Related Experiment Videos
Ultrastructure of the concentric membrane system in asci of Arthroderma vanbreuseghemii
Abstract:
An ultrastructural study was performed on the ascosporogenesis in Arthroderma vanbreuseghemii. Young gymnothecia of the fungus were treated with four different schedules: (1) glutaraldehyde and osmium tetroxide fixation, (2) potassium permanganate fixation, (3) tannic acid, with or without glutaraldehyde, and osmium tetroxide fixation, (4) periodic acid-alkaline bismuth (PABi) staining after glutaraldehyde and osmium tetroxide fixation. The glutaraldehyde- and osmium tetroxide-fixed asci had a concentric membrane system (CMS), concomitantly with the double membrane system (DMS) that eventually delimited ascospores. The CMS consisted of multiple membranes of a myelinoid appearance, and continued to the ascus plasma membrane and also to the DMS. In contrast, potassium permanganate fixation and tannic acid and osmium tetroxide fixation without glutaraldehyde failed to reveal such a structure as the CMS within the asci. PABi-positive materials were found on the marginal glycogen granules, the CMS, the DMS, and the ascus plasma membrane. These observations suggest that the CMS is lipid-poor and not composed of true membranes. It is not the direct source of the DMS, but merely participates in the production of cell wall materials during ascosporogenesis with the marginal glycogen granules as a substrate.
Insights
This study reveals the concentric membrane system (CMS) in Arthroderma vanbreuseghemii ascosporogenesis is not a true membrane and aids in cell wall production. It utilizes glycogen granules as a substrate, not directly forming the double membrane system (DMS).
Area of Science:
- Mycology
- Cell Biology
- Ultrastructural studies
Background:
- Ascosporogenesis is a critical process in fungal reproduction.
- Understanding the ultrastructural dynamics of fungal cell wall formation is essential.
Purpose of the Study:
- To investigate the ultrastructure of ascosporogenesis in Arthroderma vanbreuseghemii.
- To elucidate the role of the concentric membrane system (CMS) and double membrane system (DMS) in ascospore development.
Main Methods:
- Utilized four different fixation and staining techniques: glutaraldehyde/osmium tetroxide, potassium permanganate, tannic acid, and periodic acid-alkaline bismuth (PABi).
- Examined young gymnothecia of Arthroderma vanbreuseghemii using transmission electron microscopy.
Main Results:
- Glutaraldehyde/osmium tetroxide fixation revealed a concentric membrane system (CMS) and double membrane system (DMS) in asci.
- The CMS, characterized by myelinoid membranes, was PABi-positive and connected to the ascus plasma membrane and DMS.
- Potassium permanganate and tannic acid fixation methods failed to visualize the CMS.
- PABi staining indicated the CMS is lipid-poor, not a true membrane, and participates in cell wall material production using glycogen granules.
Conclusions:
- The concentric membrane system (CMS) is not a direct precursor to the double membrane system (DMS) during ascospore formation.
- The CMS, along with marginal glycogen granules, contributes to cell wall synthesis in Arthroderma vanbreuseghemii ascosporogenesis.