Molecular Characterization and Response of Silver Carp (Hypophthalmichthys molitrix) GLUT1 under Hypoxia Stress

As an important freshwater species with economic and ecological benefits, silver carp (Hypophthalmichthys molitrix) exhibits poor tolerance to hypoxia. Glucose transporters (GLUTs) are core membrane proteins that transport glucose to tissues and regulate essential life activities. Its expression is regulated by HIF-1a and cells in hypoxic conditions to maintain energy demand through GLUTs inducing enhanced glucose transport. We cloned H. molitrix glut1 (SLC2A1) and analyzed its sequence using bioinformatics tools. The glut1 cDNA was 2104 base pairs long and encoded a 490 amino acid protein. Phylogenetic analysis revealed that sliver carp glut1 is evolutionarily conserved and exhibited the highest sequence similarity with Ctenopharyngodon idella glut1. Glut1 expression was the highest and lowest in the gills and liver, respectively. Hypoxic stress significantly increased glut1 expression in the brain (p < 0.05); in the gills, it was the highest and lowest in the semi-asphyxia and asphyxia groups, respectively; in the liver, it was significantly higher under hypoxia than that of the normoxia group; and in the heart, it was significantly higher in the floating head, semi-asphyxia, and asphyxia groups than in the normoxia group (p < 0.05). The proposed mechanism may thus provide the basis for elucidating the molecular basis of silver carp's hypoxia stress response mediated by glut1.