Molecular analysis of recombination sites within the immunoglobulin heavy chain locus of the rabbit

Previously, recombinations involving genes of the rabbit immunoglobulin heavy chain locus have been documented serologically. These data indicated that the sites at which the causative recombination events occurred could have been anywhere from within the V_H gene cluster up to, or 3 of, C. Since these sites could not be localized further by serological methods, we attempted to do this using techniques of molecular biology. DNAs from homozygous recombinant rabbits and from the appropriate non-recombinant parental haplotypes were characterized using Southern blots hybridized with a panel of probes derived from cloned regions of the rabbit immunoglobulin heavy chain gene complex. In all three recombinants, the site was downstream of the entireV_H cluster and upstream of the J_Hcluster within an 50 kilobase (kb) egion containing expanses of repetitive-sequence DNA as well as D_H genes. D_H-specific probes further showed that in two of the recombinants, the recombination appears to have occurred within or 5 of D_H1 and 5 of D_H2 genes; in the third it occurred 3 of the D_H2 genes but at least 5 kb 5 of the J_H region.Address for correspondence and offprint request to: R. G. Mage.