Photosynthetic Structures Research Articles

Studies on the adaptive formation of photosynthetic structures in Rhodopseudomonas spheroides: I. Synthesis of macromolecules

1. 1. Dark aerobically growing cells of Rhodopseudomonas spheroides in adapting to anaerobic-light conditions undergo a lag phase, during which bacteriochlorophyll is synthesized, followed by a resumption of growth. 2. 2. The cellular levels of RNA, protein and DNA are unaltered during this adaptive period. 3. 3. Considerable fluctuations occur during this period in rate of uptake of RNA, DNA and protein precursors. These fluctuations have been ascribed to the restricted energy available to the adapting cells. 4. 4. Fractionation of cell components demonstrates that a preferential synthesis of protein occurs at the membrane site during adaption although rapidly formed RNA is not associated with these membrane fractions. 5. 5. The proportion of rapidly formed RNA which forms ribonuclease-resistant hybrids with DNA increases when aerobically grown cells are transferred to anaerobic conditions.