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SELECTIVE "STAINING" FOR ELECTRON MICROGRAPHY : THE EFFECTS OF HEAVY METAL SALTS ON INDIVIDUAL BACTERIAL CELLS
1Department of Bacteriology, The School of Medicine, University of Pennsylvania, Philadelphia, and the RCA Manufacturing Company, Camden, New Jersey.
The Journal of Experimental Medicine
|October 30, 2009
Summary
Electron microscopy can reveal selective chemical changes in cells. Heavy metal salts darken bacterial protoplasm, showing potential for microchemical analysis and studying germicidal agent effects.
Area of Science:
- Microscopy
- Cell Biology
- Analytical Chemistry
Background:
- Electron micrography relies on physical contrast for image formation.
- Selective chemical analysis can provide additional information about cell components.
- Existing methods may not fully capture subtle chemical alterations.
Purpose of the Study:
- To explore the physical basis of contrast in electron micrography for chemical analysis.
- To propose and demonstrate a method for selective microchemical analysis using electron microscopy.
- To investigate the effects of heavy metal salts on bacterial cells.
Main Methods:
- Theoretical consideration of contrast mechanisms in electron micrography.
- Application of heavy metal salt solutions to bacterial samples.
- Imaging of treated bacteria using electron microscopy.
- Analysis of differential darkening of cellular components.
Main Results:
- Electron micrographs revealed selective darkening of bacterial inner protoplasm, not cell walls, after exposure to heavy metal salts.
- Observed cellular changes included shrinkage, coagulation, and protoplasm escape.
- These effects were successfully recorded in electron micrographs.
Conclusions:
- Selective microchemical analysis is feasible in electron micrography, analogous to differential staining.
- Electron microscopy can visualize chemically induced changes in individual bacterial cells.
- This technique holds promise for studying the action of germicidal agents on bacteria.
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