Molecular Physiological Study on Na+ uptake/acid-base regulation mechanisms in Japanese medaka (Oryzias latipes)
Date Issued
2009
Date
2009
Author(s)
Lin, Chia-Chemg
Abstract
Euryhaline teleosts have to cope with the osmotic and ionic gradients of aquatic environments with diverse salinities, ion compositions, and pH values. Previous studies suggested that mitochondria-rich (MR) cells are specialized ionocytes, which are the main site responsible for ion regulation mechanisms in fish gills and embryonic skin. However, there are still many unclear issues of how transporters are functioning in fish ion regulation mechanism. The present study used Japanese medaka as a model to examine the roles of the related ion transporters in fish Na+ uptake and acid/base balance mechanisms. hree ion transporters (Na+/H+ exchanger 2/3, NHE2/3; and V-type H+-ATPase and two transcription factors (forkhead box transcription factor I 3, FOXI3; and glial cell missing 2, GCM2) related to ionocyte differentiation have been successfully cloned from Japanese medaka. Using double in situ hybridization/immunocytochemistry, Na+/K+-ATPase (NKA) and NHE were colocalized in MR cells, H+-ATPase (HA) was localized in a part of MR cells. In qRT-PCR experiments of adult medaka gills, after acclimation to acidic freshwater slc9a2 (NHE2), slc9a3 (NHE3) and atp6v1a (H+-ATPase) were up-regulated, while gcm2 was down-regulated; on the other hand, slc9a3, atp6v1a, and foxi3 were up-regulated during acclimation to low sodium water. aken together, NHE and HA may play some roles in sodium uptake/acid-base regulation pathways in medaka, and the 2 transcriptional factors, foxi3 and gcm2, may participate in the ionocyte differentiation pathway.
Subjects
medaka
ionoregulation
osmoregulation
NHE
Na+ uptake
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