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The primate cell-derived transforming gene (v-sis) of simian sarcoma virus (SSV) is represented as a single copy marker within cellular DNAs of mammalian species including human. The human analogue of v-sis can be distinguished from its rodent counterparts by Southern blotting analysis of EcoRI-restricted DNAs. By testing for the presence of the human v-sis-related fragment, c-sis (human), in somatic cell hybrids possessing varying numbers of human chromosome, as well as in segregants of such hybrids, it was possible to assign c-sis to human chromosome 22.

The allelism of the structural genes for the complex rabbit b allotypes of immunoglobulin kappa-light chains has been questioned because of observations of unexpected phenotypic expression of "latent" allotypes. We find that the coding sequences of the b4 and b5 "alleles" are only 80% homologous for the last 60 nucleotides but there is a high degree of homology (96%) in the 3' untranslated region (3'DT). The high conservation of 3' DT region sequences enabled us to detect kappa-light chain mRNAs from rabbits of different genetic types (b4, b5, b9 and bbas) on northern blots and dot blots. We can distinguish mRNA encoding b9 and b5 allotypes on dot blots with b5 fragment-probes of known sequence and detect mRNA produced by unstimulated cultured splenic lymphocytes. Analyses of mRNA from cultured cells manipulated to enhance mRNA synthesis and production of unexpected or "latent" b allotypes can now be conducted.

Seminalplasmin, an antibacterial protein present in bovine seminal plasma, is shown to be a potent inhibitor of reverse transcriptases (RNA-dependent DNA nucleotidyltransferases). Seminalplasmin inhibits RNA-directed, hybrid-directed, and DNA-directed DNA-polymerizing activities of purified reverse transcriptase from avian myeloblastosis virus and from crude viral lysates of several retroviruses by binding to the enzyme, at least in the case of avian myeloblastosis virus. Seminalplasmin does not inhibit significantly DNA synthesis either by Escherichia coli DNA polymerase I, or a mammalian alpha-DNA polymerase. The presence of seminalplasmin in the seminal fluid could provide protection to the male and/or the female reproductive tract against retroviruses.

The nucleotide sequence of the region of Gardner-Rasheed feline sarcoma virus (GR-FeSV) encoding its primary translation product, p70gag-fgr, has been determined. From the nucleotide sequence, the amino acid sequence of this transforming protein was deduced. Computer analysis indicates that a portion of P70gag-fgr has extensive amino acid sequence homology with actin, a eukaryotic cytoskeletal protein. A second region of P70gag-fgr is closely related to the tyrosine-specific kinase gene family. Thus, the v-fgr oncogene appears to have arisen as a result of recombinational events involving two distinct cellular genes, one coding for a structural protein and the other for a protein kinase.