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Negative staining can cause clumping of Bordetella pertussis fimbriae
R C Hamilton1, J Bennet, D Drane
1Research and Development Division, CSL Ltd., Parkville, Victoria, Australia.
Abstract:
The state of fimbriae type 2 (Fim 2) and fimbriae type 3 (Fim 3) preparations from Bordetella pertussis were examined by negative stain electron microscopy. Uranyl acetate induced clumping of Fim 3 regardless of pH and was unsuitable as a stain for establishing the state of fimbriae. Both ammonium molybdate and sodium phosphotungstate were able to show the differences in Fim 3 stored at pH 7.2 and pH 9.5.
Insights
This study examined Bordetella pertussis fimbriae preparations using electron microscopy. Ammonium molybdate and sodium phosphotungstate were suitable stains for visualizing differences in fimbriae type 3.
Area of Science:
- Microbiology
- Biophysics
Background:
- Bordetella pertussis fimbriae are crucial virulence factors.
- Understanding fimbriae structure is essential for vaccine development.
Purpose of the Study:
- To evaluate the state of fimbriae type 2 (Fim 2) and fimbriae type 3 (Fim 3) preparations from Bordetella pertussis.
- To determine suitable negative staining methods for electron microscopy of these fimbriae.
Main Methods:
- Negative stain electron microscopy was employed.
- Fimbriae preparations were examined using various stains, including uranyl acetate, ammonium molybdate, and sodium phosphotungstate.
- The effect of different pH levels on fimbriae stability and staining was assessed.
Main Results:
- Uranyl acetate induced clumping of Fim 3, making it unsuitable for structural analysis.
- Ammonium molybdate and sodium phosphotungstate effectively visualized Fim 3.
- Distinct differences in Fim 3 morphology were observed when stored at pH 7.2 versus pH 9.5.
Conclusions:
- The choice of stain is critical for the accurate electron microscopic examination of Bordetella pertussis fimbriae.
- Ammonium molybdate and sodium phosphotungstate are appropriate stains for studying Fim 3 structure and stability.
- Fimbriae type 3 from Bordetella pertussis exhibits pH-dependent structural variations.