engleski

Na, K-ATPase in gills of aquatic crustacea

The sodium pump, or Na, K-ATPase, provides at least part of the driving force for transepithelial movement of monovalent ions across the gills and other trasnporting tissues in many aquatic animals including the Crustacea. The crustacean Na, K-ATPase, like that in all animal cells, is composed of a catalytic alpha-subunit and an accompanying betta-subunit. The amino acid sequence of the crustacean alpha-subunit is 71-74% identical to vertebrate alpha-subunit sequences. In brachyuran Crustacea, the Na, -ATPase is more highly expressed in posterior gills compared with anterior and is found predominantly in mitochondria -rich cells that are morphologically and biochemically specialized to mediate NaCl uptake from the medium. When the external salinity is lowered from that of normal seawater, producing conditions in which many euryhaline Crustacera hyperosmoregulate their hemolymph, both the enzymatic activity of the Na, K-ATPase and the gen expression of the alpha-subunit are increased in these tissues. Although the precise regulatory mechanism is not known, evidence suggests that crustacean hyperglycemic hormone may be responsible for the induction of a range of aquatic Crustacea suggests that the level of Na, K-ATPase function in transporting tissue may be correlated with their ability to invade estuarine habitats.

Crustacea ; gill ; sodium pump ; ATPase ; osmoregulation ; mRNA expression ; moulting

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