Fuligo septica

Fuligo septica is a species of plasmodial slime mold, and a member of the class Myxomycetes. It is commonly known as the scrambled egg slime, or flowers of tan[2] because of its peculiar yellowish, bile-colored appearance. Also known as the dog vomit slime mold, it is common with a worldwide distribution, and it is often found on bark mulch in urban areas after heavy rain or excessive watering. Their spores are produced on or in aerial sporangia and are spread by wind.

Dog vomit slime mold
Fuligo septica with white and yellow tissue
Scientific classification
Domain: Eukaryota
Phylum: Amoebozoa
Class: Myxogastria
Order: Physarales
Family: Physaraceae
Genus: Fuligo
Species:
F. septica
Binomial name
Fuligo septica
(L.) F.H.Wigg (1780)
Synonyms[1]
  • Mucor septicus L. (1763)
  • Reticularia septica (L.) With. (1792)
  • Aethalium septicum (L.) Fr. (1829)

History and taxonomy

The first description of the species was provided by French botanist Jean Marchant in 1727, who referred to it as "fleur de tan" (bark flower); Marchant also classified it as "des éponges" (one of the sponges).[3] Carl Linnaeus called it Mucor septicus in his 1763 Species Plantarum.[4] The species was transferred to the genus Fuligo by German botanist Friedrich Heinrich Wiggers in 1780.[5]

Description and habitat
Close-up of the yellow aethelia

Like many slime molds, the cells of this species typically aggregate to form a plasmodium, a multinucleate mass of undifferentiated cells that may move in an ameboid-like fashion during the search for nutrients. F. septica's plasmodium may be anywhere from white to yellow-gray,[6] typically 2.5–20 cm (1.0–7.9 in) in diameter, and 1–3 cm (0.4–1.2 in) thick.[7] The plasmodium eventually transforms into a sponge-like aethalium, analogous to the spore-bearing fruiting body of a mushroom; which then degrades, darkening in color, and releases its dark-colored spores. F. septica produces the largest aethalium of any slime mold.[8] This species is known to have its spores dispersed by beetles (family Latridiidae).[9]

The spores have a two-layered wall, with a dense outer layer with spines, and a fibrous inner layer. During germination, the outer layer splits to create an opening, and more elastic inner layer ruptures later as protoplasm emerges. A remnant of the inner layer may be persistent and adhere to the protoplast after it has emerged from the spore. A peroxidase enzyme present in the inner cell wall plays a role in germination.[10]

Fuligo septica grows on rotten wood and plant debris, but can also grow on the leaves and stems of living plants.[11]

Resistance to metal toxicity

Slime molds have a high resistance to toxic levels of metals; one author was prompted to write "The levels of Zn in Fuligo septica were so high (4,000–20,000 ppm) that it is difficult to understand how a living organism can tolerate them."[12] The resistance to extreme levels of zinc appears to be unique to F. septica.[13] The mechanism of this metal resistance is now understood: F. septica produces a yellow pigment called fuligorubin A, which has been shown to chelate metals and convert them to inactive forms.[14]

Bioactive compounds

Extracts from F. septica show antibiotic activity against Bacillus subtilis and Candida albicans, and cytotoxic activity on KB cells (a cell line derived from a human carcinoma of the nasopharynx).[15]

Fuligo septica contains a yellow pigment called fuligorubin A that is thought to be involved in photoreception and in the process of energy conversion during its life cycle.[16] In 2011 a Japanese research group reported isolating and characterizing a new chlorine-containing yellow pigment from a specific strain of the organism that they called dehydrofuligoic acid.[17]

Relationship to humans

Folklore

In Scandinavian folklore, Fuligo septica is identified as the vomit of troll cats.[18]

In Finland, F. septica was believed to be used by witches to spoil their neighbors' milk. This gives it the name paranvoi, meaning "butter of the familiar spirit".[8][19] In Dutch, "heksenboter" refers to "witches' butter". In Latvian, the slime mold (amongst other slime molds) is called "ragansviests" as "witches' butter" or "raganu spļāviens" as "witches' spit" but it is unclear about the origins of these names.

Human pathogenicity

This species is known to trigger episodes of asthma and allergic rhinitis in susceptible people.[20][21]

Model of RNA processing

Introns are sections of DNA that must be properly cleaved, digested and processed prior to rendering functional mRNAs for protein synthesis. Because it has a large number of group I introns, F. septica is used as a model to understand the processing and evolution of RNA.[22][23]

References
  1. "Fuligo septica (L.) F.H. Wigg. 1780". MycoBank. International Mycological Association. Retrieved 2011-03-25.
  2. Young, A.M. (2005). A Field Guide to the Fungi of Australia. University of New South Wales Press Ltd. ISBN 9780868407425.
  3. Ainsworth GC (1976). Introduction to the History of Mycology. Cambridge, UK: Cambridge University Press. p. 60. ISBN 0-521-21013-5.
  4. Linnaeus C. (1763). Species Plantarum (2nd ed.). Stockholm: Impensis Direct. Laurentii Salvii. p. 1656.
  5. Wiggers FH, Weber GH (1780). Primitiae Florae Holsaticae (in Latin). Litteris Mich. Frider. Bartschii Acad. Typogr. p. 112.
  6. Kambly PE (1939). "The color of myxomycete plasmodia". Botany. 26 (6): 386–90. doi:10.2307/2436838. JSTOR 2436838.
  7. Emberger G. (2008). "Fuligo septica". Fungi on Wood. Retrieved 2008-12-08.
  8. the BayScience Foundation, Inc. (2012). "Fuligo (Genus)". zipcodezoo.com. Retrieved 2012-05-13.
  9. Blackwell M, Laman TG (1982). "Spore dispersal of Fuligo septica (Myxomycetes) by Lathridiid beetles". Mycotaxon. 14 (1): 58–60.
  10. Stempen H, Evans RC (1982). "Behavior of the inner wall layer of the germinating Fuligo septica spore: evidence of peroxidase activity". Mycologia. 74 (1): 26–35. doi:10.2307/3792625. JSTOR 3792625.
  11. Healy RA; Huffman DR; Tiffany LH; Knaphaus G (2008). Mushrooms and Other Fungi of the Midcontinental United States (Bur Oak Guide). Iowa City, Iowa: University of Iowa Press. p. 340. ISBN 1-58729-627-6.
  12. Setala A, Nuorteva P (1989). "High metal contents found in Fuligo septica L. Wiggers and some other slime molds (Myxomycetes)". Karstenia. 29 (1): 37–44.
  13. Zhulidov DA, Robarts RD, Zhulidov AV, Zhulidova OV, Markelov DA, Rusanov VA, Headley JV (2002). "Zinc accumulation by the slime mold Fuligo septica (L.) Wiggers in the former Soviet Union and North Korea". Journal of Environmental Quality. 31 (3): 1038–42. doi:10.2134/jeq2002.1038. PMID 12026071.
  14. Latowski D, Lesiak A, Jarosz-Krzeminska E, Strzalka K (2008). "Fuligo septica, as a new model organism in studies on interaction between metal ions and living cells". Metal Ions in Biology and Medicine and Medicine. 10: 204–9.
  15. Pereira EC; Cavalcanti LDH; Campos-Takaki GMD; Nascimento; Silene CD (1992). "Antibiotic and cytotoxic activities of crude extracts from Fuligo septica (L.) Wigg. and Tubifera microsperma (Berk. and Curt.) Martin (Myxomycetes)". Revista de Ciencias Biomedicas (13): 23–32.
  16. Rahman A. (1988). Studies in Natural Products Chemistry. Amsterdam: Elsevier. pp. 237–8. ISBN 0-444-51510-0.
  17. Shintani A, Toume K, Yamamoto Y, Ishibashi M (2010). "Dehydrofuligoic acid, a new yellow pigment isolated from the myxomycete Fuligo septica f. flava". Heterocycles. 82 (1): 839–42. doi:10.3987/com-10-s(e)18. ISSN 0385-5414.
  18. Kvideland, Reimund; Sehmsdorf, Henning K. (1988). "39. Troll Cat". Scandinavian Folk Belief and Legend. Minneapolis: U of Minnesota P. pp. 175–79. ISBN 0816619670.
  19. Discover Life (2012). "Fuligo". discoverlife.org. Retrieved 2012-05-13.
  20. Santili J, Rockwell WJ, Collins RP (1895). "The significance of the spore of the Basidiomycetes (mushrooms and their allies) in bronchial asthma and allergenic rhinitis". Annals of Allergy. 55 (3): 469–71. PMID 4037433.
  21. Gianini EH, Northy WT, Leathers CR (1975). "The allergenic significance of certain fungi rarely reported as allergens". Annals of Allergy. 35 (6): 372–6. PMID 1239229.
  22. Lundblad EW, Einvik C, Rønning S, Haugli K, Johansen S (2004). "Twelve Group I introns in the same pre-rRNA transcript of the myxomycete Fuligo septica: RNA processing and evolution". Molecular Biology and Evolution. 21 (7): 1283–93. doi:10.1093/molbev/msh126. PMID 15034133.
  23. Haugen P, Coucheron DH, Rønning SB, Haugli K, Johansen S (2003). "The molecular evolution and structural organization of self-splicing group I introns at position 516 in nuclear SSU rDNA of myxomycetes". Journal of Eukaryotic Microbiology. 50 (4): 283–92. doi:10.1111/j.1550-7408.2003.tb00135.x. PMID 15132172.
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