published_or_final_version / abstract / toc / Zoology / Master / Master of Philosophy

No description available.

The gene encoding chicken growth hormone (GH) was isolated from a chicken genomic library. The size of the gene was 4 kb. It was digested with PstI and subcloned into pUC18. Three of the PstI fragments were used for restriction fragment length polymorphisms (RFLPs) analysis at the GH locus in two chicken strains (fat and lean line). Four polymorphic sites were detected using a PstI fragment (PII) as a probe. One polymorphism was located at a SacI restriction site (PS1), and three at MspI sites (PM1, PM2 and PM3). A method based on polymerase chain reaction (PCR) was developed for detecting polymorphisms at PM3 site. A fragment of 823 base pairs which contained the PM3 polymorphic site was amplified. Three genotypes (+/+,$-$/$-$ and +/$-$) were distinguished by examining the MspI digested PCR products in either agarose or polyacrylamide gel. / Ten anonymous cDNA clones were also isolated from a chicken liver cDNA library and used for RFLPs analysis. Three of these clones were found to be able to detected RFLPs at MspI sites in chicken strains (strain 7, 8, 9, 8R, S and K) indicating that a high frequency of genes are polymorphic and can be used as markers in mapping experiments. One of the three clones was present on a haploid genetic element. Segregation analysis showed that the inheritance of this haploid gene was determined by the genotype of the female parent.

No description available.

The human wildtype p53 tumor suppressor gene contains a polymorphism at amino acid residue 72 which results in either an arginine (p53 Arg-72) or proline (p53 Pro-72) at this codon. In the present study I have examined this polymorphism at the molecular level to determine whether differences exist in the biochemical functions of these two p53 variants. No differences were observed in their sequence-specific DNA binding abilities, nor in their ability to be targeted by HPV-18 E6 oncoprotein for degradation by ubiquitination in vitro. However, differences were observed in the ability of these two variants to function as transcriptional activators: p53 Pro-72 was more transcriptionally active than p53 Arg-72. I propose that the polymorphism at codon 72 may affect the structure of the N-terminal transactivation domain of the p53 protein, which would then have an effect on the ability of these variants to interact with transcription factors in order to initiate transcription of target genes and function as a tumor suppressor.

A total of 853 milk samples with different phenotypes of $ kappa$-casein ($ kappa$-CN) and $ beta$-lactoglobulin ($ beta$-LG) and different preheating temperatures of 30, 70, 75 and 80$ sp circ$C were used for the making of individual laboratory scale Cheddar type cheese and for the determination of coagulating properties. Data obtained from milk input, cheese output and chemical analyses were used to calculate actual, 37% moisture adjusted and Van Slyke's theoretical yields and yield efficiency. Least squares analyses of data indicated that higher 37% moisture adjusted yields and yield efficiencies were obtained with milk types VII, VIII and IX, which have the B gene for $ kappa$-CN when compared to milk types I, II and III, which have the A gene for $ kappa$-CN irrespective of preheating temperatures. Moisture adjusted yield, 10.49%, was the highest when milk type VII containing $ kappa$-CN BB and $ beta$-LG AA phenotypes was preheated at 30$ sp circ$C, whereas milk type IX, which has phenotype BB for $ kappa$-CN and BB for $ beta$-LG, had the highest adjusted yields with values of 11.36, 11.91 and 11.99% when preheated at 70, 75 and 80$ sp circ$C, respectively. When cheese was made from milk preheated at 30$ sp circ$C, total solids (64.19%), fat (35.31%) and protein (25.82%) were highest in cheese obtained from milk types IX, VII and IX, respectively, all of which have the B gene for $ kappa$-CN. These three components (61.54%, 30.85% and 24.47%) were lowest in cheese made from milk types III, III and I, respectively, all of which have the A gene for $ kappa$-CN. Cheese with moisture content close to 39% were produced by milk types I and II preheated at 30$ sp circ$C. by milk types III, IV, V, VI, VII and VIII preheated at below 70$ sp circ$C and by milk type IX preheated at below 75$ sp circ$C. (Abstract shorted by UMI.)

X-linked hypophosphatemia (XLH), the most prevalent form of inherited rickets in humans, is caused by mutations in the PHEX gene, which encodes a protein with high homology to the M13 family of type-II integral membrane zinc metallopeptidases. We created an online mutation database, PHEXdb (http://data.mch.mcgill.ca/phexdb), to catalogue PHEX mutations identified in XLH patients, and found that missense mutations account for 22% of the 157 mutations reported to date. We also undertook to examine the effects of eight missense mutations (C85R, D237G, Y317F, G579R, G579V, S711R, A720T, and F731Y) on synthesis, glycosylation, cellular trafficking, and catalytic activity of the recombinant proteins using several approaches. The wild-type protein was resistant to endoglycosidase H (endo H), indicating that it is fully glycosylated. In addition, biotinylation and immunofluorescence studies revealed that the wild-type protein resides at the cell surface. The D237G, Y317F and F731Y mutant PHEX proteins were also endo H resistant and thus terminally glycosylated. In contrast, endo H digestion demonstrated that C85R, G579R, G579V, S711R and A720T were not terminally glycosylated. Furthermore, immunofluorescence showed that C85R, G579R and S711R were sequestered in the endoplasmic reticulum (ER). A secreted form of wild-type and mutant PHEX (secPHEX) proteins was generated to examine catalytic activity, using a synthetic fluorogenic peptide substrate. For this purpose, rescue of ER-trapped mutant proteins was attempted by growing transfected cells at 26°C. Low temperature was able to rescue three of the five trapped mutant proteins (G579V, S711R and A720T). Residual catalytic activity was observed with four mutant proteins (D237G, Y317F, A720T and F731Y) relative to the wild-type. However, the rescued S711R mutant was devoid of catalytic activity. Finally, limited proteolysis with trypsin and endoproteinase Glu-c revealed that the mutations D237G and F731Y induce conform

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.)

The SLC30A2 zinc transporter has been investigated due to its important role in zinc secretion into human milk. SLC30A2 is expressed in mammary epithelial cells, and the presence of genetic variations in this transporter could cause low zinc transport into the milk, leading to Transient Neonatal Zinc Deficiency (TNZD) in newborns. Through bioinformatics analysis 22 SNPs were identified. Therefore, we aim to identify the functional changes caused by 4 SNPs. By subcloning the SLC30A2 open reading frames into the Gateway expression plasmid tagged with red and green fluorescent proteins (mCherry, tGFP). Four SNPs were introduced by mutagenesis and tagged with mCherry. We transfected individual plasmids into mammary epithelial cells (HC11) and observed cellular targeting using epifluorescent imaging. The most common variants located to secreting endosomes and membrane in HC11 cells. Incorrect targeting of SLC30A2 causes mislocalization. It may be possible to identify mothers carrying risk genotypes for infant zinc deficiency.

Polymorphisms of platelet glycoproteins (GPs) are frequently targets for anti-platelet antibodies. At least 19 antigenic polymorphisms have been identified on platelet GPs. Antibodies against the HPA-lb polymorphism (a Leu to Pro switch at amino acid residue 33 of the IIIa sub-unit of GP IIb/Illa) have been attributed to as much as 90% of all cases of neonatal alloimmune thrombocytopenic purpura and posttransfusion purpura in caucasians. The HPA-lb polymorphism has also been equivocally associated with coronary artery disease, particularly early onset (<60 years of age) myocardial infarction. Current technology for identifying individuals with the HPA-lb phenotype is limited to the labor-intensive, highly technical and expensive process of DNA amplification by polymerase chain reaction and restriction fragment length polymorphism (PCR/RFLP) analysis.This study proposes an alternative method for phenotyping individuals for the HPA-1 polymorphism using the Biocytex Platelet HPA-1 kit. The kit identifies the HPA-1 polymorphism utilizing two monoclonal CD61 (platelet glycoprotein IIb/IIIa) antibodies, one of which has a lowered affinity for GP llb/Illa possessing the HPA-lb polymorphism. Fluorescent labeling of bound antibody allows for flow cytometric quantitation of antibody binding capacity (ABC) for both monoclonal antibodies, and ratios derived from the ABC can be used to phenotype previously unknown samples.The Biocytex HPA-1 kit identified 73 of 74 (98.6%) individuals possessing the HPA1 a/HPA-1 a phenotype, 22 of 22 (100%) HPA-1 a/HPA-1 b individuals and 4 of 4 (100%) HPAIb/HPA-Ib individuals. All HPA-lb phenotypes were confirmed by PCR/RFLP. Total accuracy of the test system was 99%. / Department of Biology