Soft X‐ray contact microscopy, using synchrotron radiation, of thin‐sectioned, lead‐contaminated chloragogenous tissue of the earthworm Dendrobaena rubida

Abstract

Soft X-ray ( 2 4 5 4 . 4 nm) contact microscopy, using synchrotron radiation, of ultrasections of lead-polluted chloragogenous tissue of the earthworm Dendrobaena rubida has been achieved. The positive resist, after etching to leave areas corresponding to high absorbance in the tissue, is viewed by SEM and the imaging compared with the same section viewed, after irradiation, by TEM. No radiation damage ..JS evident and the lead deposits associated with the chloragosomes and within the debris vesicles imaged clearly. The characteristics of the broad beam have thus produced a lead 'map'. Resolution is in the order of 70nm. The results are compared with the markedly different imaging of control tissue containing insignificant lead levels.

A comparison of soft X‐ray contact microscopy with light and electron microscopy for the study of algal cell ultrastructure

“…Successful imaging of three organisms has been achieved, Anabaena (a filamentous cyanobacterium or blue-green alga) and two unicellular eukaryotic algae Trebouxiu and Cyanidium. Although Cyanidium has a relatively thin cell wall the SXCM images of the cells reveal no internal detail using the previously acceptable exposure factor of 3000 mA s (Richards et al, 1986), and even with an exposure factor of 15,000 mA s little detail is seen. The high absorption of X-rays by this species must therefore be due to the cytoplasmic components of the cell.…”

Soft X‐ray contact imaging of nucleolar chromatin using synchrotron radiation: a comparative scanning and transmission electron microscope study

“…1 and 2) and by other workers. Richards et al (1986) noted the lack of fine detail in their CI when compared with the original structure and suggested that X-ray scattering effects around the edge of the specimen could result in the protection of polymer in regions adjacent to the specimen but not directly beneath it, so causing the image to 'spread'. The effects of this X-ray scattering, and probably also diffraction patterns (Cheng et al, 1986), will be exacerbated by any gap between the specimen and the resist; hence the importance of procedures that can minimize this distance, such as the use of specimens mounted on the bright side of the EM grid.…”

“…The technique is analogous to contact printing where the negative film is placed in direct contact with the photographic paper and a light source is shone through the negative image. After exposure to X-rays, the specimen is removed from the X-ray sensitive polymer resist which is then 'developed' using a solvent to leave an etched image of the original specimen (Richards et al, 1986). The higher the exposure to X-rays, the more readily the polymer is dissolved.…”

“…Two types of X-ray source are currently being used to produce contact images, synchrotron radiation sources (SRS) (Rush & Clarke, 1985;Richards et al, 1986) and gas plasmas generated by lasers (Feder er al., 1984;Rosser et al, 1985). 0 1988 The Royal Microscopical Society 127 Contact imaging has the potential to become a valuable, complementary technique for studying intermediate levels of chromosome and chromatin structure, bridging the gap between detailed structural studies, using transmission electron microscopy (TEM) and X-ray diffraction, and observations of the gross morphology of chromosomes with the light microscope.…”

X‐ray microscopy

“…X-ray penetration into the resist results in a 1 : 1 image that can be viewed by scanning or transmission electron microscopy and which reflects the absorption characteristics of the structure and chemical nature of the specimen (see Cheng et al, 1986). Resolution of <70 nm has been achieved (Richards et al, 1986).…”