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F M Rottman

Publications and source records attributed to F M Rottman.

61 records · Page 4Linked to original sources
PubMed1975

Properties of feline leukemia virus. III. Analysis of the RNA.

The kinetics of virus labeling was used to study the maturation of viral RNA in the Rickard strain of feline leukemia virus. Viral RNA labeled over differing intervals was characterized by gel electrophoresis and velocity sedimentation in sucrose gradients made up in aqueous buffer and 99% dimethyl sulfoxide. Labeled virus was found within 30 min after adding radioactive uridine to the cells and production of labeled virus reached a maximum at 4 to 5 h after pulse labeling. Native RNA from feline leukemia virus resolved into three size classes when analyzed by electrophoresis on 2.0% polyacrylamide-0.5% agarose gels: a 6.2 x 10(6) to 7.1 x 10(6) mol wt (50 to 60S) class, an 8.7 x 10(4) mol wt (approximately 8S) class, and a 2.5 x 10(4) mol wt (4 to 5S) class. From two experiments during which RNA degradation appeared minimal, these made up to 57 to 76%, 2 to 5%, and 6 to 12%, respectively, of the total RNA. The 8S RNA in feline leukemia virus has not previously been reported. The 50 to 60S RNA from virus harvested after 4 h of labeling electrophoretically migrated faster and sedimented more slowly in sucrose gradients than did the same RNA species harvested after 20 h of labeling. This argues for an intravirion modification of the high-molecular-weight RNA. The large subunits of denatured viral RNA from both 4- and 20-h labeled-viral RNA electrophoretically migrated with an estimated molecular weight of 3.2 x 10(6) but sedimented with 28S ribosomal RNA (1.8 X 10(6) mol wt) when analyzed by velocity sedimentation through 99% dimethyl sulfoxide.

Cell Line↗
PubMedDate not supplied

D-valine medium maintains prolactin production in primary culture.

Prolactin secretion by bovine pituitary cells in L-valine-containing medium decreases approximately 96% from day 3 to day 11 of culture. We hypothesized that this decrease was caused by overgrowth of these cultures by fibroblasts. Our present objective was to maintain the synthesis and secretion of PRL by bovine pituitary cells in culture. We attempted this by growing pituitary cells in D-valine-containing medium to achieve selective suppression of fibroblast growth. Substitution of D-valine for L-valine in Earle's or Swim's medium resulted in undiminished PRL synthesis and release over a 30-day culture period. In contrast, comparable measures for cells maintained in medium with L-valine decreased more than 90% from day 5 to day 20 of culture and remained low thereafter. Cells cultured in medium containing D-valine retained their ability to release PRL in response to thyrotropin-releasing hormone throughout the 30-day culture period, although there was a decrease in magnitude of response with time. Similarly, estradiol increased PRL release by pituitary cells maintained in D-valine, but this stimulatory effect was no longer demonstrable by day 20 of culture. The amount of growth hormone (GH) and luteinzing hormone (LH) released into the medium decreased with time and this decrease was independent of the valine isomer contained in the medium. We conclude that substituting D-valine for L-valine in culture medium allows PRL synthesis and release to persist undiminished for at least 30 days in culture.

Animals↗