Thesis (M.A.)--University of Wisconsin--Madison, 1937. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 13).

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Call number: LD2668 .T4 1978 S25 / Master of Science

Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

As leveduras são de relevante importância dentro da agroindústria sucroalcooleira devido sua participação no processo fermentativo de produção de álcool. Deste modo, faz-se necessário o conhecimento deste agente fermentativo com destaque para Saccharomyces cerevisiae, principal gênero. O objetivo deste trabalho foi estudar a linhagem de levedura S. cerevisiae Y904, exposta a condições não proliferantes, após fermentação em meio que sofreu adição de óleo vegetal e sua possível correlação com manutenção da viabilidade celular. Foram realizadas análises para contagem de unidades formadoras de colônias, viabilidade celular, concentração celular, nitrogênio total na levedura e no meio, carboidratos totais, trealose e glicogênio. As leveduras submetidas a condições não proliferantes apresentaram menores teores de carboidratos totais, com destaque para trealose e glicogênio, em relação às leveduras comerciais. Saccharomyces cerevisiae sofreu queda de viabilidade acentuada após 24 h em solução fisiológica, em condições não proliferantes, sob agitação de 90 rpm e temperatura de 30 ± 1°C, seguida de uma acentuada autólise a partir de 120 h (5°dia), provavelmente, devido ao teor de carboidratos de reserva da célula que se encontravam em valores extremamente baixos, da ordem de 0,15 mg de trealose em 100 mg da matéria seca e 4 mg de glicogênio em 100 mg da matéria seca. A partir desse ponto entraram em total desorganização celular. / Yeast is highly important in sugar and alcohol agroindustry due to its role in the fermentative process of alcohol production. Thus, it is necessary to know this microorganism, most specially the Saccharomyces cerevisiae, the main species. The objective of this work was to study the strain Y904 of the yeast Saccharomyces cerevisiae under non-proliferating conditions after fermentation in a medium in which it was added vegetable oil and verify its possible correlation with the maintenance of the cellular viability. Analyses were performed in order to determine colony forming units, cellular viability, cellular concentration, total nitrogen in yeast and in medium, total carbohydrates and trehalose and glycogen contents. The yeast submitted to non-proliferating conditions presented a lower content of total carbohydrates, specially trehalose and glycogen, when compared to commercial yeasts. The viability of the yeast Saccharomyces cerevisiae Y904 markedly decreased after 24 hours in physiological solution under non-proliferating conditions in a shaker for 90 rpm at 30 ± 1°C. It was observed an accentuated autolysis from the 120 th hour (5 th day) on. This was probably because of the very low content of the carbohydrates of reserve in the cells, 0.15 mg of trehalose and 4.0 mg of glycogen in 100 mg of dry weight. From this point the cells began a total cellular disorganization.

A autólise acinar post mortem em glândulas sublinguais humanas é um fenômeno que prejudica a sua análise microscópica. Com o objetivo de esclarecer e prevenir tal ocorrência, a presente investigação foi planejada no sentido de analisar morfometricamente as possíveis influências do intervalo post mortem (IPM) e do volume de fixador histológico (VF) na ocorrência de autólise de ácinos em glândulas sublinguais de ratos. Dos sessenta animais utilizados na investigação, cinqüenta deles o foram no estudo do intervalo post mortem, sendo divididos em 2 grupos: o grupo I (25 animais) foi destinado para as avaliações morfométricas e o grupo II (25 animais) para determinação do fator de retração e densidade da glândula. Os grupos I e II foram subdivididos nos subgrupos: A e A1 (controle - 0 hora), B e B1 (3 horas post mortem), C e C1 (6 horas), D e D1 (12 horas) e E e E1 (24 horas), com 5 animais em cada um. A fixação foi realizada com 20 mL de solução de formol a 10% em tampão fosfato. Os 10 animais remanescentes foram destinados ao estudo da variação de volume do fixador, e foram divididos em 2 grupos iguais: no grupo 2mL, as glândulas dos 5 animais foram fixadas com 2 mL de solução de formol a 10% tamponada, e no grupo 20mL, as glândulas dos outros 5 animais foram fixadas com 20 mL da mesma solução. O tempo de fixação foi de 7 dias para todos. As glândulas foram processadas histologicamente, sendo os cortes histológicos corados com H.E. A análise morfométrica foi realizada em 50 campos histológicos por glândula, selecionados por amostragem sistemática, usando objetiva de 100x e ocular Kpl 8x contendo um retículo de integração constituído por 100 pontos simetricamente distribuídos. A densidade de volume dos ácinos íntegros e autolisados foi avaliada pelo método morfométrico de volumetria relativa de contagem de pontos. Houve diferença estatisticamente significante entre o IPM e a autólise acinar (p< 0,05), enquanto que não houve diferença significante quanto ao VF (p= 0,690). A autólise acinar aumentou significantemente com o aumento do período post mortem (p<0,05). Baseado nos resultados obtidos foi possível concluir que a autólise acinar em glândulas sublinguais de ratos está diretamente relacionada ao intervalo post mortem, não sendo influenciada pelo volume de fixador histológico testado no experimento. / Acinar post mortem autolysis is a phenomenon that difficult the microscopic analysis in human sublingual glands. The aim of the present study is to evaluate the influence of the post mortem interval (PMI) and formalin volume (FV) in the occurrence of acinar autolysis in sublingual glands of rats. Sixty animals were used in this study. Out of them fifty animals were divided in 2 groups for PMI investigation: group I (25 animals) for morphometric quantifications and group II (25 animals) to calculate the retraction factor and the density of the glands. The groups I and II were subdivided in subgroups with 5 animals each: A and A1 (control - 0 hour), B and B1 (3 hours post mortem), C and C1 (6 hours), D and D1 (12 hours) and E and E1 (24 hours). The remaining 10 animals were used for the FV study and were divided in two groups with different volume of formalin, 2mL and 20mL respectively. The fixation period was 7 days. The glands were processed and stained with HE. The morphometric analysis was performed in 50 histological fields, selected by systematic sampling, using lens of 100x and ocular Kpl 8x containing a Zeiss II integration grid with 100 points symmetrically distributed. The volume density of intact and autolysed acini was evaluated by the morphometric method of relative volume of counting of points. There was a statiscally significant difference between volume density acinar autolysis and PMI for all group tested (p=0,0001). The difference was not significant for FV (p = 0,690). We concluded that acinar autolysis in rat sublingual glands increased significantly with the PMI, not being influenced by the FV, as tested.

Calpains are calcium-dependent, intracellular, multi-domain cysteine proteases involved in many physiological functions regulated by calcium signaling, including cell motility. How calpains are activated in the cell is still unknown because the resting intracellular concentration of Ca2+ is orders of magnitude lower than that needed for half-maximal activation of the enzyme in vitro. Several stratagems by which calpains might overcome this Ca2+ concentration differential have been proposed. It is possible that post-translational modifications like phosphorylation, or accessory proteins that bind to calpain, might facilitate the enzyme’s activation at lower than optimal Ca2+ concentrations. Autoproteolysis (autolysis) and subunit dissociation are two other proposed activation mechanisms that could release constraints on the calpain core by breaking the link between the anchor helix and the small subunit to allow the active site to form. By measuring the rate of autolysis at different sites in calpain, it was demonstrated that while the anchor helix is one of the first targets to be cut, several other potentially inactivating autolysis sites, particularly in Domain III, can also be cleaved within the first minute. Thus autolytic activation would go hand in hand with inactivation. By fractionating and identifying calpain 2 autolysis fragments, I show that the small subunit does not dissociate away from the large subunit, but is proteolyzed to a 40-45 k heterodimer of the penta-EF-hand Domains IV and VI. It is likely that this autolysis-generated heterodimer has previously been misidentified as the small subunit domain VI homodimer that would be produced by subunit dissociation. A calpastatin affinity column was constructed and used to capture recombinant calpain 2 from bacterial cell lysate. This affinity column provides a tool to screen for and capture calpain complexed to potential binding partners in the presence of Ca2+. Here I propose a model for calpain 2 activation in vitro that does not involve autolysis, subunit dissociation, or calpain activators. / Thesis (Master, Biochemistry) -- Queen's University, 2010-10-25 16:03:52.364

Autolysins are enzymes that cleave specific structural components within the bacterial cell wall. They contribute to numerous cellular activities such as cell growth, cell division, peptidoglycan recycling and turnover. In this study, twelve Enterococcal isolates (previously from the genus Streptococcus) were examined for susceptibility to the antibiotics Penicillin G and Vancomycin, using a Disk Diffusion and a Microtitre plate assay. In both methods, all twelve strains were resistant to Vancomycin. Six of these strains were susceptible to Penicillin G. The minimum inhibitory concentration (MIC) values were twice that of the disk diffusion assay values. In the presence of antibiotic, the growth rates for the six strains were halved. Autolysins were extracted from the respective cell cultures using a 4% SDS precipitation method. The protein concentrations were calculated and estimated to be within the range of 5.47- to 6.35 μg/μl. Profiles of the SDS precipitate were analyzed on SDS-PAGE. Autolytic proteins were identified and partially analyzed by renaturing SDS-PAGE (zymograms) using gels containing cell wall substrate. Seven lytic bands of molecular weights 25, 30, 50, 63, 75 95 and 145 kDa (designated Autolysin A to G, respectively) were selected for further analysis. The temporal distribution of the enzymes ranged from the mid exponential phase to the early death phase. The seven proteins were blotted onto polyvinylidene difluoride (PVDF) membranes and excised for N-terminal sequencing. Blast analysis of the respective N-terminal sequences showed autolysins A, C, D, E and F to have 100% similarity to the muramidase, amidase and peptidase from S. cremoris, S. suis, S. pneumonia, S. pyogenes and E. faecium, respectively. Biochemical characterization confirmed autolysins A, B, E and F to exhibit muramidase activity, and autolysin C and G to exhibit peptidase activity. Autolysin D displayed 100% similarity to the protein LytA, a peptidoglycan hydrolase that is known to exhibit amidase activity. Blast analysis could not determine any significant similarities for autolysins B and G to previously identified autolysins, thus indicating they may perhaps be novel autolysins. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

Thesis (Ph. D.)--Illinois State University, 1995. / Title from title page screen, viewed May 2, 2006. Dissertation Committee: Radheshyam K. Jayaswal (chair), Brian J. Wilkinson, Anthony J. Otsuka, Herman E. Brockman, Hou T. Cheung. Includes bibliographical references (leaves 131-144) and abstract. Also available in print.

Nano-sized materials are being used to address some of humanities greatest challenges— cancer therapy, food and water security, and environmental remediation. While extremely promising for these applications, the production, use, and disposal of nanomaterials have resulted in their release into environmental compartments. One major concern of any novel contaminant is how it interacts with bacteria. Bacteria play essential roles in human health, engineered systems, and ecological functioning. Bacteria are capable of macro-scale influence because they have evolved communication systems that enable coordinated behaviors. Communication among cells involves chemical signals that enter the environment, where they are subjected to its biogeochemistry, which now includes novel nanomaterials. The overall goal of this thesis was to improve understanding of the relationship between nanoparticles and cell-to-cell signaling behavior in bacteria focusing on two population-level behaviors: autolysis and quorum sensing. Specifically, this project sought to: (1) improve our understanding of how metal-oxide nanoparticles affect the autolytic process in Bacillus subtilis, by elucidating the biological response of the interactions between titanium dioxide nanoparticles and biomolecules; (2) reveal the interactions between quorum sensing signaling molecules and metal cations commonly used in antimicrobial nanomaterials, silver and copper; and (3) demonstrate the potential of quorum sensing-regulated cyanide production to affect oxidation and dissolution of gold nanoparticles in an environmentally relevant system. By addressing these objectives, the work demonstrated that: 1. TiO2 nanoparticles disrupt the autolytic process by delaying the onset of autolysis, and intercepting released autolytic enzymes, preventing the enzymes from degrading peptidoglycan in neighboring cells. 2. Quorum sensing signaling molecules form complexes with Ag+ and Cu2+, removing the most bioavailable form (free HHL, Ag+, and Cu2+) from the cells’ environment. 3. Quorum sensing-regulated cyanide production induces oxidative dissolution in Au nanoparticles, which were previously assumed to be inert in environmental systems. Taken together, this body of work highlights the relationship between nanoparticles and population-level behavior in bacteria. The presence of nanoparticles can have significant effects on population-level behaviors, and the activity of population-level behaviors can have significant effects on nanoparticles behavior. This inter-connected relationship, where the nanoparticles are both acted on and act upon their environment, must be considered in nanoparticle-based studies and applications.