Molecular cloning, expression and activity of pyruvate kinase in grass carp Ctenopharyngodon idella: Effects of dietary carbohydrate level

• PKLR was cloned from grass carp liver.
• The highest expression of PKLR was observed in liver.
• High-carbohydrate up-regulated the hepatic PK activity and mRNA expression.
• PKLR modulated the adaptation of hepatic glycolysis to dietary high carbohydrates.

The R/L type pyruvate kinase (PKLR) gene was cloned from liver of grass carp (Ctenopharyngodon idella) by degenerate oligonucleotide primed PCR, including a complete open reading frame (ORF) of 1617 bp. Homological protein analysis showed that the PKLR in grass carp shared a high degree of sequence identity with other known PK sequences. In addition, tissue distribution analysis showed that the highest expression of the PKLR was detected in liver. Then triplicate groups of grass carp (9 tanks) were fed twice daily to satiation with 91.8, 192.9, and 402.6 g kg− 1 carbohydrate diets for 8 weeks, respectively. Dietary 402.6 g kg− 1 carbohydrate decreased growth performance, feed intake and feed utilization. With increasing dietary carbohydrates, the hepatic PK activity and mRNA expression of grass carp were up-regulated significantly. The results indicated that the PKLR play a modulation role in the adaptation of hepatic glycolysis to dietary high carbohydrates in grass carp.