Respostas metabólicas, morfologia do tecido muscular e expressão dos genes relacionados ao crescimento e à atrofia muscular durante o jejum e realimentação em juvenis de tilápia-do-Nilo

• Autor(a) principal: Nebo, Caroline [UNESP]
• Data de Publicação: 2015
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/124001
• topic: Peixe; Tilápia-do-Nilo; Jejum; Peixe - Crescimento; Atrofia muscular; Genes; Fishes

The aim of this study was to investigate the morphological and physiological characteristics and the gene expression involved in muscle atrophy (MuRF-1 and atrogin-1) and genes that control muscle growth (MyoD, Myogenin, IGF-1 and IGF-1 receptor) and the Myostatin, in Nile tilapia (Oreochomis niloticus) juveniles submitted to fasting, followed by refeeding. It was used Nile tilapia juveniles with average body mass 30.2 ± 0.9 g and the experiment was completely randomized with four treatments and eight repetitions: (FC) fed control, fish were fed continuously during the 13 weeks; (F1) one week of fasting and 10 weeks of refeeding; (F2) two weeks of fasting and 10 weeks of refeeding; (F3) three weeks of fasting and 10 weeks of refeeding. Biometric performance was made after one, two and three weeks of fasting and after one, two, six and 10 weeks of refeeding. Samples were collected (n = 16 fish/treatment) after the end of each period of fasting and after 10 weeks of refeeding. It was observed significant decrease of performance index of fish during fasting. However, after 10 weeks of refeeding, fish that were fasted showed only partial compensatory growth. The feed intake and specific growth rate increased during refeeding, equaling to the FC, but it was not enough to induce total growth compensation. The survival rate did not differ among all treatments. The triglycerides and cortisol levels in fish from F1 were significantly lower than FC. The hepatosomatic index (HSI), visceral fat index (VFI), carcass lipid and liver glycogen levels decreased in fish that was fasting. However, after 10 weeks of refeeding, the lipids amount on VFI, on body composition and liver glycogen in fish from F1, F2 and F3 treatments were similar to FC. At the first week of the experiment, in the F1 and FC treatments, the morphological muscle fibers analyses showed a high quantity of small muscle fibers with central nucleus, showing the mosaic hyperplasia ...