Soft-X-ray damage to biological samples.
X-ray damage to biological samples was investigated in the wavelength region of 2.7-5 nm, which overlaps the so-called 'water-window', the wavelength range of 2.4-4.3 nm usually used in X-ray microscopy. Yeast cells and myofibrils were chosen as representatives of whole cell samples and motile protein systems, respectively. The samples were exposed to X-rays using an apparatus composed mainly of a laser-plasma X-ray source, a Wolter mirror condenser, and a sample cell. The yeast cells lost their dye exclusion ability when the X-ray flux was higher than 1 x 10(6) photons micron-2, while the myofibrils lost contractility when the X-ray flux was higher than 4 x 10(5) photons micron-2. These X-ray fluxes are lower than the flux required for the X-ray microscope observation of biological samples at a resolution higher than that of light microscopes.
Fujisaki
H
H
Nikon Corporation, Tsukuba Research Laboratory, Ibaraki, Japan. fujisaki@tsukubagw.nikon.co.jp
Takahashi
S
S
Ohzeki
H
H
Sugisaki
K
K
Kondo
H
H
Nagata
H
H
Kato
H
H
Ishiwata
S
S
D000818:Animals; D009210:Myofibrils / Q000528:radiation effects*; D011817:Rabbits; D011829:Radiation Dosage; D013997:Time Factors; D015003:Yeasts / Q000528:radiation effects*