Study of genes involved in muscle atrophy of juvenile Nile Tilapia submitted to fasting and refeeding

Abstract

The growth rate of farmed fish is one of the most important factors for successful aquaculture. The understanding of the cellular events that occur in skeletal muscle when the fish undergo periods of fasting and refeeding can result in alternative feed strategies to improved muscle growth of commercially cultivated species, while promoting reduction of cost production. The aim of this study is to investigate the growth performance, physiology, muscle morphology and the expression of genes involved in muscle atrophy (MuRF-1 and MAFbx) and muscle growth control (MyoD, Myogenin, Myostatin and IGF-1) in juvenile Nile tilapia subjected to different periods of fasting and refeeding.The experiment was conducted at the Laboratory of Aquatic Organisms Nutrition of the Aquaculture Center, UNESP, SP, Brazil. Fish (26.4 ± 3.8 g) were stored into tanks with 150 liters of water and constant aeration. The experiment lasted 13 weeks, and a fixed period of 10 weeks of reffeding was maintained for all treatments. Fish were randomly distributed into four experimental treatments and eight replicates: (FC) control, feeding continuously during the 13 weeks; (F1) one week of fasting and refeeding for 10 weeks, (F2) two weeks of fasting and refeeding for 10 weeks; (F3) three weeks of fasting and refeeding for 10 weeks. Biometrics was done weekly and muscle samples were collected after one, two and three weeks of fasting and after two, six and ten weeks of refeeding (16 fish/treatment for molecular analysis and 16 for carcass analysis). At the present time, were performed the analysis of zootechnical performance, blood parameters (glucose, triglycerides, total protein and cholesterol), physiology (HSI and GVSI), RNA extraction of muscle tissue and cDNA synthesis. Morphological and chemical analyzes are being processed and analyzed. The Doctorate Sandwich Program will be conducted in collaboration with Professor Ken Overturf at the United States Department of Agriculture - Agricultural Research Service (USDA-ARS) in Hagerman Fish Culture Experiment Station, Hagerman, Idaho, United States. It is intended to perform primers construction for the genes related to muscle atrophy (MuRF-1 and MAFbx) and the reference genes (²-actin and EF1-±). This laboratory is a reference in the area of gene expression of skeletal muscle in fish; with the primers designed and the analysis of the first samples, the completation of the analysis of gene expression will be performed by real-time PCR after reverse transcription (RT-qPCR) at the Laboratory of Biology of Muscle Striated (LBME), Department of Morphology, IB / UNESP / Botucatu-SP, Brazil. (AU)