Does astaxanthin protect Haematococcus against light damage?

摘要

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 mu mol photon m(-2) s(-1)); 3) Addition of O-1(2) generators (methylene blue rose bengal) under noninductive conditions (low light of 100 mu mol photon m(-2) s(-1))induced astaxanthin accumulation. This can be reversed by an exogenous O-1(2) 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 agent; 2) O-1(2) is involved indirectly in astaxanthin accumulation process. [References: 43]