镉胁迫对脊尾白虾的毒性效应研究

为揭示重金属镉对脊尾白虾的毒性效应,采用急性毒性实验方法,研究了不同浓度镉(Cd~(2+))对脊尾白虾(Exopalaemon carinicauda)血清氧化应激相关生理指标的活性以及肌肉组织中腺苷酸转移酶基因(ANT)和热激蛋白70基因(HSC70)表达水平的影响。共设置4个Cd2+浓度胁迫(0、0.0002、0.001、0.005 mmol·L~(-1)),分别在0、3、6、9、12、24、36、48、72和96 h共10个时间点对相关指标进行测定。结果显示:不同浓度镉胁迫下,脊尾白虾血清中H_2O_2含量、MDA含量和GSH含量均表现为先升高后降低的趋势,H2O2含量在胁迫3 h时即出现明显的升高,而MDA和GSH则均在9 h时出现升高趋势,表现为一定的滞后性。H2O2含量在0.005 mmol·L~(-1)胁迫3 h时出现峰值,MDA含量在0.005 mmol·L~(-1)胁迫9 h时出现峰值,GSH含量在0.001mmol·L~(-1)胁迫48 h时出现峰值,且均与对照组存在显著性差异(P0.05)。HSC70基因的表达量在不同浓度胁迫下均表现为先升高后降低的趋势,且均在24 h时达到峰值,具体表达量水平的顺序为:0.0002 mmol·L~(-1)0.001 mmol·L~(-1)0.005 mmol·L~(-1)。ANT基因的表达量在不同浓度下则均表现为明显的下调趋势。由此可见,急性Cd~(2+)胁迫不仅影响脊尾白虾的氧化应激相关生理指标,还影响机体内组成型HSC70及与能量传递有关的ANT基因的表达水平。

Toxicity Effects of Cadmium on the Ridgetail White Prawn Exopalaemon carinicauda

To investigate cadmium toxicity in the ridgetail white prawn Exopalaemon carinicauda, individual prawns were exposed to cadmium at different concentrations (0, 0.0002, 0.001, and 0.005 mmol?L^-1) for 0, 3, 6, 9, 12, 24, 36, 48, 72 and 96 hours. A number of indexes were used to evaluate how the prawns were affected by Cd stress, including content of H₂O₂, MDA and GSH, and expression level of genes encoding adenine nucleotide translocase (ANT) and heat shock cognate 70 (HSC70). The results showed that the content of H₂O₂, MDA and GSH increased initially, and then decreased with the duration of Cd stress. The content of H₂O₂ tended to increase after exposure to different Cd concentrations for 3 hours. In contrast, the content of MDA and GSH increased, following a lag period, after being stressed for 9 hours. After exposure to 0.005 mmol?L^-1 for 3 hours, the content of H₂O₂ reached its maximum value, but for MDA and GSH, the maximum values appeared after 9 hours at 0.005 mmol?L^-1 (MDA) and after 48 hours at 0.001 mmol?L^-1 (GSH). The differences between treatment and control for the maximum values were significant (P < 0.05). HSC70 expression in each treatment tended to increase at first, and then reach a plateau after 24 hours, before decreasing. For expression levels, the order of maximum values after 24 hours occurred at concentrations of: 0.0002 mmol?L^-1 > 0.001 mmol?L^-1 > 0.005 mmol?L^-1. Compared to the control, ANT expression was inhibited after Cd stress. Therefore, in E. carinicauda, cadmium influenced not only the activity of physiological indicators related to oxidative stress, but also the expression levels of HSC70 and ANT mRNA.