Molecular characterization and function of hif1a and fih1 in response to acute thermal stress in American shad (Alosa sapidissima)

Abstract

Abstract In order to evaluate the function of hypoxia-inducible factor-1 alpha (hif1α) and factor inhibiting hif1α (fih1) in response to thermal stress, we firstly conducted functional analysis of A. sapidissima hif1α and fih1, and determined hif1α and fih1 expressions in different tissues in response to thermal stress based on identified housekeeping genes (HKGs). The results showed hif1α and fih1 were mainly located in the nucleus and cytoplasm. The full length cDNA sequence of hif1α and fih1 was 4073 bp and 2759 bp, respectively. The cDNA sequence of hif1α includes 15 exons encoding 750 amino acid residues and the full length cDNA sequence of fih1 contains 9 exons encoding 354 amino acid residues. During the acute thermal stress transferring from 16±0.5 oC (control) to 20±0.5 oC, 25±0.5 oC, and 30±0.5 oC for 15 min, it was found that the expression trends of hif1α and fih1 showed an inhibitory regulation in the heart, while they consistently expressed in other tissues. In conclusion, this is the first study to identify the tissue-specific HKGs in A. sapidissima and found that ef1α and β-actin are the most suitable HKGs. Hif1α and Fih1 is mainly the nuclear protein and cytoplasmic protein, respectively, both having high level in the heart and brain. Alosa sapidissima countered a temperature increasing from 16 ℃ to 25 ℃ by regulating the expressions of hif1α and fih1, but its physiological regulatory function was unable to cope with acute thermal stress at a temperature difference of 14 ℃ (from 16 ℃ to 30 ℃).