No abstract

No abstract

A flow visualization study of instabilities caused by Coriolis effects in plane rotating Poiseuille flow has been carried out. The primary instability takes the form of regularly spaced roll cells aligned in the flow direction. They may occur at Reynolds numbers as low as 100, i.e. almost two orders of magnitude lower than the critical Reynolds number for Tollmien-Schlichting waves in channel flow without rotation. The development of such roll cells was studied as a function of both the Reynolds number and the rotation rate and their properties compared with results from linear spatial stability theory. The theoretically obtained most unstable wavenumber agrees fairly well with the experimentally observed value. At high Reynolds number a secondary instability sets in, which is seen as a twisting of the roll cells. A wavytype disturbance is also seen at this stage which, if the rotational speed is increased, develops into large-scale ‘turbulence’ containing imbedded roll cells.

The major late adenovirus promoter is active early after infection, selectively producing messenger RNAs coding for polypeptides with molecular weights of 55,000, 52,000 and 14,000. This selective expression suggests that a differential splicing pattern occurs at the transition from early to late viral gene expression. Activation of the late promoter and splicing of the 55, 52K mRNAs does not require newly synthesized virus polypeptides.

A rat cell line (A2T2C4) transformed with adenovirus type 2 elicited cytotoxic T Iymphocytes in syngeneic rats. Cytotoxicity was abolished by a rabbit antiserum directed against the major histocompatibility (AgB) antigens and by a syngeneic rat antiserum raised against the virus-transformed cellline. The syngeneic antiserum immunoprecipitated surface proteins with apparent molecular weights of 45,000 19,000, 17,000, and 12,000 from the A2T2C4 cells but it displayed no reactivity against primary rat fibroblasts and spleen cells. The rabbit antiserum against AgB antigens precipitated a 19,000-dalton component from the A2T2C4 cells which was not observed in primary rat fibroblasts. Sequential immunoprecipitation revealed identity between the major polypeptides recognized by the two antisera. Because the rabbit anti-AgB antigen serum was specific for the transplantation antigen subunits and because the syngeneic rat antiserum against the A2T2C4 cells failed to react with the AgB antigens in normal cells, it is concluded that the 19,000-dalton component is coprecipitated with the A&B antigens. Antisera directed specifically against #2-microglobulin and the alloantigenic AgB antigen subunit also coprecipitated the 19,000-dalton component.