scholarly journals Hepatic phosphoenolpyruvate carboxykinase gene expression is not repressed by dietary carbohydrates in rainbow trout (Oncorhynchus mykiss)

2001 ◽  
Vol 204 (2) ◽  
pp. 359-365 ◽  
Author(s):  
S. Panserat ◽  
E. Plagnes-Juan ◽  
J. Breque ◽  
S. Kaushik
Keyword(s):  
Gene Expression ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Nutritional Regulation ◽  
Dietary Carbohydrates ◽  
Base Pairs ◽  
Reading Frame ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Highly Active

Phosphoenolpyruvate carboxykinase (PEPCK) is a rate-limiting enzyme in hepatic gluconeogenesis and therefore plays a central role in glucose homeostasis. The aim of this study was to analyse the nutritional regulation of PEPCK gene expression in rainbow trout (Oncorhynchus mykiss), which are known to use dietary carbohydrates poorly. A full-length hepatic PEPCK cDNA (2637 base pairs with one open reading frame putatively encoding a 635-residue protein) was cloned and found to be highly homologous to mammalian PEPCKs. The presence of a putative peptide signal specific to a mitochondrial-type PEPCK in the deduced amino acid sequence suggests that this PEPCK gene codes for a mitochondrial form. In gluconeogenic tissues such as liver, kidney and intestine, this PEPCK gene was expressed at high levels and, in the liver we found no regulation of PEPCK gene expression by dietary carbohydrates. These results suggest that the first step of the hepatic gluconeogenic pathway in rainbow trout is functional and highly active irrespective of the dietary carbohydrate supply.

scholarly journals Nutritional regulation and tissue specificity of gene expression for proteins involved in hepatic glucose metabolism in rainbow trout (Oncorhynchus mykiss)

2001 ◽  
Vol 204 (13) ◽  
pp. 2351-2360 ◽  
Author(s):  
S. Panserat ◽  
E. Plagnes-Juan ◽  
S. Kaushik
Keyword(s):  
Gene Expression ◽  
Rainbow Trout ◽  
Glucose Metabolism ◽  
Nutritional Status ◽  
Oncorhynchus Mykiss ◽  
Nutritional Regulation ◽  
Dietary Carbohydrates ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Hepatic Glucose Metabolism ◽  
Hepatic Glucose

SUMMARY Rainbow trout (Oncorhynchus mykiss) are known to use dietary carbohydrates poorly. One of the hypotheses to explain the poor utilisation of dietary glucose by these fish is a dysfunction in nutritional regulation of hepatic glucose metabolism. In this study, we obtained partial clones of rainbow trout cDNAs coding for a glucose transporter (Glut2), and for the enzymes 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (6PF-2K/F-2,6BPase), fructose-1,6-bisphosphatase (FBPase) and pyruvate kinase (PK). Their deduced amino acid sequences were highly similar to those of mammals (up to 80% similarity). In a study of nutritional regulation, the Glut2 gene was highly expressed in the liver irrespective of the nutritional status of the trout, in agreement with the role of this transporter in the input (during refeeding) and output (during fasting) of glucose from the liver. Moreover, whereas PK and FBPase gene expression was high irrespective of the nutritional status, levels of hepatic 6PF-2K/F-2,6BPase mRNA were higher in fish fed with carbohydrates than in fish deprived of food. The high levels of hepatic PK, Glut2 and 6PF-2K/F-2,6BPase gene expression observed in this study suggest a high potential for tissue carbohydrate utilisation in rainbow trout. The persistence of a high level of FBPase gene expression suggests an absence of regulation of the gluconeogenic pathway by dietary carbohydrates.

scholarly journals New insights into the nutritional regulation of gluconeogenesis in carnivorous rainbow trout (Oncorhynchus mykiss): a gene duplication trail

2015 ◽  
Vol 47 (7) ◽  
pp. 253-263 ◽  
Author(s):  
Lucie Marandel ◽  
Iban Seiliez ◽  
Vincent Véron ◽  
Sandrine Skiba-Cassy ◽  
Stéphane Panserat
Keyword(s):  
Rainbow Trout ◽  
Gene Duplication ◽  
Oncorhynchus Mykiss ◽  
High Carbohydrate Diet ◽  
Evolutionary Analysis ◽  
Nutritional Regulation ◽  
Dietary Carbohydrates ◽  
Carbohydrate Diet ◽  
High Carbohydrate ◽  
Rainbow Trout Oncorhynchus Mykiss

The rainbow trout ( Oncorhynchus mykiss) is considered to be a strictly carnivorous fish species that is metabolically adapted for high catabolism of proteins and low utilization of dietary carbohydrates. This species consequently has a “glucose-intolerant” phenotype manifested by persistent hyperglycemia when fed a high-carbohydrate diet. Gluconeogenesis in adult fish is also poorly, if ever, regulated by carbohydrates, suggesting that this metabolic pathway is involved in this specific phenotype. In this study, we hypothesized that the fate of duplicated genes after the salmonid-specific 4th whole genome duplication (Ss4R) may have led to adaptive innovation and that their study might provide new elements to enhance our understanding of gluconeogenesis and poor dietary carbohydrate use in this species. Our evolutionary analysis of gluconeogenic genes revealed that pck1, pck2, fbp1a, and g6pca were retained as singletons after Ss4r, while g6pcb1, g6pcb2, and fbp1b ohnolog pairs were maintained. For all genes, duplication may have led to sub- or neofunctionalization. Expression profiles suggest that the gluconeogenesis pathway remained active in trout fed a no-carbohydrate diet. When trout were fed a high-carbohydrate diet (30%), most of the gluconeogenic genes were non- or downregulated, except for g6pbc2 ohnologs, whose RNA levels were surprisingly increased. This study demonstrates that Ss4R in trout involved adaptive innovation via gene duplication and via the outcome of the resulting ohnologs. Indeed, maintenance of ohnologous g6pcb2 pair may contribute in a significant way to the glucose-intolerant phenotype of trout and may partially explain its poor use of dietary carbohydrates.

Effects of high-soy diet on S100 gene expression in liver and intestine of rainbow trout (Oncorhynchus mykiss)

2019 ◽  
Vol 86 ◽  
pp. 764-771 ◽  
Author(s):  
Patrick C. Blaufuss ◽  
T. Gibson Gaylord ◽  
Wendy M. Sealey ◽  
Madison S. Powell
Keyword(s):  
Gene Expression ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
S100 Gene
Sign in / Sign up

Export Citation Format

Share Document