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Negative stain
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<h2 id="bright-field-microscopy">Bright field microscopy</h2> <p class="note">Main article: <a href="/facts/Bright-field_microscopy/pWu3Dqkr">Bright-field microscopy</a></p> <p>For <a href="/facts/Bright-field_microscopy/pWu3Dqkr">bright-field microscopy</a>, negative staining is typically performed using a black ink fluid such as <a href="/facts/Nigrosin/CdEWDFlB">nigrosin</a> and <a href="/facts/India_ink/2XDG4WMh">India ink</a>. The specimen, such as a wet <a href="/facts/Bacteria/wC8xSCsU">bacterial</a> culture spread on a glass slide, is mixed with the negative stain and allowed to dry. When viewed with the <a href="/facts/Microscope/ldJp0CI3">microscope</a> the bacterial cells, and perhaps their <a href="/facts/Spore/6qDRdcrs">spores</a>, appear light against the dark surrounding background. An alternative method has been developed using an ordinary waterproof marking pen to deliver the negative stain.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> </p> <h2 id="transmission-electron-microscopy">Transmission electron microscopy</h2> <p class="note">Main article: <a href="/facts/Transmission_electron_microscopy/Rpr8jpCn">Transmission electron microscopy</a></p> <p>In the case of <a href="/facts/Transmission_electron_microscopy/Rpr8jpCn">transmission electron microscopy</a>, opaqueness to <a href="/facts/Electron/L0KBo5cW">electrons</a> is related to the <a href="/facts/Atomic_number/bgAr581S">atomic number</a>, i.e., the number of protons. Some suitable negative stains include <a href="/facts/Ammonium_molybdate/cN9qnHkp">ammonium molybdate</a>, <a href="/facts/Uranyl_acetate/a7RXsw2p">uranyl acetate</a>, <a href="/facts/Uranyl_formate/5Y2RyVCG">uranyl formate</a>, <a href="/facts/Phosphotungstic_acid/dge1T9Gj">phosphotungstic acid</a>, <a href="/facts/Osmium_tetroxide/cxmYVnFK">osmium tetroxide</a>, osmium ferricyanide<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> and auroglucothionate. These have been chosen because they scatter electrons strongly and also adsorb to biological matter well. The structures which can be negatively stained are much smaller than those studied with the light microscope. Here, the method is used to view <a href="/facts/Virus/mf88Bcbl">viruses</a>, bacteria, bacterial <a href="/facts/Flagella/nvQRcbgJ">flagella</a>, <a href="/facts/Biological_membrane/ljBsfK4r">biological membrane</a> structures and <a href="/facts/Protein/Jxmagu3E">proteins</a> or protein aggregates, which all have a low electron-scattering power. Some stains, such as osmium tetroxide and osmium ferricyanide, are very chemically active. As strong oxidants, they cross-link lipids mainly by reacting with unsaturated carbon-carbon bonds, and thereby both fix biological membranes in place in tissue samples and simultaneously stain them.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a><a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p><p>The choice of negative stain in <a href="/facts/Electron_microscopy/XtaBktwF">electron microscopy</a> can be very important. An early study of plant viruses using negatively stained leaf dips from a diseased plant showed only spherical viruses with one stain and only rod-shaped viruses with another. The verified conclusion was that this plant suffered from a mixed infection by two separate viruses. Negative staining at both light microscope and electron microscope level should never be performed with <a href="/facts/Infection/182XrncP">infectious</a> organisms unless stringent safety precautions are followed. Negative staining is usually a very mild preparation method and thus does not reduce the possibility of operator infection. </p> <h2 id="other-applications">Other applications</h2> <p>Negative staining transmission electron microscopy has also been successfully employed for study and identification of aqueous lipid aggregates like <a href="/facts/Lamellar/GtQ7hVIA">lamellar</a> <a href="/facts/Liposome/l9P4LVbS">liposomes</a> (le), inverted spherical <a href="/facts/Micelle/eMG9whea">micelles</a> (M) and inverted <a href="/facts/Hexagonal/DPzuCzWE">hexagonal</a> HII cylindrical (H) phases (see figure).<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> </p> <h2 id="external-links">External links</h2> <ul><li><a href="http://www.snaggledworks.com/em_for_dummies/negative_stain.html">"Negative staining for dummies"</a>. Retrieved 2009-06-06.</li> <li><a href="https://archive.today/20121225080122/http://web.uct.ac.za/depts/mmi/stannard/negstain.html">"Negative staining"</a>. Archived from <a href="http://web.uct.ac.za/depts/mmi/stannard/negstain.html">the original</a> on 2012-12-25. Retrieved 2009-06-06.</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Woeste, S; Demchick, P (1991). "New version of the negative stain". Applied and Environmental Microbiology. 57 (6). American Society for Microbiology: 1858–1859. doi:10.1128/aem.57.6.1858-1859.1991. ISSN 0099-2240. PMC 183484. PMID 1714705. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC183484" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC183484</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>D. Chadwick (2002). Role of the sarcoplasmic reticulum in smooth muscle. John Wiley and Sons. pp. 259–264. ISBN 0-470-84479-5. <a href="0-470-84479-5" target="_blank">0-470-84479-5</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Bozzola, John J.; Russell, Lonnie D. (1999). "Specimen Preparation for Transmission Electron Microscopy". Electron microscopy : principles and techniques for biologists. Sudbury, Mass.: Jones and Bartlett. pp. 21–31. ISBN 978-0-7637-0192-5. <a href="978-0-7637-0192-5" target="_blank">978-0-7637-0192-5</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>M. A. Hayat (2000). Principles and techniques of electron microscopy: biological applications. Cambridge University Press. pp. 45–61. ISBN 0-521-63287-0. <a href="0-521-63287-0" target="_blank">0-521-63287-0</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Yashroy, R. C. (1990). "Lamellar dispersion and phase separation of chloroplast membrane lipids by negative staining electron microscopy". Journal of Biosciences. 15 (2). Springer Science and Business Media LLC: 93–98. doi:10.1007/bf02703373. ISSN 0250-5991. S2CID 39712301. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> </ol>