Segmental homology among cattle (Bos taurus), Indian muntjac (Muntiacus muntjak vaginalis) and Chinese muntjac (M-reevesi) karyotypes

In an attempt to examine homologies between Indian and Chinese muntjac karyotypes at a subchromosomal level, five bovine cosmids were comparatively mapped by heterologous fluorescence in situ hybridization (FISH). In the Indian muntjac (2n = 6) all cosmids mapped to chromosome 1, whereas in the Chinese muntjac (2n = 46) two cosmids mapped to chromosome 3 and one cosmid each mapped to chromosomes 1, 7, and 17. These markers have maintained their intrachromosomal position relative to a centromere/telomere axis in cattle and in Chinese and Indian muntjac chromosomal arms. Our results corroborate the tandem-fusion hypothesis for muntjac karyotypic evolution and establish orientational homology between the involved Chinese muntjac chromosomes and the discrete segments on Indian muntjac chromosome 1. Furthermore, our data disclose regional homologies between cattle and muntjac genomes and demonstrate the validity of intergeneric cosmid-FISH for investigations on karyotype evolution.