Studies on the adaptive formation of photosynthetic structures in Rhodopseudomonas spheroides: II. Nucleotide compositions during adaptation

Abstract

1. 1. Nucleotide compositions of total RNA isolated from Rhodopseudomonas spheroides were identical for cells grown under both aerobic and anaerobic conditions, and during the adaptation period from aerobic-dark to anaerobic-light conditions. 2. 2. Studies employing proflavine showed that with increasing times of [ 14C]-uracil incorporation a greater proportion of radioactivity was in the form of stable RNA, while at short time periods of incorporation (6 min), over 80 % of the RNA formed was unstable. 3. 3. Nucleotide compositions of rapidly labelled RNA are different from total RNA but showed no variation during the adaptation period from aerobic-dark to anaerobic-light conditions. 4. 4. It is concluded that if specific changes in the kind or amount of RNA species are occurring as R. spheroides responds to adaptive changes, they must be relatively minor in character and undetectable by the methods employed in the present studies.