title: Cloning two full-length beta-tubulin isotype cDNAs from Cooperia oncophora, and screening for benzimidazole resistance-associated mutations in two isolates.
abstract: Two full-length beta-tubulin cDNAs, representing isotypes 1 and 2, were cloned from the cattle nematode Cooperia oncophora. The predicted protein sequences span 448 amino acids, and show a high degree of identity to beta-tubulins from other nematodes. While C. oncophora isotype 1 sequence had the highest identity to Haemonchus contortus isotype 1 and Teladorsagia circumcincta sequences (95% identity), the C. oncophora isotype 2 sequence was most similar to H. contortus isotype 2 and Trichostrongylus colubriformis (92% identity). Alignment of the two C. oncophora sequences with other trichostrongylid beta-tubulins deposited in GenBank showed a clear distinction between isotype 1 and 2 beta-tubulin classes. The two classes differed at 19 amino acid positions, most notably at the carboxy terminus. These isotype-defining residues were conserved among different trichostrongylid species within a class. Analysis of fragments of both genes revealed a high degree of genetic variability in coding and non-coding regions. However, all nucleotide differences detected in the coding region were silent, as they did not result in any amino acid substitution. Analysis of 2 groups of worms for the codon 200 polymorphism associated with benzimidazole resistance revealed a proportion of worms in 1 of the groups bearing a tyrosine at this position.
authors.affiliation: Institute of Parasitology, McGill University, 21 111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, Canada H9X 3V9.
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; D000871:Anthelmintics / Q000494:pharmacology*; D001483:Base Sequence; D001562:Benzimidazoles / Q000494:pharmacology*; D003001:Cloning, Molecular; D004351:Drug Resistance / Q000235:genetics; D014644:Genetic Variation; D008969:Molecular Sequence Data; D010802:Phylogeny; D017354:Point Mutation; D018807:Polymorphism, Single-Stranded Conformational; D020033:Protein Isoforms; D018510:RNA, Helminth / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D014251:Trichostrongyloidea / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D014404:Tubulin / Q000737:chemistry / Q000235:genetics*
chemical_list: D000871:Anthelmintics; D001562:Benzimidazoles; D020033:Protein Isoforms; D018510:RNA, Helminth; D014404:Tubulin