New information on the mechanism of forcible ascospore discharge from Ascobolus immersus

Many ascomycete fungi spurt their spores from asci pressurized by osmosis. This paper explores the details of this process in the coprophilous species Ascobolus immersus, through a combination of biomechanical and biochemical experiments, and mathematical modeling. A. immersus forms large asci that...

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Bibliographic Details
Published in:Fungal genetics and biology 2004-07, Vol.41 (7), p.698-707
Main Authors: Fischer, Mark, Cox, Justin, Davis, Diana J., Wagner, Andrew, Taylor, Richard, Huerta, Alfred J., Money, Nicholas P.
Format: Article
Language:English
Subjects:
Ascobolus immersus
Ascomycete
Ascomycota - chemistry
Ascomycota - growth & development
Ascomycota - physiology
Ascospore
Biomechanical Phenomena
Gas Chromatography-Mass Spectrometry
Glycerol
Glycerol - analysis
Mathematics
Models, Biological
Osmolytes
Osmotic Pressure
Proline - analysis
Spores, Fungal - growth & development
Spores, Fungal - physiology
Turgor
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Summary:Many ascomycete fungi spurt their spores from asci pressurized by osmosis. This paper explores the details of this process in the coprophilous species Ascobolus immersus, through a combination of biomechanical and biochemical experiments, and mathematical modeling. A. immersus forms large asci that expel 8 spores as a single, mucilage-embedded projectile. Measurements of ascus turgor using a microprobe attached to a strain gauge showed a pressure of 0.3 MPa or 3 atm. Analysis of ascus sap using GC/MS identified glycerol as a major osmolyte, accounting for 0.1 MPa of the osmotic pressure within the ascus sap. A mathematical model indicated that a pressure of 0.2 MPa would be sufficient to propel the cluster of ascospores over the distance measured in previous studies. The difference between the measured and predicted pressures is ascribed to loss of pressure as the spores are forced through the tip of the open ascus.
ISSN:1087-1845
1096-0937
DOI:10.1016/j.fgb.2004.03.005