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.)

1. The DNA sequence of the human complement C4A gene from a cosmid clone Cos 3A3 was determined and the complete exon-intron structure elucidated. The 5' flanking region of the C4 gene contains three TATA sequences and a transcriptional enhancer core sequence, which are >200 nucleotides (nt) and 60-70 nt upstream from the CAP site, respectively. The gene consists of 42 exons coding for a precursor protein of 1745 residues. The first exon codes for a 51 nt 5' untranslated sequence, a leader peptide of 19 residues, and the N-terminus of the β chain. The β-α and the α-γ chain junctions are encoded by exons 17 and 34, respectively. The anaphylatoxin C4a and the thiolester site are encoded by phase 1-1 symmetrical exons. Most of the amino acids encoded at the splice junctions are polar or charged. Between exons 10 and 11 is a 6-7 kb intron that is flanked by direct long terminal repeats and may be absent in some C4 genes located at the second C4 locus. The last exon codes for the C-terminus of the γ chain and a 140 bp 3' untranslated sequence. The intergenic region between the C4 gene and its neighbouring 21-hydroxylase (210Hase) gene is ~3028 bp. 2. Eighteen polymorphic amino acids on C4 have been identified through genomic DNA, cDNA and protein sequencing. Fourteen of them are located on the* chain (C4a: 2 changes; C4d: 12 changes). The rest are scattered on the β and the γ chains. There are potential size variations by one residue on the β chain, and by a tripeptide that contains a sulphation site on the α chain. 3. Four common and rare C4 alleles have been cloned from individuals whose C4 proteins were chemically and serologically characterised. Analysis of the sequences at the C4d regions has allowed the identification of the C4A/C4B isotypic residues at positions 1101-6: C4A has the sequence PCPVLD, while C4B has the sequence LSPVIH. Presumably these isotypic residues are the cause of the class-specific, differential chemical reactivates. Moreover, the probable locations for the two Eodgers (Kg) and the six Chido (Ch) antigenic determinants were deduced. The C4B isotypic residues may be involved in the expression of the Ch2 and the Ch4 epitopes, while the C4A isotypic residues may not be related to either of the Eg determinants. 4. Definitive restriction fragment length polymorphisms (RFLPs) representing the exact locations responsible for the isotypicity between C4A and C4B, and for their generally associated Rg1 and Ch1 antigenic determinants, have been designed. In combination with the Taq I polymorphic patterns specific for the C4 and for the 210Hase gene loci, it has been shown that the null allele of the HLA haplotype B44 DR6 C4A 3 C4B QO is not a C4B allele, but probably encodes another C4A 3 allotype at the second C4 locus.

A genetic approach to lowering protease (plasmin) levels in milk, requires the presence of polymorphism of bovine plasminogen. This study was conducted to determine to what extent genetic polymorphism exists in dairy cattle. Bovine plasminogen was first purified from Holstein cow plasma by affinity chromatography on Lysine-Sepharose and antibodies to bovine plasminogen were raised by monthly intramuscular injection of the isolated bovine plasminogen into rabbits. For plasminogen phenotyping, blood samples were collected at random from 50 Holstein and Ayrshire cattle, and plasminogen was isolated from the plasma using lysine-Sepharose and then treated with neuraminidase. After separation by isoelectric focusing (pH 3.5-9.5) in polyacrylamide gels, Plasminogen polymorphs were detected immunologically using rabbit anti-bovine plasminogen antibodies. Additionally, the plasminogen isoforms were evaluated with a functional assay (caseinolytic overlay technique) after activation of the plasminogen with urokinase. Six plasminogen phenotypes were identified which represent products of 5 variant alleles. The 5 plasminogen variants were characterized based on their isoelectric points and designated PLG A$ sb2$ (pI 6.5 and 7.0), B$ sb2$ (pI 7.6 and 7.8), C$ sb1$ (pI 6.8), D$ sb2$ (pI 7.8 and 8.0), and E$ sb2$ (pI 6.8 and 7.0). PLG A$ sb2$ and PLG B$ sb2$ were the most common variants in these cattle. The 6 phenotypes were $ rm A sb2A sb2, B sb2B sb2, A sb2B sb2, B sb2C sb1, A sb2D sb2 and D sb2E sb2$. The phenotypic frequencies in Holstein and Ayrshire were very different, $ rm A sb2A sb2 and B sb2B sb2$ being respectively the most frequent phenotype. In addition, DNA polymorphism at bovine plasminogen gene was detected when genomic DNA was digested with the restriction enzyme Msp I and hybridized with mouse plasminogen cDNA. This is the first description of plasminogen polymorphism reported in dairy cattle. If different variants have altered activity, the detrimental effect

No description available.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Also available in print.

Thesis (Ph. D.)--University of Adelaide, 1968. / Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Also available online.

Thesis (M. Phil.)--University of Hong Kong, 2008.