Expression of growth-related genes in muscle during fasting and refeeding of juvenile Atlantic halibut, Hippoglossus hippoglossus L.
The aim of this study was to establish a fasting-refeeding protocol to investigate the expression of growth-related genes during the transition between catabolic and anabolic states in Atlantic halibut (Hippoglossus hippoglossus L.). Juveniles of approximately 950 g were maintained at ambient temperature (5-8 degrees C) until the 1st of May, then fasted for two months and refed for two months at 7.7-8.0 degrees C under continuous low light. Fast epaxial myotomal muscle was sampled at -64 d (days), -38 d, 0 d (start of refeeding), 3 d, 7 d, 14 d, 30 d and 60 d. Average body mass was unchanged over the fasting period but increased by 24.4% following 60 d refeeding. qPCR was used to analyse the stability of expression of five potential reference genes (Eef2, Fau, 18SrRNA, Actb and Tubb2) with GeNorm and Normfinder. Expression of the growth-related genes, cathepsin B (ctsb), cathepsin D (ctsd), insulin-like growth factor-I and II (IGF-I and II) and insulin-like growth factor-I receptor 1a (IGF-IRa) was normalised using the geometric average of the two most stable housekeeping genes, Fau and 18SrRNA. IGF-I mRNA showed a transient 2.6-fold increase in abundance with refeeding at 7 d whilst transcripts for IGF-II and IGF-IRa were elevated during fasting and decreased 3.8-fold and 3-fold between the 0 d and 3 d samples respectively. Ctsb expression increased between -64 d and 0 d and then decreased approximately 10-fold by 14 d refeeding. In contrast, ctsd was relatively unaffected by the fasting-refeeding cycle, showing a modest (approximately 35%) transient decrease in expression between the 0 d and 30 d refeeding samples. It was concluded that the experimental protocol adopted and housekeeping genes identified were suitable for investigating the catabolic-anabolic transition in halibut skeletal muscle.
Hagen
Ørjan
Ø
School of Biology, University of St Andrews, St Andrews, Scotland, UK. Oerjan.Hagen@hibo.no
Fernandes
Jorge M O
JM
Solberg
Christel
C
Johnston
Ian A
IA
D000818:Animals; D001835:Body Weight; D002401:Cathepsin B / Q000235:genetics; D002402:Cathepsin D / Q000235:genetics; D004435:Eating / Q000502:physiology*; D005215:Fasting / Q000502:physiology*; D005432:Flounder / Q000235:genetics / Q000254:growth & development*; D005786:Gene Expression Regulation; D006128:Growth / Q000235:genetics*; D007334:Insulin-Like Growth Factor I / Q000235:genetics; D007335:Insulin-Like Growth Factor II / Q000235:genetics; D018482:Muscle, Skeletal / Q000254:growth & development*; D012333:RNA, Messenger / Q000032:analysis
D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D002401:Cathepsin B; D002402:Cathepsin D