The Key Sericultural Laboratory of the Agricultural Ministry of China, Southwest University, Chongqing 400716, China.
J Econ Entomol. 2011 Feb;104(1):101-6. doi: 10.1603/ec10260.
Organophosphorus (OP) insecticides are widely used in agriculture, which are toxic to insect pests and nontarget organisms. The current study mainly assessed the effect of the pesticide phoxim on oxidative stress by certain biomarkers in the fat body and midgut of the silkworm, Bombyx mori (L.), after exposure to 50% lethal concentration (LC50) of phoxim for 2 h. Malondialdehyde (MDA) content, activity of glutathione transferase (GST), and expression of GST at transcriptional level were assayed. LC50 value of phoxim was 2.5 mg/liter at 2-h exposure for the day 3 of the fifth-instar larvae. After exposure of phoxim, MDA content in the fat body significantly increased at 4-20 h posttreatment (p.t.),the highest increase was approximately 4.11-fold from 0.451 +/- 0.053 to 1.854 +/- 0.113 nmol/mg protein compared with corresponding control. In the midgut, significant increase in the MDA content (from 1.40- to 3.16-fold) was observed at 8-42 h p.t. The activity of GSTs increased to 1.48-2.00-fold at 24-42 h p.t. and 1.33-1.48-fold at 20-24 h p.t. in the fat body and midgut, respectively. The peroxidase activity of GSTs also was induced, which increased to 1.46-2.06-fold and 1.31-1.50-fold in the fat body and midgut, respectively. BmGSTe8 showed a late up-regulation of transcripts at 24-42 h after exposure to phoxim, which might contribute to the improved phoxim tolerance of silkworm larvae. These results indicated that phoxim could trigger oxidative stress and that MDA content and GST activity might be used as biomarkers of OP insecticide exposure. In addition, activity of GSTs were more inducible in the fat body than in midgut.
有机磷（OP）杀虫剂在农业中被广泛使用，对害虫和非靶标生物有毒。本研究主要评估了杀虫剂辛硫磷在暴露于辛硫磷 50%致死浓度（LC50）2 小时后，通过某些生物标志物对家蚕（Bombyx mori（L.））脂肪体和中肠的氧化应激的影响。测定了丙二醛（MDA）含量、谷胱甘肽转移酶（GST）活性和 GST 转录水平的表达。第 5 龄幼虫第 3 天暴露于辛硫磷的 LC50 值为 2.5mg/L。暴露于辛硫磷后，脂肪体中 MDA 含量在处理后 4-20 小时（p.t.）显著增加，与相应的对照相比，最高增加约 4.11 倍，从 0.451±0.053 增加到 1.854±0.113 nmol/mg 蛋白。在中肠中，在处理后 8-42 小时 MDA 含量显著增加（增加 1.40-3.16 倍）。脂肪体和中肠中 GSTs 的活性分别在处理后 24-42 小时增加到 1.48-2.00 倍和 1.33-1.48 倍，20-24 小时增加到 1.33-1.48 倍。GSTs 的过氧化物酶活性也被诱导，分别增加到 1.46-2.06 倍和 1.31-1.50 倍，在脂肪体和中肠中。BmGSTe8 在暴露于辛硫磷后 24-42 小时表现出转录物的晚期上调，这可能有助于提高家蚕幼虫对辛硫磷的耐受性。这些结果表明，辛硫磷可引发氧化应激，MDA 含量和 GST 活性可能可作为有机磷杀虫剂暴露的生物标志物。此外，GSTs 在脂肪体中的诱导活性高于中肠。
