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Expression and functions of inositol monophosphatase (IMPA) in seawater (SW)‐acclimated euryhaline teleosts
Author(s) -
Cramb Gordon,
Kalujnaia Svetlana,
Gellatly Steven,
Hazon Neil,
Villasenor Alfredo,
Yancey Paul
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.937.7
Subject(s) - euryhaline , osmoregulation , inositol , osmolyte , biology , gene isoform , oreochromis mossambicus , tilapia , killifish , inositol phosphate , fundulus , microbiology and biotechnology , biochemistry , ecology , salinity , fish <actinopterygii> , receptor , fishery , gene
Organic osmolytes are essential for cell volume regulation in SW‐acclimated euryhaline teleosts. Inositol is an essential osmolyte for osmoregulation in both eels and tilapia. De novo synthesis of inositol is dependent on inositol monophosphatase (IMPA), which de‐phosphorylates inositol phosphate produced from glucose 6‐phosphate by myo‐inositol phosphate synthase. In most species, two IMPA genes (IMPAs 1 and 2) with slightly different kinetics and tissue expression profiles have been characterised. As a result of tandem and whole genome duplication events, teleost fish express up to six IMPA isoforms, although in most species some isoforms have been lost during evolution. In the eel, three IMPA1 and two IMPA2 isoforms, and in tilapia four IMPA1 isoforms have been identified which exhibit differential tissue expression. The IMPA1.1 isoform predominates in the major osmoregulatory tissues of the eel, and its expression is upregulated when fish enter SW. Although IMPA1.3 is the most abundant isoform in all tilapia tissues, again it is only IMPA1.1 expression that is increased after SW transfer. In both species, increases in tissue inositol levels are responsible for cell volume regulation in response to the increased extracellular salinity. The volume regulatory effects of inositol are particularly important in tissues directly exposed to the SW environment, such as the gills, skin and fin. Funding: NERC, UK