mRNA expression patterns for GH, PRL, SL, IGF-I and IGF-II during altered feeding status in rabbitfish, Siganus guttatus.
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Feeding time is a major synchronizer of many physiological rhythms in many organisms. Alteration in the nutritional status, specifically fasting, also affects the secretion rhythms of growth hormone (GH) and insulin-like growth factor-I (IGF-I). In this study, we investigated whether the expression patterns for the mRNAs of GH, prolactin (PRL) and somatolactin (SL) in the pituitary gland, and insulin-like growth factor I and II (IGF-I and IGF-II) in the liver of juvenile rabbitfish (Siganus guttatus) follow a rhythm according to feeding time and whether these hormone rhythms changes with starvation. Hormone mRNA levels were determined by real time PCR. The daily expression pattern for the mRNAs of GH, PRL and SL was not altered whether food was given in the morning (10:00 h) or in the afternoon (15:00 h). The daily GH mRNA expression pattern, however, was affected when food was not available for 3 days. In contrast, the daily expression pattern for IGF-I mRNA reaches its peak at roughly 5–6 h after feeding. This pattern, however, was not observed with IGF-II mRNA. During 15-day starvation, GH mRNA levels in starved fish were significantly higher than the control fish starting on the 9th day of starvation until day 15. The levels returned to normal after re-feeding. In contrast to GH, PRL mRNA levels in starved fish were significantly lower than the control group starting on the 6th day of starvation until 3 days after re-feeding. SL mRNA levels were not significantly different between the control and starved group at anytime during the experiment. Both IGF-I and IGF-II mRNA levels in starved group were significantly higher than the control fish on the 3rd and 6th day of starvation. mRNA levels of both IGF-I and II in the starved fish decreased starting on the 9th day of starvation. While IGF-I mRNA levels in the starved group continued to decrease as starvation progressed, IGF-II mRNA levels were not significantly different from the control during the rest of the starvation period. The results indicate that aside from GH and IGF-I, PRL and IGF-II are likewise involved in starvation in rabbitfish.
CitationAyson, F. G., de Jesus-Ayson, E. G. T., & Takemura, A. (2007). mRNA expression patterns for GH, PRL, SL, IGF-I and IGF-II during altered feeding status in rabbitfish, Siganus guttatus.
Feeding behaviour; Growth rate; Hormones; Nutrition; Pituitary gland; Reef fish; Secretion; Starvation; Feeding; Gene expression; Food availability; Liver; Food; Polymerase chain reaction; Siganus guttatus; Growth hormone; Prolactin; Somatolactin; Insulin-like growth factor-I; Insulin-like growth factor-II; Rabbitfish; mRNA; Feeding time; Reef fish; Rhythms; Fasting; Nutritional status
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Conference paperN Ishida, T Koshiishi, T Tsuzaki, S Yanagi, S Katayama, M Satoh & S Satoh - In MR Catacutan, RM Coloso & BO Acosta (Eds.), Development and Use of Alternative Dietary Ingredients or Fish Meal Substitutes in Aquaculture Feed Formulation … Ingredients or Fish Meal Substitutes in Aquaculture Feed Formulation, 9-11 December 2014, Nay Pyi Taw, Myanmar, 2015 - Aquaculture Department, Southeast Asian Fisheries Development CenterA non-fish meal diet using plant and/or animal protein materials for yellowtail, Seriola quinqueradiata was developed. Three kinds of non-fish meal diets and a control diet containing 50% fish meal were processed. In the non-fish meal diets, the fish meal was replaced with commercially available plant or animal materials and supplemented with taurine and other ingredients for maintaining palatability. These diets were fed to one year old yellowtail (body weight: 753±96 g) in net cages. No significant differences in growth, daily weight gain, daily feed rate, feed conversion ratio and protein efficiency ratio were observed among fish given the diets. Non-fish meal diets were processed in a factory and their biological characteristics were studied such as uptake, stomach evacuation rate, and disease resistance. In addition, the diet palatability of each substitute protein source for fish was examined and ingredients that enhanced palatability of the non-fish meal diets were identified. Non-fish meal diets have the potential to support the growth of one year old yellowtail.