title: Isolated and combined exposure to ammonia and nitrite in giant freshwater pawn (Macrobrachium rosenbergii): effects on the oxidative stress, antioxidant enzymatic activities and apoptosis in haemocytes.
abstract: The residual contaminators such as ammonia and nitrite are widely considered as relevant sources of aquatic environmental pollutants, posing a great threat to shrimp survival. To study the toxicological effects of ammonia and nitrite exposure on the innate immune response in invertebrates, we investigated the oxidative stress and apoptosis in haemocytes of freshwater prawn (Macrobrachium rosenbergii) under isolated and combined exposure to ammonia and nitrite in order to provide useful information about adult prawn immune responses. M. rosenbergii (13.44 ± 2.75 g) were exposed to 0, 5, and 25 mg/L total ammonia-N (TAN) and 0, 5, and 20 mg/L nitrite-N for 24 h. All ammonia concentrations were combined with all nitrite concentrations, making a total of nine treatments studied. Following the exposure treatment, antioxidant enzyme activity, reactive oxygen species (ROS) generation, nitric oxide (NO) generation, and apoptotic cell ratio of haemocytes were measured using flow cytometry. Results indicated that ROS generation was sensitive to the combined effect of ammonia and nitrite, which subsequently affected the Cu-Zn SOD activity. In addition, CAT showed the highest activity at 5 mg/L TAN while GPx decreased at 5 mg/L TAN and returned towards baseline at 25 mg/L. NO generation synchronized with the apoptotic cell ratio in haemocytes, indicating that NO production was closely associated with programmed cell death. Both NO production and apoptotic ratios significantly decreased following 25 mg/L TAN, which may be due to the antagonistic regulation of NO and GPx. We hypothesized that the toxicological effect of nitrite exhibited less change in physiological changes compared to that of ammonia, because of the high tolerance to nitrite exposure in mature M. rosenbergii and/or the competitive effects of chloride ions. Taken together, these results showed that ammonia and nitrite caused a series of combined oxidative stress and apoptosis in M. rosenbergi, but further studies are of great need to explain the mechanisms.
authors.affiliation: Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, Key Laboratory of Safe and Healthy Aquaculture in Guangdong Province, College of Life Science, South China Normal University, Guangzhou, 510631, People's Republic of China.
authors.forename: Yufan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, Key Laboratory of Safe and Healthy Aquaculture in Guangdong Province, College of Life Science, South China Normal University, Guangzhou, 510631, People's Republic of China. ycx@scnu.edu.cn.
authors.forename: Chaoxia
authors.initials: C
authors.lastname: Ye
authors.affiliation: Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, Key Laboratory of Safe and Healthy Aquaculture in Guangdong Province, College of Life Science, South China Normal University, Guangzhou, 510631, People's Republic of China. wanganl@scnu.edu.cn.
authors.forename: Anli
authors.initials: A
authors.lastname: Wang
authors.affiliation: Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, Key Laboratory of Safe and Healthy Aquaculture in Guangdong Province, College of Life Science, South China Normal University, Guangzhou, 510631, People's Republic of China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, Key Laboratory of Safe and Healthy Aquaculture in Guangdong Province, College of Life Science, South China Normal University, Guangzhou, 510631, People's Republic of China.
authors.forename: Changhong
authors.initials: C
authors.lastname: Chen
authors.affiliation: Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, Key Laboratory of Safe and Healthy Aquaculture in Guangdong Province, College of Life Science, South China Normal University, Guangzhou, 510631, People's Republic of China.
authors.forename: Jianan
authors.initials: J
authors.lastname: Xian
authors.affiliation: Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, Key Laboratory of Safe and Healthy Aquaculture in Guangdong Province, College of Life Science, South China Normal University, Guangzhou, 510631, People's Republic of China.
authors.forename: Zhenzhu
authors.initials: Z
authors.lastname: Sun
mesh_terms: D000641:Ammonia / Q000633:toxicity*; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D006434:Hemocytes / Q000737:chemistry / Q000378:metabolism; D007113:Immunity, Innate / Q000187:drug effects*; D009573:Nitrites / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects*; D033541:Palaemonidae / Q000187:drug effects* / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D009573:Nitrites; D014874:Water Pollutants, Chemical; D000641:Ammonia
keywords: Ammonia; Apoptosis; Flow cytometry; Innate immunity; Macrobrachium rosenbergii; Nitrite