Insight into the genome of Aspergillus fumigatus: analysis of a 922 kb region encompassing the nitrate assimilation gene cluster.
ABSTRACT Aspergillus fumigatus is the most ubiquitous opportunistic filamentous fungal pathogen of human. As an initial step toward sequencing the entire genome of A. fumigatus, which is estimated to be approximately 30 Mb in size, we have sequenced a 922 kb region, contained within 16 overlapping bacterial artificial chromosome (BAC) clones. Fifty-four percent of the DNA is predicted to be coding with 341 putative protein coding genes. Functional classification of the proteins showed the presence of a higher proportion of enzymes and membrane transporters when compared to those of Saccharomyces cerevisiae. In addition to the nitrate assimilation gene cluster, the quinate utilisation gene cluster is also present on this 922 kb genomic sequence. We observed large scale synteny between A. fumigatus and Aspergillus nidulans by comparing this sequence to the A. nidulans genetic map of linkage group VIII.
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ABSTRACT: Neurospora crassa is a central organism in the history of twentieth-century genetics, biochemistry and molecular biology. Here, we report a high-quality draft sequence of the N. crassa genome. The approximately 40-megabase genome encodes about 10,000 protein-coding genes--more than twice as many as in the fission yeast Schizosaccharomyces pombe and only about 25% fewer than in the fruitfly Drosophila melanogaster. Analysis of the gene set yields insights into unexpected aspects of Neurospora biology including the identification of genes potentially associated with red light photobiology, genes implicated in secondary metabolism, and important differences in Ca2+ signalling as compared with plants and animals. Neurospora possesses the widest array of genome defence mechanisms known for any eukaryotic organism, including a process unique to fungi called repeat-induced point mutation (RIP). Genome analysis suggests that RIP has had a profound impact on genome evolution, greatly slowing the creation of new genes through genomic duplication and resulting in a genome with an unusually low proportion of closely related genes.Nature 05/2003; 422(6934):859-68. · 38.60 Impact Factor
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ABSTRACT: Adherence of the opportunistic fungus Aspergillus fumigatus to the extracellular matrix components is considered a crucial step in the establishment of the infection. Given the high carbohydrate content of these glycoproteins and the role of carbohydrate-protein interactions in numerous adherence processes, the presence of a lectin in A. fumigatus was investigated. Different fungal extracts obtained by sonication or grinding in liquid nitrogen from resting or swollen conidia, as well as from germ tubes and mycelium, were tested by hemagglutination assays using rabbit erythrocytes. A lectin activity was recovered in all the extracts tested. However, sonication of resting conidia resulted in the highest specific activity. Purification of the lectin was achieved by gel filtration followed by ion-exchange and hydrophobic-interaction chromatographies. Analysis of the purified lectin by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed an apparent molecular mass of 32 kDa, which is similar to that of the alkaline protease already identified from different strains of A. fumigatus. However, as evidenced by the use of an alkaline protease-deficient mutant, the two activities were supported by distinct proteins. In addition, hemagglutination inhibition experiments using different saccharides and glycoproteins demonstrated the specificity of the lectin for sialic acid residues. Together these results suggest that this lectin may contribute to the attachment of conidia to the extracellular matrix components through the recognition of the numerous terminal sialic acid residues of their carbohydrate chains.Infection and Immunity 01/2003; 70(12):6891-5. · 4.07 Impact Factor
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ABSTRACT: Nosocomial aspergillosis, a life-threatening infection in immunocompromised patients, is thought to be caused primarily by Aspergillus organisms in the air. A 3-year prospective study of the air, environmental surfaces, and water distribution system of a hospital in which there were known cases of aspergillosis was conducted to determine other possible sources of infection. Aspergillus species were found in the hospital water system. Significantly higher concentrations of airborne aspergillus propagules were found in bathrooms, where water use was highest (2.95 colony-forming units [cfu]/m(3)) than in patient rooms (0.78 cfu/m(3); P=.05) and in hallways (0.61 cfu/m(3); P=.03). A correlation was found between the rank orders of Aspergillus species recovered from hospital water and air. Water from tanks yielded higher counts of colony-forming units than did municipal water. An isolate of Aspergillus fumigatus recovered from a patient with aspergillosis was genotypically identical to an isolate recovered from the shower wall in the patient's room. In addition to the air, hospital water systems may be a source of nosocomial aspergillosis.Clinical Infectious Diseases 04/2002; 34(6):780-9. · 9.37 Impact Factor