Section de Bioénergétique, Département de Biologie Cellulaire et Moléculaire, Centre d'Etudes de Saclay, 91191, Gif-sur-Yvette Cedex, France.
Photosynth Res. 1993 Apr;36(1):25-34. doi: 10.1007/BF00018072.
Characteristics of thermoluminescence (TL) glow curves were studied in thylakoids (isolated from pea leaves) or in intact pea leaves after an exposure to very high light for 2 min in the TL device. The inhibition of photosynthesis was detected as decreases of oxygen evolution rates and/or of variable fluorescence.In thylakoids exposed to high light, then dark adapted for 5 min, a flash regime induced TL glow curves which can be interpreted as corresponding to special B bands since: 1) they can be fitted by a single B band (leaving a residual band at -5°C) with a lower activation energy and a shift of the peak maximum by -5 to -6°C and, 2) the pattern of oscillation of their amplitudes was normal with a period of 4 and maxima on flashes 2 and 6. During a 1 h dark adaptation, no recovery of PS II activity occurred but the shift of the peak maximum was decreased to -1 to -2°C, while the activation energy of B bands increased. It is supposed that centers which remained active after the photoinhibitory treatment were subjected to reversible and probably conformational changes.Conversely, in intact leaves exposed to high light and kept only some minutes in the dark, TL bands induced by a flash regime were composite and could be deconvoluted into a special B band peaking near 30°C and a complex band with maximum at 2-5°C. In the case of charging bands by one flash, this low temperature band was largely decreased in size after a 10 min dark adaptation period; parallely, an increase of the B band type component appeared. Whatever was the flash number, bands at 2-5°C were suppressed by a short far red illumination given during the dark adaptation period and only remained a main band a 20°C; therefore, the origin of the low temperature band was tentatively ascribed to recombinations in centers blocked in state S2QA (-)QB (2-). In vivo, the recovery of a moderately reduced state in the PQ pool, after an illumination, would be slow and under the dependence of a poising mechanism, probably involving an electron transfer between cytosol and chloroplasts or the so-called 'chlororespiration' process.
研究了在 TL 设备中暴露于强光 2 分钟后，从豌豆叶片中分离的类囊体或完整的豌豆叶片中的热释光（TL）发光曲线的特征。通过降低氧气释放速率和/或可变荧光来检测光合作用的抑制。在暴露于强光下然后在黑暗中适应 5 分钟的类囊体中，闪光状态诱导的 TL 发光曲线可以解释为对应于特殊的 B 带，因为：1）它们可以用单个 B 带拟合（在-5°C 处留下残留带），具有较低的活化能和峰最大值的-5 至-6°C 的位移，并且 2）其幅度的振荡模式正常，周期为 4 个，最大值在闪光 2 和 6 上。在 1 小时的暗适应期间，PS II 活性没有恢复，但峰最大值的位移减小至-1 至-2°C，而 B 带的活化能增加。假设在光抑制处理后仍保持活性的中心经历了可逆且可能的构象变化。相反，在仅在黑暗中暴露几分钟的完整叶片中，由闪光状态诱导的 TL 带是复合的，可以分解为特殊的 B 带，在 30°C 附近达到峰值和具有 2-5°C 最大值的复杂带。在由一个闪光对充电带的情况下，在 10 分钟的暗适应期后，低温带的大小大大减小；同时，B 带类型成分的增加。无论闪光次数如何，在暗适应期间进行短暂的远红照射都可以抑制 2-5°C 处的带，仅在 20°C 处保留一个主带；因此，低温带的起源被暂定为在 S2QA（-）QB（2-）中阻塞的中心的重组。在体内，PQ 池在光照后恢复到中度还原状态会很慢，并且依赖于平衡机制，可能涉及细胞质和叶绿体之间的电子转移或所谓的“氯呼吸”过程。
