O.S. Reddi

Genetic effects of microwave radiation in mice

Abstract Micriwave radiations are being increasingly used in radar, space research, telecommunication, medicine and in ovens. Microwaves have been found to induce chromatid and chromosomal aberrations in human lymphocyte cultures [1], mice spermatogonia [8], Chinese hamster corneal epithelial cells [13], root tips of garlic [7] and Vicia faba [4]. In the present study we have investigated the mutagenic potential of 2450 MHz microwave radiation in mice using the dominant lethal test and sperm abnormality assay.

Lack of Genetic and Cytogenetic Effects in Mice Fed on Irradiated Wheat

Experiments were conducted to test the mutagenicity of wheat irradiated with 20 and 200 krad gamma-rays by feeding male and female mice for various periods starting from weaning time. The results obtained from dominant lethal tests, specific locus mutation test, studies on chromosome rearrangements in males and gonadal cell survival studies indicated no positive evidence for genetic and cytogenetic effects.

Iodine-125 induced micronuclei and sperm head abnormalities in mice

Swiss albino mice were injected with 0 (controls) 5, 10 or 15 microCi of iodine-125 (125I) and a high incidence of micronuclei in young bone marrow erythrocytes and of sperm head abnormalities was observed. The percentage of polychromatic erythrocytes containing micronuclei in mice treated with 0, 2.5, 5 and 7.5 microCi of 125I administered twice (at 30 and 6 h before sampling) was 0.23, 0.44, 0.56 and 0.72, respectively. The percentage (mean) of abnormal sperm recorded in controls during 1-3, 4-5 and 6-8 weeks was 3.3, 3.7 and 3.7 respectively, whereas the values for the same periods in the 5 microCi (5.5, 6.4 and 7.3), 10 microCi (7.7, 8.4 and 10.0) and 15 microCi (10.3, 9.9 and 10.2) groups were significantly higher. These results suggest that 125I can induce genetic damage in both somatic and germ cells.

Dominant Lethal Induction and Testicular Uptake of Iodine-125 in Mice

The mutagenic potential of 125I was studied using dominant lethal (DL) and testicular uptake studies. Dominant lethality (DL) represents embryonic death resulting from the chromosomal breakage in gametes of parents. When compared to controls, mice treated with different doses of 125I showed significant levels of induced DL. Significant pre-implantation losses were observed and variations in live implantations indicated total losses by the isotope. Dead implantations per pregnant female in the isotope treated groups showed a significant increase from controls indicating induced levels of post-implantation losses. All the stages of spermatogenesis, i.e., spermatozoa, spermatid, spermatocyte and spermatogonia were found to be sensitive to the induction of post-implantation losses, the spermatid stage being the most sensitive. Testicular uptake was measured from 1/2 hour to 72 hours after injection and maximum uptake was recorded at 1/2 hour, indicating the permeability of the blood/testis barrier.

The Genetical Response of Radiation Spermatozoa to Different Types of Radiation Treatment

SummaryDrosophila spermatozoa were exposed to x-rays in air, x-rays in nitrogen and neutrons in air. Each treatment was given either to males or inseminated females. After x-irradiation in air the frequencies of sex-linked lethals and translocations were highest among the progeny of treated inseminated females, lower in the first-day progeny of treated males, and lowest in the second-day progeny of treated males. After x-irradiation in nitrogen or after neutron radiation, all three frequencies were the same. This suggests that both differences (male versus female treatment; first versus second day) have the same basic cause. Experiments in which x-rayed males were mated after one or two days of storage without females indicate that this cause is differential radiosensitivity between fully and nearly mature spermatozoa.

Chromosomal abnormalities induced by iodine-125 in mouse germ cells

Swiss albino male mice were injected intraperitoneally with 0, 185, 370 or 555 kBq (0, 5, 10 or 15 microCi) of iodine-125 (125I). All the animals were killed on the sixtieth day and chromosomal aberrations were screened in spermatocytes at meiotic metaphase I. A significant increase in the percentage of chromosomal aberrations including translocations (0, 1.2, 1.8 and 2.3 per cent translocations in controls, 185, 370 and 555 kBq groups respectively) was recorded at all dose levels indicating the clastogenic effects of 125I in mouse spermatocytes.

Dominant lethal mutations induced by14C in mice

The mutagenic potential of 1.0 μCi14C was evaluated in Swiss albino male mice by the dominant lethal assay. A significant increase in post-implantation loss was seen, the maximum being in the 3rd week after treatment.