Abstract
We have cloned Caenorhabditis elegans lev-8 and demonstrated that it encodes a novel nicotinic acetylcholine receptor (nAChR) subunit (previously designated ACR-13), which has functional roles in body wall and uterine muscles as part of a levamisole-sensitive receptor. LEV-8 is an alpha subunit and is the first to be described from the ACR-8-like group, a new class of nAChR with atypical acetylcholine-binding site (loop C) and channel-lining motifs. A single base pair change in the first intron of lev-8 in lev-8(x15) mutants leads to alternative splicing and the introduction of a premature stop codon. lev-8(x15) worms are partially resistant to levamisole-induced egg laying and paralysis, phenotypes rescued by expression of the wild-type gene. lev-8(x15) worms also show reduced rates of pharyngeal pumping. Electrophysiological recordings from body wall muscle show that currents recorded in response to levamisole have reduced amplitude in lev-8(x15) compared with wild-type animals. Consistent with these phenotypic observations, green fluorescent protein fused to LEV-8 is expressed in body wall and uterine muscle, motor neurons and epithelial-derived socket cells. Thus, LEV-8 is a levamisole receptor subunit and exhibits the most diverse expression pattern of any invertebrate nAChR subunit studied to date.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Action Potentials / drug effects
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Amino Acid Sequence
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Animals
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Animals, Genetically Modified
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Antinematodal Agents / pharmacology
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Behavior, Animal
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Blotting, Northern / methods
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Body Size / genetics
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Bridged Bicyclo Compounds, Heterocyclic / pharmacology
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Caenorhabditis elegans
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Caenorhabditis elegans Proteins / chemistry
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Caenorhabditis elegans Proteins / metabolism*
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Caenorhabditis elegans Proteins / physiology
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Cloning, Molecular / methods
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Electrophysiology / methods
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Epithelial Cells / physiology
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Feeding Behavior / physiology
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Gene Expression
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Genomics / methods
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Green Fluorescent Proteins / metabolism
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Levamisole / pharmacology
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Movement / drug effects
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Movement / physiology
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Muscles / drug effects
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Muscles / physiology
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Mutation
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Neuromuscular Junction / drug effects
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Neuromuscular Junction / physiology
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Neurons / metabolism
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Nicotine / pharmacology
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Nicotinic Agonists / pharmacology
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Pharynx / drug effects
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Pharynx / physiology
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Phenotype
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Pyridines / pharmacology
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RNA, Messenger / biosynthesis
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Receptors, Nicotinic / chemistry
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Receptors, Nicotinic / metabolism*
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Receptors, Nicotinic / physiology
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Reproduction / drug effects
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Reverse Transcriptase Polymerase Chain Reaction / methods
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Sequence Analysis, DNA
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Sequence Homology, Amino Acid
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Transgenes
Substances
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Antinematodal Agents
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Bridged Bicyclo Compounds, Heterocyclic
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Caenorhabditis elegans Proteins
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Nicotinic Agonists
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Pyridines
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RNA, Messenger
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Receptors, Nicotinic
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Green Fluorescent Proteins
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Levamisole
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Nicotine
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epibatidine