Ferry N, Raemaekers R J M, Majerus M E N, Jouanin L, Port G, Gatehouse J A, Gatehouse A M R
School of Biology, University of Newcastle Upon Tyne, Newcastle, NE1 7RU, UK.
Mol Ecol. 2003 Feb;12(2):493-504. doi: 10.1046/j.1365-294x.2003.01736.x.
Insect-resistant transgenic plants have been suggested to have deleterious effects on beneficial predators through transmission of the transgene product by the pest to the predator. To test this hypothesis, effects of oilseed rape expressing the cysteine protease inhibitor oryzacystatin-1 (OC-1) on the predatory ladybird Harmonia axyridis were investigated using diamondback moth Plutella xylostella as the pest species. As expected, oilseed rape expressing OC-1 had no effects on either development or survival of the pest, which utilizes serine digestive proteases. Immunoassays confirmed accumulation of the transgene product in pest larval tissues at levels of up to 3 ng per gut. Characterization of proteolytic digestive enzymes of H. axyridis demonstrated that larvae and adults utilize cysteine and aspartic proteases; the former activity was completely inhibited by oryzacystatin in vitro. However, when H. axyridis larvae consumed prey reared on OC-1 expressing plants over their entire life cycle, no significant effects upon survival or overall development were observed. The inhibitor initially stimulated development, with a shortening of the developmental period of the second instar by 27% (P < 0.0001) accompanied by a 36% increase in weight of second instar larvae (P = 0.007). OC-1 had no detrimental effects on reproductive fitness of adult H. axyridis. Interestingly there was a significant increase in consumption of OC-1 dosed prey. The results show that prey reared on transgenic plants expressing a protein which inhibited ladybird digestive enzymes in vitro had no effects in vivo; the ladybird was able to up-regulate digestive proteases in response to the inhibitor.
有人提出，抗虫转基因植物可能会通过害虫将转基因产物传递给有益捕食者，从而对其产生有害影响。为了验证这一假设，以小菜蛾为害虫物种，研究了表达半胱氨酸蛋白酶抑制剂水稻巯基蛋白酶抑制剂-1（OC-1）的油菜对捕食性瓢虫异色瓢虫的影响。正如预期的那样，表达OC-1的油菜对利用丝氨酸消化蛋白酶的害虫的发育或存活均无影响。免疫分析证实，转基因产物在害虫幼虫组织中的积累量最高可达每肠道3纳克。对异色瓢虫蛋白水解消化酶的特性分析表明，幼虫和成虫利用半胱氨酸和天冬氨酸蛋白酶；前者的活性在体外被水稻巯基蛋白酶完全抑制。然而，当异色瓢虫幼虫在其整个生命周期中取食在表达OC-1的植物上饲养的猎物时，未观察到对其存活或整体发育有显著影响。该抑制剂最初刺激了发育，二龄幼虫的发育期缩短了27%（P<0.0001），同时二龄幼虫体重增加了36%（P=0.007）。OC-1对成年异色瓢虫的繁殖适合度没有不利影响。有趣的是，取食添加了OC-1的猎物的量显著增加。结果表明，在体外表达一种能抑制瓢虫消化酶的蛋白质的转基因植物上饲养的猎物，在体内没有影响；瓢虫能够响应抑制剂上调消化蛋白酶。
