Genetic analysis of a switch in cell specificity of P lysozyme expression inmolossinusmice

Abstract

SummaryAn electrophoretic survey of concentrations of lysozymes M and P was carried out with seven species in the house mouse group (spretus, hortulanus, abbotti, musculus, castaneus, domesticusandmolossinus). In most species M is the predominant lysozyme in all tissues tested, except the small intestine, where P predominates if present. In inbred strains ofmolossinusmice P is more abundant than M in all tissues tested. The phenotypes of high expression of P lysozyme and low expression of M lysozyme in peritoneal and alveolar macrophages were examined genetically. Results of interspecific crosses and backcrosses todomesticusmice support the model that the phenotypes are caused by mutation(s) tightly linked to the lysozyme locus. Alleles at the regulatory loci show additive inheritance.