Estuarine euryhaline teleosts, such as the killifish Fundulus heteroclitus, normally experience rapid salinity changes and are therefore good models for investigations of the regulation of salt transport in teleosts (Wood and Marshall, 1994; Marshall and Bryson, 1998). Adaptation to sea water in eur...
| Other Authors: | |
|---|---|
| Format: | Text |
| Language: | English |
| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.606.5174 http://people.stfx.ca/bmarshal/web page/JeB99-Time course.pdf |
| Summary: | Estuarine euryhaline teleosts, such as the killifish Fundulus heteroclitus, normally experience rapid salinity changes and are therefore good models for investigations of the regulation of salt transport in teleosts (Wood and Marshall, 1994; Marshall and Bryson, 1998). Adaptation to sea water in euryhaline teleosts is thought to involve the development of ion secretion pathways in the mitochondria-rich cells of the gill epithelium under the influence of cortisol, growth hormone and insulin-like growth factors (for reviews, see Bern and Madsen, 1992; Jacob and Taylor, 1983; Mancera and McCormick, 1998). In a euryhaline freshwater teleost, the Mozambique tilapia Oreochromis mossambicus, cortisol and growth hormone levels are elevated 1 and 4 days after transfer to sea water but not when these animals are transferred to brackish water or fresh water (Morgan et al., 1997). Nakano et al. (1998) similarly observed an increase in growth hormone levels after transfer of tilapia to 70 % sea water, but at 12 h only. Transfer of tilapia through brackish water to full-strength sea water increases the size and number of mitochondria-rich cells in the opercular epithelium with a concomitant increase in Cl-secretion rate (Foskett et al., 1981, 1983). Hence, freshwater-resident teleosts with euryhaline capability, such as the tilapia, readily adapt to salinity change over days if intermediate salinities are provided (Foskett et al., 1983; Nakano et al., 1998). Anadromous salmonid teleosts enter sea water once or twice in their life cycles, first as smolts and, in some species, as post-spawn kelts. Brook trout (Salvelinus fontinalis) show increases in plasma cortisol levels and accelerated cortisol secretion during adaptation to sea water (Nichols et al., 1985). Atlantic salmon (Salmo salar) kelts show acceleration of cortisol metabolism and utilization, but only subtle changes in plasma cortisol levels (Nichols and Weisbart, 1985). Cortisol |
|---|