https://3demmethods.i2pc.es/index.php?action=history&feed=atom&title=2004Leapman_EnergyLoss 2026-05-24T20:40:46Z Revision history for this page on the wiki MediaWiki 1.44.2 https://3demmethods.i2pc.es/index.php?title=2004Leapman_EnergyLoss&diff=1835&oldid=prev 2009-04-30T06:31:27Z

<p></p> <p><b>New page</b></p><div>== Citation ==<br /> <br /> Leapman RD, Kocsis E, Zhang G, Talbot TL, Laquerriere P (2004)<br /> Three-dimensional distributions of elements in biological samples<br /> by energy-Wltered electron tomography. Ultramicroscopy<br /> 100:115–125<br /> <br /> [http://scholar.google.es/scholar?hl=en&amp;lr=&amp;cites=612488479537165351 Cited by]<br /> <br /> == Abstract ==<br /> <br /> By combining electron tomography with energy-filtered electron microscopy, we have shown the feasibility of determining the three-dimensional distributions of phosphorus in biological specimens. Thin sections of the nematode, Caenorhabditis elegans were prepared by high-pressure freezing, freeze-substitution and plastic embedding. Images were recorded at energy losses above and below the phosphorus L2,3 edge using a post-column imaging filter operating at a beam energy of 120 keV. The unstained specimens exhibited minimal contrast in bright-field images. After it was determined that the specimen was sufficiently thin to allow two-window ratio imaging of phosphorus, pairs of pre-edge and post-edge images were acquired in series over a tilt range of +/-55 degrees at 5 degrees increments for two orthogonal tilt axes. The projected phosphorus distributions were aligned using the pre-edge images that contained inelastic contrast from colloidal gold particles deposited on the specimen surface. A reconstruction and surface rendering of the phosphorus distribution clearly revealed features 15-20 nm in diameter, which were identified as ribosomes distributed along the stacked membranes of endoplasmic reticulum and in the cytoplasm. The sensitivity of the technique was estimated at &lt; 35 phosphorus atoms per voxel based on the known total ribosomal phosphorus content of approximately 7000 atoms. Although a high electron dose of approximately 10(7)e/nm2 was required to record two-axis tilt series, specimens were sufficiently stable to allow image alignment and tomographic reconstruction.<br /> <br /> == Keywords ==<br /> <br /> Chemical mapping, energy loss<br /> <br /> == Links ==<br /> <br /> Article http://www.ncbi.nlm.nih.gov/pubmed/15219696<br /> <br /> == Related software ==<br /> <br /> == Related methods ==<br /> <br /> == Comments ==</div>

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