Characterizing dose-responses of catalase to nitrofurazone exposure in model ciliated protozoan Euplotes vannus for ecotoxicity assessment: enzyme activity and mRNA expression.
In environmental studies, some biological responses, known as biomarkers, have been used as a powerful bioassay tool for more than four decades. Disparity between enzyme activity and mRNA abundance leads to correlation equivocality, which makes the application of biomarkers for environmental risk assessment more complicated. This study investigates this disparity in the case of catalase when used as a biomarker for detecting ecotoxicity induced by antibiotics in aquatic ecosystems. In particular, dose-responses for catalase activity and mRNA expression abundance were investigated in Euplotes vannus which were exposed to graded doses of nitrofurazone for several discrete durations, and dose-response models were developed to characterize the dose-response dynamics. Significant differences were found in both catalase activity and mRNA expression abundance among the E. vannus treated with nitrofurazone. Catalase activity showed a hormetic-like effect in terms of dose-response, characterized by a biphasic relationship which was more clearly evident after a longer exposure period, while mRNA expression abundance increased linearly with the exposure duration. Additionally, the correlation between catalase activity and mRNA expression abundance reversed along with the duration of exposure to nitrofurazone. Taken together, our results demonstrate that catalase mRNA expression offers a more straightforward dose-response model than enzyme activity. Our findings suggest that both catalase enzyme activity and mRNA expression abundance can be used jointly as bioassay tools for detecting ecotoxicity induced by nitrofurazone in aquatic ecosystems.
Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, Guangdong, China. Electronic address: lijiqiu@126.com.
Jiqiu
J
Li
Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, Guangdong, China.
Liang
L
Zhou
Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, Guangdong, China.
Xiaofeng
X
Lin
Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, College of Life Science, South China Normal University, Guangzhou 510631, Guangdong, China.
Zhenzhen
Z
Yi
Zoology Department, King Saud University, Riyadh 11451, Saudi Arabia.
Khaled A S
KA
Al-Rasheid
D015415:Biomarkers / Q000032:analysis; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D054750:Ecotoxicology / Q000379:methods*; D004789:Enzyme Activation / Q000187:drug effects; D016812:Euplotes / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D009583:Nitrofurazone / Q000633:toxicity*; D012333:RNA, Messenger / Q000235:genetics*; D018570:Risk Assessment; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D015415:Biomarkers; D012333:RNA, Messenger; D014874:Water Pollutants, Chemical; D002374:Catalase; D009583:Nitrofurazone
Biomarker; Catalase; Ciliated protozoan; Dose responses dynamic; Nitrofurazone