ABSTRACT
We studied radiation effects in day 19 fetuses of the mouse strain 'Heiligenberger' after exposure (2.8 Gy, 137 Cs gamma rays, dose rate 0.28 Gy/h) of their fathers. We observed an increased lethality (exclusively due to preimplantation death and early resorptions) after exposure of all stages of spermatogenesis with the exception of early spermatogonia. In addition, there was a significant increase in the frequency of malformed fetuses (gastroschises only); this increase was observed primarily after exposure of the meiotic stages.
Subject(s)
Congenital Abnormalities/etiology , Spermatogenesis/radiation effects , Spermatozoa/radiation effects , Animals , Embryonic Development/radiation effects , Female , Gamma Rays , Male , Meiosis/radiation effects , Mice , Paternal Exposure , PregnancyABSTRACT
We describe a method for isolating chromosomes from testes of the desert locust, Schistocerca gregaria, and their subsequent incubation with antibodies directed against chromosomal proteins. The procedure involves hypotonic pretreatment of the germ cells, centrifugation onto coverslips in a cytocentrifuge and immunolabeling, while still unfixed, using a chromatin-stabilizing buffer. In the present case, an antibody specific for the acetylated isoforms of histone H4 was tested. After the antibody treatment, the preparations are fixed using formaldehyde, stained with a DNA-specific fluorescent dye and mounted. Analysis of the preparations revealed good preservation of chromosome structure in prophase spermatogonia and late prophase I spermatocytes. Fully condensed chromosomes were not observed and are probably lost during preparation. The bright fluorescence of the autosomes indicates that the reaction between the antibody against acetylated histone H4 and its chromosomal antigen is not impeded. In contrast, the X univalent remained unstained with the exception of a small terminal band. Thus, cytospin preparations of locust germ cells allow high resolution immunolabeling with antibodies against chromosome-associated proteins.
Subject(s)
Chromosomes , Grasshoppers/genetics , Grasshoppers/metabolism , Histones/analysis , Animals , Fluorescent Antibody Technique, Indirect , Male , TestisABSTRACT
We used the 'comet assay' to compare the amount of radiation-induced DNA damage in three tumour cell lines (MeWo, PECA 4451 and PECA 4197) and the extent of DNA repair in two of these lines (MeWo and PECA 4197). Tumour cells were irradiated with X-rays (0.1-10 Gy), embedded in agarose on slides, lysed with sodium dodecyl sulphate and exposed to an electric field. DNA migrated within the agarose and formed comets whose length depended on the amount of DNA damage. When the cells were incubated at 37 degrees C for various time intervals before electrophoresis started, the comets shrank in the course of time, indicating repair of DNA damage. All three cell lines showed the same extent of DNA damage after radiation exposure, despite the fact that in the colony-forming assay MeWo and PECA 4451 were much more sensitive to radiation exposure than PECA 4197. The repair characteristics, however, were markedly different for MeWo and PECA 4197 cells. PECA 4197 cells showed a much faster restoration of the original shape of the cell nucleus than MeWo cells.
Subject(s)
DNA Damage , DNA Repair , Radiation Tolerance , Humans , Tumor Cells, CulturedABSTRACT
Pre-implantation embryos of the mouse were studied for the occurrence of an adaptive response, i.e. induction of radio-resistance by a previous low dose. Various experimental designs were checked (initial doses between 3 and 10 cGy; second dose 2-6 Gy at 6-24 h after the first dose). Some of the experiments were carried out in exactly the same way that resulted in an adaptive response of human lymphocytes reported previously. However, when cell proliferation and differentiation of mouse embryos were examined, none of the conditions tested indicated the induction of an adaptive response.
