Breed-associated variations in the sequence of the pig 3β-hydroxysteroid dehydrogenase gene

The entire sequence of the pig 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) gene has recently become known. This gene is deemed to be important in androstenone metabolism in pig liver, and its defective expression has been shown to be related to androstenone accumulation in adipose tissue and the development of boar taint. The aim of the present work was to do the following: 1) define the structure of the pig 3 beta-HSD gene and 2) compare 3 beta-HSD DNA sequences from pigs of different breeds, which vary in adipose tissue androstenone levels, with the purpose of identifying a polymorphism that might be responsible for differential 3 beta-HSD expression. The 5 ' flanking and the coding region of 3 beta-HSD were cloned and sequenced by conventional techniques. The 3 beta-HSD coding regions were identical in pigs of different breeds and in animals with high and low androstenone levels. Significant sequence variations were found in the 5 ' flanking region of the 3 beta-HSD gene, where differences in the number of TTAT repeats and 3 SNP were observed. The SNP were associated with the number of the TTAT repeats. These variations in the DNA sequence of the 3 beta-HSD gene were not associated with the androstenone level in s.c. adipose tissue but were breed-dependent. The results of this work might be used for detection of the presence of Meishan genes in Western pig breeds, especially if the phenotype is not clearly established.