Comparative study of the genetic effect of various tritium compounds in male mice

Comparative study of the genetic effect of some tritiated biogenic++ compounds and tritiated water was carried out. Reciprocal translocations induced in mice stem spermatogonia by 3H-glucose, 3H-glycine and 3H-lysine occur with similar frequency, whereas the difference in values of the absorbed doses of beta-irradiation in some cases was about two-fold. The highest genetic effect per unit of activity of 3H-nucleosides (3H-TdR and 3H-CdR) was revealed at lowest activities. The frequency of reciprocal translocations induced by 3H-TdR was twice as that induced by 3H-CdR.     

Comparison of Three Inbred Mouse Strains with Respect to General and Genetic Radiosensitivity

The radiosensitivities of three mouse strains (BALB/cLacY, C3H/SnY, and 101/HY) have been compared using the following parameters: survival after irradiation at a dose of 6–7 Gy, chromosome aberration frequency in bone marrow cells after irradiation at a dose of 1.5 Gy, and the change in testis weight and frequency of abnormal sperm heads (ASHs) after irradiation at doses from 0.5 to 4 Gy. Strain BALB/c is the most radiosensitive with respect to the survival and chromosome aberration frequency in the bone marrow but the most resistant with respect to the change in testis weight and the frequency of abnormal sperm heads. Strain 101/HY was the most resistant with respect to survival and chromosome aberration frequency in bone marrow after irradiation but the most radiosensitive with respect to testis damage.     

Genetic damage in domestic mice inhabiting in the areas with elevated background radiation

Genetic effects of irradiation in males of wild house mice which were caught in the region of Chernobyl Nuclear Power Station were studied. The dose rate on the ground surface varied from 0.04 to 200 mR/h of gamma-irradiation. The increasing yield of dominant lethal mutations was only observed in males from the most contaminated sector. Reciprocal translocations were observed in spermatocytes of mice at all the levels of contamination. The rate of reciprocal translocations was relatively low and increased linearly with the elevation of the dose rate. The extent of testis damages increased also, as the dose rate grew. The frequency of abnormal sperm heads, the yield of recessive lethal mutations, litter size and radiosensitivity of the first progeny were not changed, depending on the dose rate.     

Genetic effects in mice exposed to the 10-km area around the Chernobyl Atomic Energy Station

Mice (CBAxC57BL) F of both sexes were exposed within the 10 km zone of Chernobyl nuclear power station. Genetic damage of phone chronic effect of increased radiation in exposed adult mice and in the course of embryogenesis was studied. The total absorbed radiation doses in testes varied from 1.85 to 0.42 Gy in embryos and from 3.4 to 2.7 Gy in adult males. Increase of dominant lethal mutations (DLM) and abnormal sperm heads (ASH) was only observed right after the end of exposure of adult males. The yield of reciprocal translocations (RT) in these males was relatively low. Among the males exposed at the stage of early embryogenesis, 4 heterozygotes for RT were revealed. In other males of this group the RT yield was low.     

Genetic action of 131I and 125I on the germ cells of male mice

A study was made of the genetic effects of iodine radioactive isotopes in male germ cells of (CBA X C57Bl)F1 hybrid mice. After a single intraperitoneal administration of Na131I (1.48 to 740 kBq/g) or Na125I (148 to 7400 kBq/g) to males the occurrence of dominant lethal mutations (DLM), reciprocal translocations (RT), and abnormal sperm heads (ASH) was studied. The radioactive iodine isotopes induced DLM at the postmeiotic spermatogenesis stages only. After the effect of the isotopes, the frequency of RT increased insignificantly with dose. The frequency of ASH was only increased with the highest 131I dose. Relative biological effectiveness of 131I and 125I was less than 1 with a reference to the indices under study.     

Transposition of Regulatory Elements by P-Element-Mediated Rearrangements in Drosophila melanogaster

Previously we described highly unstable mutations in the yellow locus, induced by the chimeric element and consisting of sequences from a distally located 1A unique genomic region, flanked by identical copies of an internally deleted 1.2-kb P element. Here we show that a sequence, which is part of the yellow 1A region, can be transmitted to the AS-C by successive inversion and reinversion generated by yellow- and AS-C-located P elements. The chimeric element contains a regulatory element from the 1A region that specifically blocks yellow wing and body enhancers and simultaneously stimulates yellow expression in bristles. These results suggest that P-element-generated chimeric elements may play a certain role in rapid changes of regulatory regions of genes during evolution.     

Study of long-distance functional interactions between Su(Hw) insulators that can regulate enhancer-promoter communication in Drosophila melanogaster

The Su(Hw) insulator found in the gypsy retrotransposon is the most potent enhancer blocker in Drosophila melanogaster. However, two such insulators in tandem do not prevent enhancer-promoter communication, apparently because of their pairing interaction that results in mutual neutralization. Furthering our studies of the role of insulators in the control of gene expression, here we present a functional analysis of a large set of transgenic constructs with various arrangements of regulatory elements, including two or three insulators. We demonstrate that their interplay can have quite different outcomes depending on the order of and distance between elements. Thus, insulators can interact with each other over considerable distances, across interposed enhancers or promoters and coding sequences, whereby enhancer blocking may be attenuated, cancelled, or restored. Some inferences concerning the possible modes of insulator action are made from collating the new data and the relevant literature, with tentative schemes illustrating the regulatory situations in particular model constructs.     

Effect of indralin on genetic disruption induced by radiation in mice

The effect of indralin on frequency of mutations induced by radiation in germ cells, reciprocal translocations, and testicle weight of male mice. The level of protective effect against genetic damage varied depending on the radiation dose and spermatogenesis stage. The values of the defense coefficient ranged from 0.16 to 0.35.     

The Estimation of Molecular and Cytogenetic Effects in Mice Exposed to Chronic Low Dose-Rate Gamma-Radiation

Molecular and cytogenetic parameters were estimated in male CBA/lac mice exposed to chronic low dose-rate -radiation (62 cGy/year) for 40, 80, 120, 210, and 365 days. After 40 days of exposure (6.7 cGy), spleen lymphocyte susceptibility to hydrogen peroxide was shown to increase. However, beginning from the day 120 of the treatment (20.4 cGy), the opposite effect was observed. An increase in number of the DNA–protein crosslinks was recorded in spleen lymphocytes only on day 40 of the experiment. The number of DNA breaks increased significantly beginning from day 120 of the experiment, as shown by the DNA-comet method. On the day 210 of irradiation, the frequency of abnormal sperm heads in the mice significantly increased. The number of normochromatic micronucleated erythrocytes of the peripheral blood remained unchanged.