Melanin is an essential component for the integrity of the cell wall of Aspergillus fumigatus conidia

BACKGROUND: Aspergillus fumigatus is the most common agent of invasive aspergillosis, a feared complication in severely immunocompromised patients. Despite the recent commercialisation of new antifungal drugs, the prognosis for this infection remains uncertain. Thus, there is a real need to discover new targets for therapy. Particular attention has been paid to the biochemical composition and organisation of the fungal cell wall, because it mediates the host-fungus interplay. Conidia, which are responsible for infections, have melanin as one of the cell wall components. Melanin has been established as an important virulence factor, protecting the fungus against the host\u27s immune defences. We suggested that it might also have an indirect role in virulence, because it is required for correct assembly of the cell wall layers of the conidia. RESULTS: We used three A. fumigatus isolates which grew as white or brown powdery colonies, to demonstrate the role of melanin. Firstly, sequencing the genes responsible for biosynthesis of melanin (ALB1, AYG1, ARP1, ARP2, ABR1 and ABR2) showed point mutations (missense mutation, deletion or insertion) in the ALB1 gene for pigmentless isolates or in ARP2 for the brownish isolate. The isolates were then shown by scanning electron microscopy to produce numerous, typical conidial heads, except that the conidia were smooth-walled, as previously observed for laboratory mutants with mutations in the PKSP/ALB1 gene. Flow cytometry showed an increase in the fibronectin binding capacity of conidia from mutant isolates, together with a marked decrease in the binding of laminin to the conidial surface. A marked decrease in the electronegative charge of the conidia and cell surface hydrophobicity was also seen by microelectrophoresis and two-phase partitioning, respectively. Ultrastructural studies of mutant isolates detected considerable changes in the organisation of the conidial wall, with the loss of the outermost electron dense layer responsible for the ornamentations seen on the conidial surface in wild-type strains. Finally, analysis of the conidial surface of mutant isolates by atomic force microscopy demonstrated the absence of the outer cell wall rodlet layer which is composed of hydrophobins. CONCLUSION: These results suggest that, in addition to a protective role against the host\u27s immune defences, melanin is also a structural component of the conidial wall that is required for correct assembly of the cell wall layers and the expression at the conidial surface of adhesins and other virulence factors

Joint Observation of the Galactic Center with MAGIC and CTA-LST-1

MAGIC is a system of two Imaging Atmospheric Cherenkov Telescopes (IACTs), designed to detect very-high-energy gamma rays, and is operating in stereoscopic mode since 2009 at the Observatorio del Roque de Los Muchachos in La Palma, Spain. In 2018, the prototype IACT of the Large-Sized Telescope (LST-1) for the Cherenkov Telescope Array, a next-generation ground-based gamma-ray observatory, was inaugurated at the same site, at a distance of approximately 100 meters from the MAGIC telescopes. Using joint observations between MAGIC and LST-1, we developed a dedicated analysis pipeline and established the threefold telescope system via software, achieving the highest sensitivity in the northern hemisphere. Based on this enhanced performance, MAGIC and LST-1 have been jointly and regularly observing the Galactic Center, a region of paramount importance and complexity for IACTs. In particular, the gamma-ray emission from the dynamical center of the Milky Way is under debate. Although previous measurements suggested that a supermassive black hole Sagittarius A* plays a primary role, its radiation mechanism remains unclear, mainly due to limited angular resolution and sensitivity. The enhanced sensitivity in our novel approach is thus expected to provide new insights into the question. We here present the current status of the data analysis for the Galactic Center joint MAGIC and LST-1 observations

MAGIC and H.E.S.S. detect VHE gamma rays from the blazar OT081 for the first time: a deep multiwavelength study

https://pos.sissa.it/395/815/pdfPublished versio

Contribution des tests platelia et de la PCR au diagnostic d'infection fongique invasive chez le patient neutropénique

LILLE2-BU Santé-Recherche (593502101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Les dermatophytes : les difficultés du diagnostic mycologique

<p>RésuméLes dermatophytes sont des champignons filamenteux responsables de lésions variées de la peau et des phanères, dont le diagnostic n’est pas toujours évident cliniquement. Devant une lésion évoquant une dermatophytie, un examen mycologique s’impose donc le plus souvent. Cependant, bien que cette recherche soit d’usage courant dans les laboratoires d’analyses médicales, la mise en évidence d’une étiologie fongique n’est pas assurée pour autant. En effet, pour obtenir un résultat fiable, le biologiste doit surmonter plusieurs niveaux d’obstacles : 1. la réalisation du prélèvement selon le type de lésion, 2. l’examen direct des différents produits biologiques, ainsi que leur mise en culture, 3. l’identification des champignons isolés, 4. l’interprétation des résultats. Les difficultés susceptibles d’être rencontrées au cours des différentes étapes du diagnostic des dermatophyties reposent essentiellement sur l’absence de standardisation des prélèvements et des techniques mycologiques, ainsi que sur le manque de commercialisation de certains réactifs et milieux de culture. Les auteurs se proposent de passer en revue les principaux pièges à éviter.</p&gt

Reappraisal of Conventional Diagnosis for Dermatophytes

International audienc

Erratum to: Reappraisal of Conventional Diagnosis for Dermatophytes

International audienc

Fungal respiratory infections in cystic fibrosis: Diagnostic challenges in the clinical laboratory

International audienc

Fungal respiratory infections in cystic fibrosis: Diagnostic challenges in the clinical laboratory

International audienc

Detecting filamentous fungi in cystic fibrosis

International audienc