Enhanced recovery of radiation-induced translocations from spermatogonial stem cells of p53 null mice

X-ray-induced (4 Gy) chromosomal translocations were studied in mouse spermatogonial stem cells with different p53 status by meiotic analysis at the spermatocyte stage, many cell generations after the moment irradiation. The results show enhanced recovery of translocations from p53 −/− mice relative to +/− and +/+ littermates. The enhanced recovery is probably due to an altered cell cycle distribution of the stem cells in the −/− mice leading to less radioresistant G0–G1 transition cells, rather than differences in apoptotic response. Experiments with the poly(ADP-ribose)polymerase inhibitor 3-aminobenzamide (3-AB) indicate that, in contrast to the situation in +/+ mice, no sensitization in the p53-deficient mice occurred for both testis weight loss and the recovery of induced translocations. This result also points to the presence of less radioresistant stem cells in the testis of p53 null mice. [Copyright &y& Elsevier]