title: Comparative analyses of the cholinergic locus of ChAT and VAChT and its expression in the silkworm Bombyx mori.
abstract: The cholinergic locus, which encodes choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT), is specifically expressed in cholinergic neurons, maintaining the cholinergic phenotype. The organization of the locus is conserved in Bilateria. Here we examined the structure of cholinergic locus and cDNA coding for ChAT and VAChT in the silkworm, Bombyx mori. The B. mori ChAT (BmChAT) cDNA encodes a deduced polypeptide including a putative choline/carnitine O-acyltransferase domain and a conserved His residue required for catalysis. The B. mori VAChT (BmVAChT) cDNA encodes a polypeptide including a putative major facilitator superfamily domain and 10 putative transmembrane domains. BmChAT and BmVAChT cDNAs share the 5'-region corresponding to the first and second exon of cholinergic locus. Polymerase chain reaction analyses revealed that BmChAT and BmVAChT mRNAs were specifically expressed in the brain and segmental ganglia. The expression of BmChAT was detected 3 days after oviposition. The expression level was almost constant during the larval stage, decreased in the early pupal stage, and increased toward eclosion. The average ratios of BmChAT mRNA to BmVAChT mRNA in brain-subesophageal ganglion complexes were 0.54±0.10 in the larvae and 1.92±0.11 in adults. In addition, we examined promoter activity of the cholinergic locus and localization of cholinergic neurons, using a baculovirus-mediated gene transfer system. The promoter sequence, located 2kb upstream from the start of transcription, was essential for cholinergic neuron-specific gene õexpression. Cholinergic neurons were found in several regions of the brain and segmental ganglia in the larvae and pharate adults.
authors.affiliation: Department of Biological Sciences, Kanagawa University, Hiratsuka, Kanagawa, Japan.
authors.forename: Kota
authors.initials: K
authors.lastname: Banzai
authors.affiliation: Department of Biological Sciences, Kanagawa University, Hiratsuka, Kanagawa, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Adachi
authors.affiliation: Department of Biological Sciences, Kanagawa University, Hiratsuka, Kanagawa, Japan. Electronic address: izumi-bio@kanagawa-u.ac.jp.
authors.forename: Susumu
authors.initials: S
authors.lastname: Izumi
mesh_terms: D000818:Animals; D012831:Bombyx / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D002795:Choline O-Acetyltransferase / Q000235:genetics*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D056426:Genetic Loci / Q000235:genetics; D009928:Organ Specificity; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017421:Sequence Analysis; D061987:Sf9 Cells; D018411:Spodoptera; D050494:Vesicular Acetylcholine Transport Proteins / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D050494:Vesicular Acetylcholine Transport Proteins; D002795:Choline O-Acetyltransferase
keywords: ChAT; Cholinergic neuron; Gene expression; Silkworm; VAChT