INCORPORATION OF RADIOACTIVE TRACERS OF SOME LABELLED COMPOUNDS INTO DNA, RNA, AND PROTEIN IN CHLORELLA CELLS AT VARIOUS STAGES OF THE CELL CYCLE IN SYNCHRONOUS CULTURE

Abstract

Radioisotopically labelled compounds (¹⁴CO₂, ³²P-phosphates, [2-¹⁴C]-acetate, L-[4, 5-³H]leucine, [6-³H]thymidine, [2-¹⁴C]thymine, [5-³H]-uridine and [2-¹⁴C]uracil) were fed for 1hr to synchronized Chlorella cells at various stages of the cell cycle, and uptake and incorporation of the tracers into DNA, RNA, and protein of algal cells were examined. They showed more or less characteristic patterns in the process studied. The three kinds of macromolecular cell constituents took up the radioactivities of all the compounds tested, except in the case of [6-³H]-thymidine, whose radioactivity was incorporated into DNA and protein but not into RNA. ¹⁴C of CO₂ seemed to be specifically or preferentially incorporated into chloroplast macromolecules under photosynthesizing conditions.