title: Odorant binding characteristics of three recombinant odorant binding proteins in Microplitis mediator (Hymenoptera: Braconidae).
abstract: 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.
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
authors.forename: Keming
authors.initials: K
authors.lastname: Li
authors.forename: Shanning
authors.initials: S
authors.lastname: Wang
authors.forename: Kang
authors.initials: K
authors.lastname: Zhang
authors.forename: Liyan
authors.initials: L
authors.lastname: Ren
authors.forename: Abid
authors.initials: A
authors.lastname: Ali
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jingjiang
authors.initials: J
authors.lastname: Zhou
authors.forename: Yuyuan
authors.initials: Y
authors.lastname: Guo
mesh_terms: D015057:1-Naphthylamine / Q000031:analogs & derivatives / Q000378:metabolism; D000447:Aldehydes; D000818:Animals; D057506:Arthropod Antennae; D001522:Behavior, Animal; D005260:Female; D005456:Fluorescent Dyes / Q000378:metabolism; D005786:Gene Expression Regulation; D006927:Hymenoptera / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D045792:Norisoprenoids; D018035:Receptors, Odorant / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000447:Aldehydes; D005456:Fluorescent Dyes; D019476:Insect Proteins; D045792:Norisoprenoids; D018035:Receptors, Odorant; D011994:Recombinant Proteins; C045648:odorant-binding protein; C008664:nonanal; C005444:N-phenyl-1-naphthylamine; D015057:1-Naphthylamine; C008157:beta-ionone