A new class of genetically transmitted retravirus isolated from Mus cervicolor.

Abstract

Electron Microscopy. Tissues and cell pellets were fixed in 2.5% glutaraldehyde, rinsed with several changes of 0.01 M phosphate-buffered saline, treated with Dalton's chromeosmium, and rinsed again with several changes of distilled, deionized water (6). The specimens were stained overnight with 1% uranyl-acetate in 50% ethanol, dehydrated with increasing concentrations of ethanol, followed by propylene oxide, and embedded in Luft Epon. Thin sections were stained with lead citrate. Negative stains were prepared by mixing isopycnically banded virus in 0.05 M sodium citrate (pH 6.0) with 2% potassium phosphotungstate (pH 4.0). The mixture was deposited on a carbon-coated grid, drained, and air-dried just prior to use. Viral Polymerase Assays. Virus from culture supernatants was concentrated and assayed for viral reverse transcriptase as described (2, 3). Reactions were carried out in a total volume of 0.1 ml using 0.5 Ml of virus (10 Mig of protein) and contained 50 mM Tris-HCI (pH 7.8), 4 mM dithiothreitol, 60 mM KCI, 0.03% Triton X-100, and MnCl2 or MgCl2 as indicated. Po-

Intracisternal A-particle genes: identification in the genome of Mus musculus and comparison of multiple isolates from a mouse gene library.

“…26) and are genetically related to extracellular viruses found in other mouse species (6,27), they themselves do not have an infectious extracellular phase and it has not been possible to obtain complete DNA copies for mapping studies. The present results will permit us to directly compare the IAP genome with that of the genetically related M432 retrovirus of M. cervicolor (6)(7)(8). In preliminary studies a cDNA representing the M432 virus has revealed the same Pst I and HindIII restriction patterns as did the IAP 35S RNA when tested by blot hybridization against digests of M. musculus DNA (R. Callahan, personal communication).…”

“…On the other hand, only'20-25 copies of the related genes were found in the DNAs of M. cervicolor and M. caroli (6)(7)(8)10), from whose progenitors M. musculus diverged about 5 million years ago (7,11). Thus, the evolution of The publication costs of this article were defrayed in part by page charge payment.…”

“…There are no close sequence homologies between the genomic RNA of IAPs and those of representative type B and type C viruses of M. musculus (1, 2, 4, 5). However,-IAPs do share partial sequence homology (6) with a distinctive class of.retrovirus endogenous to the Asian murine species M. cervicolor and M. caroli (7,8).Hybridization kinetics have indicated that DNA sequences homologous to IAP RNAs are reiterated to the extent of 500 or more copies per haploid genome of both somatic and germ cells of M. musculus (6, 9). On the other hand, only'20-25 copies of the related genes were found in the DNAs of M. cervicolor and M. caroli (6-8, 10), from whose progenitors M. musculus diverged about 5 million years ago (7, 11).…”

“…There are no close sequence homologies between the genomic RNA of IAPs and those of representative type B and type C viruses of M. musculus (1, 2, 4, 5). However,-IAPs do share partial sequence homology (6) with a distinctive class of.retrovirus endogenous to the Asian murine species M. cervicolor and M. caroli (7,8).…”

Expression of Truncated Eukaryotic Initiation Factor 3e (eIF3e) Resulting from Integration of Mouse Mammary Tumor Virus (MMTV) Causes a Shift from Cap-dependent to Cap-independent Translation

“…In most of the cases, integration of MMTV activates genes adjacent to the integration site (e.g. Wnt, Fgf, and Rspo) via the effect of strong enhancers present in the viral long terminal repeats on the expression of previously silent genes in the mammary gland (2,3). However, for the common integration sites Notch-4 and Int6, the viral integration events occur within the gene (4,5).…”