Heat Shock Protein 70 (HSP70) Responses in Tissues of White Sturgeon and Green Sturgeon Exposed to Different Stressors

Abstract

AbstractA factorial experiment was conducted to compare the responses of heat shock protein 70 (Hsp70) in seven different tissues of White Sturgeon Acipenser transmontanus and Green Sturgeon A. medirostris after they were exposed to four different stressors. Three White Sturgeon (2.3 ± 0.1 kg [mean ± SE]) and three Green Sturgeon (2.3 ± 0.1 kg [mean ± SE]) were each subjected to one of four different stressors, after which the Hsp70 levels in seven different tissues were measured using Western blot. The four stressors were heat shock, cold shock, air exposure, and food deprivation; and the seven tissues sampled were mucus, heart, liver, gastrointestinal tract, gill, spleen, and white muscle. We also sampled tissues of three White Sturgeon and three Green Sturgeon without any stressor, and measured their Hsp70 levels as a control. We compared Hsp70 responses of the stressed sturgeon with those of the control, which was set at 100%, and found that Hsp70 responses were significantly (P < 0.05) affected by the different stressors and also varied significantly among the tissues. For both species of sturgeon, heat shock was shown to be the most effective stressor inducing Hsp70 responses and mucus was the most responsive tissue. Under heat shock stress, Hsp70 responses in all tissues except liver were significantly higher in the White Sturgeon than in the Green Sturgeon. When both species of fish were exposed to heat shock, cold shock, or food deprivation, White Sturgeon showed significantly higher Hsp70 responses in mucus than did Green Sturgeon. In summary, heat shock elicited the highest Hsp70 responses and mucus was the most sensitive tissue. Based on the tissue Hsp70 responses, White Sturgeon were predicted to have a better defense mechanism against heat shock than Green Sturgeon.