Reduced hypoosmoregulatory ability and alteration in gill chloride cell distribution in mature chum salmon (Oncorhynchus keta) migrating upstream for spawning |
| |
Authors: | K Uchida T Kaneko A Yamaguchi T Ogasawara T Hirano |
| |
Institution: | (1) Ocean Research Institute, University of Tokyo, 1-15-1, Minamidai, Nakano, Tokyo 164, Japan, JP;(2) Faculty of Science, Kanagawa University, Hiratsuka, Kanagawa 259-12, Japan, JP |
| |
Abstract: | Osmoregulatory ability of mature chum salmon (Oncorhynchus keta) during spawning migration was examined by following the changes in gill Na+, K+-ATPase activity and in the distribution and morphology of chloride cells. Mature chum salmon caught in Otsuchi Bay, northern
Honshu Island, Japan, died within 5 d in seawater (SW) in association with a marked increase in plasma osmolality, whereas
the fish transferred to fresh water (FW) maintained plasma osmolality efficiently. Gill Na+, K+-ATPase activity decreased in both SW-maintained and FW-transferred fish. Well-developed chloride cells, identified by immunocytochemical
staining specific for Na+, K+-ATPase, were present mainly in the filament epithelium of immature fish caught in the ocean. In mature fish caught in the
bay, however, additional chloride cells were also found in the lamellar epithelium. The number of filament chloride cells
decreased markedly in the mature fish both in SW and in FW, whereas the number of lamellar chloride cells was maintained.
These results suggest that the loss of hypoosmoregulatory ability in mature chum salmon may be attributable to the decrease
in filament chloride cells and associated decrease in gill Na+, K+-ATPase activity, and also that appearance of lamellar chloride cells may be preparatory to the forthcoming upstream migration.
Received: 14 April 1997 / Accepted: 5 May 1997 |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|