title: Beta-tubulin complementary DNA sequence variations observed between cyathostomins from benzimidazole-susceptible and -resistant populations.
abstract: The molecular mechanism of benzimidazole (BZ) resistance in cyathostomins of horses is still unclear. Previous studies revealed that the TTC or TAC polymorphism in codon 200 of the beta-tubulin isotype 1 gene is not as strictly correlated with BZ resistance as in trichostrongyles in sheep. To identify further sites of polymorphism within the beta-tubulin gene related to BZ resistance, complete complementary DNAs (cDNAs) encoding beta-tubulin of adult worms of Cylicocyclus nassatus, Cyathostomum pateratum, Cyathostomum coronatum, Cyathostomum catinatum, Cylicostephanus longibursatus, and Cylicostephanus goldi of a BZ-resistant cyathostomin population were characterized using specific primers. The cDNA sequence of each species spans 1,429 bp, encoding a protein of 448 amino acids. The interspecific identities are 95.2-99.6% at the nucleotide and 98.7-100.0% at the peptide level. The comparison of the amino acid sequences of individuals isolated from the BZ-resistant cyathostomin population with those from individuals of Cc. nassatus, Cy. coronatum, Cy. pateratum, and Cy. catinatum of a BZ-susceptible one showed differing amino acids in 11 positions. The commonness of a phenylalanine to tyrosine mutation at position 167 in all the 6 cyathostomin species isolated from a BZ-resistant population suggests its involvement in the molecular mechanism in BZ resistance.
authors.affiliation: Institute of Parasitology, Hannover School of Veterinary Medicine, Buenteweg 17, Hannover D-30559, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Drogemuller
authors.forename: T
authors.initials: T
authors.lastname: Schnieder
authors.forename: G
authors.initials: G
authors.lastname: von Samson-Himmelstjerna
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D001483:Base Sequence; D001562:Benzimidazoles / Q000494:pharmacology*; D018076:DNA, Complementary / Q000737:chemistry*; D004351:Drug Resistance / Q000235:genetics; D014644:Genetic Variation; D008969:Molecular Sequence Data; D009154:Mutation; D016366:Open Reading Frames / Q000235:genetics; D011110:Polymorphism, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D013320:Strongyloidea / Q000187:drug effects* / Q000235:genetics*; D014404:Tubulin / Q000737:chemistry / Q000235:genetics*
chemical_list: D000871:Anthelmintics; D001562:Benzimidazoles; D018076:DNA, Complementary; D012333:RNA, Messenger; D014404:Tubulin