蓝藻挥发物α-紫罗酮诱导莱茵衣藻细胞程序性死亡

Programmed cell death in Chlamydomonas reinhardtii induced by cyanobacterial volatile α-ionone

摘要:

[目的] 蓝藻挥发性有机化合物（VOCs）对其他藻类的化感作用可促进蓝藻成为富营养化水体优势种群，本研究旨在以VOCs主要成分α-紫罗酮为例揭示其化感致死机制。[方法] 采用α-紫罗酮处理莱茵衣藻，测定藻细胞生长以及致死浓度下藻细胞光合性能、caspase-likes活性和DNA ladders。[结果] 采用0.05和0.1 mmol/L α-紫罗酮处理24 h后，莱茵衣藻细胞生长均受到明显抑制，其中0.1 mmol/L处理时部分藻细胞发生死亡，死亡率为38.3%。采用0.2 mmol/L α-紫罗酮处理时，藻细胞全部死亡，同时光合色素逐渐降解、Fv/Fm逐渐降低并消失，这表明藻细胞死亡并非坏死。在藻细胞死亡过程中，caspase-9-like和caspase-3-like活性明显增强；DNA在处理1 h时出现ladders，并逐渐降解为100-250 bp片段。[结论] 这表明蓝藻VOCs可通过诱导细胞程序性死亡以发挥化感作用。

Abstract:

[Objective] Allelopathic effects of cyanobacterial volatile organic compounds (VOCs) on other algae promote cyanobacteria becoming the dominant species in eutrophicated waters. The aim of the present study is to uncover the allelopathic lethal mechanism of cyanobacterial VOCs by using α-ionone.[Methods] In the treatment with α-ionone, the cell growth of Chlamydomonas reinhardtii was investigated, and the photosynthetic abilities, caspase-like activities and DNA ladders were investigated at lethal concentration.[Results] When C. reinhardtii cells were treated with α-ionone at 0.05 and 0.1 mmol/L, the cell growth was significantly inhibited, and 38.3% of the cells were killed by 0.1 mmol/L α-ionone. However, all the cells were killed by 0.2 mmol/L α-ionone. During the cell death, the photosynthetic pigments gradually degraded with prolonging the treatment time, and Fv/Fm gradually declined and even disappeared, indicating that the cell death is not a necrosis. Meanwhile, the activities of caspase-9-like and caspase-3-like increased remarkably. In the treatment with 0.2 mmol/L α-ionone for 1 h, DNA showed ladders and then gradually degraded to the fragments of 100-250 bp.[Conclusion] This suggests that cyanobacterial VOCs play the allelopathic role by inducing programmed cell death.