Open AccessThe Effects of Brackish Water on Growth Hormone/Insulin‐like Growth Factor‐1 Gene Expression of the Caspian Trout, Salmo trutta caspius (Kessler, 1877), During the Early Stage of Smoltification
Author(s) -
Sharif Sepideh,
Shoae Alireza,
Mojazi Amiri Bagher,
Farahmand Hamid
Publication year - 2015
Publication title -
journal of the world aquaculture society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.655
H-Index - 60
eISSN - 1749-7345
pISSN - 0893-8849
DOI - 10.1111/jwas.12180
Subject(s) - biology , salmo , brackish water , juvenile , brown trout , insulin like growth factor , trout , fishery , zoology , juvenile fish , endocrinology , ecology , salinity , growth factor , genetics , fish <actinopterygii> , receptor
Caspian trout, Salmo trutta caspius , a subspecies of brown trout, S. trutta , is a commercially important but endangered fish species found in the Caspian Sea. To investigate the effect of changes in salinity during migration on the growth of Caspian trout, juvenile fish were challenged in brackish water, and the levels of growth hormone ( GH ) and insulin‐like growth factor 1 ( IGF ‐1) expression were quantified in the pituitary gland and the liver. Specifically, juvenile fish were reared in freshwater to a weight of 15–20 g and subsequently transferred to brackish water for 28 d. Fish were sampled at 1, 3, 5 and 28 d post‐transfer, and target gene mRNA was quantified using a real‐time qPCR assay. A significant increase in the specific growth rate ( SGR ) as well as in the abundance of GH and IGF ‐1 mRNA was observed in fish that were reared in brackish water ( P < 0.05). Two transcripts of GH with 90% homology in the open reading frame and the complete transcript of IGF‐1Ea4 were identified based on gene cloning. In conclusion, our results suggest that brackish water adaptation stimulates the SGR via the GH / IGF ‐1 axis and that GH and IGF ‐1 have been highly conserved during the evolution of the Caspian trout.