Misra H S, Desai T S
Molecular Biology & Agriculture Division, Bhabha Atomic Research Centre, Trombay, Bombay, India.
Biochem Biophys Res Commun. 1993 Aug 16;194(3):1001-7. doi: 10.1006/bbrc.1993.1920.
Alternating peaks of photosynthetic activity (P-phase) and nitrogen fixing activity (N-phase) were shown in Plectonema boryanum grown under diazotrophic condition in continuous light. In N-phase photosystem I activity increased by 35-45% and oxygen evolution decreased by 70-80% which was partially restored to 45-55% in the presence of 2,6-dichloro-p-benzoquinone. Thermoluminescence glow curve in P-phase consists of a major band at 25 degrees C which was shifted to 10 degrees C in N-phase. Both these bands are sensitive to DCMU and tetranitromethane. Flash excitation studies with major thermoluminescence band in P and N-phase showed oscillations with same periodicity of four having maxima at 2nd and 6th flashes. On the basis of these observations it is suggested that photosynthetic electron transport under diazotrophic growth condition is regulated by the redox levels of the secondary quinone acceptor QB.
在连续光照下的固氮条件下生长的鞘丝藻中，呈现出光合活性（P 相）和固氮活性（N 相）的交替峰值。在 N 相中，光系统 I 的活性增加了 35 - 45%，氧气释放减少了 70 - 80%，在 2,6 - 二氯对苯醌存在的情况下，氧气释放部分恢复到 45 - 55%。P 相的热释光发光曲线在 25℃ 有一个主要峰带，在 N 相中该峰带移至 10℃。这两个峰带都对二氯苯基二甲基脲（DCMU）和四硝基甲烷敏感。对 P 相和 N 相主要热释光峰带的闪光激发研究表明，振荡具有相同的四个周期，在第 2 次和第 6 次闪光时出现最大值。基于这些观察结果，有人提出在固氮生长条件下，光合电子传递受次级醌受体 QB 的氧化还原水平调节。
