994 resultados para L-Lactate production


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Insect cell cultures have been extensively utilised for means of production for heterologous proteins and biopesticides. Spodoptera frugiperda (Sf9) and Trichoplusia ni (High Five(TM)) cell lines have been widely used for the production of recombinant proteins, thus metabolism of these cell lines have been investigated thoroughly over recent years. The Helicoverpa zea cell line has potential use for the production of a biopesticide, specifically the Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus (HaSNPV). The growth, virus production, nutrient consumption and waste production of this cell line was investigated under serum-free culture conditions, using SF900II and a low cost medium prototype (LCM). The cell growth ( growth rates and population doubling time) was comparable in SF900II and LCM, however, lower biomass and cell specific virus yields were obtained in LCM. H. zea cells showed a preference for asparagine over glutamine, similar to the High Five(TM) cells. Ammonia was accumulated to significantly high levels (16 mM) in SF900II, which is an asparagine and glutamine rich medium. However, given the absence of asparagine and glutamine in the medium ( LCM), H. zea cells adapted and grew well in the absence of these substrates and no accumulation of ammonia was observed. The adverse effect of ammonia on H. zea cells is unknown since good production of biologically active HaSNPV was achieved in the presence of high ammonia levels. H. zea cells showed a preference for maltose even given an abundance supply of free glucose. Accumulation of lactate was observed in H. zea cell cultures.

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The aim of this study was to determine nitric oxide (NO) production of a murine macrophage cell line (RAW 264.7 cells) when stimulated with Porphyromonas gingivalis lipopolysaccharides (Pg-LPS). RAW264.7 cells were incubated with i) various concentrations of Pg-LPS or Salmonella typhosa LPS (St-LPS), ii) Pg-LPS with or without L-arginine and/or N-G-monomethyl-L-arginine (NMMA), an arginine analog or iii) Pg-LPS and interferon-gamma (IFN-gamma) with or without anti-IFN-gamma antibodies or interleukin-10 (IL-10). Tissue culture supernatants were assayed for NO levels after 24 h in culture. NO was not observed in tissue culture supernatants of RAW 264.7 cells following stimulation with Pg-LPS, but was observed after stimulation with St-LPS. Exogenous L-arginine restored the ability of Pg-LPS to induce NO production; however, the increase in NO levels of cells stimulated with Pg-LPS with exogenous L-arginine was abolished by NMMA. IFN-gamma induced independent NO production by Pg-LPS-stimulated macrophages and this stimulatory effect of IFN-gamma could be completely suppressed by anti-IFN-gamma antibodies and IL-10. These results suggest that Pg-LPS is able to stimulate NO production in the RAW264.7 macrophage cell model in an L-arginine-dependent mechanism which is itself independent of the action of IFN-gamma.

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Cet article s'attache à l'analyse approfondie de la périphrase auxiliaire aller / venir + V. infinitif dans un emploi peu documenté que la tradition nomme allure extraordinaire. Il prend appui sur un corpus de 500 occurrences relevé dans divers genres du discours (journalistique, littéraire, conversationnel, électronique). On propose dans un premier temps une description générale du fonctionnement de l’extraordinaire; on explicite ensuite précisément cet effet de sens, avant d'expliquer le mécanisme de sa production.

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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.