Institut de Biologie Intégrative et des Systèmes, Université Laval, Quebec, Canada G1V 0A6.
J Insect Physiol. 2013 Jan;59(1):11-8. doi: 10.1016/j.jinsphys.2012.11.002. Epub 2012 Nov 28.
Maternal factors of female wasps that are injected into hosts with their eggs at oviposition play a major role in strategies used by insect parasitoids to overcome host immunity, and to regulate host physiology during early stages of parasitism. Here, we attempted to precisely determine and compare the protein patterns injected by the endoparasitoid Aphidius ervi into two different host systems. Chitosan beads of aphid size designed as artificial and physiologically inert hosts were used as oviposition medium, to be compared with the natural aphid host as young nymphs of Macrosiphum euphorbiae. Proteins that the A. ervi wasp injects into hosts at oviposition were separated by SDS-PAGE, complemented with proteomic techniques. Analyses confirm the identification of A. ervi γ-glutamyl transpeptidase (γ-GT) as a key component in the venom of the endoparasitoid. Using proteomic techniques, the quantity of γ-GT injected by the A. ervi wasp into aphids along with the egg was estimated as approximately 4ng per oviposition strike. We suggest that similar quantities suffice to explain natural parasitization success in A. ervi, which do not rely on polydnavirus to establish into hosts. Moreover, an enolase that showed a high level of sequence identity with teratocyte A. ervi enolase was detected both in chitosan beads extracts, and in extracts of mature eggs excised from the A. ervi ovaries, but not in its venom glands extracts. Detecting enolase shortly after oviposition in the artificial inert hosts at a stage of parasitism when the A. ervi egg is still in the primary chorionated undifferentiated stage suggests the enolase as a chorionic protein of the mature egg. The possible functions of this enolase enzyme for the establishment and early development of A. ervi in aphid hosts are discussed.
产卵时注入宿主的雌性黄蜂的母体因素在昆虫寄生蜂利用的策略中起着重要作用，这些策略旨在克服宿主免疫，并在寄生的早期阶段调节宿主的生理机能。在这里，我们试图精确确定和比较内寄生蜂蚜茧蜂注入两种不同宿主系统的蛋白质图谱。设计为人工的、生理惰性的大小与蚜虫相当的几丁质珠被用作产卵媒介，与作为幼蚜的大造桥虫相比。通过 SDS-PAGE 分离寄生蜂在产卵时注入宿主的蛋白质，并辅以蛋白质组学技术。分析证实了蚜茧蜂γ-谷氨酰转肽酶（γ-GT）作为内寄生蜂毒液的关键成分的鉴定。使用蛋白质组学技术，估计蚜茧蜂在产卵时与卵一起注入蚜虫的γ-GT 数量约为每个产卵攻击 4ng。我们认为，类似的数量足以解释蚜茧蜂自然寄生成功，而不需要依赖多粒病毒进入宿主。此外，在几丁质珠提取物中检测到与teratocyteAphidiuservi 烯醇酶具有高度序列同一性的烯醇酶，在从蚜茧蜂卵巢中取出的成熟卵的提取物中也检测到，但在其毒液腺的提取物中没有检测到。在寄生的早期阶段，即在蚜茧蜂卵仍处于初级原壳化未分化阶段时，在人工惰性宿主中产卵后不久就检测到烯醇酶，这表明烯醇酶是成熟卵的绒毛蛋白。讨论了这种烯醇酶对于蚜茧蜂在蚜虫宿主中的建立和早期发育的可能作用。
