13 LOCI PHYSICALLY ASSIGNED TO SHEEP CHROMOSOME-2 BY CELL HYBRID ANALYSIS AND IN-SITU HYBRIDIZATION

Sheep x hamster cell hybrids containing sheep metacentric Chromosome ( Chr) 2 were produced by fusing blood leukocytes from normal sheep with hamster auxotrophic Ade F-minus mutants. Cell clones that were isocit rate dehydrogenase I (IDH1) positive were cytogenetically characterize d, confirming that they contained sheep Chr 2. The following loci were newly assigned by Southern hybridization to sheep Chr 2: lipoprotein lipase (LPL), glycoprotein-4-beta galactosyltransferase 2 (GGT82), neu rofilament light polypeptide (68 kDa; NEFL), surfactant-associated pro tein 2 (SFTP2), lymphocyte-specific protein tyrosine kinase (LCK), and nebulin (NEB). These new assignments and the in situ localization of grelsolin (GSN) to sheep Chr 2pter-p24 are consistent with the predict ed homology of cattle Chr 8 (U18) with sheep Chr 2p, and of cattle Chr 2 (U17) with sheep 2q. In addition, the assignment by cell hybrid ana lysis of loci previously mapped to Chr 2 in sheep, viz., cholinergic r eceptor, nicotinic, delta polypeptide (CHRND), collagen type III alpha 1 (COL3AI), fibronectin 1 (FN1), isocitrate dehydrogenase (IDH1), and villin 1 (VIL1), confirmed the localization of sheep syntenic group U 11 to this chromosome. By nutritional selection and complementation of the hamster auxotrophic Ade F mutation, the multifunctional enzyme lo cus phosphoribosylaminoimidazolecarboxamide formy/transferase (AICAR t ransformylase)/IMP cyclohydrolase (inosinicase) (provisionally given t he symbol PRACFT) has also been newly assigned to sheep Chr 2. This re port significantly extends the number of loci physically mapped to she ep Chr 2 and confirms its close homology with cattle Chrs 2 and 8.