Parallels of genomic organization and of endogenous retrovirus organization in cat and man

Abstract

A combination of technical advances (most notably heterologous cell fusion, high resolution G-banding, and molecular cloning) has contributed to an accelerated advance in genetic analysis in mammals. The present human genetic map contains over 400 gene assignments and the map is growing rapidly as each ncw molecular clone or immunological reagent is developed. In our laboratory, we have devclopcd a panel of rodent x human somatic cell hybrids that have been utilized in chromosomc assignment of several classes of genes including oncogenes @us, ruj) and endogcnous human retroviral sequences (ERM, 2, etc). Using similar techniques, a biochemical gcnetic map of the domestic cat has been derived. The cat has 19 chromosome pairs and, to date, 40 genes have been mapped to 16 linkage or syntenic groups. Comparison of linkage relationships between homologous enzymes has revealed a striking conversation of chromosomal linkage association between cat and man. A comparison of syntenically homologous, highly extended high resoultion G-banded chromosomes between the two mammalian families revealed that 20-25%, by length, of the human karyotype can be precisely aligned (chromomere to chromomere) between cats and man despite the evolutionary divergence of the species nearly 80 million years ago.Moderately repetitive families of retrovirus-related DNAs exist within the feline and the human genomes. We have isolated molecular clones of several members of the feline RD-114 retrovirus family from a genomic library of normal cat cellular DNA. The endogenous sequences analyzed were similar to each other in that they were colinear with RD-114 proviral DNA, were bounded by long terminal redundancies, and conserved many restriction sites in the gag and pol regions. Several sequences were apparently deleted, relative to the previously characterized inducible RD-114 gcnome. The env regions of a number of endogenous RD-114 sequences examined were suhstantially deleted or diverged; a subset of these sequences contained information at the position of the env region that was not homologous to inducible RD-114. The RD-114 virogenes were dispersed to several cat *Based on a lecture delivered in September 1983, at the International Conference in Biochemical and Developmental Genetics, Kos, Greece.