Chondrodysplasia of Texel sheep : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand

Piripi, Susan Amanda

Chondrodysplasia of Texel sheep : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand

dc.contributor.author	Piripi, Susan Amanda
dc.date.accessioned	2009-05-04T21:20:14Z
dc.date.available	NO_RESTRICTION	en_US
dc.date.available	2009-05-04T21:20:14Z
dc.date.issued	2008
dc.description.abstract	Chondrodysplasia of Texel sheep is a newly described recessively inherited disorder distinct from other chondrodysplasias described in sheep. Phenotypically normal at birth, affected lambs develop microscopic lesions as early as 9 days of age, and usually demonstrate gross deformities and markedly reduced rates of bone growth by 2 to 3 weeks. Individual bone growth rates are most severely affected in the proximal bones of the forelimbs. Chondrodysplastic lambs typically have short stature, angular limb deformities, a barrel-shaped chest and a wide-based stance. Gross lesions include tracheal narrowing and contortion, enlarged costochondral junctions, and erosion of articular cartilage in major limb joints. Microscopic lesions are confined to hyaline cartilage, and are characterised by degeneration of the interterritorial matrix and dense perichondrocytic rings consisting predominantly of type VI collagen. These lesions are identical in appearance to those in achondrogenesis 1b and diastrophic dysplasia, two diseases caused by defects of the diastrophic dysplasia sulphate transporter (DTDST) in human beings. An investigation to measure the uptake of radiolabelled sulphate by dermal fibroblasts in vitro did not provide evidence of a defect in the DTDST in chondrodysplastic Texel sheep. A linkage disequilibrium study of ovine chromosomes 1, 5, 6, 13 and 22 using microsatellite DNA markers was unable to identify evidence of a mutation causing this form of chondrodysplasia. Capillary electrophoresis of unsaturated chondroitin sulphate disaccharides demonstrated a relative reduction in the ratio of chondroitin 4-sulphate to chondroitin 6-sulphate in affected animals of all ages. This biochemical feature enables the potential determination of the phenotype of newborn lambs prior to the emergence of gross or microscopic lesions. The pathology of the disease, combined with the findings of the genetic, biochemical and in vitro studies, suggest that a mutation may be present in the CHST11 gene. This gene is a good candidate for future studies aimed at discovering the genetic defect in chondrodysplasia of Texel sheep and developing a test to identify heterozygous animals.	en_US
dc.identifier.uri	http://hdl.handle.net/10179/800
dc.language.iso	en	en_US
dc.publisher	Massey University	en_US
dc.rights	The Author	en_US
dc.subject	Chondrodysplasia	en_US
dc.subject	Texel sheep	en_US
dc.subject	Genetic defects	en_US
dc.subject	Inherited diseases	en_US
dc.subject.other	Fields of Research::300000 Agricultural, Veterinary and Environmental Sciences::300500 Veterinary Medicine::300506 Pathology	en_US
dc.title	Chondrodysplasia of Texel sheep : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand	en_US
dc.type	Thesis	en_US
massey.contributor.author	Piripi, Susan Amanda
thesis.degree.discipline	Veterinary pathology	en_US
thesis.degree.grantor	Massey University	en_US
thesis.degree.level	Doctoral	en_US
thesis.degree.level	Doctoral	en
thesis.degree.name	Doctor of Philosophy (Ph.D.)	en_US