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  • 1
    Digitale Medien
    Digitale Medien
    Existence of Two Acetylcholinesterases in the Mosquito Culex pipiens (Diptera: Culicidae) (1996)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 67 (1996), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: Two acetylcholinesterases (AChEs), AChE1 and AChE2, differing in substrate specificity and in some aspects of inhibitor sensitivity, have been characterized in the mosquito Culex pipiens. The results of ultracentrifugation in sucrose gradients and nondenaturing gel electrophoresis of AChE activity peak fractions show that each AChE is present as two molecular forms: one amphiphilic dimer possessing a glycolipid anchor and one hydrophilic dimer that does not interact with nondenaturing detergents. Treatment by phosphatidylinositol-specific phospholipase C converts each type of amphiphilic dimer into the corresponding hydrophilic dimer. Molecular forms of AChE1 have a lower electrophoretic mobility than those of AChE2. However, amphiphilic dimers and hydrophilic dimers have similar sedimentation coefficients (5.5S and 6.5S, respectively). AChE1 and AChE2 dimers, amphiphilic or hydrophilic, resist dithiothreitol reduction under conditions that allow reduction of Drosophila AChE dimers. In the insecticide-susceptible strain S-LAB, AChE1 is inhibited by 5 × 10−4M propoxur (a carbamate insecticide), whereas AChE2 is resistant. All animals are killed by this concentration of propoxur, indicating that only AChE1 fulfills the physiological function of neurotransmitter hydrolysis at synapses. In the insecticide-resistant strain, MSE, there is no mortality after exposure to 5 × 10−4M propoxur: AChE2 sensitivity to propoxur is unchanged, whereas AChE1 is now resistant to 5 × 10−4M propoxur. The possibility that AChE1 and AChE2 are products of tissue-specific posttranslational modifications of a single gene is discussed, but we suggest, based on recent results obtained at the molecular level in mosquitoes, that they are encoded by two different genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1471-4159.1996.67052115.x
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  • 2
    Digitale Medien
    Digitale Medien
    Native Molecular Forms of Head Acetylcholinesterase from Adult Drosophila melanogaster: Quaternary Structure and Hydrophobic Character (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 50 (1988), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: The native molecular forms of acetylcholinesterase (AChE) present in adult Drosophila heads were characterized by sedimentation analysis in sucrose gradients and by nondenaturing electrophoresis. The hydrophobic properties of AChE forms were studied by comparing their migration in the presence of Triton X100. 10-oleyl ether, or sodium deoxycholate, or in the absence of detergent. We examined the polymeric structure of AChE forms by disulfide bridge reduction. We found that the major native molecular form is an amphiphilic dimer which is converted into hydrophilic dimer and monomer on autolysis of the extracts, or into a catalytically active amphiphilic monomer by partial reduction. The latter component exists only as trace amounts in the native enzyme. Two additional minor native forms were identified as hydrophilic dimer and monomer. Although a significant proportion of AChE was only solubilized in high salt, following extractions in low salt, this high salt-soluble fraction contained the same molecular forms as the low salt-soluble fractions: thus, we did not detect any molecular form resembling the asymmetric forms of vertebrate cholinesterases.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1471-4159.1988.tb13251.x
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  • 3
    Digitale Medien
    Digitale Medien
    Structure of the gene for human butyrylcholinesterase. Evidence for a single copy (1990)
    s.l. : American Chemical Society
    Biochemistry 29 (1990), S. 124-131 
    Details
    ISSN: 1520-4995
    Quelle: ACS Legacy Archives
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/bi00453a015
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  • 4
    Digitale Medien
    Digitale Medien
    Multiple ace genes encoding acetylcholinesterases of Caenorhabditis elegans have distinct tissue expression (2003)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 18 (2003), S. 0 
    Details
    ISSN: 1460-9568
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: ace-1 and ace-2 genes encoding acetylcholinesterase in the nematode Caenorhabditis elegans present 35% identity in coding sequences but no homology in noncoding regions (introns, 5′- and 3′-untranslated regions). A 5′-region of ace-2 was defined by rescue of ace-1;ace-2 mutants. When green fluorescent protein (GFP) expression was driven by this regulatory region, the resulting pattern was distinct from that of ace-1. This latter gene is expressed in all body-wall and vulval muscle cells (Culetto et al., 1999), whereas ace-2 is expressed almost exclusively in neurons. ace-3 and ace-4 genes are located in close proximity on chromosome II (Combes et al., 2000). These two genes were first transcribed in vivo as a bicistronic messenger and thus constitute an ace-3;ace-4 operon. However, there was a very low level of monocistronic mRNA of ace-4 (the upstream gene) in vivo, and no ACE-4 enzymatic activity was ever detected. GFP expression driven by a 5′ upstream region of the ace-3;ace-4 operon was detected in several muscle cells of the pharynx (pm3, pm4, pm5 and pm7) and in the two canal associated neurons (CAN cells). A dorsal row of body-wall muscle cells was intensively labelled in larval stages but no longer detected in adults. The distinct tissue-specific expression of ace-1, ace-2 and ace-3 (coexpressed only in pm5 cells) indicates that ace genes are not redundant.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1460-9568.2003.02749.x
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  • 5
    Digitale Medien
    Digitale Medien
    Vertebrate insulin induces diapause termination in Pieris brassicae pupae (1987)
    Springer
    Development genes and evolution 196 (1987), S. 527-530 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Insulin ; Diapause termination ; Pieris brassicae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Due to its close structural homology with the 4K prothoracicotropic hormone isolated from Bombyx mori, we tested the ability of vertebrate insulin to break pupal diapause in a Lepidopteran, Pieris brassicae. Injection of 5μg of bovine insulin in diapausing pupae led to diapause termination and synchronous adult eclosion; the effect of insulin was dose-dependent. Bovine insulin-A chain and B chain injected separately failed to show any biological activity suggesting that the intact structure of the molecule is required. Bovine insulin also promoted adult development of decapitated diapausing animals. We show that insulin triggers a reactivation of the neuroendocrine system leading to a neosynthesis of ecdysone beginning 6 days after treatment. This neosynthesis also occurred in beheaded animals suggesting that insulin stimulates the prothoracic glands without acting via the brain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00399877
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  • 6
    Digitale Medien
    Digitale Medien
    Duplication of theAce.1 locus inCulex pipiens mosquitoes from the Caribbean (1996)
    Springer
    Biochemical genetics 34 (1996), S. 351-362 
    Details
    ISSN: 1573-4927
    Schlagwort(e): acetylcholinesterase ; gene duplication ; Culex pipiens ; insecticide resistance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract InCulex pipiens mosquitoes, AChE1 encoded by the locusAce.1 is the target of organophosphorus and carbamate insecticides. In several resistant strains homozygous forAce.1 RR , insensitive AChE1 is exclusively found. An unusual situation occurs in two Caribbean resistant strains where each mosquito, at each generation, displays a mixture of sensitive and insensitive AChE1. These mosquitoes are not heterozygotes,Ace.1 RS , as preimaginal mortalities cannot account for the lethality of both homozygous classes. This situation is best explained by the existence of twoAce.1 loci, coding, respectively, a sensitive and an insensitive AChE1. Thus, we suggest that in the Caribbean a duplication of theAce.1 locus occurred before the appearance of insecticide resistance at one of the two copies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00554410
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  • 7
    Digitale Medien
    Digitale Medien
    Proposed nomenclature for human butyrylcholinesterase genetic variants identified by DNA sequencing (1991)
    Springer
    Cellular and molecular neurobiology 11 (1991), S. 79-89 
    Details
    ISSN: 1573-6830
    Schlagwort(e): butyrylcholinesterase ; serum cholinesterase ; pseudocholinesterase ; anionic site ; atypical ; silent ; fluoride resistant ; K variant ; succinylcholine apnea
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary 1. New information identifying nucleotide alterations of human butyrylcholinesterase allows the use of more specific nomenclature for the variants commonly known as atypical, fluoride, silent, and K variant. 2. In addition to suggesting a system of trivial names and abbreviations, we provide a list of formal names that follow the guidelines of the Committee for Human Gene Nomenclature. 3. It is suggested that formal names be included in publications whenever possible.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00712801
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