高温胁迫对筛豆龟蝽成虫抗氧化能力的影响

Antioxidant responses of Megacopta cribraria(Hemiptera:Plataspidae)adults exposed to high temperature stress

为探索筛豆龟蝽Megacopta cribraria(Fabricius)对高温的耐受性及其体内抗氧化系统对极端高温胁迫的响应机制。以25℃为对照温度,经高温37℃、40℃、43℃和46℃胁迫处理4 h后,测定筛豆龟蝽成虫存活率及其体内超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)的活性以及总抗氧化(T-AOC)能力和丙二醛(MDA)含量的变化。在37℃~46℃高温胁迫下,筛豆龟蝽成虫存活率与对照无显著差异,其体内SOD和CAT活性较对照组均显著增加,其中,SOD活性在37℃最高,随着温度进一步升高,其活性有所下降,但仍显著高于对照。CAT一直保持较高活性,随着处理温度的升高CAT活性呈逐渐升高趋势,在极端高温46℃时其活性最高。POD活性在37℃~40℃显著高于对照,43℃和46℃处理与对照无显著差异。T-AOC活性在各处理温度下均显著高于对照,且随着处理温度的升高T-AOC活性呈先升高后降低趋势。各处理MDA含量与对照无显著差异。筛豆龟蝽体内3种抗氧化酶的活力、总抗氧化能力和MDA在适应高温胁迫过程中发挥了重要作用。

This study aims to explore the tolerance of Megacopta cribraria to high temperature,so as to investigate the mechanism of antioxidant system in response to extreme high temperature stress.In this study,we investigated the effect of high temperatures(37℃,40℃,43℃and 46℃)for 4 h on the survival rate and activities of antioxidant enzymes,including superoxide dismutase(SOD),catalase(CAT),peroxidases(POD)and total antioxidant capacity(TAC)as well as malondialdehyde(MDA)concentrations in M.cribraria adults.A control group was reared at 25℃.Under the high temperature stress from 37℃to 46℃,there was no significant difference in adult survival rate between the treatment and the control,but the activities of SOD and CAT in M.cribraria adults were significantly increased as compared with the control.The activity of SOD was the highest at 37℃,and then its activity decreased with the temperature increased,which was still significantly higher than the control.CAT activity was significantly rose from 37℃to 46℃,kept a high level in the treatment groups compared with the control,reached the highest value at extreme high temperature(46℃).There was significant difference in POD activity of M.cribraria adults from 37℃to 46℃compared with that in the control,except 43℃and 46℃.T-AOC activity was a significant increase for all treatment temperatures compared to the control,it was increasing firstly and then decreased,and reached the highest at 40℃and the lowest at 46℃.There was no significant difference in MDA content of M.cribraria adults for all treatment temperatures compared to the control.The activity,total antioxidant capacity and MDA of the three kinds of antioxidant enzymes play an important role in adapting to high temperature stress.