Although the murine retrovirus SL3-3 is highly leukaemogenic, in both the structure of its genome and in its properties of replication in tissue culture it closely resembles the nonleukaemogenic retrovirus Akv (refs 3, 4). An earlier investigation of the properties of recombinant SL3-3-Akv viruses localized the major determinant of leukaemogenicity outside the env gene, in a region of the viral genome that includes the gag gene and the noncoding long terminal repeat (LTR). To localize the determinant of SL3-3's leukaemogenicity more precisely we have now construced a recombinant provirus containing the LTR of SL3-3 and the coding region of Akv. The leukaemogenicity of these recombinants demonstrates that the determinant of leukaemogenicity lies within the SL3-3 LTR. Nucleotide sequencing of the LTRs of SL3-3 and Akv shows that they differ by a set of changes in the region thought to contain a transcriptional enhancer element. We suggest that enhancer region sequences are the major determinants of leukaemogenicity in these viruses.

Animals↗

PubMedDate not supplied

Effects of experimental embolization of superior mesenteric artery branch on the intestine.

A primary mesenteric branch of the superior mesenteric artery was embolized with Amicar-mixed clots in seven dogs and with gelatin sponges in five dogs. All of the dogs embolized with Amicar-mixed clots survived the experimental period and no mesenteric damage was found with postmortem studies. Three of the five dogs embolized with gelatin sponges showed a local stricture within the embolized segment of intestine. Collateral blood supply to the strictured segment of bowel in these three dogs developed via arterial arcades, mural branches of the vasa recta and omental arteries.

Aminocaproates↗