Comparative mapping of the immunoglobulin genes in domestic cattle

Abstract

Bovine genomic IGL and IGHM probes were used to map these immunoglobulin genes to bovine syntenic group U23 and BTA21 using bovine-hamster hybrid somatic cells. These cells segregate bovine chromosomes while retaining a full complement of the hamster genome. A human IGHG4 probe was used to map the immunoglobulin heavy chain gamma constant region to bovine chromosome 21 (syntenic group U4). FOS, FES, PDGFB, IL1, SCN2A, and MYCN were also mapped to bovine syntenic groups, and uncovered many interesting areas of evolutionary differences between bovine, human and murine syntenic groups. The syntenic assignments also allowed predictions to be made regarding the chromosomal location of the gene markers on human and mouse chromosomes. The probes used for mapping were used to screen cattle of several different breeds for restriction fragment length polymorphisms (RFLPs). It is hoped that the polymorphisms generated by this study will be linked to traits of economic importance, and, as such, can be used in breeding programs. The IGHG4 probe was used to screen a bovine sperm DNA library for homologous sequences. Three clones were isolated, two of which appeared to be identical based on restriction analysis. Restriction maps are reported for the clones. Further analysis of the clones through sequencing, in addition to mapping more markers to the bovine syntenic groups containing the immunoglobulin genes, will add to our knowledge of mammalian genome evolution, and the evolution of the immunoglobulin genes in particular.