Navegando por Orientadores "SENA, Chubert Bernardo Castro de"

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Acúmulo de colesterol por Mycobacterium smegmatis como possível modulador da biossíntese de lipomanana e lipoarabinomanana
(Universidade Federal do Pará, 2015-02-26) SANTOS, Ana Cristina Doria dos; SENA, Chubert Bernardo Castro de; http://lattes.cnpq.br/8620752020290438
Mycobacterial cell wall is a hallmark of Mycobacterium genus, constituted of bioactive lipids and glycoconjugates: phosphatidylinositol mannoside (PIMs), lipomannan (LM) and lipoarabinomannan (LAM). The chronic infection inside lung macrophages is related with cholesterol accumulation into host cells as an alternative source of carbon and energy to maintain the bacilli with its physiological functions. To understand the activity of these immunomodulatory glycoconjugates during adaptation under the unusual environment inside the host infected cells, the present work propose to investigate the possible modulation of LM/LAM biosynthesis in Mycobacterium smegmatis (saprophytic) after culture in minimal medium (MM), supplemented with glycerol and/or cholesterol. Our results showed that saprophytic bacilli are able to accumulate the cholesterol and change the bacterial physiology due to slow growth and restrict cell density. Furthermore, the cholesterol consumption decreased the accumulation of PIMs and promoted morphological changes and bacterial aggregates, even maintaining the cell wall with its specific physic-chemistry characteristic (alcohol-acid resistance). The most impressive change after cholesterol consumption was the LAM biosynthesis, which showed distinct electrophoresis migration, compatible to high molecular weight of LAM from non-saprophytic bacilli (from 25 – 30 KDa to 30 – 50 KDa). These results showed that cholesterol consumption, when utilized as principal alternative of carbon and energy source, is able to induce physiological changes in mycobacteria, mainly in LAM biosynthesis, one of the most immunoregulatory molecules of cell wall. Ours data suggest that similar changes in mycobacteria may occur inside the granuloma, and that changes may help the evolution of tuberculosis to chronic and multibacillary form, hallmarked by immunodeficient aspect against the bacilli.
Acesso aberto (Open Access)
O papel do colesterol na biossíntese da parede celular de Mycobacterium smegmatis
(Universidade Federal do Pará, 2015-02-26) MARINHO, Victor Hugo de Souza; SENA, Chubert Bernardo Castro de; http://lattes.cnpq.br/8620752020290438
Different Mycobacterium species are causative agents of disease in humans, for example, the tuberculosis. All mycobacteria have a complex cell wall, distinct of others bacteria, conferring specific physic-chemical characteristic to Mycobacterium genus, due to protect against immune system and waterproofing against the intake of much antibiotics. During infection, the bacillus is able to adapter to harsh environment, due to consumption of cholesterol from itself host cell (macrophages) as alternative carbon and energy source. That nutritional aspect has been considered as essential for division of bacilli and consecutive progress of tuberculosis disease. The present study has as objective to evaluate in vitro the modulation of saprophytic Mycobacterium smegmatis cell wall biosynthesis after cholesterol consumption as primordial energy and carbon source. As results, we are found by Thin Layer Chromatography (TLC) that bacillary adaptation to microenvironment with poor nutrient (minimal media – MM) maintained the biosynthesis and accumulation of essential cell wall components, when the growth occurs in presence of someone defined carbon and energy source (glycerol and/or cholesterol). Among them without changes, we analyzed Trehalose Dimicolate (TDM) and the phospholipids (phosphatidylinositol (PI), phosphatidylinositol manosides (PIMs), Cardiolipin (CL) and phosphatidylethanolamine (PE)). Differently of these results, the micolic acid showed representative accumulation, comparing with 7H9 culture, only when the MM was supplemented with glycerol. This result was confirmed by alcohol-acid staining using fluorescent auroamine dye, suggesting some changes in physic-chemistry cell wall properties. On the other hands, the MM culture induced the accumulation of glycopeptidolipids (GPLs), independently of glycerol/cholesterol supplementation. Such disturbance in cell wall biosynthesis also changed the bacillary hydrophobicity in all MM groups, but does not change the resistance and sensibility to antibiotics. Those results clearly show that cell wall biosynthesis might be modulate during nutritional shortage, and such presence or absence of cholesterol, as occurs during infection, does not significantly change the bacillary physiology to become vulnerable for antibiotics. It suggests that such modulations might also occur during infection, maintaining the bacilli available to develop the tuberculosis diseases.