Localization by FISH of the 31 Texas nomenclature type I markers to both Q- and R-banded bovine chromosomes

A series of 31 marker genes (one per chromosome) were localized precisely t o both Q- and R-banded bovine chromosomes by fluorescence in situ hybridiza tion (FISH), as a contribution to the revised chromosome nomenclature of th e three major domestic bovidae (cattle, sheep and goat). All marker genes e xcept one (LDHA) are taken from the Texas Nomenclature of the cattle karyot ype published in 1996. Homologous probes for each marker gene were obtained by screening a bovine BAC library by PCR with specific primer pairs. After labeling with biotin, each probe preparation was divided into two fraction s and hybridized to bovine chromosomes identified either by Q or R banding. Clear signals and good quality band patterns were observed in all cases. R esults of the two series of hybridizations are totally concordant both for Q and R band chromosome numbering and precise band localization. This work permits an unambiguous correlation between the Q/G- and R-banded 31 bovine chromosomes, including chromosomes 25, 27 and 29 which remained unresolved in the Texas Nomenclature (1996). Hybridization of the chromosome 29 marker gene to metaphase spreads from a 1;29 Robertsonian translocation bull carr ier showed a positive signal on the short arm of this rearranged chromosome , confirming that the numbering of this long-known translocation in cattle is correct when referring to the Texas Nomenclature (1996). Taking into acc ount that cattle, goat and sheep have very similar banded karyotypes, the d ata presented here will help to establish a definite and complete reference chromosome nomenclature for these species. Copyright (C) 2000 S. Karger AG , Basel.