Application of x-rays to the analysis of DNA packaging in mammalian sperm.
X-ray microscopy has been performed on unlabeled and gold labeled rat sperm nuclei using a tantalum x-ray laser (44.83 angstrom) and an x-ray zone plate lens. Transmission images of nuclei labeled with gold using an antibody to protamine 1 show large clusters of gold as well as individual 400 angstrom gold particles coating the surface of the chromatin. Images of the same nuclei obtained with a scanning x-ray microscope demonstrate that the initial exposure of the sperm nucleus to a photon intensity of 3.0 X 10{sup 14} W/cm{sup 2} for a duration of 500 ps did not destroy or grossly distort their structure. Other nuclei labeled with an antibody to protamine 2 were partially decondensed during the labeling process and contained large vacuole-like regions. Images were also obtained of unlabeled sperm nuclei. Data obtained from one unlabeled nucleus imaged with both the atomic force and x-ray laser microscopes was used to determine the thickness of the chromatin and estimate the amount of water that must be associated with the DNA-protamine complex in air-dried nuclei. These results suggest that even air-dried sperm nuclei are extensively hydrated and that tightly bound water may comprise as much as one-third of the volume of the dried sperm nucleus.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 925205
- Report Number(s):
- ANL/XFD/CP-114650; TRN: US200807%%256
- Resource Relation:
- Conference: SPIE's 1992 International Symposium on Optical Applied Science and Engineering; Jul 19-21, 1992; San Diego, CA
- Country of Publication:
- United States
- Language:
- ENGLISH
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