F1 hybrids of BALB/c and C57BL/6 mouse strains respond differently to low-dose ionizing radiation exposure

There are evidences to show that response to ionizing radiations have genetic influence. To investigate this further, reciprocal F-1 hybrids were genereted by crossbreeding the radiation-susceptible BALB/c mouse strain with resistant C57BL/6 in a sex-specific manner (BALB/c a (TM),x C57BL/6 a (TM) Euro = B6BcF(1); C57BL/6 a (TM), x BALB/c a (TM) Euro = BcB6F(1)). These hybrids were compared with each other and to the parental strains with respect to transcriptional responses to low-dose ionizing radiation exposure (LDIR). The two F-1 hybrids showed drastic differences in their gene expression profiles to ionizing radiation exposure particularly in case of the genes involved in DNA damage response and repair process. Also, the inheritance pattern of the gene expression was found to be complex and could not be explained solely on the basis of parental expression pattern. It was concluded that there is a differential transmission of susceptible trait alleles from the parents to F-1 progeny which is dependent on the sex of the parent mouse strain used to set up the crosses and other environmental factors.