Localization of the glucose phosphate isomerase gene to the p12→q21 segment of chromosome 6 in pig by in situ hybridization

The glucose phosphate isomerase GPI locus is closely linked to the halothane sensitivity locus in pig. The chromosomal localization of GPI in pig was confirmed to 6p12→q21 by using in situ hybridization. Of the total grains, 25 percent were located on chromosome 6, with about 65 percent clustered in the cent→q21 segment, suggesting the presence of the GPI gene on the very proximal part of the q arm. The efficiency of hybridization was found to be affected by ultraviolet irradiation of metaphases for RBA‐banding before hybridization. The irradiated metaphases had higher background grains than the non‐irradiated metaphases.