The acute and regulatory phases of time-course changes in gill mitochondrion-rich cells of seawater-acclimated medaka (Oryzias dancena) when exposed to hypoosmotic environments

Chao Kai Kang, Wen Kai Yang, Shang Tao Lin, Chin Cheng Liu, Huei Ming Lin, Hong Huan Chen, Chien Wen Cheng, Tsung Han Lee, Pung Pung Hwang

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

The recent model showed that seawater (SW) mitochondrion-rich (MR) cells with hole-type apical openings secrete Cl- through the transporters including the Na+, K+-ATPase (NKA), Na+, K+, 2Cl- cotransporter (NKCC), and cystic fibrosis transmembrane conductance regulator (CFTR). The present study focused on the dynamic elimination of the Cl- secretory capacity and illustrated different phases (i.e., acute and regulatory phases) of branchial MR cells in response to hypoosmotic challenge. Time-course remodeling of the cell surfaces and the altered expressions of typical ion transporters were observed in the branchial MR cells of SW-acclimated brackish medaka (Oryzias dancena) when exposed to fresh water (FW). On the 1st day post-transfer, rapid changes were shown in the acute phase: the flat-type MR cells with large apical surfaces replaced the hole-type cells, the gene expression of both Odnkcc1a and Odcftr decreased, and the apical immunostaining signals of CFTR protein disappeared. The basolateral immunostaining signals of NKCC1a protein decreased throughout the regulatory phase (>1day post-transfer). During this period, the size and number of NKA-immunoreactive MR cells were significantly reduced and elevated, respectively. Branchial NKA expression and activity were maintained at constant levels in both phases. The results revealed that when SW-acclimated brackish medaka were transferred to hypoosmotic FW for 24h, the Cl- secretory capacity of MR cells was eliminated, whereas NKCC1a protein was retained to maintain the hypoosmoregulatory endurance of the gills. The time-course acute and regulatory phases of gill MR cells showed different strategies of the euryhaline medaka when subjected to hypoosmotic environments.

Original languageEnglish
Pages (from-to)181-191
Number of pages11
JournalComparative Biochemistry and Physiology - A Molecular and Integrative Physiology
Volume164
Issue number1
DOIs
Publication statusPublished - 2013

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Physiology
  • Molecular Biology

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