ANALYSIS OF RECOMBINATIONAL HOT-SPOTS ASSOCIATED WITH THE P-HAPLOTYPEOF THE MOUSE-MHC

Most of the recombination events detected within the major histocompat ibility complex (MHC) of the mouse fall into areas of limited physical size that have been designated recombinational hot spots. One of thes e hot spots, associated with the Ea gene, appears to be active only in the presence of the p haplotype of the MHC. To study the regulation o f the Ea recombinational hot spot and its haplotype specificity, a hig h-resolution comparative map of the MHC and adjacent regions was compl eted in four different backcrosses carrying the p haplotype. This mapp ing study utilized a total of 29 PCR-based molecular markers, includin g 7 newly developed markers spanning the region between Pim1 and D17Mi t11 on Chromosome 17. The analysis of a total of 1093 backcross animal s: (1) revealed that the presence of the p haplotype of the MHC is not sufficient to induce recombination at the Ea hot spot in a dominant m anner, and (2) resulted in the definition of a new intra-MHC recombina tional hot spot between the Tnfb and the H2-D genes. (C) 1994 Academic Press, Inc.