Differential thermal effects on the energy distribution between photosystem II and photosystem I in thylakoid membranes of a psychrophilic and a mesophilic alga.
Sensitivity of the photosynthetic thylakoid membranes to thermal stress was investigated in the psychrophilic Antarctic alga Chlamydomonas subcaudata. C. subcaudata thylakoids exhibited an elevated heat sensitivity as indicated by a temperature-induced rise in F(o) fluorescence in comparison with the mesophilic species, Chlamydomonas reinhardtii. This was accompanied by a loss of structural stability of the photosystem (PS) II core complex and functional changes at the level of PSI in C. reinhardtii, but not in C. subcaudata. Lastly, C. subcaudata exhibited an increase in unsaturated fatty acid content of membrane lipids in combination with unique fatty acid species. The relationship between lipid unsaturation and the functioning of the photosynthetic apparatus under elevated temperatures is discussed.
Morgan-Kiss
Rachael
R
Department of Microbiology, University of Illinois, Urbana, IL 61801, USA.
Ivanov
Alexander G
AG
Williams
John
J
Mobashsher Khan
Huner
Norman P A
NP
D000818:Animals; D000864:Antarctic Regions; D002696:Chlamydomonas / Q000737:chemistry; D002734:Chlorophyll / Q000737:chemistry; D000460:Chlorophyta / Q000737:chemistry*; D005227:Fatty Acids / Q000032:analysis; D005231:Fatty Acids, Unsaturated / Q000032:analysis; D005453:Fluorescence; D006358:Hot Temperature; D045342:Light-Harvesting Protein Complexes; D008563:Membrane Lipids / Q000737:chemistry; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D020524:Thylakoids / Q000737:chemistry*
D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D045342:Light-Harvesting Protein Complexes; D008563:Membrane Lipids; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; C001785:chlorophyll P 700