title: Adaptive alterations on gill Na⁺, K⁺-ATPase activity and mitochondrion-rich cells of juvenile Acipenser sinensis acclimated to brackish water.
abstract: Understanding the physiological changes and osmoregulatory strategy is critical for anadromous species to adapt to large changes between freshwater and marine environments. In this study, juvenile Chinese sturgeon (Acipenser sinensis) were acclimated for 2 months to freshwater (FW, c. 0‰) and brackish water (BW, 15‰). Blood was assessed for changes in osmolality and ions. Gill tissue was assayed for Na(+), K(+)-ATPase (NKA) activity and immunohistochemical analysis on mitochondria-rich cells (MRCs). Serum osmolality and ions concentrations (Na(+), Cl(-) and K(+)) examined, except K(+), increased significantly in those specimens adapted to BW. However, the variations were within the range of effective hyperosmotic adaptation. The specific activity of gill NKA of juveniles adapted to BW was significantly higher (c. 1.6 times) than that of fish adapted to FW. MRCs were mainly presented in the interlamellar region of the filament and at the base of the lamella in either FW- or BW-acclimated individuals. In BW, the number and size of MRCs on filaments greatly increased. However, there was no significant difference in the number and size of the MRCs at the lamella region. Results show that juvenile Chinese sturgeon keep osmotic homeostasis in hyperosmotic environments by increasing gill NKA activity and MRCs' size and number, which is similar to other sturgeons and euryhaline teleosts.
authors.affiliation: Key Laboratory of Fisheries Ecology of the Yangtze Estuary, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, China. drzhaofeng@hotmail.com.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Fisheries Ecology of the Yangtze Estuary, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, China.
authors.forename: Beibei
authors.initials: B
authors.lastname: Wu
authors.affiliation: Key Laboratory of Fisheries Ecology of the Yangtze Estuary, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Yang
authors.affiliation: Key Laboratory of Fisheries Ecology of the Yangtze Estuary, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Fisheries Ecology of the Yangtze Estuary, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, China. pzhuang@ecsf.ac.cn.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhuang
mesh_terms: D000064:Acclimatization; D000222:Adaptation, Physiological; D000818:Animals; D005399:Fishes / Q000502:physiology*; D005618:Fresh Water; D005880:Gills / Q000502:physiology*; D006706:Homeostasis; D017136:Ion Transport; D008928:Mitochondria / Q000378:metabolism*; D009994:Osmolar Concentration; D000068357:Saline Waters; D054712:Salinity; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014882:Water-Electrolyte Balance
chemical_list: D000254:Sodium-Potassium-Exchanging ATPase
keywords: Acipenser sinensis; Mitochondria-rich cell; Na+, K+-ATPase; Osmoregulation; The Yangtze Estuary