title: Transcriptomic analysis of liver from grass carp (Ctenopharyngodon idellus) exposed to high environmental ammonia reveals the activation of antioxidant and apoptosis pathways.
abstract: High concentration of ammonia in aquatic system leads to detrimental effects on the health of aquatic animals. However, the mechanism underlying ammonia-induced toxicity is still not clear. To better understand the mechanism of ammonia toxicity effects on fish, juvenile grass carp was employed in the present study. RNA high-throughput sequencing technique was applied to analyze the total RNAs extracted from the liver of fish after 8 h post exposure to the water containing 2 mM NH4HCO3which experimentally mimicked the high environmental ammonia (HEA). A total of 49,971,114 and 53,826,986 clean reads were obtained in control and 2 mM HEA group, respectively, in which there were 911 differently expressed genes (DEGs) including 563 up-regulated and 348 down-regulated genes. In addition, 10 DEGs were validated by quantitative PCR. These DEGs were involved in several pathways related with oxidative stress or apoptosis. Further analysis on oxidative stress, histopathology and cellular apoptosis in grass carp liver after HEA exposure revealed interesting findings. Increased reactive oxygen species (ROS) content and superoxide dismutase (SOD) activity together with the decreased catalase (CAT) activity were detected, which may be effected by DEGs and related pathways such as FOXO signaling pathway. The histopathology and TUNEL assays results confirmed that apoptosis was induced in liver when fish had suffered HEA. Combined with the results of transcriptomic experiments, c-Myc-Bax-Caspase9 apoptosis pathway could be involved in grass carp liver apoptosis induced by ammonia stress.
authors.affiliation: Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
authors.forename: Jiali
authors.initials: J
authors.lastname: Jin
authors.affiliation: Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
authors.forename: Zhixin
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
authors.forename: Abeer
authors.initials: A
authors.lastname: Hergazy
authors.affiliation: Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
authors.forename: Jiangfeng
authors.initials: J
authors.lastname: Lan
authors.affiliation: Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, 510225, China.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China. Electronic address: chennan@mail.hzau.edu.cn.
authors.forename: Nan
authors.initials: N
authors.lastname: Chen
authors.affiliation: Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, 510225, China. Electronic address: linli@mail.hzau.edu.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Lin
mesh_terms: D000641:Ammonia / Q000378:metabolism / Q000633:toxicity*; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects*; D002347:Carps / Q000378:metabolism*; D020869:Gene Expression Profiling / Q000662:veterinary; D005786:Gene Expression Regulation / Q000187:drug effects*; D008658:Inactivation, Metabolic; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D059467:Transcriptome; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D014874:Water Pollutants, Chemical; D000641:Ammonia
keywords: Apoptosis; Ctenopharyngodon idellus; High environmental ammonia; Oxidative stress; Transcriptomic analysis