Single-strand conformation polymorphism analysis (SSCP) and restriction fragment length polymorphism analysis (RFLP) were used to determine the genotype of Holsteins at the $ kappa$-casein ($ kappa$-CN) locus. A 432-bp fragment within exon IV containing nucleotide substitutions diagnostic of the A- and B-variants of $ kappa$-CN was amplified using the polymerase chain reaction (PCR). The sires from the earliest years of the AI industry had a significantly higher (p $<$ 0.01) frequency of allele than sires in modern usage. These data indicate that selection or milk production parameters may discriminate against the B-allele. SSCP analysis was also used for detecting polymorphisms within the regulatory region of $ kappa$-CN gene. A 640-bp fragment within the 5$ sp prime$-flanking region of bovine $ kappa$-CN gene which contained the TATA box, CAAT box, and exon I was amplified using PCR. The SSCP analysis of this fragment revealed no variation, possibly due to the lower detection efficiency of SSCP with large fragment size. Nested primers were, therefore, designed to amplify fragments of 234- and 486-bp. Polymorphism was detected only in the 486-bp fragment and the two variants were designated M$ sb1$ and M$ sb2.$ The allelic frequencies of M$ sb1$ and M$ sb2$ in bulls used by AI industry before 1970 were 0.67 and 0.33, and in bulls used by AI industry after 1980 the frequencies were 0.68 and 0.32, respectively. The frequency of these alleles were not significantly different in Holsteins used by AI industry before 1970 and after 1980. Unlike the apparent change in frequency of the A- and B-variants noted within exon IV, this polymorphism seems to have not responded to selection. However, a higher frequency of M$ sb1$ allele appeared to be associated with B-variant (exon IV) genotypes. The presence of these variants within the regulatory region may possibly be involved in the quantitative expression of $ kappa$-CN gene. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.23409 |
| Date | January 1996 |
| Creators | Masoudi, Mehrnoush |
| Contributors | Zadworny, David (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 | Master of Science (Department of Animal Science.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001506200, proquestno: MM12237, Theses scanned by UMI/ProQuest. |
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