title: Changes in amount and synthesis of poly(A)- and poly(A)+ RNA in growing and resting cultures of Tetrahymena.
abstract: This investigation deals both qualitatively and quantitatively with the changes of RNA content and synthesis during the culture growth cycle of Tetrahymena. Affinity chromatography with an oligo(dT) column was used to separate poly(A)+ RNA from total RNA. The rates of synthesis of poly(A)- and poly(A)+ RNA were determined in terms of the incorporation of [5-3H]uridine. During the log phase, the cellular RNA and protein contents decreased steadily, whereas during the resting stage, both were constant. The extents of decrease of both fractions of RNA were essentially the same (54.4% and 50.6% for total and poly(A)+ RNA, respectively). Therefore, the relative contents of poly(A)+ RNA was constant from the beginning of the log to the resting stage (4.58%). The decrease in protein content, however, amounted to only 24.8%. Theoretically, a change in the age distribution during culture growth would cause a lower content of both fractions of RNA. The extents of the decrease in the rate of synthesis of both fractions were the same (75% and 79% for poly(A)- and poly(A)+ RNA, respectively). However, this reduction is so large that it cannot be solely the result of a shift of the age distribution of the cell population.
mesh_terms: D000818:Animals; D007700:Kinetics; D011061:Poly A / Q000302:isolation & purification / Q000378:metabolism*; D012313:RNA / Q000302:isolation & purification / Q000378:metabolism*; D013768:Tetrahymena / Q000254:growth & development / Q000378:metabolism*
chemical_list: D011061:Poly A; D012313:RNA