Investigation of hyperthermia-induced dominant lethal mutations in male mice

The mutagenic potential of hyperthermia was investigated in a random-bred stock of mice to determine if this is one mechanism by which elevated ambient temperature exerts its deleterious effects on mammalian reproduction. Two dominant lethal assays were conducted to measure mutagenicity during the meiotic and post-meiotic stages of spermatogenesis following various periods of heat stress. Indirect evidence for hyperthermia-induced dominant lethality was obtained in the form of increases in the frequencies of preimplantation loss and sterile matings. However, the large number of sterile matings precluded unambiguous statistical analysis of the incidence of early embryonic mortality that would have provided direct evidence of induced dominant lethality. Control data indicated that the stock of mice used in this experiment is an excellent choice for dominant lethal studies because of the large number of implants and the low frequency of embryonic mortality.