The raphidophyte Chattonella antiqua is a single-celled alga that forms ‘red tides’ in coastal areas. C. antiqua produces superoxide anions (O₂⁻), the excessive production of which has been associated with fish mortality. It is suggested that putative NADPH oxidase in the outer membrane oxidizes intracellular NADPH to produce O₂⁻ and secrete it externally. Earlier studies revealed that photosynthetic electron transport, a major producer of NADPH in photosynthetic organisms, is involved in the production of O₂⁻ in C. antiqua but the details of the O₂⁻ production mechanism have yet to be elucidated. Since nutrient deficiency adversely affects the formation of blooms of C. antiqua, in this study, we examined the effects of nutrient deficiency on O₂⁻ production in C. antiqua. When cells were grown under nitrogen (N)- or phosphorus (P)-deficient conditions, the production of O₂⁻ was stimulated. In particular, the extracellular levels of O₂⁻ under N- or P-deficient conditions were high during the dark period when photosynthetic activities in terms of actual quantum efficiency and photochemical quenching were low. The extracellular levels of O₂⁻ under the nutrient-deficient conditions were unaffected by the presence of 3-(3,4-dichlorophenyl)-1,1‑dimethylurea (DCMU), an inhibitor of photosynthetic electron transport, but decreased when the nutrients were present. Furthermore, the intracellular ratio of NADPH to NADP⁺ under N- or P-deficient conditions was higher than that under nutrient-replete conditions. These observations suggest that another metabolic pathway, independent of photosynthesis, provides NADPH for the production of O₂⁻ under nutrient deficiency.

斜纹藻属Chattonella antiqua是一种单细胞藻类，在沿海地区形成“赤潮”。C.蝇产生（O超氧阴离子₂ ^- ），过量产生其中已与鱼的死亡率。有人建议，在外膜中推定的NADPH氧化酶的细胞内氧化NADPH产生ö ₂ ^-和外部分泌它。早先的研究发现，光合电子传递，NADPH的光合生物的主要生产商，业务涉及生产Ø ₂ ^-在C.蝇但将O的细节₂ ^-生产机制尚未阐明。由于营养缺乏绽放的形成产生不利影响C.蝇，在这项研究中，我们研究了O对营养缺乏的影响，₂ ^-生产C.蝇。或磷（P）缺陷的条件下，生产的-O -当细胞氮（N）下生长₂ ^-被刺激。特别地，澳细胞外水平₂ ^- N型或P缺乏条件下分别在黑暗时期高时的实际量子效率和光化学淬灭术语光合活性低。的O-胞外水平₂ ^-在营养缺乏的条件下，不受光合电子传输抑制剂3-（3,4-二氯苯基）-1,1-二甲基脲（DCMU）的影响，但是当存在营养时其含量降低。此外，在缺氮或缺磷条件下，NADPH与NADP ⁺的细胞内比率高于在营养丰富的条件下。这些观察表明，另一种代谢途径，独立于光合作用，提供NADPH生产的O ₂ ^-下营养缺乏。