Janice M. Simonson

Genetic Analysis of Hybrid Cells Using Isozyme Markers as Monitors of Chromosome Segregation

The construction of somatic cell hybrids between different mammalian species has provided an important technique for the development of genetic maps of a variety of biologic species. The human genetic map has been derived almost exclusively from genetic analysis of rodent × human cells (Ruddle and Creagan, 1975; McKusick and Ruddle, 1977). The murine genetic map originally progressed largely through sexual genetic analysis between inbred strains homozygous for different alleles at various loci (Miller and Miller, 1972; Davisson and Roderick, 1980). However, the addition to the map of numerous biochemical loci which did not vary between inbred strains has more recently been provided by analysis of mouse × hamster cell hybrids which preferentially segregate murine chromosomes (Lalley et al., 1978a,b; Francke and Taggart, 1980; Womack, 1980). In addition, fairly extensive biochemical genetic maps of chimpanzee, gorilla, orangutan, and the domestic cat have been prepared using similar technologies (Pearson et al., 1979, 1981; O’Brien and Nash, 1982).

Deposition of retrovirus associated antigens (p30 and gp70) on cell membranes of feline and murine leukaemia virus infected cells.

A quantitative estimation of retrovirus associated cell membrane antigens of murine and feline cells infected with their respective type C leukosis virus is presented. Using a radio-immune assay with three broadly reactive antisera, the minimum estimated number of retrovirus associated antigenic determinants on YAC [Moloney leukaemia virus (MuLV) infected murine] and FL-74 [feline leukaemia virus (FeLV) infected feline] cells was 1.3 x 10(6) and 1.6 x10(6) determinants per cell respectively. The virus structural proteins p27-30 and gp70 were detected by three component specific antisera on murine and feline cell surfaces in amounts which varied between cell isolates. MuLV infected cells produced as many as 1.9 x 10(5) p30 antigenic determinants and 7.5 x 10(5) gp70 determinants on infected cells. FeLV infected cells (FL-74) expressed 5.6 x 10(5) p27 and 7.5 x 10(5) gp70 antigenic determinants per single cell surface. The major core protein (p27-30) and the major envelope glycoprotein (gp70) antigens are sufficiently physically separated on cell surfaces so that binding of either of the membrane antigens with component specific antibodies does not interfere with binding of antibodies specific for the other. Despite the expression of interspecies determinants for p30, gp70, and other retrovirus associated antigens detected by antibody procedures, interspecies determinants of cell mediated immunity could not be demonstrated in immune mice bearing Moloney sarcoma virus (MSV) induced tumours. Furthermore, xenogeneic immunization of mice with FL-74 cells failed to protect mice against the growth of MSV induced lymphoma or sarcoma.