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Clamp connection
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<h2 id="formation">Formation</h2> <p>Clamp connections are formed by the terminal hypha during elongation. Before the clamp connection is formed this terminal segment contains two nuclei. Once the terminal segment is long enough it begins to form the clamp connection. At the same time, each nucleus undergoes <a href="/facts/Mitotic_division/ExxrSUs8">mitotic division</a> to produce two daughter nuclei. As the clamp continues to develop it uptakes one of the daughter (green circle) nuclei and separates it from its sister nucleus. While this is occurring the remaining nuclei (orange circles) begin to migrate from one another to opposite ends of the cell. Once all these steps have occurred a <a href="/facts/Hypha/xogd3AHz">septum</a> forms, separating each set of nuclei.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> </p> <h2 id="use-in-classification">Use in classification</h2> <p>Clamp connections are structures unique to the phylum <a href="/facts/Basidiomycota/LuFeC7D2">Basidiomycota</a>. Many fungi from this phylum produce spores in <a href="/facts/Basidiocarp/xgaQV94l">basidiocarps</a> (fruiting bodies, or mushrooms), above ground. Though clamp connections are exclusive to this phylum, not all species of Basidiomycota possess these structures. As such, the presence or absences of clamp connections has been a tool in categorizing <a href="/facts/Genera/m8EFjSms">genera</a> and <a href="/facts/Species/oDg6b96r">species</a>.<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> <h2 id="fossil-record">Fossil record</h2> <p>A fungal mycelium containing abundant clamp connections was found that dated to the <a href="/facts/Pennsylvanian_(geology)/Fc1LAJSX">Pennsylvanian</a> era (298.9–323.2 <a href="/facts/Mya_(unit)/DXcnXuAw">Mya</a>). This fossil, classified in the <a href="/facts/Form_genus/9kauURYH">form genus</a> <i>Palaeancistrus</i>, has hyphae that compare with extant <a href="/facts/Saprophyte/sJkDfrJW">saprophytic</a> basidiomycetes.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> The oldest known clamp connections exist in fossilized hyphae growing in the fossil fern <i>Botryopteris antiqua</i>, which predate <i>Palaeancistrus</i> by about 25 <a href="/facts/Megaannum/51V242hh">Ma</a>.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>C.J. Alexopolous, Charles W. Mims, M. Blackwell et al., Introductory Mycology, 4th ed. (John Wiley and Sons, Hoboken NJ, 1996) ISBN 0-471-52229-5 <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"Clamp Connection Formation". hawaii.edu. <a href="http://www.botany.hawaii.edu/faculty/wong/Bot201/Basidiomycota/Clamp_connection_formation.htm" target="_blank">http://www.botany.hawaii.edu/faculty/wong/Bot201/Basidiomycota/Clamp_connection_formation.htm</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Kuo M. "Using a Microscope: Clamp Connections". MushroomExpert.Com. Retrieved 2010-12-15. <a href="http://www.mushroomexpert.com/microscope_clamps.html" target="_blank">http://www.mushroomexpert.com/microscope_clamps.html</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Furtado, João S. (1966). "Significance of the clamp-connection in the basidiomycetes". Persoonia. 4 (1): 125–144. <a href="http://www.repository.naturalis.nl/document/570025" target="_blank">http://www.repository.naturalis.nl/document/570025</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Dennis, Robert L. (1970). "A middle Pennsylvanian basidiomycete mycelium with clamp connections". Mycologia. 62 (3): 578–584. doi:10.2307/3757529. JSTOR 3757529. <a href="http://www.cybertruffle.org.uk/cyberliber/59350/0062/003/0578.htm" target="_blank">http://www.cybertruffle.org.uk/cyberliber/59350/0062/003/0578.htm</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Krings, Michael; Dotzler, Nora; Galtier, Jean; Taylor, Thomas N. (2011). "Oldest fossil basidiomycete clamp connections". Mycoscience. 52 (1): 18–23. doi:10.1007/s10267-010-0065-4. hdl:1808/13681. S2CID 86132001. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> </ol>