EFFECT OF DIFFERENT LEVELS OF DIETARY NUCLEOTIDES ON OSMOREGULATION OF PYLORIC CAECA IN CASPIAN SEA SALMON (SALMO TRUTTA CASPIUS)

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Abstract

Nucleotides are considered as cellular component which do regulatory effect and key function in all biological process. The aim of the present study was to investigate the effect of dietary nucleotide intake on osmoregulatory function of pyloric caeca in juvenile salmon of Caspian sea. This experiment was done in two levels of dietary nucleotide (0.25 % and 0.5%) and a control group (0%) for 8 weeks. After then, 12 fishes from each treated group were transferred into saline water (18 ppt). 72 hours later, fishes were fixed for histological and immunohistochemical studies. Histological studies were done by Hematoxiline-Fushin staining and light microscope. Immunolocalization of Na+,K+-ATPase was done by fluorescent microscope. Results showed that in all samples immunofluorescence of Na+,K+-ATPase can be seen in the baso-lateral parts of pyloric ceaca entrocytes. Treated groups showed higher fluorescence compared to the control. In this respect 0.5% group showed the highest values for immunofluorescence of Na+,K+-ATPase. Alternation in Na+, K+-ATPase values of epithelial pyloric caeca in response to dietary nucleodtides intake can be attributed to its role in adaptation of fish to 18 ppt saline

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