Robust and regulatory expression of defensin A gene driven by vitellogenin promoter in transgenic Anopheles stephensi

The use of genetically modified mosquitoes to reduce or replace field populations is a new strategy to control mosquito-borne diseases. The precondition of the implementation of this strategy is the ability to manipulate the genome of mosquitoes and to induce specific expression of the effector molecules driven by a suitable promoter. The objective of this study is to evaluate the expression of defensin A gene of Anopheles sinensis under the control of a vitellogenin promoter in transgenic Anopheles ste- phensi. The regulatory region of Anopheles gambiae vitellogenin was cloned and subcloned into transfer vector pSLFa consisting of an expression cassette with defensin A coding sequence. Then, the expression cassette was transferred into transformation vector pBac[3xP3-DsRedafm] using Asc I di- gestion. The recombinant plasmid DNA of pBac[3xP3DsRed-AgVgT2-DefA] and helper plasmid DNA of phsp-pBac were micro-injected into embryos of An. stephensi. The positive transgenic mosquitoes were screened by observing specific red fluorescence in the eyes of G1 larvae. Southern blot analysis showed that a single-copy transgene integrated into the genome of An. stephensi. RT-PCR analysis showed that the defensin A gene expressed specifically in fat bodies of female mosquitoes after a blood meal. Interestingly, the mRNA of defensin A is more stable compared with that of the endogenous vitellogenin gene. After multiple blood meals, the expression of defensin A appeared as a reducible and non-cycling type, a crucial feature for its anti-pathogen effect. From data above, we concluded that the regulatory function of the Vg promoter and the expression of defensin A gene were relatively con- served in different species of anopheles mosquitoes. These molecules could be used as candidates in the development of genetically modified mosquitoes.     

合理选用蚊帐灭蚊剂剂型

药帐对蚊虫具有引诱、触杀、持效、兴奋驱避、拒食（不叮人吸血）等效果，对人畜安全，使用成本低，简便易行，群众容易接受，同时对其他室内卫生害虫也有触杀作用，显著地减少疾病传播，特别是减少症疾的传播。针对蚊虫的习性，合理选用处理蚊帐的药物，剂型和方法，可收事倍功半之效。处理蚊帐的药物有两种。用驱避性很强的药物处理蚊帐，蚊虫避而远之，不来接触药帐；用对蚊虫驱避性小的或无驱避性的药物处理蚊帐；蚊虫才会来接触药帐，经兴奋、麻痹、瘫痪等过程而死亡。蚊虫中毒后在兴奋阶段，寻找血食的行为已被抑制，失去了叮咬的能力…     

利用污泥制备微生物灭蚊剂的研究

以活菌数、芽孢数和毒效为参数,通过摇瓶发酵试验探讨了污泥为原料制备微生物灭蚊剂的可行性.结果表明,在含固率适宜的条件下,污泥是微生物灭蚊菌株Bacillus thuringiensis subsp. israelensis 187(简称Bti 187)和 Bacillussphaericus 2362(简称Bs 2362)的优良产孢产毒培养基.Bti 187和Bs 2362在污泥中发酵42h,活菌数分别可达3.7×108CFU/mL、3.6×108CFU/mL;抗热性芽孢数分别可达2.6×108CFU/mL、3.5×108CFU/mL,均显著高于常规LB培养基.毒力测定表明,在污泥中发酵42h后,Bti 187发酵液对淡色库蚊和白纹伊蚊的LC50分别为1.05μg/mL、0.93μg/mL,Bs 2362发酵液对淡色库蚊和白纹伊蚊的LC50分别为0.69μg/mL和103.4μg/mL.与常规LB培养基相比,杀蚊幼虫毒效显著提高.采用污泥发酵制备微生物灭蚊剂可降低生产成本,且发酵性能优良,为污泥资源化开辟了新途径.