Due to the importance of insulin-like growth factor-I (IGF-I) in regulating many physiological and metabolic processes, the IGF-I gene was chosen as a candidate gene to study trait associated polymorphisms in chickens. A PstI restriction fragment length polymorphism (RFLP) was detected at the 5' region of the gene and mapped to about 7 Kb upstream of the published promoter sequence. Analysis for association of the marker with traits of economic importance in an unselected, random-bred population of 359 White Leghorns revealed a significant association with egg weight (P ≤ 0.05) and specific gravity (P ≤ 0.05). There was also a trend for association with juvenile body weight (P = 0.08) but not adult body weight. For egg weight the PstI (-/-) genotype was associated with lower egg weight as compared to the heterozygote or the PstI (+/+) genotype. The PstI marker also was found to be significantly associated with differences in trait correlations. A regulatory loop that co-ordinated feed consumption, body weight, egg weight and rate of egg laying was detected, and this regulatory loop differed among the IGF-I genotypic classes. In the PstI (+/-) genotype, the degree of correlation between some of the traits was time dependent, while in the PstI (+/+) genotype it remained constant through the different periods of measurement. Since IGF-I is known to play an important role in immune functions, the association of the IGF-I genotypes with immune traits was also investigated. A significant association was found for delayed type hypersensitivity, interferon production and T-cell count (P ≤ 0.05). Individuals belonging to the PstI (+/-) genotypic class exhibited higher immune response, reflected by the delayed type hypersensitivity reaction and antibody the interactive effects of marker genotypes in the GH, GH-receptor and IGF-I genes on traits and trait correlations indicated that the three are part of an epistatic pathway, wherein the phenotypic consequences of
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.35902 |
| Date | January 1996 |
| Creators | Joseph, Suman C. |
| Contributors | Kuhnlein, Urs (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Animal Science.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001658883, proquestno: NQ50197, Theses scanned by UMI/ProQuest. |
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