title: Does astaxanthin protect Haematococcus against light damage?
abstract: The photoprotective function of the ketocarotenoid astaxanthin in Haematococcus was questioned. When exposed to high irradiance and/or nutritional stress, green Haematococcus cells turned red due to accumulation of an immense quantity of the red pigment astaxanthin. Our results demonstrate that: 1) The addition of diphenylamine, an inhibitor of astaxanthin biosynthesis, causes cell death under high light intensity; 2) Red cells are susceptible to high light stress to the same extent or even higher then green ones upon exposure to a very high light intensity (4000 mumol photon m(-2)s(-1)); 3) Addition of 1O2 generators (methylene blue, rose bengal) under noninductive conditions (low light of 100 mumol photon m(-2)s(-1) induced astaxanthin accumulation. This can be reversed by an exogenous 1O2 quencher (histidine); 4) Histidine can prevent the accumulation of astaxanthin induced by phosphate starvation. We suggest that: 1) Astaxanthin is the result of the photoprotection process rather than the protective; 2) 1O2 is involved indirectly in astaxanthin accumulation process.
authors.affiliation: Microalgal Biotechnology Laboratory, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Israel.
authors.forename: L
authors.initials: L
authors.lastname: Fan
authors.forename: A
authors.initials: A
authors.lastname: Vonshak
authors.forename: A
authors.initials: A
authors.lastname: Zarka
authors.forename: S
authors.initials: S
authors.lastname: Boussiba
mesh_terms: D000460:Chlorophyta / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D008027:Light; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D017382:Reactive Oxygen Species; D024341:Xanthophylls; D019207:beta Carotene / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000494:pharmacology
chemical_list: D011837:Radiation-Protective Agents; D017382:Reactive Oxygen Species; D024341:Xanthophylls; D019207:beta Carotene; C005948:astaxanthine; D010100:Oxygen