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Size Matters: Measurement of Capsule Diameter in Cryptococcus neoformans
Published on: February 27, 2018
Capsular localization of the Cryptococcus neoformans polysaccharide component galactoxylomannan
Magdia De Jesus1, André Moraes Nicola, Marcio L Rodrigues
1Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Eukaryotic Cell
|October 28, 2008
Summary
Galactoxylomannans (GalXM) in Cryptococcus neoformans capsules were localized using novel antibodies. GalXM appears to be secreted and transient, functioning as an exopolysaccharide rather than a structural component.
Area of Science:
- Mycology
- Immunology
- Biochemistry
Background:
- The Cryptococcus neoformans capsule, crucial for virulence, comprises glucuronoxylomannan (GXM) and galactoxylomannans (GalXM).
- The precise location and function of GalXM within the capsule remain poorly understood due to a lack of specific detection tools.
Purpose of the Study:
- To develop specific serological reagents for detecting GalXM.
- To investigate the localization and potential function of GalXM in the C. neoformans capsule.
Main Methods:
- Conjugation of GalXM to Bacillus anthracis protective antigen to create immunogens.
- Generation of immune serum and a single-chain variable fragment antibody for GalXM detection.
- Immunofluorescence microscopy to visualize GalXM localization in acapsular and encapsulated C. neoformans cells.
- Analysis of vesicle fractions for GalXM transport.
Main Results:
- Successfully generated antibodies specific to GalXM.
- Localized GalXM to the cell wall of acapsular cells and discrete pockets at the capsule edge of encapsulated cells.
- Observed abundant GalXM on nascent capsules of budding cells.
- Evidence suggests vesicular transport of GalXM.
- GalXM partially colocalized with oxidized carbohydrates.
Conclusions:
- GalXM is a transient component of the C. neoformans capsule, secreted during cell maturation.
- GalXM likely functions as an exopolysaccharide, contributing to capsule dynamics rather than structural integrity.
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