Photosensitizers Neutral Red (Type I) and Rose Bengal (Type II) Cause Light-Dependent Toxicity in Chlamydomonas reinhardtii and Induce the Gpxh Gene via Increased Singlet Oxygen Formatio

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• 作者：Beat B. Fischer ; Anja Krieger-Liszkay ; and Rik I. L. Eggen
• 刊名：Environmental Science & Technology
• 出版年：2004
• 出版时间：December 1, 2004
• 年：2004
• 卷：38
• 期：23
• 页码：6307 - 6313
• 全文大小：292K
• 年卷期：v.38,no.23(December 1, 2004)
• ISSN：1520-5851

文摘

The connection between the mode of toxic action and thegenetic response caused by the type I photosensitizerand photosynthesis inhibitor neutral red (NR) and the typeII photosensitizer rose bengal (RB) was investigated inthe green alga Chlamydomonas reinhardtii. For bothphotosensitizers, a light intensity-dependent increase intoxicity and expression of the glutathione peroxidasehomologous gene (Gpxh) was found. The toxicity of RBwas reduced by the singlet oxygen (¹O₂) quenchers 1,4-diazabicyclo[2.2.2]octane and L-histidine, and the RB-inducedGpxh expression was stimulated in deuterium oxide-supplemented growth medium. These observations clearlyindicate the involvement of ¹O₂ in both toxicity and thegenetic response caused by RB. NR up-regulated theexpression of typical oxidative and general stress responsegenes, probably by a type I mechanism, and also stronglyinduced the Gpxh expression. The stimulating effect ofdeuterium oxide in the growth medium suggested theinvolvement of ¹O₂ also in the NR-induced response. Indeed,an increased ¹O₂ formation was detected with EPR-spintrapping in NR-treated spinach thylakoids. However, noneof the ¹O₂ quenchers could reduce the light-dependenttoxicity of NR in C. reinhardtii, indicating that NR has adifferent mode of toxic action than RB.