OATAO - Open Archive Toulouse Archive Ouverte Open Access Week

Detection and functional validation of genomic reigons affecting resistance to gastro-intestinal nematodes in sheep

Sallé, Guillaume. Detection and functional validation of genomic reigons affecting resistance to gastro-intestinal nematodes in sheep. PhD, Institut National Polytechnique de Toulouse, 2012

(Document in English)

PDF - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader

Official URL: http://ethesis.inp-toulouse.fr/archive/00002139/


Gastro-intestinal nematodes, among which Haemonchus contortus are a major threat to the meat sheep industry. They are responsible for production losses and the apparition of worm populations resistant to drugs limits their use as worm control strategy. Breeding more resistant sheep is among the most practicable alternative strategy. However its implementation requires a deeper understanding of underlying mechanisms. This PhD aims at identifying regions of the ovine genome affecting resistance to gastro-intestinal nematodes. A statistical analysis of existing associations between genetic markers and resistance traits of a Martinik Black-belly x Romane cross-bred sheep flock unraveled a limited number of key players. Among these, a fragment of the chromosome 12 was chosen to perform marker-assisted matings and to validate its role in resistance to H. contortus. The effect of this region was validated in the progenies born from matings. It seems this chromosomic fragment limits female worms fertility and is associated to a stronger immune response. The putative role played by a fragment of the chromosome 21 in plasmatic pepsinogen concentration (a biomarker of abomasal lesions) was also confirmed in this work. A candidate gene underlying this region has been sequenced and the analysis of the detected polymorphisms should confirm its role. Further, two other genes in its vicinity could also play a role in this biological phenomenon and they should also deserve future considerations. This work illustrated both the existing genetic variation for resistance to H. contortus and the associated complexity of underlying mechanisms. Additional sequencing and gene expression sequencing studies should help understanding gene functions and interactions.

Item Type:PhD Thesis
Uncontrolled Keywords:
Institution:Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Laboratory name:
Research Director:
Jacquiet, Philippe and Moreno, Carole
Deposited On:19 Dec 2013 22:58

Repository Staff Only: item control page