| Helicoverpa armigera (Htlbner) is an eruptive agricultural pest in China. It can perceive certain chemical volatiles in the environment as the chemical information sources for its behavioral reactions such as to locate their mates, food sources and oviposition and hibernation sites, and to avoid dangerous situations or unsuitable habitats and hosts, and so on, and these volatile chemicals can be used to montior and trap-kill pest. In recent years, the behavioral-chemical models of H.armigera have been widely researched, however, there is nearly no report so far concerned with the molecular mechanism of the odor recognition in H.armigera. So to explore the molecular mechanism of insect olfaction is not only helpful for opening out the intrinsical law of insect behavior and providing theoretical evidences in developing effective attractant or deterrent, but also offer an ideal model system for studying the molecular details of olfaction for invertebrate or vertebrate. In this paper, recombinant OBPs of H.armigera were obtained by gene expression. Based on which high specific antibody was prepared following the distribution of PBP and GOBP2 in olfactory sensilla was studied by immuno-electron microscopy. At the same time, an antennal-specific gene in Helicoverpa armigera was cloned by dd-PCR and RACE. The primary results are as follows:(1) Antennae of H.armigera are in linear shape and made up of scapus, pedicle and flagella. Both the antennae of male and female moth contain five kinds of antennal sensilla, namely, sensillum trichodeum, sensillum basiconicum, sensillum chaeticum, ear-shaped sensillum and sensillum coeloconicum. Olfaction Sensillum in antennae of H.armigera consists of cuticular-wall, dendrites, sensillum lymph and sheath cells. Sensillum trichodeum and sensillum basiconicum is the main chemical odor receptors on antennae of H.armigera and there are significant differences between the internal morpha structures of them.(2) Three OBP genes of H.armigera (the accession numbers ofPBP-Harm, GOBPl-Harm and GOBP2-Harm are AJ278992, AY049739 and AJ278991 in GenBank, respectively)and a GOBP2 gene of Spodoptera exigua (the accession number of GOBP2-Sexi is AJ294809 in GenBank) were cloned by PCR and RACE techniques.(3) Northern blot showed that PBP-Harm and GOBP2-Harm are specifically expressed in the antenna of H.armigera. However, PBP-Harm is more abundantly expressed in male antenna than that in female antenna. During the antennal development, PBP-Harm is firstly expressed about 4d prior to adult eclosion and rises to a plateau 2d prior to adult eclosion.Contrast with PBP-Harm, expression level of GOBP2-Harm in male antenna is the same as the in female antenna. GOBP2-Harm is firstly expressed about 3d prior to adult eclosion and rises to a plateau Id prior to adult eclosion. Southern blot analysis showed that neither PBP-Harm nor GOBP2-Harm is sex-linked and two genes exist as a single copy in genome.(4) Bacterical expression vectors of PBP-Harm and GOBP2-Harm genes were constructed and successfully expressed in E.coli. The recombant proteins were purified by affinity chromatography and gel filtration. Polyclonal antibodies against PBP-Harm and GOBP2-Harm were prepared to mark the distribution of the protein in olfactory sensilla by immuno-electron microscopy. In labeled sensilla, very strong labeling was always observed in the sensillum lymph, in the hair lumen as well as in the sensillum lymph cavity below the hair base. In the male, PBP-Harm is mainly expressed in sensilla trichodea and not in sensilla basiconica. GOBP2Harm is mainly expressed in sensilla basiconica and in some medium-sized sensilla trichodea. While in the female, PBP-Harm is expressed in a few sensilla basiconica and medium-sized sensilla trichodea. GOBP2Harm is expressed in partial sensilla basiconica, medium-sized sensilla trichodea and long sensilla trichodea.(5) Three antennal-specialized cDNA fragment from the antennae of H.armigera were obtained by differential display polymerase...
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