Combined Q-banding and fluorescence in situ hybridization for the identification of bovine chromosomes 1 to 7.

Eleven probes were assigned to bovine chromosomes 1 to 7 by fluorescence in situ hybridization (FISH). The identification of chromosomes was based on QFQ-banding prior to in situ hybridization and comparison with the Reading Conference (1976) and ISCNDA (1989) standards. The probes used for FISH can now be utilized as identification and discrimination features for bovine chromosomes 1 to 7 and particularly for chromosomes 4 and 6, which are difficult to distinguish. Comparison of our mapping data with previous assignments and of the standard chromosome banding patterns prompt us to propose a change in the ISCNDA nomenclature: ISCNDA chromosome 4 should be named chromosome 6 and vice versa. Chromosome 4 is marked by the ribosomal RNA cluster RNR3, and chromosome 6 is characterized by the casein gene cluster and an anonymous satellite (D6Z1).