Inhibition of Photosystem II activity of Symbiodinium by menthol：Approach on effects and mechanism

• Main Authors: Tzu-Ying Chu, 朱姿縈
• Other Authors: Jih-Terng Wang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/09355047708508891376

碩士 === 大仁科技大學 === 生物科技研究所 === 99 === When menthol was used to anesthetize corals, they were bleached during paralysis. The aim of this study was to study the cause of menthol-induced bleaching. Firstly, we supposed that menthol result in bleaching of coral which may inhibit photosynthesis of Symbiodinium of coral. DIVING-PAM was used in this study to determine the activity of photosystem II (PS II) of Symbiodinium in the menthol treated. We confirmed inhibition of PS II activity of Symbiodinium by menthol and then determined concentration of 50% inhibition (IC50) with menthol for Symbiodinium in four hour. We analyzed tolerance of different sub-clade of Symbiodinium for menthol, and used the 3- (3,4-dichlorophenyl) -1,1-dimethylurea (DCMU) to as a positive control. The results showed inhibition of the photosynthesis of Symbiodinium and phenomenon of dose by menthol, and compared with the positive control of DCMU that inhibition of menthol was about probably one in one hundred thousand folds for DCMU. Different sub-clade of Symbiodinium in the menthol IC50 of four hour are B1：1.96 ± 0.13mM, D1a：1.07 ± 0.07mM, C15：1.01 ± 0.01mM, C3：0.86 ± 0.02mM, C1：0.72 ± 0.09mM; these in the DCMU IC50 of four hour are B1: 77 ± 5pM, D1a: 47 ± 11pM, C15: 33 ± 3pM, C3: 37 ± 1pM, C1: 36 ± 12pM. These results further lead to a possible mechanism, menthol inhibit the photosynthesis of Symbiodinium which may produce excess reactive oxygen species (ROS) in Symbiodinium and then damaged activity of PSII. To approach whether ROS could produced by menthol then to damage activity of PSII, used 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA) as a probe measured ROS of Symbiodinium. The result show that menthol can cause a significant level of ROS generation in C15、C3、C1 sub-clade of Symbiodinium, but that can’t cause a significant level of ROS generation in B1and D1a sub-clade of Symbiodinium. We suggested that menthol mechanism of inhibition for photosynthesis of Symbiodinium have not necessarily correlation with ROS generation which may differences due to different sub-clade of Symbiodinium.