title: Modulation of ion transporter expression in gill mitochondrion-rich cells of eels acclimated to low-Na(+) or-Cl(-) freshwater.
abstract: In this study, we aimed to establish an experimental model to study the role of the gill mitochondrion-rich cells (MRCs) of freshwater fish in Na(+) uptake and to examine the effect of adjusting external Na(+) and Cl(-) ions on selected ion transporters in gill MRCs. Japanese eels (Anguilla japonica) acclimated to deionized (DI) water for 2 weeks were transferred directly to (a) ion-supplemented artificial freshwater (AF), (b) Na(+) -deficient AF, or (c) Cl(-) -deficient AF for 2 days. The effects of the transfer on the expression levels of ion transporters in isolated gill cells were investigated. Our data demonstrated that the 2-day acclimation in ion-supplemented AF, Na(+) -deficient AF, or Cl(-) -deficient AF led to a significant increase in serum osmolarity attributed mainly to an increase in serum Na(+) and/or Cl(-) levels when compared with DI-acclimated eel. Significant inductions of V-type H(+) -ATPase (V-H(+) -ATPase) and cotransporter (NBC1) mRNA expression in gill MRCs were detected in AF-acclimated fish. In fish acclimated to Na(+) -deficient AF, mRNA expression levels of V-H(+) -ATPase, NBC1, and Na(+) /H(+) -exchanger-3 (NHE3) were significantly increased in MRCs. Fish acclimated to Cl(-) -deficient AF showed no observable change in expression levels of ion transporters in gill MRCs. In addition, expression levels of ion transporters in pavement cells were stable throughout the 2-day experiments. These data indicate that the level of Na(+) in freshwater is important for altering the mRNA expression of ion transporters in gill MRCs, which supports the notion that gill MRCs play important roles in freshwater Na(+) uptake.
authors: Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong. kftse@aori.u-tokyo.ac.jp
authors: William K F
authors: WK
authors: Tse
authors: S C
authors: SC
authors: Chow
authors: K P
authors: KP
authors: Lai
authors: D W T
authors: DW
authors: Au
authors: Chris K C
authors: CK
authors: Wong
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D002712:Chlorides / Q000378:metabolism; D004524:Eels / Q000378:metabolism*; D005618:Fresh Water; D005786:Gene Expression Regulation; D005880:Gills / Q000166:cytology* / Q000378:metabolism; D007477:Ions; D008928:Mitochondria / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012964:Sodium / Q000172:deficiency / Q000378:metabolism; D027982:Sodium-Bicarbonate Symporters / Q000235:genetics / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D025262:Vacuolar Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism
chemical_list: D002712:Chlorides; D007477:Ions; D012333:RNA, Messenger; D027982:Sodium-Bicarbonate Symporters; D017923:Sodium-Hydrogen Exchangers; D027981:Symporters; D012964:Sodium; D025262:Vacuolar Proton-Translocating ATPases