Concordance of the RNA termini of recombinants from crosses between avian retroviruses with different termini.

In previous work we have analyzed the RNA of recombinants issuing from crosses between avian retroviruses with distinguishable oligonucletoide maps and have the origins of the different segments of the recombinant RNA. Several recombinants appeared to contain the 5′-proximal part of one parent and the 3′-proximal part of the other parent, however, the terminal regions themselves were not analyzed. We have now examined the 5′- and 3′-terminal RNase T₁-resistant oligonucleotides of the parents and the progeny of two crosses and found that in all cases the 5′- and 3′-terminal regions were derived from only one of the parents. Inasmuch as the parental RNAs are subterminally redundant, as in the ase of Pr RSV-C and AMV RNA, the progeny RNA have the same property. It is remarkable that the crossovers appear to take place with a high frequency close to the termini of the viral RNA.     

Quantitative thin layer chromatography for the analysis of skin surface lipids

Summary Recently a new thin layer chromatography plate (Whatman LK 6D) became available which is extremely easy to handle and permits highly reproducible qualitative and quantitative analysis. This plate proved to be of great value for the investigation of skin surface lipids. The use of a fatty acid methyl ester as an internal standard makes it unnecessary to employ additional gravimetrical or photometrical methods for quantitative lipid analysis. The method presented in this paper is simpler and requires much less time than alternative procedures and allows a large number of lipid samples to be processed simultaneously.     

MOTION PICTURE STUDY OF THE TOXIC ACTION OF STREPTOLYSINS ON LEUCOCYTES

The initial morphologic alteration in rabbit polymorphonuclear leucocytes exposed to streptolysin is rapid and extensive lysis of cytoplasmic granules. The granules appear to rupture directly into the cell sap. Within a few minutes following degranulation, the leucocyte rounds up, filamentous processes appear on the cell membrane, the cytoplasm liquefies, and finally the nuclear lobes swell and fuse. Streptolysin O causes these changes in intact leucocytes when added in concentrations only slightly higher than those required for release of hydrolases from isolated liver lysosomes, and furthermore exerts its action on granulocytes promptly. On the other hand streptolysin S acts on white cells only after a 15 to 30 minute delay, and the levels necessary to disrupt granules in leucocytes are considerably higher than those which act on lysosome suspensions. Exposure of rabbit alveolar macrophages to streptolysin O also results in lysis of granules, soon followed by alterations in the cytoplasm and membrane. The observations are in accord with the hypothesis that streptolysins penetrate the leucocyte membrane and bring about lysis of granules. Autolytic enzymes released from the granules might then be responsible for the subsequent damage seen in various other cell structures.