Abstract
Twenty-eight heavy-chain variable (VH1) region genes and the immunoglobulin (IgM) heavy-chain constant region of an isogenic Xenopus hybrid, X. laevis/X. gilli, LG7, have been sequenced. The LG7 clone represents the first Xenopus hybrid that is homozygous for the IgH locus. The VH1 family was specifically investigated because VH1 genes are used by the antibodies produced during the Xenopus antidinitrophenol (DNP) response, These VH1 germ-line sequences establish a so-called "dictionary" that is available for studying somatic hypermutational mechanisms in immunized frogs.