Relationships of Salinity Tolerance to Immunolocalization of Na⁺,K⁺-ATPase in the Gill Epithelium during Seawater and Freshwater Adaptation of the Guppy, Poecilia reticulata

Abstract

The relationships of salinity tolerance to immunolocalization of Na+,K(+)-ATPase in the gill epithelium were examined during seawater and freshwater adaptation of the guppy. In fresh water, immunoreactivity for Na+,K(+)-ATPase appeared in two types of chloride cells, which are located on the primary lamellae of the gills. Immunoreactivity was strong in the chloride cells located at the base of the secondary lamellae and weak in the chloride cells located at the interlamellar region. During seawater adaptation, the strongly-immunoreactive chloride-cells increased in number and size while the weakly-immunoreactive chloride-cells decreased in number with an increase in salinity tolerance. In the fish of the seawater-adapted strain, on the other hand, most of the chloride cells were located at the base of the secondary lamellae and showed strong immunoreactivity. During freshwater adaptation, the strongly-immunoreactive chloride-cells decreased in number and size while the weakly-immunoreactive chloride-cells increased in number with a decrease in salinity tolerance. A positive correlation was observed between the salinity tolerance and the occupying area of the strongly-immunoreactive chloride-cells while a negative correlation was observed between the salinity tolerance and the occupying area of the weakly-immunoreactive chloride-cells during the seawater and freshwater adaptation. These results directly suggested that not only the occupying area of chloride cells but also the expression of Na+,K(+)-ATPase protein in the cells is important with respect to the osmoregulatory function in the gills and hypoosmoregulatory ability at the individual level.

Seawater acclimation causes independent alterations in Na+/K+- and H+-ATPase activity in isolated mitochondria-rich cell subtypes of the rainbow trout gill

“…However, to have this occur and still be congruent with increases in total Na + /K + -ATPase activity on a whole gill basis, there must be a large increase in the total number of PNA + MR cells in seawater fish, thereby increasing total Na + /K + -ATPase activity. When examining sections of gills by light microscopy, although there has been a substantial (up to fivefold in some studies) increase in the total number of chloride cells in seawater-adapted fish (Borgatti et al, 1992;Shikano and Fujio, 1998) this cannot entirely account for the noted drop in the average cell Na + /K + -ATPase activities found in the present study. A second possible explanation for the noted decrease in Na + /K + -ATPase activity in PNA + MR cells during seawater adaptation is methodological.…”

Ontogenetic changes in location and morphology of chloride cells during early life stages of the Nile tilapia Oreochromis niloticus adapted to fresh and brackish water

“…The sodium pump Na + /K + ‐ATPase has been localized to teleost and elasmobranch chloride cells (Cutler et al , 1995; Shikano & Fujio, 1998 a , b ; Piermarini & Evans, 2000; Feng et al , 2002) and more specifically to the basolateral aspect of the cell (Lee et al , 1998; Cutler et al , 2000; Piermarini & Evans, 2000; Varsamos et al , 2002 a ), where it is localized densely on the membranes of the tubular network and generates the driving force for other salt transport systems operating in the chloride cells in both freshwater and seawater models (Hirose et al , 2003). This is in agreement with the present immunocytochemical staining, which resulted in cytoplasmic labelling throughout the cell but left the nucleus unstained.…”

Immunolocalization of Na+, K+-ATPase-rich cells in the gill and urinary system of Persian sturgeon,Acipenser persicus, fry

“…In most fish, gills are the main sites for osmoregulation processes via the Na + , K + ‐ATPase‐rich cells, which are the main sites for active ion transport. Na + , K + ‐ATPase‐rich cells or chloride cells have been reported in the gill filaments and gill lamellae of several freshwater and seawater‐acclimated teleost species (Avella, Berhaut & Bornancin 1993; Uchida, Kaneko, Yamauchi & Hirano 1996; Ura, Soyano, Omoto, Adachi & Yamauchi 1996; Shikano & Fujio 1998; Lin & Sung 2003). They secrete ions in seawater‐adapted fish (by NKCC co‐transporter aid) and in freshwater‐adapted fish, absorb ions and maintain the acid–base balance (Wood & Marshall 1994).…”