Specific chromosomes of sheep have been selectively "captured" in hamster x sheep cell hybrids produced by fusing different Chinese hamster auxotrophs with lymphocytes from sheep carrying normal or Robertsonian translocation chromosomes. A minipanel has been established comprising sheep chromosomes 1; 3; t1 = rob(6;24); t2 = rob(9;10); and X in a predominantly monochromosomal state. Using this targeted cell fusion approach the nutritional markers, uridine monophosphate synthetase (UMPS), mapped onto human chromosome 3 (HSA3), phosphoribosylglycinamide synthetase, and phosphoribosylaminoimidazole synthetase (GART) (HSA21), are reported to be located on sheep chromosome 1q; and phosphoribosyl pyrophosphate amidotransferase (PPAT) (HSA4) has been assigned to sheep chromosome 6. By isozyme analysis and Southern hybridization, transferrin (TF) and superoxide dismutase 1 (SOD1), both in the bovine syntenic group U10, were assigned to sheep chromosome 1q; adenylate kinase 1 (AK1), in the bovine syntenic group U16, to sheep chromosome 3p; lactate dehydrogenase B (LDHB) and phenylalanine hydroxylase (PAH) on bovine chromosome 5 (BTA5) to sheep chromosome 3q; phosphoglucomutase 2 (PGM2) (bovine syntenic group 15) to sheep chromosome 6 (t1q); avian myelocytomatosis viral oncogene homolog (MYC) and Moloney murine sarcoma viral oncogene homolog (MOS) (BTA 14) to sheep 9 (t2q); and glutathione reductase (GSR) (bovine syntenic group U14) to sheep 24 (t1p).