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Genetics of avermectin resistance in the nematode parasite Haemonchus contortus

The objectives of this study are to estimate the degree to which a glutamate-gated chloride channel gene (HcGluCla) contributes to survival of moxidectin treatment and to study the relative dominance of those alleles. The phenotype of individual adult H. contortus with respect to feeding was determined using an inulin uptake assay. Genotype was determined using a diagnostic PCR assay. In the absence of moxidectin, homozygous susceptible genotypes fed significantly more than homozygous resistant genotypes. The effect of the susceptible allele was dominant. In the presence of moxidectin, feeding in the susceptible homozygotes was reduced to the level found in the resistant homozygotes, which were unaffected by the drug. These results suggest that the function of the two alleles is different and that they also respond differently to the drug, the resistant allele being unaffected by the drug. / The selection coefficient, s, is the selective difference between the resistant and susceptible genotypes with regard to feeding. Parasites with the resistant allele were seen to feed less in the absence of the drug, i.e., the effect is recessive. In the presence of the drug, there was no difference between resistant and susceptible parasite feeding. These results suggest that resistance may have hidden complexities. (Abstract shortened by UMI.)

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.81357
Date January 2004
CreatorsLevitt, Nancy
PublisherMcGill University
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
LanguageEnglish
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Formatapplication/pdf
CoverageMaster of Science (Institute of Parasitology.)
RightsAll items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated.
Relationalephsysno: 002185812, proquestno: AAIMR06420, Theses scanned by UMI/ProQuest.

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