title: Structural isoforms of the circadian neuropeptide PDF expressed in the optic lobes of the cricket Gryllus bimaculatus: immunocytochemical evidence from specific monoclonal antibodies.
abstract: Pigment-dispersing factor (PDF) is an 18-mer peptide that acts as a principal neurotransmitter of the insect circadian clock. Our previous study, utilizing anti-Uca beta-PDH polyclonal antibody (pAb) to immunolabel the optic lobe of the cricket Gryllus bimaculatus, suggested the existence of an alternative PDF-like peptide in the outer cells of the first neuropile, or lamina (La), which were much less immunoreactive than the inner cells of the second neuropile, the medulla (Me). To obtain structural information about such a PDF-like peptide, we prepared 10 anti-Gryllus PDF monoclonal (mAb) and pAb antibodies and analyzed their detailed epitope specificities. The PDFMe and PDFLa inner cells and their axonal projections were clearly immunoreactive to all these antibodies, revealing the widespread immunocytochemical organization of the PDF system in the optic lobe, as seen previously with anti-Uca beta-PDH pAb and anti-Gryllus PDF mAb, the epitope structures of which were also clarified in this study. The lamina outer cells, which we found lacked a target pdf mRNA, displayed specific immunoreactivities, indicating that the cells contain a distinct PDF-like peptide possessing both N- and C-terminal structures. These cells were not immunolabeled by some other monoclonal antibodies, however, implying that the PDFLa outer cells have a PDF isoform peptide devoid of Asn at positions 6 and 16. This isoform was also identified in a varicose arborization in the lamina. These results suggest not only the structure of the peptide, but also the possibility of additional functions of this novel PDF isoform.
authors.affiliation: Laboratory of Structure-Function Biochemistry, Department of Chemistry, Faculty and Graduate School of Sciences, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Honda
authors.forename: Ayami
authors.initials: A
authors.lastname: Matsushima
authors.forename: Kazunori
authors.initials: K
authors.lastname: Sumida
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Chuman
authors.forename: Kazuyasu
authors.initials: K
authors.lastname: Sakaguchi
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Onoue
authors.forename: Ian A
authors.initials: IA
authors.lastname: Meinertzhagen
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Shimohigashi
authors.forename: Miki
authors.initials: M
authors.lastname: Shimohigashi
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity / Q000276:immunology; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D002940:Circadian Rhythm / Q000502:physiology; D029721:Drosophila Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D018604:Epitope Mapping / Q000379:methods; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D006135:Gryllidae / Q000033:anatomy & histology / Q000378:metabolism*; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D009479:Neuropeptides / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D009899:Optic Lobe, Nonmammalian / Q000166:cytology / Q000378:metabolism*; D020033:Protein Isoforms / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D013045:Species Specificity
chemical_list: D000911:Antibodies, Monoclonal; D029721:Drosophila Proteins; D000939:Epitopes; D009479:Neuropeptides; D020033:Protein Isoforms; C113883:pdf protein, Drosophila