VISUALIZATION OF CYTOSKELETAL ELEMENTS IN THE TRANSMISSION-X-RAY MICROSCOPE

Transmission X-ray microscopy has been used to study the arrangement o f cytoskeletal filaments in interphase PtK2 cells. Extraction of the s oluble proteins and of some organelles with the nonionic detergent Tri ton X-100 was important in obtaining sufficient image contrast between the insoluble cytoskeletal filaments and the surrounding cytoplasm. I f this step is not performed cytoskeletal filaments are not visualized and transmission X-ray micrographs of the cytoplasm instead show pred ominantly membrane-bound organelles such as vesicles and the endoplasm ic reticulum. Transmission X-ray micrographs of the cytoskeletal filam ents and endoplasmic reticulum in air-dried specimens, as well as in s pecimens examined in the wet state, can be directly compared with tran smission electron micrographs of cytoskeletons prepared in the same wa y. The profiles seen with the two techniques are similar, although, cu rrently, transmission X-ray micrographs have a limit of resolution of similar to 50 nm. Transmission X-ray micrographs appear to show some s ubstructure in interphase nuclei in cells fixed either with glutaralde hyde or by cryofixation and examined in a hydrated condition. (C) 1998 Academic Press.