Production of extracellular superoxide contributes to photosynthesis via elimination of reducing power and regeneration of NADP in the red-tide-forming raphidophyte Chattonella marina complex.

The raphidophyte Chattonella marina complex (hereafter Chattonella) consists of noxious red-tide-forming algae that are damaging to fish farms. Chattonella produces and secretes large amounts of the superoxide anion (•O), and the production of extracellular •O has been associated with fish mortality. We reported previously that photosynthetic electron transport is correlated with the production of •O in the genus Chattonella.

Strain, cell density, and nutrient condition affect patterns of diurnal vertical migration and superoxide production in a red-tide alga.

A red tide occurs when cell densities of autotrophic microalgae and some heterotrophic protists increase dramatically and thereby change the color of the sea. Red tides sometimes have negative impacts on human activities, such as fisheries and tourism. Most red-tide flagellates display diurnal vertical migration (DVM) in which cells normally migrate upward during the day and downward at night.

Recovery of photosynthesis after long-term storage in the terrestrial cyanobacterium Nostoc commune.

The terrestrial cyanobacterium Nostoc commune is an anhydrobiotic organism with extreme longevity. Recovery of photosynthesis by rehydration was examined using our laboratory stocks of dry N. commune thalli after long-term storage in a desiccated state.

Superoxide Production by the Red Tide-Producing Complex (Raphidophyceae) Correlates with Toxicity to Aquacultured Fishes.

The marine raphidophyte complex forms red tides, causing heavy mortalities of aquacultured fishes in temperate coastal waters worldwide. The mechanism for fish mortality remains unresolved. Although several toxic chemicals have been proposed as responsible for fish mortality, the cause is still unclear.

Specific Incorporation of Polyunsaturated Fatty Acids into the -2 Position of Phosphatidylglycerol Accelerates Photodamage to Photosystem II under Strong Light.

Free fatty acids (FFAs) are generated by the reaction of lipases with membrane lipids. Generated polyunsaturated fatty acids (PUFAs) containing more than two double bonds have toxic effects in photosynthetic organisms. In the present study, we examined the effect of exogenous FFAs in the growth medium on the activity of photosystem II (PSII) under strong light in the cyanobacterium sp.

The NAD Kinase Slr0400 Functions as a Growth Repressor in Synechocystis sp. PCC 6803.

NADP+, the phosphorylated form of nicotinamide adenine dinucleotide (NAD), plays an essential role in many cellular processes. NAD kinase (NADK), which is conserved in all living organisms, catalyzes the phosphorylation of NAD+ to NADP+. However, the physiological role of phosphorylation of NAD+ to NADP+ in the cyanobacterium Synechocystis remains unclear.

Nutrient deficiency stimulates the production of superoxide in the noxious red-tide-forming raphidophyte Chattonella antiqua.

The raphidophyte Chattonella antiqua is a single-celled alga that forms 'red tides' in coastal areas. C. antiqua produces superoxide anions (O), the excessive production of which has been associated with fish mortality.

Extracellular secretion of superoxide is regulated by photosynthetic electron transport in the noxious red-tide-forming raphidophyte Chattonella antiqua.

The raphidophyte Chattonella antiqua is a noxious red-tide-forming alga that harms fish culture and the aquatic environment. Chattonella antiqua produces and secretes superoxide anions (O), and excessive secretion of O into the water has been associated with fish mortality. It is known that strong light stimulates the production of O in Chattonella spp.