Li Keming, Wang Shanning, Zhang Kang, Ren Liyan, Ali Abid, Zhang Yongjun, Zhou Jingjiang, Guo Yuyuan
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
J Chem Ecol. 2014 Jun;40(6):541-8. doi: 10.1007/s10886-014-0458-5. Epub 2014 Jun 14.
Odorant binding proteins (OBPs) are believed to be important for transporting semiochemicals through the aqueous sensillar lymph to the olfactory receptor cells within the insect antennal sensilla. In this study, three new putative OBP genes, MmedOBP8-10, were identified from a Microplitis mediator (Hymenoptera: Braconidae) antennal cDNA library. Quantitative real-time PCR (qRT-PCR) analysis revealed that all three of the OBP genes were expressed mainly in the antennae of adult wasps. The three OBPs were recombinantly expressed in Escherichia coli and purified by Ni ion affinity chromatography. Fluorescence competitive binding assays were performed using N-phenyl-naphthylamine as a fluorescent probe and 45 small organic compounds as competitors. These assays demonstrated that the three M. mediator OBPs can bind a broad range of odorant molecules with different binding affinities. They can bind the following ligands: nonane, farnesol, nerolidol, nonanal, β-ionone, acetic ether, and farnesene. In a Y-tube assay with these ligands as odor stimuli and paraffin oil as a control, all ligands, except nerolidol and acetic ether, were able to elicit behavioral responses in adult M. mediator. The wasps were significantly attracted to β-ionone, nonanal, and farnesene and repelled by nonane and farnesol. The results of this work provide insight into the chemosensory functions of the OBPs in M. mediator.
气味结合蛋白（OBPs）被认为对于将信息化学物质通过水相的感器淋巴运输到昆虫触角感器内的嗅觉受体细胞至关重要。在本研究中，从一种茧蜂（膜翅目：茧蜂科）触角cDNA文库中鉴定出三个新的假定OBP基因，即MmedOBP8 - 10。定量实时PCR（qRT-PCR）分析表明，所有这三个OBP基因主要在成年黄蜂的触角中表达。这三种OBP在大肠杆菌中进行重组表达，并通过镍离子亲和层析进行纯化。使用N-苯基萘胺作为荧光探针和45种小有机化合物作为竞争物进行荧光竞争结合试验。这些试验表明，三种茧蜂OBP能够以不同的结合亲和力结合广泛的气味分子。它们能够结合以下配体：壬烷、法尼醇、橙花叔醇、壬醛、β-紫罗兰酮、乙酸乙酯和法尼烯。在以这些配体作为气味刺激物且石蜡油作为对照的Y型管试验中，除橙花叔醇和乙酸乙酯外，所有配体都能够在成年茧蜂中引发行为反应。黄蜂对β-紫罗兰酮、壬醛和法尼烯有显著的吸引力，而对壬烷和法尼醇有排斥作用。这项工作的结果为茧蜂中OBP的化学感受功能提供了深入了解。
