GENETIC-CONTROLS OF SUSCEPTIBILITY AND RESISTANCE TO 4-NITROQUINOLINE1-OXIDE-INDUCED TONGUE CARCINOMAS IN RATS

We analyzed the incidence of infiltrative mass-type tongue carcinomas (IMTC) induced in 550 rats by continuous oral administration of 0.001% 4-nitroquinoline 1-oxide solution for 180 days. The study included va rious crosses of susceptible Dark-Agouti rats (DA) and resistant Wista r/Furth rats (WF), DA showed a 93.6% incidence of IMTC measuring more than 5 mm in their largest diameter, while WF showed only a 4% inciden ce. Reciprocal F-1 and F-2 hybrids mated by DA and WF showed 47.5% and 45.8% incidences, respectively. Meanwhile, reciprocal backcrossed hyb rids to DA and WF showed 73.7%, and 24.6% incidences, respectively. Se gregation of the incidences suggests that there are two autosomal domi nant genes, one linked to the susceptibility of DA and the other to th e resistance of WF.