GENETIC ANALYSIS OF LIVER NEURAMINIDASE ISOZYMES IN RATTUS NORVEGICUS: INDEPENDENT CONTROL OF NEU-1 AND NEU-2 PHENOTYPES

Paul B. Samollow ¹, John L. Vandeberg ¹, Allen L. Ford ¹, Heinz W. Kunz ², and Thomas J. Gill III ²

¹ Department of Genetics, Southwest Foundation for Biomedical Research, P.O. Box 28147, San Antonio, Texas 78284
² Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261

Two recently identified isozymes of neuraminidase in rat liver were examined for transmission patterns and linkage relationships, and for variation among inbred strains. The isozymes, designated neuraminidase-1 (NEU-1) and neuraminidase-2 (NEU-2), exhibited no electrophoretic mobility variants among the 22 inbred strains examined, but did possess striking interstrain variation in activity phenotypes on electrophoretic gels. The results of a backcross analysis involving the KGH and ACP strains revealed that NEU-1 and NEU-2 phenotypes are independently controlled, each by a single autosomal locus with additively acting alleles. The two loci are unlinked to one another, but the gene controlling NEU-1 is tightly linked to RT1, the rat major histocompatibility complex. This gene is almost certainly identical to Neu-1, a gene identified previously through its effect on "total" activity levels of liver neuraminidase as determined by fluorometric assay of tissue homogenates. NEU-2 and the gene controlling its phenotype were not detected by the fluorometric technique. We designate the genes controlling the NEU-1 and NEU-2 phenotypes as Neu-1 and Neu-2, respectively. Data from this and other studies place Neu-1 between Glo-1 and dw-3. The location of Neu-2 is unknown.