Diet driven regulation of nutrient transporters of the piscine splanchnic system


Amberg, Jon J.. (2008). Diet driven regulation of nutrient transporters of the piscine splanchnic system. Theses and Dissertations Collection, University of Idaho Library Digital Collections.

Diet driven regulation of nutrient transporters of the piscine splanchnic system
Amberg, Jon J.
Salmonidae--Digestive organs
Animal Physiology
Following the consumption of a meal, a key mechanism that an animal can use to regulate metabolism is controlling the movement of nutrients across the brush border and basolateral membranes of intestinal enterocyte and then into the hepatocyte. Understanding these mechanisms is important for deciphering the physiological requirements of altricial larvae and for developing economical diets as the aquaculture industry begins to include greater amounts of plant protein in fish diets. To date, this area of research has been virtually ignored in fish nutrition. Therefore, to establish a foundation, I used a gene expression approach to determine if diet affects the transcriptional expression of sugar and peptide transporters from intestinal tissues and the liver of fish. It was found that PepT1 is structurally conserved which suggests that it would be functionally conserved. Diet appeared to up-regulate PepT1 following first- feeding. However, altricial larvae fed their natural diet had greater expression of PepT1 than larvae fed rotifers. Also, juvenile rainbow trout (Oncorhynchus mykiss) are able to modulate the expression of pylorus GLUT2 in response to dietary carbohydrate level and elevated blood-glucose levels. However, there were no differences observed in the sugar or peptide transporters of the anterior small intestine. This finding further stresses the importance of regionalization in the teleost digestive tract. Also, hepatic GLUT2 was only significantly up-regulated when blood-glucose levels were low. This may be a fundamental difference in the ability of mammals and rainbow trout to utilize dietary carbohydrates. Finally, the splanchnic system of rainbow trout was able to adapt to changes in the dietary carbohydrate level. However, this adaption required more than 4 weeks suggesting the importance of an adaptational period in nutritional studies. These findings will help in the development of plant-based diets for juvenile salmonids and improvements in culture strategies for altricial larvae for a more sustainable aquaculture industry.
Thesis (Ph. D., Animal Physiology)--University of Idaho, August 2008.
Major Professor:
Ronald W. Hardy.
Defense Date:
August 2008.
Format Original:
xv, 135 leaves :ill. (some col.) ;29 cm.

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