A chromosome 15 quantitative trait locus controls levels of radiation-induced jejunal crypt cell apoptosis in mice

Jejunal crypt cells undergo apoptosis in response to ionizing radiation exp osure. In mice the number of cells deleted by apoptosis is determined by se veral factors including the dose of radiation, the time of day the apoptosi s level is quantified, and the strain of mouse irradiated. We previously fo und that the difference in radiation-induced apoptosis levels between C57BL /6J (B6) and C3Hf/Kam (C3H) mice is controlled by multiple genes, and this set of genes is distinct from that controlling thymocyte apoptosis levels i n the same strain combination. Here, we report that a new quantitative trai t locus on chromosome 15, Rapop5, partly accounts for the murine strain dif ference in susceptibility to radiation-induced jejunal crypt cell apoptosis . In addition, we show sexual dimorphism in the extent of radiation-induced jejunal crypt cell apoptosis, with female mice having higher levels. (C) 2 001 Academic Press.