DISTRIBUTION AND TURNOVER OF PHOSPHATE COMPOUNDS IN GROWING CHLORELLA CELLS

• Published in: Plant and cell physiology 1961-11, Vol.2 (4), p.405-414
• Main Authors: MIYACHI, SHIGETOH, TAMIYA, HIROSHI
• Format: Article
• Language: English
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/oxfordjournals.pcp.a077695

Using the Chlorella cells which had been uniformly labeled with 32P, the distribution of phosphorus in various fractions of cell material was investigated. Uniformly 32P-labeled Chlorella was further grown in a P-free medium or in a standard “cold“ medium, and the change of distribution of 32P (as well as the uptake of exogenous P) in various cell fractions was followed. Analysis of the 32P-labeled algal cells showed that the highest in P-content was the fraction of RNA followed by those of polyphosphates, lipid, nucleotidic labile phosphate compounds, DNA and protein (in decreasing order). ATP and ADP were found to be only minor fractions of the total labile phosphates. On incubating the 3P-labeled alga in a P-free medium, the P.contents in the fractions of DNA, protein, lipid and ATP increased, those in polyphosphates and ADP decreased, and that in RNA remained almost unchanged. When the 32P-labeled alga was further grown in the normal “cold” medium, DNA and protein increased with the expenditure of endogenous 32P, but with practically no incorporation of external P. In the meantime the P in polyphosphates decreased considerably, and the RNA fraction incorporated a large amount of external P but only a little of endogenous32P. It was inferred that, under the experimental conditions of the present study, the phosphorus used in the syntheses of DNA and protein was primarily taken from polyphosphates, while that used in the syntheses of RNA, phospholipid and polyphosphates was, for the most part, taken from the extracellular P-source.