Faculty Bibliography

Using [5-3H]orotic acid and [5-3H]uridine as precursors, we compared the efficiency of labeling and the localization of labeled RNA during compensatory hypertrophy of the mouse kidney. [5-3H]orotic acid in tubules labeled RNA 15 times more intensely that [5-3H]uridine, presumably because of greater incorporation of orotic acid into tubular cells. Of the orotic acid label, 97% was in tubular cells, mostly in the proximal tubules. Only about 80% of the uridine label was in the tubules; the ratio in proximal tubules compared with that in distal tubules was 2:1. No changes in distribution within the nephron were produced during compensatory hypertrophy. [5-3H]uridine should be used as the precursor of generalized labeling is desired, but [5-3H5orotic acid is the better precursor of RNA for many studies of compensatory hypertrophy since it is more efficient and concentrates in the segments of greatest biologic activity.

Extracts of spleen cells obtained from a rabbit hyperimmunized with Type III pneumococcal vaccine and transformed with simian virus 40, were subjected to agarose gel electrophoresis in the presence of an [(125)I]S3 polysaccharide-protein conjugate. Binding of radioactivity in the gamma globulin region was observed. Extracts and media obtained from labeled cell cultures contained a protein that bound to an S3, but not to an S8 or inactivated S3 immunoadsorbent. After elution, the bound protein showed a single band on isoelectric focusing which corresponded in isoelectric point to one of the serum anti-S3 antibodies of the donor rabbit. These observations strongly suggest that a normal committed lymphoid cell may be brought into continuous culture by virus transformation and yet retain its ability to synthesize specific antibody.

While amylase secretion from both parotid and pancreas is mediated by cyclic AMP, only parotid secretion is influence by isoproterenol. Adenyl cyclase in both tissues is stimulated by isoproterenol, but there is much less enzyme activity in preparations from pancreas. After in vivo administration of isoproterenol, parotid cyclic AMP levels are greatly elevated whereas little change is observed in pancreas