Kazuko Tsuchihara

Ligand carrier protein genes expressed in larval chemosensory organs of Bombyx mori.

Expressed sequence tags (ESTs) of the maxillary galea of the silkworm were analyzed to identify proteins involved in food selection systems. From the 1251 redundant genes of the ESTs, we identified 7 odorant-binding protein-like genes (bmObpL), 6 takeout-like genes (bmToL), and 6 chemosensory protein genes (bmCsp). Quantitative RT-PCR analysis indicated that bmObpL1, bmObpL2, bmObpL3, bmObpL5, bmToL1, bmToL3, and bmorCsp15 were predominantly expressed in the larval oral appendages, such as the maxilla, labrum, labium and antenna. Immunocytochemical analysis indicated that the proteins of bmObpL1, bmObpL3, and bmToL1 were localized in the gustatory chemosensilla on the maxillary galea and olfactory sensilla in the antenna. The proteins encoded by bmObpL1 and bmObpL3 were detected in the gustatory chemosensilla of the epipharynx. However, bmObpL1 and bmToL1 were also detected in tactile hairs and in the epidermis of several chemosensory organs. The bmObpL2 protein was localized inside and in the epidermis around the chemosensilla, tactile hairs, and wide surface of the epipharynx. From these results, bmObpL3 is the most likely to have a dedicated role in chemoreception in the silkworm, Bombyx mori.

A putative binding protein for lipophilic substances related to butterfly oviposition

A unique protein of 23 kDa (Jf23) was found in the tarsus of the female swallowtail butterfly, Atrophaneura alcinous. Jf23 has 38% identity with a bilin‐binding protein, which was found in the cabbage butterfly, Pieris brassicae, and which has two consensus sequences in common with the members of the lipocalin family, suggesting that it is a binding protein for lipophilic ligands. Western blot analysis showed that Jf23 was expressed only in the female, and not in the male. Electrophysiological response of the female tarsi was stimulated by methanolic extract of their host plant, Dutchmans pipe (Aristolochia debilis). The stimulated response was depressed by the presence of Jf23 antiserum. These results suggest that Jf23 is one of the chemosensory signaling proteins, which plays one or more roles in female butterfly oviposition.

Characterization of chemoreceptive protein binding to an oviposition stimulant using a fluorescent micro-binding assay in a butterfly

A native female‐specific chemoreceptive protein of a swallowtail butterfly [oviposition stimulant binding protein (OSBP)] was shown to specifically bind to aristolochic acid, a main stimulant for oviposition from its host plant. Oviposition stimulants are recognized by chemoreceptive organs of insects. OSBP isolated previously from the chemoreceptive organs was assumed to bind to an oviposition stimulant. Using a highly sensitive fluorescent micro‐binding assay, we clarified OSBP bound to aristolochic acid. Three‐dimensional molecular modeling revealed the structure of the OSBP‐aristolochic acid complex. This is the first report of a native chemoreceptive protein binding to an oviposition stimulant as a ligand in insects.

An oviposition stimulant binding protein in a butterfly: Immunohistochemical localization and electrophysiological responses to plant compounds.

Oviposition is evoked by plant compounds, which are recognized by chemoreceptive organs of insects. The swallowtail butterfly, Atrophaneura alcinous, oviposits its eggs on the host plant, Aristolochia debilis, in the presence of only two stimulating compounds: an alkaloid, aristolochic acid, and a monosaccharide, sequoyitol. In our previous study, a unique protein of 23 kDa [Oviposition stimulant(s) binding protein (OSBP)] was found in the forelegs of female, but not male, A. alcinous. The electrophysiological response of A. alcinous to an extract of A. debilis was depressed by the presence of OSBP antiserum, suggesting that OSBP presumably binds to oviposition stimulant(s). We show here, using a highly sensitive fluorescence micro-binding assay that native OSBP binds to a main oviposition stimulant, aristolochic acid, from its host plant, A. debilis. Three-dimensional molecular modeling studies also gave a reasonable structure for the OSBP / aristolochic acid complex. This is the first report of a native chemoreceptive protein binding to an oviposition stimulant ligand in insects.

Corrigendum to: A putative binding protein for lipophilic substances related to butterfly oviposition (FEBS 23957): [FEBS Letters 478 (2000) 299–303]

Corrigendum to: A putative binding protein for lipophilic substances related to butter£y oviposition (FEBS 23957) [FEBS Letters 478 (2000) 299^303 ]C Kazuko Tsuchiharaa;b, Kohei Uenoc, Akira Yamanakad, Kunio Isonoc, Katsuhiko Endod, Ritsuo Nishidae, Kazuo Yoshiharaa, Fumio Tokunagab;* aSuntory Institute for Bioorganic Research, Shimamoto-cho, Mishima-gun, Osaka 618-8503, Japan bDepartment of Biological Science and Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan cGraduate School of Information Science, Tohoku University, Sendai, Miyagi 980-8577, Japan dDepartment of Physics, Biology and Informatics, Faculty of Science, Yamaguchi University, Yamaguchi 753-8512, Japan eLaboratory Chemical Ecology, Gradual School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan