Morphological alteration in two types of gill chloride cells in Japanese eels (Anguilla japonica) during catadromous migration

Abstract

Gill chloride cell morphology and Na+,K+-ATPase activity were examined in cultured Japanese eels (Anguilla japonica) acclimated to fresh water (FW) or seawater (SW), and in yellow and silver eels caught in wild stocks. Gill Na+,K+-ATPase activity was higher in SW-acclimated cultured eels than in FW eels. Chloride cells were detected in both filament and lamellar epithelia by immunocytochemical staining using anti-Na+,K+-ATPase serum. The filament chloride cells were more abundant and larger in SW eels than in FW eels, whereas there was no apparent difference in lamellar chloride cells. In wild-caught eels, gill Na+,K+-ATPase activity increased as they developed from yellow to silver eels. Filament chloride cells in silver eels were more active than those in yellow eels. In contrast, lamellar chloride cells, which were frequently observed in yellow eels, had decreased in number or disappeared in silver eels. These findings suggest that chloride cells in the filament are responsible for excretion of excess salt in hyperosmotic environments, and that lamellar chloride cells may play a significant role in hypoosmotic environments, presumably acting as sites of ion uptake. The excellent euryhalinity of the Japanese eel may be due, at least in part, to the presence of functionally different types of chloride cells. The activation of filament chloride cells in silver eels in FW, together with the increase in Na+,K+-ATPase activity, could be interpreted as a preadaptive response to forthcoming entry into SW.

Time course of saltwater adaptation in Spotted Scat (Scatophagus argus) (Pisces): A histomorphometric approach

“…On the other hand, coincident degeneration of lamellar chloride cells during saltwater adaptation in the current study confirms the assumed association of these cells with adaptation to freshwater and their responsibility for ion uptake (Laurent & Dunel 1980;Perry & Laurent 1989;Perry 1997). The presence of lamellar chloride cells, even in low numbers as in spotted scat, may allow rapid adjustments to salinity changes (Sasai et al 1998;Fielder et al 2007), with even fully retained cells in saltwater acclimated Japanese eel (Sasai et al 1998) and Australian snapper (Fielder et al 2007). Furthermore, the relative dominance of lamellar chloride cells in some marine fish, including yellow tail (Seriola quinqueradiata) and frogfish (Phrynelox tridens) (Hughes & Umezawa 1983), alongside our observation of decreased filament chloride cell densities during late acclimatization, supports the suggestion that dynamic shifts between lamellar and filament chloride cell densities play a role in adaptation (Lee et al 1996;Fielder et al 2007).…”

“…Our results generally support the view that filament chloride cells are responsible for excretion of salt from fish in saltwater and that saltwater adaptation can be achieved by upregulation of filament chloride cell densities. Similar changes in filament chloride cell abundance also follow the transfer of freshwater fish to seawater Uchida et al , 2000Wales 1997;Sasai et al 1998;Khodabandeh et al 2008). Interestingly, the number of filament chloride cells did not change in a few species of fish transferred from 30 to 60 g/l salinities (Yoshikawa et al 1993;Caberoy & Quinitio 2000;Fielder et al 2007).…”

Functional Morphology of Mitochondrion-Rich Cells in Euryhaline and Stenohaline Teleosts

“…In most euryhaline and migratory species, such as Mozambique tilapia, Japanese eel and salmonids, MR cells become larger and denser when fish are transferred from FW to SW (Langdon et al 1985;Richman et al 1987;Uchida et al , 2000Sasai et al 1998a), and this is often accompanied by enhanced gill Na + /K + -ATPase activity. Thus, its activity has generally been considered to serve as a reliable index of SW adaptability in those fishes (McCormick 1995).…”

Variation in salinity tolerance, gill Na+/K+-ATPase,Na+/K+/2Cl– cotransporter and mitochondria-rich cell distribution in three salmonids Salvelinus namaycush, Salvelinus fontinalis and Salmo salar

“…MRCs are responsible for ion secretion in seawater (Pisam et al, 1988;Uchida et al, 1996;Sasai et al, 1998;Hirai et al, 1999;Seidelin et al, 2000;Zydlewski and McCormick, 2001;Pelis et al, 2001). However, lamellar MRCs were still found in lake trout and brook trout acclimated to seawater.…”