滞育发动前家蚕滞育性与非滞育性卵的谷胱甘肽氧化还原循环状态分析

An Analysis on Status of Glutathione Redox Cycle Between Diapause and Non-diapause Eggs of the Silkworm,Bombyx mori,Before Diapause Initiation

为了调查滞育和非滞育性家蚕卵的谷胱甘肽氧化还原循环在滞育发动前是否存在差异,利用分光光度法检测滞育发动前(25℃中蚕卵产下后0～24 h)滞育与非滞育蚕卵的谷胱甘肽含量和相关代谢酶活性。滞育发动前,滞育性家蚕卵中的还原型谷胱甘肽(GSH)含量、氧化型谷胱甘肽(GSSG)含量、总谷胱甘肽(GSH+2GSSG)含量和GSH/GSSG比值变化不显著,谷胱甘肽S-转移酶(GST)活性变化不显著,但硫氧还蛋白过氧化物酶(TPX)活性下降23%,谷胱甘肽还原酶(GR)活性升高57%;非滞育性家蚕卵中的GSH含量及TPX和GST活性变化不显著,但GSSG含量升高61%,GSH+2GSSG含量升高41%,GSH/GSSG比值下降33%,GR活性下降16%。与非滞育性家蚕卵相比,滞育发动前滞育性家蚕卵中的GSH含量、GSSG含量和GSH+2GSSG含量较低,GSH/GSSG比值较高,TPX活性较低,GST活性无显著差异,GR活性较高。两种蚕卵中都未能检测到谷胱甘肽过氧化物酶(GPX)和硫氧还蛋白还原酶(TrxR)活性。结果表明,滞育发动前滞育性家蚕卵中较低的TPX活性和较高的GR活性共同导致较高的GSH/GSSG比值,使其谷胱甘肽氧化还原循环处于相对还原态。

In order to understand whether the glutathione redox cycle is different in diapause eggs and non-diapause eggs of the silkworm（Bombyx mori） before diapause initiation,glutathione content and activity of related metabolic enzymes in diapause and non-diapause eggs before diapause initiation（from 0 h to 24 h post-oviposition at 25 ℃） were determined using spectrophotometric methods.It was discovered that,before diapause initiation,diapausing eggs had no significant variation in contents of reduced glutathione（GSH）,oxidized glutathione（GSSG） and total glutathione（GSH＋2GSSG）,in ratio of GSH/GSSG,and in activity of glutathione S-transferase（GST）.However,the activity of thioredoxin peroxidase（TPX） was reduced by 23% and the activity of glutathione reductase（GR） was increased by 57%.Non-diapausing eggs had no significant variation in GSH content and activity of TPX and GST,either.But GSSG content was increased by 61%,GSH＋2GSSG content was increased by 41%,the ratio of GSH/GSSG was reduced by 33%,and activity of GR was reduced by 16%.Compared to non-diapausing eggs,diapausing eggs had lower contents of GSH,GSSG and GSH＋2GSSG,higher ratio of GSH/GSSG,lower activity of TPX,no significant difference in activity of GST,and higher activity of GR.However,activity of glutathione peroxidase（GPX） and thioredoxin reductase（TrxR） was undetectable in both diapause and non-diapause eggs.These results indicate that higher ratio of GSH/GSSG in diapause eggs before diapause initiation is resulted from lower activity of TPX and higher activity of GR,making the glutathione redox cycle remain at a relatively reduced state.