Radiation damage to chromosomes in the scanning transmission x-ray microscope

Shawn P. Williams; Chris J. Jacobsen; Janos Kirz; Xiaodong Zhang; Jack Van't Hof; Susan Lamm

doi:10.1117/12.138747

13 January 1993 Radiation damage to chromosomes in the scanning transmission x-ray microscope

Shawn P. Williams, Chris J. Jacobsen, Janos Kirz, Xiaodong Zhang, Jack Van't Hof, Susan Lamm

Proceedings Volume 1741, Soft X-Ray Microscopy; (1993) https://doi.org/10.1117/12.138747
Event: San Diego '92, 1992, San Diego, CA, United States

Abstract

Imaging with soft x rays having energies between the carbon and oxygen K edge (284 - 531 eV) yields large absorption contrast for wet organic specimens, but these soft x rays are known to be very effective in damaging biological specimens. The commonly used criterion of mass loss was employed for assessing radiation damage in the scanning transmission x-ray microscope. Multiple images of freeze-dried V. faba chromosomes show no significant mass loss after 150 Mrad. Experiments performed on fixed hydrated chromosomes revealed them to be radiation sensitive. The greater total mass loss observed in multiple low dose images compared to that incurred during a single high dose image suggests that the effects of radiation damage occur slower than the acquisition time for neighboring pixels. The radiation sensitivity of chromosomes depends critically on the fixative used, with damage minimized in glutaraldehyde fixed samples. Radiation damage to chromosomes is independent of ionic strength above 65 mM, but increases for ionic strengths below 65 mM. Using free radical scavengers in the buffer, and changing the design of the sample cell reduced the amount of damage incurred as a function of dose.

Citation Download Citation

Shawn P. Williams, Chris J. Jacobsen, Janos Kirz, Xiaodong Zhang, Jack Van't Hof, and Susan Lamm "Radiation damage to chromosomes in the scanning transmission x-ray microscope", Proc. SPIE 1741, Soft X-Ray Microscopy, (13 January 1993); https://doi.org/10.1117/12.138747

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