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Five size groups of hatchery reared cod (2–109 g) and three size groups of wild cod (447–2213 g) were reared at a range of constant temperatures. All groups were fed to satiation, the hatchery fish on dry feed and the wild fish on capelin and shrimp. The optimal temperature for growth decreased linearly with fish weight on a log scale from 17C for 2 g fish(More)
This study examines changes in gill Na(+),K(+)-ATPase (NKA) alpha- and beta-subunit isoforms, Na(+),K(+),2Cl(-) cotransporter (NKCC) and cystic fibrosis transmembrane conductance regulator (CFTR I and II) in anadromous and landlocked strains of Atlantic salmon during parr-smolt transformation, and after seawater (SW) transfer in May/June. Gill NKA activity(More)
To elucidate possible mechanisms behind the endocrine control of parr-smolt transformation, the daily plasma profiles in thyroid hormones (TH; free thyroxine (FT(4)), total thyroxine (TT(4)), and total 3,5,3'-triiodothyronine (TT(3))), growth hormone (GH) and cortisol were studied in Atlantic salmon parr and smolts under simulated-natural winter (8 L:16D)(More)
To elucidate which factors regulate growth hormone (GH) secretion in rainbow trout, dopaminergic innervation of the rainbow trout pituitary along with the action of dopamine in vitro, were studied. Brains with attached pituitaries were double-labeled for putative dopaminergic neuronal fibers and somatotropes, using fluorescence immunohistochemistry. A(More)
The effects of size and gender on several humoral immune parameters in cod were examined under different environmental conditions. Serum samples were collected from wild cod of different sizes. Two samplings were undertaken: In the spring in relatively cold waters off the north west coast of Iceland and in the fall in relatively warm waters off the west(More)
Growth hormone (GH) secretion in salmonids and other fish is under the control of a number of hypothalamic factors, but negative feed-back regulation by circulating hormones can also be of importance for the regulation of GH secretion. Mammalian studies show that GH has a negative feed-back effect on its own secretion. In order to elucidate if GH levels(More)
Juvenile rainbow trout, Oncorhynchus mykiss, were injected with estradiol-17β (E2) in order to study the source of extra calcium needed during vitellogenesis. E2-treatment increased the calcium uptake from the external medium as well as calcium mobilization from muscle and scale. Judged by the increase in plasma protein-bound calcium levels, the E2-induced(More)
The present study compares developmental changes in plasma levels of growth hormone (GH), insulin-like growth factor I (IGF-I) and cortisol, and mRNA levels of their receptors and the prolactin receptor (PRLR) in the gill of anadromous and landlocked Atlantic salmon during the spring parr-smolt transformation (smoltification) period and following four days(More)
The effects of hypophysectomy on the plasma ionic and osmotic balance in juvenile rainbow trout (Salmo gairdneri) kept in 1/3 sea water for various periods were studied. Hypophysectomy caused a decrease in the plasma levels of ionized calcium and chloride within a week after the operation. At 2-5 weeks after hypophysectomy, the plasma levels of ionized(More)
Arctic charr Salvelinus alpinus of the Hólar strain (mean ± s.e. body mass = 152·1 ± 3·1 g) were reared at four different salinity regimes at a constant temperature of 7·4° C. Two groups were given a three-month acclimation in salinity 18 before the salinity was increased to either 25 or 29 (groups called A25 and A29), and two groups were reared in(More)