Gh. Deknudt

Chromosome aberrations in employees from fossil-fueled and nuclear-power plants.

Chromosome aberrations were scored in 59 persons from fossil-fueled plants, in 89 persons from nuclear-power plants and in 23 controls. A significant increase in acentric chromosome fragments and dicentric chromosomes compared to the control group was observed in both types of workers. Moreover, the number of abnormal cells was significantly greater in workers of conventional plants than in those of nuclear-power plants. When adjusted for loss of lymphocytes according to a half-life of 3 years, this difference was also significant for the number of dicentric chromosomes observed. A significant effect of length of exposure or of frequency of radiological examinations could be discerned only in the group of workers from conventional plants.

PERSISTENCE OF CHROMOSOME REARRANGEMENTS INDUCED IN MALE MICE BY X- IRRADIATION OF PRE-MEIOTIC GERM CELLS.

Abstract Male C57BL mice received local irradiation to the testes with an exposure of 600 R of X-rays. The irradiated mice were killed 60–600 days after treatment, the testes were removed and meiotic preparations made by an air-drying method. Most of the cells showed 20 bivalents (20II), but multivalent configurations were recorded in the spermatocytes from irradiated animals and from old control males. In the irradiated males, the percentage of spermatocytes with chromosome rearrangements increased from 8.4 after 60 days to 12.6 after 100 days. The yield of abnormal cells remained at that level from 100 days to 200 days and then decreased up to 450 days after irradiation. A small increase occurred after 500 and 600 days.

Mutagenicity tests with aflatoxins in the mouse.

Introduction Aflatoxins, a collective term for eight compounds of related molecular configuration (i.e., aflatoxins BI, B2, B2a, GI, G2, G2a, MI, and M2), are metabolites of Aspergillus flavus, a common contaminant of stored human and animal foodstuffs (refs. I, 5, 24). Aflatoxin BI and GI are the most abundant and active compounds of this group. They are acutely hepatotoxic and have been shown to be potent carcinogens in the rat 4,7,15,2., and rainbow trout 3. Aflatoxin BI is known to inhibit protein synthesis and DNA-dependent RNA synthesise,~5,2s. Various types of genetic effects following aflatoxin t reatment of whole organisms, or cells in culture, have been described in different organisms. Aflatoxin BI has been shown to be mutagenic in the Bacillus subtilis transforming DNA assay in vitro 19 and in Neurospora crassa2°, ~1. I t inhibits the mitotic process in human embryonic lung cells 16 and produces chromosome aberrations in seedling roots of Vicia faba is, in Al l ium cepa 2~, in a cell line derived from the rat Kangaroo 12, and in human leucocytes in vitrog,22, 27. Aflatoxin BI is able to induce autosomal recessive-lethal mutations in Drosophila melanogaster ~4 whereas a mixture of aflatoxins BI and GI causes an increase in the dominant lethals in male mice 1°. In the present experiments the capacity of aflatoxin BI to produce heritable chromosomal changes in mice has been tested by analysing the spermatocyte I chromosomes of the treated males (spermatocyte test on treated males) and of their offspring (VI translocation test) 17.

The radiosensitivities of lymphocytes from pig, sheep, goat and cow

Dose-effect curves for X-irradiation in vitro were determined on cultured blood lymphocytes of four mammalian species-cow, goat, sheep and pig-having approximately the same number of chromosome arms, the same nuclear volume and the same DNA content. The data from cow, but not those from the other species, exhibited significant inhomogeneity between the experiments. On inspection the numerical yields appear not to differ greatly in the lower dose range. Evaluation of the parameters according to the quadratic law and the power law, however, demonstrate significant differences. Pig differs from the other species regardless of which presentation is chosen. For the power law a significant difference is also found between goat and sheep.

Chromosome rearrangements induced in the mouse by embryonic X-irradiation: II. Irradiation of male foetuses at the 13.5th day of gestation

Pregnant females were exposed to 0, 100, 200 or 300 R of whole body X-irradiation at day 13.5 of pregnancy. Except for the dose of 300 R where only 7 males were used, 10 males chosen from the litters of different females were sacrificed 100 days after birth and for each testis 100 dividing spermatocytes were examined for the presence of chromosome rearrangements. No chromosome rearrangement could be detected in the spermatocytes of adult male mice irradiated at the foetal stage. On the other hand dividing spermatocytes are known to carry translocation configurations after exposure at the spermatogonial stage in the adult male mice. Thus large differences exist in this respect between the dividing gonocytes of the foetal male mouse and the type-A spermatogonia of the mature one.

Chromosome rearrangements induced in the mouse by embryonic x-irradiation. I. Pronuclear stage.

Abstract BALB/c females with vaginal plugs (day 0.5 after copulation) received X-irradiation to the whole body. 100 R killed about 45% of the embryos. 38 males and 24 females irradiated at the pronuclear stage were mated with control mice from the same strain, and the testes of their sons were examined for the presence of chromosome rearrangements. Three males irradiated at day 0.5 were found to be heterozygous for different reciprocal translocations. The overall frequency of induction of translocations per genome was 2.53%. Mitotic preparations made from bone-marrow of the 3 translocated animals showed no recognizably abnormal chromosomes.