Response of AFP, CIRP, HMGB1 and YB-1 Gene of Takifugu rubripes to Low-Temperature Stress

Abstract

Environmental conditions regulate the growth and reproduction of fish. The increase in sea temperature during winter may have adverse effects on Takifugu rubripes. To study the mechanism of low-temperature tolerance of T. rubripes, the expression of antifreeze protein (AFP) gene, cold-induced RNA binding protein (CIRP) gene, high mobility group protein box-1 (HMGB1) gene, and Y-box binding protein (YB-1) gene in the liver, spleen, kidney, brain, heart, intestine, muscle, gonad, and skin tissues of T. rubripes obtained from different temperatures (18℃, 13℃, 8℃, and 5℃) was analyzed by quantitative real-time PCR. The results showed that the AFP gene was widely expressed in tissues, with the highest expression in the muscle (P < 0.05). With the decrease in temperature, the expression of the AFP gene in each tissue showed a significant increasing trend, reaching the highest value in the 5℃ group. The expression of the CIRP gene was the highest in the muscle (P < 0.05). With a decrease in temperature, the trend of CIRP gene expression in various tissues was different. The CIRP gene expression levels of liver, kidney, brain, heart, intestine, and skin showed a trend of initial increase, followed by a decrease, and then an increase. The expression levels in the spleen, muscle, and gonads showed an upward trend, reaching the highest value in the 5℃ group. The expression of the HMGB1 gene was the highest in muscle (P < 0.05), followed by that in the brain, liver, heart and skin. As the temperature decreased, the expression of the HMGB1 gene in all tissues except the liver increased first and then decreased, and reached the maximum value in the 8℃ group, which was significantly higher than that of the other groups (P < 0.05). The expression of the YB-1 gene was the highest in the muscle (P < 0.05), with the lowest expression level in other tissues. As the temperature decreased, the expression level of most tissues (brain, heart, intestine, kidney, liver, muscle, and spleen) increased first, then decreased, and then increased, reaching the minimum value in the 8℃ group (P < 0.05). These results show that the expression levels of the four genes are different at different temperature, reflecting the functional specificity of these four genes. Under low-temperature stress, these genes responded positively. Their expression changed to varying degrees, suggesting that the four genes may have potentially important roles in the adaptation of T. rubripes to low temperatures. In addition, by analyzing the law of gene expression, 8℃ may be the key regulatory point for T. rubripes to deal with low-temperature stress. Too low temperature may cause its regulation disorder. The results of this study can provide a relevant basis for studying the regulation mechanism of the low-temperature response of T. rubripes