Localization of the tryptophanyl tRNA synthetase gene (WARS) on human and bovine chromosomes by in situ hybridization

Abstract

Bovine tryptophanyl-tRNA synthetase (ECC 6.1.1.2.; WARS) is one of the best studied synthetases from multicellular organisms. Previous assignment of the WARS gene to the long arm of human Chromosome (Chr) 14 has been made by somatic cell hybrid techniques (Denney and Craig 1976; Shimizu et al. 1976). Francke and co-workers (1977) mapped it on 14q21q32. We describe here the localization of the WARS gene to the bovine and human chromosomes with specific cDNA probes (Frolova et al. 1991) for in situ hybridization. Detailed protocols for the in situ hybridization, chromosome staining, and silver grain distribution analysis have been given previously (Graphodatsky et al. 1992). Standard nomenclatures of the human and cattle chromosomes were used (ISCN 1985; ISCNDA 1989). Our results confirm the previously reported assignment of the tryptophanyl-tRNA synthetase gene to Chr 14 (Denney and Craig 1976; Shimizu et al. 1976; Francke et al. 1977). Twenty-four percent of all grains (202 grains from 104 total metaphases) were mapped on Chr 14 (• = 185.0; P < 0.001). Sixty-three percent of the grains over Chr 14 were localized to the 14q23q31 region; 33% to the 14q24 band. These results demonstrate the location of the WARS gene in the 14q23Lq31 region and presumably more precisely in the 14q24 band. Unexpected results were obtained with bovine chromosomes probed with cloned human cDNA. Thirteen percent of all the grains (353 grains per 103 metaphases) were mapped on Chr 3 (• = 53.6; P < 0.001). However, these grains were not condensed in one locus but were concentrated in two separate loci: 38% of grains on BTA3 were found over the qll--q21 region and 36% over the q42-45 region. Figure 1 shows the Gand RBG-banding patterns of cattle 3 (BTA3) Chr and human Chr 14 (HSA14).