Differential expression of two distinct endogenous retrovisus genomes in developing tissues of the domestic cat
Niman, H.L.; Akhavi, M.; Gardner, M.B.; Stephenson, J.R.; Roy-Burman, P.
Journal of the National Cancer Institute 64(3): 587-594
1980
ISSN/ISBN: 0027-8874 PMID: 6243723 Document Number: 166293
DNA and RNA sequences related to those of RD-114 retrovirus and feline leukemia virus (FeLV) were measured by molecular hybridization in embryonic tissues of the domestic cat. The expression of the major internal protein (p30) of these 2 viruses in the embryonic tissues was determined by group-specific competition radioimmunoassays. Multiple copies of both RD 114- and FeLV-related sequences were detected in the DNA of all embryo tissues examined. Although there was a uniform distribution of about 12-15 copies of the RD114-related genetic sequences and 6-7 copies of the FeLV-related genetic sequences/haploid genome, these sequences were differentially expressed in a tissue-specific manner. Embryo thymus tissues contained relatively high levels of RD114 RNA and p30, whereas the expression of FeLV RNA and p30 was low in this tissue. All specimens of placenta expressed intermediate levels of both RD114 and FeLV RNA, and a fraction of each virus-specific RNA was polyadenylated. The presence of RD114 RNA in the placenta correlated with the detection of RD114 p30, but the translation of FeLV RNA to the corresponding p30 was not generally detected. Low levels of both RD114 and FeLV RNA were found in embryo spleens and livers, whereas the steady-state concentrations of these sequences were either very low or undetectable in the RNA extracted from whole cat embryos and embryonic kidney and brain tissues. The differential expression of these 2 retroviral genomes in specific embryo tissues of noninbred randomly selected cats suggests a coordinated but not necessarily an essential relationship with embryogenesis and immunologic development.