Genetic heterozygosity in a natural population of Mus musculus assessed using two-dimensional electrophoresis

Since the introduction of gel electrophoresis to population genetics, estimates of genic heterozygosity at allozyme loci have been made for many organisms. However, attempts to extend the range of proteins surveyed have been hampered by concern that there may have been bias in the loci sampled: nearly all proteins for which population data are available are soluble in low-salt extracts and most are enzymes belonging to particular groups such as the nonspecific esterases and phosphatases, various dehydrogenases and the enzymes of the glycolytic pathways and the citric acid cycle. Until recently, there were no techniques for estimating protein variation which were without such bias. Two-dimensional gel electrophoresis, however, offered hope of overcoming this bias, and it has proved useful for the resolution of proteins in crude homogenates and for estimating genetic variation. We have examined heterozygosity in a wild population of the house mouse (Mus musculus) by means of two-dimensional electrophoresis of whole kidney. As we report here, the observed level (2%) is substantially below the level detected by starch gel electrophoresis. Our results corroborate similar differences observed in Drosophila and man.