Abstract
Human peripheral lymphocytes have been cultured with and without a mitogen, leucoagglutinin, and the labelling of nuclear and cytoplasmic RNA selected by oligo(dT) cellulose have been studied. Leucoagglutinin stimulates incorporation of [ 8H]thymidine in DNA and [ 8H]uridine in RNA by about 7-fold. 1. 1. Nuclear RNA of lymphocytes contains about 6% species having an attached poly(A) segment while the figure for cytoplasmic RNA is 4%. Stimulation does not change these figures. 2. 2. Labelling of nuclear and cytoplasmic RNA with a poly(A) segment is about 3 times greater than that of RNA lacking poly(A). The relative labelling rates remain roughly equal on stimulation. 3. 3. The proportion of radioactivity in poly(A) containing nuclear RNA species remains unchanged as compared to the total radioactivity in nuclear RNA, about 20%, between incorporation times of 45 min and 12 h. In contrast, the relative radioactivity in poly(A) containing cytoplasmic RNA decreases from 45 to 18%. Stimulation does not affect these proportions. 4. 4. Agarose-acrylamide gels of radioactive RNA samples reveal quantitative differences between fractions obtained from resting or stimulated cells. These data suggest that activation of lymphocytes with mitogens leads to increased incorporation of radioactive uridine into mRNA and rRNA in equal proportions.
Published Version
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