Synthesis of chloroplast membrane lipids and chlorophyll in synchronous cultures of Chlamydomonas reinhardi.

Chloroplast membrane lipid synthesis has been studied in synchronously growing cultures of Chlamydomonas reinhardi. The synthesis of sulfolipid and phospholipid were measured by incorporation of 35SO4(2-) and 32PO4(3-) during a 1-h pulse. Galactolipid synthesis was measured by H14CO3- incorporation into lipid fractions separated by thin layer chromatography. Lipid synthesis occurs principally during the light portion of the synchronous cycle. Phosphatidylglycerol is synthesized between 3-4 h in the light and sulfolipid is labeled between 7-9 h in the light. Galactolipid synthesis appears to reach maximal rates shortly after the lights go on and again at 7 h. Chlorophyll reaches maximal rates of synthesis after 7 h. These lipids are made and inserted into the chloroplast membrane prior to major increases in photosynthetic capacity. Our results also show that chloroplast membrane lipids are synthesized in a sequential or multistep process.