IMMUNOGLOBULIN HEAVY-CHAIN CONSTANT AND HEAVY-CHAIN VARIABLE REGION GENES IN PHYLOGENETICALLY DIVERSE SPECIES OF BONY FISH

Genomic DNA from 18 phylogenetically diverse species of bony fish was hybridized with probes specific for the channel catfish immunoglobulin heavy chain constant (CH) gene, as well as with immunoglobulin heavy chain variable (VH) probes specific for five channel catfish VH gene f amilies. The results showed that CH probes strongly hybridized only to genomic fragments from other catfish species. In contrast, restricted DNA from most other species hybridized with at least two channel catf ish VH probes. In those species whose DNA hybridized with multiple VH probes, the restriction pattern of hybridizing fragments was probe-dep endent. These studies suggest that (1) the CH gene defined in channel catfish appears to share similarity only with CH genes in other catfis h species, (2) families of VH genes appear to have diverged in early p hylogenetic lineages of teleosts, and (3) VH genes similar to those de fined in catfish appear to be widely represented in phylogenetically d iverse species of teleosts.