The buoyancy of cryptococcal cells and its implications for transport and persistence of <i>Cryptococcus</i> in aqueous environments
Notice bibliographique
Résumé
ABSTRACT Cryptococcus is a genus of saprophytic fungi with global distribution. Two species complexes, Cryptococcus neoformans and Cryptococcus gattii , pose health risks to humans and animals. Cryptococcal infections result from inhalation of aerosolized spores and/or desiccated yeasts from terrestrial reservoirs such as soil and trees. More recently, C. gattii has been implicated in infections in marine mammals, suggesting that inhalation of cells from the air-water interface is also an important, yet understudied, mode of respiratory exposure. Based on historical records and epidemiological factors, water transport has been hypothesized to play a role in the spread of C. gattii from tropical to temperate environments. However, the dynamics of fungal persistence and transport in water have not been fully studied. The size of the cryptococcal capsule was previously shown to reduce cell density and increase buoyancy. Here, we demonstrate that cell buoyancy is also impacted by the salinity of the solution in which cells are suspended, with the formation of a halocline significantly slowing the rate of settling and resulting in persistence of C. neoformans within 1 cm of the water surface for over 60 min and C. gattii for 4–6 h. During the culture of three strains of C. gattii in yeast peptone dextrose media, we also identified aggregates of extracellular polysaccharide with complex structures, which we hypothesize from rafts that entrap cells and augment buoyancy. These findings illustrate new mechanisms by which cryptococcal cells may persist in aquatic environments, with important implications for aqueous transport and pathogen exposure. IMPORTANCE Cryptococcosis is a major fungal disease leading to morbidity and mortality worldwide. Cryptococcus neoformans is a major fungal species of public health concern, causing opportunistic systemic infections in immunocompromised patients. Cryptococcus gattii was traditionally a pathogenic fungus confined primarily to tropical regions, but in the 1990s, it emerged in the temperate climates of British Columbia, Canada and the Pacific Northwest of the United States. Outbreaks in these areas also led to the first host record of cryptococcosis in free-ranging cetaceans. C. gattii is particularly concerning as an emerging fungal pathogen due to its capacity to cause clinical disease in immunocompetent patients, its recent spread to a new ecological niche, and its higher resistance to antifungal therapies. Our research defines fungal characteristics that influence the transport of cryptococci through water and persistence of fungal cells near the water surface, improving our understanding of potential mechanisms for cryptococcal environmental transport.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».