Hypoxia is a common stressor in aquaculture and severely compromises the physiological health of fish. The present study investigated the expression pattern and transcriptional response of the sirt1 gene (sirtuin1) in yellow catfish (Pelteobagrus fulvidraco) under acute hypoxia stress. Sequence analysis of the yellow catfish sirt1 gene indicated that the Sirt1 protein exhibits a high degree of sequence conservation among vertebrates. Tissue distribution analysis under normoxic conditions revealed that sirt1 mRNA was most abundantly expressed in the brain and intestine of yellow catfish. Results from the hypoxia stress trial (dissolved oxygen 1.1 ± 0.2 mg/L) demonstrated that sirt1 was the most hypoxia-responsive member of the sirt family, being significantly upregulated approximately 4.5-fold at 12 h. Subsequent functional validation experiments showed that sirt1 expression was significantly decreased at 6 h of acute hypoxia; together with the marked upregulation at 12 h observed in the time-course experiment, this suggests that the response of sirt1 to acute hypoxia is time-dependent. On this basis, a bidirectional intervention was performed using small interfering RNA (siRNA)-mediated knockdown of sirt1 and resveratrol-mediated activation to analyze the effects of sirt1 on downstream gene expression and intestinal histopathology. The results showed that inhibition of sirt1 led to compensatory upregulation of pdk1, impairment of ampkα signaling and a further decrease in stat3 expression, and aggravated hypoxia-induced intestinal histological damage, whereas resveratrol pretreatment partially restored the expression of the related genes and alleviated tissue injury. These findings indicate that sirt1 is a transcriptionally responsive gene involved in the response of yellow catfish to hypoxia stress, and provide a reference for further investigation into hypoxia adaptation in yellow catfish.
Ku et al. (Sat,) studied this question.