by EMS in adults could be observed independently of the developmental stages (larvae or imago) pretreated with 1,4-DHP. The protective effect of this new antimutagen against the alkylating agent depended on both the 1,4-DHP dose and the level of the EMS-induced mutation rate. The effect of 1,4-DHP was more pronounced than that of the studied radioprotectors. It is concluded that dihydropyridine-type compounds are able to protect eukaryote germs cells from genetic damage produced by direct-acting mutagens such as EMS.     

Pallister-Killian syndrome: rapid decrease of isochromosome 12p frequency during amniocyte subculturing. Conclusion for strategy of prenatal cytogenetic diagnostics.

Pallister-Killian syndrome (PKS) is characterized cytogenetically by mosaic tetrasomy of chromosome 12p. Routine prenatal diagnosis of PKS is still complicated because of the difficulties of discriminating between the supernumerary isochromosome 12p and the duplication 21q and because of the variable level of mosaicism. The frequency of cells with an extra metacentric chromosome i(12)(p10) is usually determined by tissue-limited or tissue-specific mosaicism. We demonstrated a decrease of the abnormal clone with extra i(12p) in the amniotic fluid cells of the PKS fetus during amniocyte subculturing. The rapid loss of the i(12p) in the course of amniocyte subculturing should be the focus of attention during prenatal karyotyping. This is especially necessary for cultures with slow growth, which require further interpretation of the result during cytogenetic diagnosis of PKS.     

Association of immune system gene polymorphisms with quantitative traits pathogenetically important for chronic virus hepatitis

The IL4 C(?590)T, IL4RA Ile50Val, and TNF G(?308)A polymorphisms were tested for association with quantitative traits important for chronic virus hepatitis, including the levels of IL4, IL10, IL12, TNF-α, fibronectin, collagenase, the proteinase inhibitor, macroglobulin, and free and protein-bound (PBO) oxyproline. Allele A of the TNF G(?308)A polymorphism was associated with a lower TNF-α production by mononuclear cells, a higher production of IL4 and IL12, and a lower PBO level. The genotype CT of the IL4 C(?590)T polymorphism was associated with a high PBO level.     

The comparison of mycoplasma detection methods in the urogenital tract infection

Six different methods have been employed to detect M. hominis (Mh) and U. urealyticum (Uu) in clinical samples collected from 67 men. The results obtained by PCR and IF test were approximately equal: 13.6 and 13.44%--Mh and 44.4 and 48.8%--Uu, respectively. Mycoplasmas were detected by cultural method less frequently (9.6%--Mh, 32.2%--Uu). The highest infection rates were obtained in the test for blood antigens (40%--Mh and 63%--Uu). At present a commercial diagnosticum to detect mycoplasma antigents in blood is lacking. Sometimes the results of cultural method are positive, while the PCR results are negative. So the optimal scheme based on both PCR and culture has been proposed.     

Transgenerational accumulation of radiation damage in small mammals chronically exposed to Chernobyl fallout

The purpose of this investigation has been the analysis of the long-term development of biological damage in natural populations of a model mammalian species, the bank vole (Clethrionomys glareolus, Schreber), which were chronically exposed to low doses of ionizing radiation over 22 animal generations within 10 years following the Chernobyl accident. The time course of the biological end-points (chromosome aberrations in bone marrow cells and embryonic lethality) was compared with the time course of the whole-body absorbed dose rate from external and internal exposure in the studied populations inhabiting monitoring sites in Belarus with different ground deposition of radionuclides. The yield of chromosome aberrations and, in lesser degree, embryonic lethality was associated with the radionuclide contamination of the monitoring areas in a dose-dependent manner. As a main feature of the long-term development of biological damage under low dose rate irradiation, permanently elevated levels of chromosome aberrations and an increasing frequency of embryonic lethality have developed over 22 animal generations. This contrasts with the assumption that the biological damage would gradually disappear since in the same period of time the whole-body absorbed dose rate decreased exponentially with a half-value time of about 2.5–3 years. Furthermore, gravid females were captured, and their offspring, born and grown up under contamination-free laboratory conditions, showed the same enhanced level of chromosome aberrations. Therefore the authors suggest that, along with the biological damage attributable to the individual exposure of each animal, the observed cellular and systemic effects reflect the transgenerational transmission and accumulation, via genetic and/or epigenetic pathways, of damage attributable to the chronic low-dose rate exposure of the preceding generations of animals. They also suggest that the level of the accumulated transmissible damage in the investigated populations will decrease in future due to the further recession of the chronic exposure and as a consequence of selection processes.     

The effects of UV-irradiation of barley plants on the morphophysiological parameters and productivity of the offsprings

In a greenhouse experiment effects have been studied the UV-B-irradiation of barley (intensity of biologically active UV-B-radiation was 0.15, 0.29 and 0.45 W/m2) on the morphophysiologic parameters, productivity and reproductive sphere of offsprings of two succeeding generations. It has been shown that along with a decrease in the specific leaf mass and biomass M1-generation plants exhibited an increase in the stem height and assimilative leaf area. The reduction of grain yield in offsprings of the first post-radiation generation was mainly caused by the reduced size in the reproductive organs and by reduced number of caryopsides in a ear. The observed effects were independent of the UV-B exposure levels to the precursors. The aftereffect of UV-B-irradiation for M2-generation plants shown itself as changes in the specific leaf area, less pronounced compared to the precursors, and reduction in the vegetative mass and grain yield, most significant in offsprings of plants exposed to the maximum UV-B levels. Disturbances in the reproductive sphere appeared as reduction in the size of developing grains. The data derived suggest that long-term effects of UV-B-irradiation are possible not only in the first but also in the second generation of impacted plants.     

Features of moss mat structure and productivity in forest-bog complexes of West Siberia

The species composition and distribution of mosses over microrelief features on bogs have been assessed with various types of the water-mineral nutrient supply. The density of moss stalks in different moss species mats has been examined. Fraction analysis has been applied to weight and morphological characteristics of moss stalks. The contributions made by each fraction to the biomass production have been estimated. The linear and weight parameters of the photosynthesizing layer in mosses have been determined.     

DNA-repair modulation using derivatives of 1,4-dihydroisonicotinic acid as an example

The influence of two derivatives of 1,4-dihydroisonicotinic acid on DNA-repair involved in chemical mutagenesis in Drosophila germ cells has been investigated. The compounds tested decreased the level of EMS-induced chromosome breakage and point mutations due to stimulation of maternal repair of DNA primary damage induced in spermatozoa as well as due to activation of DNA-repair in larvae and imago premeiotic stages of Drosophila males. Deficiency of DNA-repair systems leads to decrease in female and male germ-cell sensitivity to antimutagen action.     

Association study of the Ile50Val polymorphism of interleukin-4 receptor gene (IL4RA) with chronic viral hepatitis

The study was performed to estimate association of the Ile50Val polymorphism in IL4RA and clinical characteristics of chronic viral hepatitis including course of disease manifestation which is determined by degree of hepatic fibrosis. The group under investigation included 61 patient diagnosed with chronic viral hepatitis. Control group consisted of 128 randomly selected inhabitants of Tomsk city. Genotyping of Ile50Val polymorphism in the groups was performed by RFLP (restriction fragment length polymorphism) analysis. There was no significant differences in genotypes and alleles frequencies between cases and controls. However differences in genotype distribution depend on fibrosis stage were detected. Ile/Val heterozygote frequency in subgroup of patients without hepatic fibrosis was lower (7.1%) than in controls (51.6%) (p = 0.002) due to increase of both homozygote classes. Subgroup of patients without hepatic fibrosis differed by genotype frequencies both from patients with moderate and severe disease stage (p = 0.035; p = 0.004).