Project description:Novosphingobium resinovorum strain SA1 is one of few strains capable of degrading sulfanilic acid which is a widely used representative of sulfonated aromatic compounds. In order to identify the elements involved in the biodegradation process and to understand the metabolic responces of the cells exposed to this aromatic compound, we performed a whole transcriptome analysis of cells grown on sulfanilic acid and glucose. Additionally, for distinguish the potential stress/starvation effects of the xenobiotic we compared the transcript profiles of samples taken from both the exponential and stationary growth phases.
Project description:We have developed a monoclonal antibody (mAb) C7 that reacts with Als3p and enolase present in Candida albicans cell wall and exerts three anti-Candida activities: candidacidal activity and inhibition of both adhesion and filamentation. To investigate the mode of action of mAb C7 on fungal viability, we examined changes in the genome-wide gene expression profile of C. albicans grown in presence of a subinhibitory concentration of mAb C7 (12.5 µg/ml) by using microarrays. A total of 49 genes were found to be differentially expressed upon treatment with mAb C7. Of these, 28 were found to be up-regulated and 21 down-regulated. The categories of up-regulated genes with the largest number of variations were those involved in iron uptake or related to iron homeostasis (42.86%), while the energy-related group accounted for 38.10% of the down-regulated genes (8/21). Results were validated by real Time PCR. Since these effects resembled those found under iron-limited conditions, the activity of mAb C7 on C. albicans mutants with deletions in key genes implicated in the three iron acquisition systems described in this yeast was also assessed. Only mutants lacking TPK1 and TPK2 genes were less sensitive to the candidacidal effect of mAb C7. FeCl3 or hemin at concentrations ≥ 7.8µM reversed the candidacidal effect of mAb C7 on C. albicans, on a concentration dependent manner. The results presented in this study provide evidence that the candidacidal effect of mAb C7 is related to the blockage of the reductive iron uptake pathway of C. albicans. A saturated culture of C. albicans grown overnight was diluted to an optical density at 600 nm of approximately 0.1 and divided in two aliquots. One of them was used untreated as control and the second one was treated with a subinhibitory concentration (12.5 µg/ml) of monoclonal antibody C7 . Both cultures were incubated for 18 h at 37ºC before harvesting cells. Antibody added and control samples were obtained each time. The experiment was repeated once. Dye-swap technique was used for hybridization and four arrays were analyzed to compare the expresion of over six thousands genes in response to antibody C7.