Cytogenetic characterization of radiosensitive mouse mutants

X-ray-induced chromosomal aberrations and cell killing in somatic and germ cells of the scid mouse

To characterize further the radiosensitivity of severe combined immunodeficiency (scid) mice, the induction of micronuclei (MN) in polychromatic erythrocytes as well as cell killing and translocation induction in stem cell spermatogonia was studied. Scid mice turned out to be clearly hypersensitive for X-ray-induced cell killing of both bonemarrow cells and spermatogonial stem cells. The frequencies of recorded micronuclei in polychromatic erythrocytes were comparable with that reported for the normal mouse, whereas the recovery of translocations was extremely low in the scid mouse. The dose-response relationship for induced translocations was bell shaped with a maximum of about 0.5% around doses of 0.5-1.5 Gy X-rays.

Effects of prostaglandin E2 on the micronucleus formation in mouse bone marrow cells by various mutagens

The effects of prostaglandin E2 (PGE2), as a trigger of erythroid progenitor cells into the cell cycle, were studied on the induction of micronuclei by various mutagens; with mitomicin C (MMC) the optimal protocol was established. PGE2 itself did not induce any micronuclei in this experiment. The highest frequency of micronuclei and dose-response relationship between PGE2 doses and micronucleus frequency were observed 30 h after injection of MMC to mice administered PGE2 24 h previously. Sensitization by PGE2 pretreatment was also found for other mutagens, such as vincristine, 5-fluorouracil, benzo[a]pyrene, 1,1-dimethylhydrazine and 2-naphthylamine. These results support the hypothesis that accelerating the erythropoiesis increases the frequency of micronuclei induced by mutagens.