Editing Slime mold (section)

=== Plasmodial slime molds ===

[[File:Physarum polycephalum strain LU352 - 4.jpg|thumb|Long strands of ''[[Physarum polycephalum]]'' streaming along as it forms a [[plasmodium (life cycle)|plasmodium]] with many nuclei without individual cell membranes ]]

Plasmodial slime molds begin life as [[amoeba]]-like [[cell (biology)|cells]]. These unicellular amoebae are commonly [[haploid]] and feed on small prey such as [[bacteria]], yeast cells, and fungal spores by [[phagocytosis]], engulfing them with its [[cell membrane]]. These amoebae can mate if they encounter the correct [[mating type]] and form [[zygote]]s that then grow into [[plasmodium (life cycle)|plasmodia]]. These contain many [[cell nucleus|nuclei]] without [[cell membranes]] between them, and can grow to meters in size. The species ''[[Fuligo septica]]'' is often seen as a slimy yellow network in and on rotting logs. The amoebae and the plasmodia engulf microorganisms.<ref name="Ling">{{cite web|url=http://npsnj.org/articles/myxomycetes.html |archive-url=https://web.archive.org/web/20150609104451/http://npsnj.org/articles/myxomycetes.html |archive-date=9 June 2015 |last=Ling |first=H. |date=2012 |title=Myxomycetes: Overlooked Native Plants |work=The Native Plant Society of New Jersey|access-date=29 May 2018}}</ref> The plasmodium grows into an interconnected network of protoplasmic strands.<ref>{{Cite web|url=http://www.hup.harvard.edu/catalog.php?isbn=978-0-674-97591-0 |title=Life at the Edge of Sight |last1=Chimileski |first1=Scott |last2=Kolter |first2=Roberto |publisher=Harvard University Press |website=www.hup.harvard.edu |access-date=2018-01-26 |archive-date=October 19, 2023 |archive-url=https://web.archive.org/web/20231019151352/http://www.hup.harvard.edu/catalog.php?isbn=978-0-674-97591-0}}</ref> Within each protoplasmic strand, the cytoplasmic contents rapidly stream, periodically reversing direction. The streaming protoplasm within a plasmodial strand can reach speeds of up to 1.35&nbsp;mm per second in ''Physarum polycephalum'', the fastest for any microorganism.<ref>{{cite book |last=Alexopoulos |first=C.J. |date=1962 |edition=Second |title=Introductory Mycology |location=New York, N.Y. |publisher=John Wiley and Sons |page=78 |url=https://archive.org/details/dli.ernet.286173}}</ref>

[[File:Plasmodial slime mold life cycle English.png|thumb|upright=1.75|Life cycle of a plasmodial slime mold. Haploid gametes undergo sexual fusion to form a diploid cell. Its nucleus divides (but the cell does not) to form a multinucleate plasmodium. [[Meiosis]] halves the number of [[chromosome]]s to form haploid cells with just one nucleus.<ref name="Dee 1960">{{Cite journal |last=Dee |first=Jennifer |date=1960 |title=A Mating-type System in an Acellular Slime-mould |journal=Nature |volume=185 |issue=4715 |pages=780–781 |doi=10.1038/185780a0 |bibcode=1960Natur.185..780D |s2cid=4206149}}</ref>]]

Slime molds are [[Isogamy|isogamous]], which means that their [[gamete]]s (reproductive cells) are all the same size, unlike the eggs and sperms of animals.<ref name="Moskvitch-2018">{{Cite web |url=https://www.quantamagazine.org/slime-molds-remember-but-do-they-learn-20180709/ |title=Slime Molds Remember – but Do They Learn? |last=Moskvitch |first=Katia |website=Quanta Magazine |date=9 July 2018 |access-date=2019-11-02}}</ref> ''[[Physarum polycephalum]]'' has three [[gene]]s involved in reproduction: ''mat''A and ''mat''B, with thirteen variants each, and ''mat''C with three variants. Each reproductively mature slime mold is [[diploid]], meaning that it contains two copies of each of the three reproductive genes.<ref name="Judson-2002">{{Cite book |last=Judson |first=Olivia |title=Dr. Tatiana's Sex Advice To All Creation |publisher=Henry Holt and Company |year=2002 |isbn=978-0-8050-6332-5 |location=New York |pages=187–193}}</ref> When ''P.&nbsp;polycephalum'' is ready to make its reproductive cells, it grows a bulbous extension of its body to contain them.<ref name="Renner-2006">{{Cite web |url=http://bioweb.uwlax.edu/bio203/2010/renner_brad/reproduction.htm |last=Renner |first=B. |date=2006 |title=Slime Mold Reproduction |work=BioWeb |publisher=University of Wisconsin System |access-date=2019-11-02 |archive-date=November 2, 2019 |archive-url=https://web.archive.org/web/20191102001509/http://bioweb.uwlax.edu/bio203/2010/renner_brad/reproduction.htm}}</ref> Each cell has a random combination of the genes that the slime mold contains within its [[genome]]. Therefore, it can create cells of up to eight different gene types. Released cells then independently seek another compatible cell for fusion. Other individuals of ''P. polycephalum'' may contain different combinations of the ''mat''A, ''mat''B, and ''mat''C genes, allowing over 500 possible variations. It is advantageous for organisms with this type of reproductive cell to have many mating types because the likelihood of the cells finding a partner is greatly increased, and the risk of [[inbreeding]] is drastically reduced.<ref name="Judson-2002" />