No description available.

Previously cloned bacteriophage encoded HyIP 1 from the genome sequenced organism Streptococcus pyogenes SF370 was expressed in Escherichia coli and purified to homogeneity. The protein, previously assigned to glycoside hydrolase family 69 (GH69) was biochemically recharacterised as a polysaccharide lyase and reassigned to family 16 (PL16). The enzyme demonstrated a Km of 1.47 mg m1-1 and a kcat of 7.2 s-1. Biochemically the enzyme had an optimum pH of 6.5 and temperature of 37 °C. The enzyme required no additional divalent ions for catalysis. The enzyme demonstrated strict substrate specificity only degrading hyaluronate and with no activity against related substrates chondroitin 4 sulphate and chondroitin 6 sulphate. HPAEC indicated the HylP1 had an endo mechanism of cleavage producing a range of differently sized oligosaccharides with the smallest being a tetramer. Site directed mutagenesis revealed a role for residues D157 and Y169 with substitution of these residues with alanine resulted in a 88.5% and 91.9 % loss of activity respectively. The location of these residues within the solved structure of HylP1 falls within the triple stranded (3 helix formed by the trimerised protein. This region of the protein was cloned, expressed and characterised and demonstrated similar kinetics as the full length protein (Km of 0.53 mg m1-1 and keat of 11.1 s-1). The activity of the enzyme when compared to other hyaluronate lyases shows it to be relatively inefficient yet when compared to other bacteriophage encoded hyaluronate lyases, HylP 1 was very similar. The proposed role of these bacteriophage encoded hyaluronate lyases is one of degradation of the hyaluronate capsule surrounding the streptococcal cells to allow for penetration of the bacteriophage during infection. Using the sequence of HylP1 the recently completed genome of Streptococcus equi was searched using bioinformatics tool BLAST. This revealed the presence of a protein, SEQ2045, sharing 85 % identity with HylPl. The protein was cloned and expressed in E. colt and biochemically characterised as a hyaluronate lyase. The enzyme demonstrated a Km of 2.05 mg m1-1 and a kcat of 6.2 s-1 which when compared to those of Hy1P 1 is suggestive that the two enzymes are strongly related. The enzyme had an optimum pH of 6.5 and temperature of 37 °C and like Hy1P 1 demonstrated only activity against hyaluronate and had an endo mechanism of cleavage with the smallest product of digestion being a tetramer. Site directed mutagenesis of the same residues as in HylP1 again yielded reduced activity (91.3 % and 87.6 % respectively). Bioinformatic analysis of the genome of S. equi was performed by BLAST searching with the proposed gene sequences of S. equi flanking SEQ2045. This allowed for the production of a prophage map which shows distinct similarities to the prophage map of S. pyogenes suggesting both may be of the same origin. Purified SEQ2045 was used in western blot analysis with S. equi convalescent horse serum. A strong positive reaction demonstrated a possible role for SEQ2045 during an infection suggesting that the bacteria have acquired this enzyme as a potential virulence factor by horizontal gene transfer. This presents a useful opportunity for the study of both S. pyogenes and S. equi infection process and the role of bacteriophage by the use of S. equi as a model for S. pyogenes.

No description available.

The 1999-2000 restricted-use School and Staffing Survey (SASS) dataset was used to construct hierarchical linear models to determine to what degree administrative support, resources, collegiality, parental support, school atmosphere, credentialing requirements, professional development, classroom and school autonomy, and compensation can predict teacher satisfaction in public, private, and charter schools after controlling for teacher background and school characteristics. Variables were selected in part because it is possible for them to be manipulated by policy. The study also reports on efforts to refine and validate subscales of items chosen based on theory and literature from the SASS to represent teacher satisfaction and predictors of satisfaction. SASS collected a nationally representative complex random sample of public, private, and charter schools with teachers randomly selected from schools. The conceptual framework of this study identifies level of opportunity and amount of power to access and use resources as the most significant aspects of a position as related workplace conditions. Though teaching is often characterized by isolation from adults, results of this study show that relationships with others are important. Key relationships focus on principals of schools for administrative support and leadership, teachers and school staff for cooperative environment and collegiality, parents for parental support, and students in terms of respect and behavior. Teachers also report higher levels of satisfaction when they have adequate resources like time and materials, when they have autonomy in their own classrooms, and when they are satisfied with their class sizes and salary. Principals of schools appear to be in the best position to directly influence teacher job satisfaction, but they need support from their community and school districts.

Made available in DSpace on 2016-04-28T20:13:52Z (GMT). No. of bitstreams: 1 2008 - Monica Desiderio.pdf: 410384 bytes, checksum: 192b4da53a335f1ce74d0a1e8cdcf92d (MD5) Previous issue date: 2008-02-25 / Ce travail pr?tent servir de base pour une d?bat centr?e sur l? role symbolique de la perspective institutionelle sur la percpetion des acteurs du cons?rcio modular relactive a sa capacit? du governance e coordination, que peuvent soutenir la convertion des ressources en comp?tences et garantiront l avantage comparatif institutionelle. Pour cela, le point de d?part est constitu? par l hypot?se que l environement des entreprises a connu d extraordinaires changements dans ces derni?res decennies, qui sont reflet?s surtout dans le relations diferenci?es d organisation des entreprises. Des considerations faites concernant des organisations, institutions, l innovation et changements, ansi que des reseaux, governance, capacit? de coordination, resources et comp?tences, montrent l importance du sujet pour le milieu de l entreprise, acad?mique et de la soci?t? dans son ensemble. Dans ce contexte, le proc?s de l institutionalisation est reforc?e pour la perception des acteurs aussi que pour sa participation dans le march?. Considerations sont ?tablies sur des pratiques currents du secteur industrielle, ansi que ignoration de la racionalit? substantive des acteurs. / O presente trabalho pretende servir como base para uma discuss?o acerca de como, via perspectiva institucional, a percep??o dos atores do consorcio modular relativamente aos mecanismos de governanca e coordena??o podem impactar a convers?o de recursos em compet?ncias, e por fim proporcionar determinada vantagem comparativa institucional. Isto porque o ambiente organizacional tem conhecido significativas transforma??es nas ?ltimas d?cadas, sobretudo no que se refere ?s formas diferenciadas de organiza??o empresarial. Considera??es feitas a respeito das organiza??es, institui??es, inova??o e mudan?as organizacionais, assim como a respeito de redes, governanca, mecanismos de coordena??o, recursos e compet?ncias permitem mostrar a import?ncia do tema para a Academia e para o meio empresarial. Nesse sentido, o processo de institucionaliza??o do cons?rcio modular, que lhe garante uma vantagem comparativa institucional, ? comprovada tanto do ponto de vista da percep??o dos atores, como do ponto de vista do mercado (lideran?a e participa??o). Ressalvas s?o feitas quanto as pr?ticas correntes no setor industrial, quanto ao embotamento da racionalidade substantiva dos atores.