title: Genetic variability of glutamate-gated chloride channel genes in ivermectin-susceptible and -resistant strains of Cooperia oncophora.
abstract: The glutamate-gated chloride channels (GluCls) are members of the ligand-gated ion channel superfamily that are thought to be involved in the mode of action of ivermectin and mechanism of resistance. Using reverse-transcriptase PCR techniques, 2 full-length GluCl cDNAs, encoding GluClalpha3 and GluClbeta subunits, were cloned from Cooperia oncophora, a nematode parasite of cattle. The two sequences show a high degree of identity to similar subunits from other nematodes. The C. oncophora GluClalpha3 subunit is most closely related to the Haemonchus contortus GluClalpha3B subunit, while C. oncophora GluClbeta subunit shares high sequence identity with the H. contortus GluClbeta subunit. Using single-strand conformation polymorphism, the genetic variability of these two genes was analysed in an ivermectin-susceptible isolate and an ivermectin-resistant field isolate of C. oncophora. Statistical analysis suggested an association between the C. oncophora GluClalpha3 gene and ivermectin resistance. No such association was seen with the GluClbeta gene.
authors.affiliation: Institute of Parasitology, McGill University, Ste-Anne-de-Bellevue, Quebec, Canada.
authors.forename: A I
authors.initials: AI
authors.lastname: Njue
authors.forename: R K
authors.initials: RK
authors.lastname: Prichard
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000969:Antinematodal Agents / Q000494:pharmacology*; D018118:Chloride Channels / Q000235:genetics*; D004351:Drug Resistance / Q000235:genetics*; D014644:Genetic Variation; D018698:Glutamic Acid / Q000502:physiology*; D015801:Helminth Proteins / Q000235:genetics; D015640:Ion Channel Gating / Q000235:genetics; D007559:Ivermectin / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014251:Trichostrongyloidea / Q000235:genetics* / Q000502:physiology
chemical_list: D000969:Antinematodal Agents; D018118:Chloride Channels; D015801:Helminth Proteins; C109777:glutamate-gated chloride channels; D018698:Glutamic Acid; D007559:Ivermectin