Related Experiment Videos
Eletron microscopic observations on the structure of Treponema zuelzerae and its axial filaments
Abstract:
The fine structure of the spirochete Treponema zuelzerae, and particularly of its axial filaments, was investigated by using the electron microscope. The cell consists of a protoplasmic core surrounded by two concentric envelopes, each approximately 12 nm in width. Between these envelopes are two axial filaments, one originating at each pole of the cell, which overlap and lie side by side in the central region of the cell. The diameter of the axial filaments is 18.0 to 18.5 nm. The terminal region of each filament at its proximal end consists of a hook-like structure, very similar in appearance to the proximal end of a bacterial flagellum. The outer envelope of the cell is readily disrupted with distilled water, and this treatment often results in the release of the filaments from their axial position. A sheath is seen surrounding the filaments when cells are treated with distilled water for no more than 1 min and fixed immediately with osmium tetroxide or glutaraldehyde. This sheath has a striated fine structure and a diameter of 46 nm.
Insights
Electron microscopy revealed the fine structure of Treponema zuelzerae. Two axial filaments within concentric envelopes possess hook-like ends, similar to bacterial flagella.
Area of Science:
- Microbiology
- Cell Biology
- Electron Microscopy
Background:
- Spirochetes are a unique group of bacteria characterized by their helical shape and motility.
- The structure and function of axial filaments are crucial for spirochete locomotion.
- Treponema zuelzerae is a representative species for studying spirochete ultrastructure.
Purpose of the Study:
- To elucidate the detailed fine structure of the spirochete Treponema zuelzerae.
- To specifically investigate the morphology and arrangement of its axial filaments.
- To compare the structure of Treponema zuelzerae axial filaments with bacterial flagella.
Main Methods:
- Transmission electron microscopy was employed to examine the ultrastructure of Treponema zuelzerae.
- Cells were subjected to distilled water treatment to observe filament release and sheath formation.
- Osmium tetroxide and glutaraldehyde fixation were used for high-resolution imaging.
Main Results:
- The Treponema zuelzerae cell comprises a protoplasmic core enclosed by two concentric envelopes (approx. 12 nm width each).
- Two axial filaments (18.0-18.5 nm diameter) are located between the envelopes, originating from opposite poles and overlapping centrally.
- A hook-like structure at the proximal end of each filament resembles the proximal end of a bacterial flagellum; a striated sheath (46 nm diameter) surrounds the filaments after water treatment.
Conclusions:
- The study provides a detailed ultrastructural description of Treponema zuelzerae, highlighting its unique cellular organization.
- The axial filaments exhibit distinct morphological features, including hook-like terminal structures, suggesting a functional similarity to flagella.
- The observed sheath formation indicates a dynamic structural component associated with the axial filaments.