Functional exploration of SNP mutations in HIF2αb gene correlated with hypoxia tolerance in blunt snout bream (Megalobrama amblycephala)

Abstract

Blunt snout bream (Megalobrama amblycephala) is sensitive to hypoxia environment. Hypoxia-inducible factor (HIF) is the most critical factor in HIF pathway, which strictly regulates the hypoxia stress process of sh. In this study, we found six hifα genes in blunt snout bream that demonstrated different expression under hypoxia conditions. In HEK293T cells, all six hifαs were detected to activate HRE region by luciferase reporter assay. More importantly, we identi ed two linkage-disequilibrium SNP sites at exon 203 and 752 of hif2αb gene in blunt snout bream. Haplotype II (A 203 A 752 ) and its homozygous diplotype II (A 203 A 203 A 752 A 752 ) appeared frequently in a selected strain of blunt snout bream with hypoxia-tolerance.Diplotype II has a lower oxygen tension threshold for loss of equilibrium (LOE crit ) over a similar range of temperatures. Moreover, its erythrocyte number increased signi cantly (p < 0.05) than those in diplotype I and diplotype III strains at 48 h of hypoxia. The enzymes related with hypoxia tolerant traits, i.e. reduced glutathione, superoxide dismutase and catalase, were also signi cantly (p < 0.05) induced in diplotype II than those in diplotype I or III. In addition, the expression of epo in the liver of diplotype II was signi cantly (p < 0.01) higher than those in the diplotype I or III strains at 48 h of hypoxia. Taken together, our results found that the hypoxia-tolerant related diplotype II of hif2αb has the potential used as a molecular marker in future genetic breeding of hypoxia-tolerant strain.

FishSNP: a high quality cross-species SNP database of fishes

“…The presence of homologous genes or sequences initially complicates allele identification, however the simplicity with which SNPs can be scored promotes allele discrimination 6 . SNP markers have been widely employed in fish disease resistance 7 , 8 , feed conversion efficiency 9 , 10 , growth rate 11 , 12 , muscle yield 13 , reproductive characteristics 14 , 15 and tolerance to environmental stressors 16 , 17 since the emergence of high-throughput sequencing technology. Similarly, SNP marker-related sequencing data increased rapidly.…”