Surface‐replica cytochemistry as a tool for studying cell‐surface enzyme activity: Membrane ecto‐ATPase localization in liver cell cultures

Ito

et al. 1994

Journal of Microscopy

Summary X‐ray contact microscopy with a 300‐ps‐duration laser‐plasma X‐ray source has been used to image hydrated human chromosomes. Clearly imaged are individual nucleosomes and their higher‐order particles (superbeads), elementary chromatin fibrils c. 30 nm in diameter and their higher‐order fibres of various sizes up to c. 120 nm in diameter. The results demonstrate that X‐ray microscopy is now capable of opening a new path of investigation into the detailed structures of hydrated chromosome fibres in their natural state.

Section: Development and Observationmentioning

confidence: 99%

Direct imaging in a water layer of human chromosome fibres composed of nucleosomes and their higher‐order structures by laser‐plasma X‐ray contact microscopy

Kinjo¹,

Ito

et al. 1994

Journal of Microscopy

“…Briefly, the chromosomes were removed from the PMMA with sodium hypochlorite (chlorine concentration, c. 0.5%). The PMMA was then developed with a mixture of methylisobutylketone and isopropanol (1 : 3) for 20 s. The developed images were observed under T E M by means of the replica method with a plasma polymerization-film made of naphthalene produced in a glow discharge apparatus (Tanaka, 1983;Karasaki & Tanaka, 1984). The thickness of the replica film was 10-20nm.…”

Section: Materials a N D Methodsmentioning

confidence: 99%

“…It is important in determining real structures of biological components to observe biological specimens at high resolution without any artefacts which may be produced by the process of fixation and staining. In this respect, it has been proposed that X-ray microscopy has advantages over other types of microscopy in biology: for example, (i) less absorbed energy than in electron microscopy; consequently there is less damage to the specimen and it is easier to observe wet specimens and thick specimens, and (ii) ease of handling (Kirz & Sayre, 1980). For these reasons, we are interested in observing the structure of intact human chromosomes by X-ray microscopy.…”

Section: Introductionmentioning

confidence: 99%

Fine structure of unstained human chromosome fibres dried with no fixative as observed by X‐ray contact microscopy

Nakano

Kinjo³

et al. 1990

Journal of Microscopy

SUMMARY X‐ray contact microscopy was used to examine unstained human chromosomes dried without any fixative. This is the first report of the observation of single human chromosome fibres at high resolution without any modification(s) such as staining or fixation. The ‘beads‐on‐a‐string’ structure was observed in stretched portions of chromosome fibres. The diameters of the thin filaments and small particles were 7–15 nm (mean ± SD of 12·2 ± 2·1 nm) and 16–69 nm (31·4 ± 13·2 nm), respectively. These sizes correspond to those of fibres composed of nucleosomes (10–15 nm in diameter) and particle units (15–50 nm in diameter) called superbeads (unit structures composed of a multiple association of nucleosomes). These results are in good agreement with the current nucleosome and superbead model for chromosome fibre structure.

A New Approach to the Observation of the Resist in X‐ray Contact Microscopy

Photochem & Photobiology

Aoki

Yanagihara

et al. 1986

Self Cite

X‐ray microscopy is one of the useful applications of synchrotron radiation researches, and at present, X‐ray contact microscopy is the best developed method in this field. The images on the resist in X‐ray contact microscopy have been observed with a scanning electron microscope, and there have been some attempts to use the transmission electron microscope, but few have used the replica method. We have applied the replica method with plasma polymerization‐film to observe X‐ray images on the resist with a transmission electron microscope and found it to be applicable. A long exposure time is required when we use the monochromatic synchrotron radiation with a grasshopper monochromator. Our preliminary experiments with a new light source, undulator radiation, showed that it is very intense and useful for X‐ray contact microscopy.