Lecture 24 slime molds
- 1. Plasmodial Slime Molds
- 2. http://www.ucmp.berkeley.edu/chromista/chromistasy.html Ribosomal RNA phylogenies place slime molds as unrelated, early branching eurkaryote lineages
- 3. Baldauf and Doolittle, 1997. PNAS 94 (22): 12007-12012 Actin, elongation factor, and β-tubulin phylogenies place the plasmodial and cellular slime molds as a monophyletic group close to Animal + FungI
- 4. Classification Mycetozoa = cellular, plasmodial slime molds plus protostelids Cellular slime molds and protostelids now placed in phylum Myxomycota Names imply a fungal-like affinity
- 5. Myxomycota Myxomycetes--5 orders, 13 families, 62 genera, 800 species Characterized by plasmodium Engulfs bacteria, fungal spores, small pieces of organic matter
- 6. Physarum life cycle meiosis microcyst karyogamy Synchronous mitotic divisions macrocyst
- 7. Stages in Life Cycle Spores (2n n) 4-20 µm, pigmented ornamented; meiosis in spore = 4 nuclei; 3 degenerate
- 8. Stages in Life Cycle Myxamoebae (n) feed, divide, convert to swarm cells, function as gametes; form microcysts under adverse conditions www.uoguelph.ca/~gbarron/ MISCE2002/myxamo2.jpg
- 9. Stages in Life Cycle Swarm cells (n) 1-4 anterior whiplash flagella, amoeboid posterior; feed (absorption and engulfment), function as gametes can’t undergo cell division http://www.botany.hawaii.edu/faculty/wong/Bot201/Myxomycota/S warm_Cells2.jpg
- 10. Stages in Life Cycle Zygote (2n) Formed by fusion of myxamoebae or swarm cells; enlarges through synchronous nuclear division Plasmodium (2n) Multinucleate, wall-less protoplasm Photo by Stephen Sharnoff http://www.plant.uga.edu/mycology- herbarium/myxogal/Physros3.jpg
- 11. Stages in Life Cycle Sporophore (2n) Entire plasmodium is converted into sporophore(s) Sclerotium or macrocyst (2n) Resistant stage formed by plasmodium
- 12. Types of plasmodia Phaneroplasmodium Conspicuous, often colored, with protoplasm forming veins with reversible streaming Aphanoplasmodium With a network of fine, transparent threads and homogenous protoplasm Protoplasmodium Microscopic, with homogenous protoplasm, giving rise to one sporophore
- 13. Sporophores Mass of spores formed inside peridium, spores intermingled with: Capillitium • threadlike, often ornamented Elaters • Threadlike, ornamented, not connected at ends Pseudocapillitium • Threads, bristles, membrane or platelike network Lime may be present on peridium, stalk, columella or capillitium, or nodes of pseudocapillitum
- 14. Capillitium (top left; photo by David Geiser) Pseudocapillium (top right; photo from Fifth Kingdom) Elaters (bottom left) www.botany.hawaii.edu/.../Bot201/ Myxomycota/elaters.jpg
- 15. Sporocarp—stalked or sessile May have columella
- 16. Aethalium Large, cushion-shaped sporophore, one per plasmodium
- 17. Pseudoaethalium Cluster of sporophores grouped tightly together Photo by David Geiser
- 18. Plasmodiocarp Sporophore developing along veins of phaneroplasmodium; takes on reticulate shape of veins
- 19. Photo by Stephen Sharnoff
- 20. Liceales-- Pale or brown spores, capillitium and lime absent, pseudocapillitium may be present Dictydium Lycogala Photo by Stephen Sharnoff
- 21. Trichiales--Pale spores (yellow, orange or red) and abundant, conspicuous capillitium Trichia Arcyria
- 22. Physarales--Purplish-brown spores, usually with abundant and conspicuous lime on or in sporophore Badhamia Leocarpus Fuligo
- 23. Stemonitales--Violet-brown spores, lime absent Lamproderma Diachea
- 24. Photo by Stephen Sharnoff Stemonitis
- 25. Ceratiomyxales--Exosporous sporophores; probably belongs in protostelids (one genus, Ceratiomyxa) Photo by Stephen Sharnoff Photo by David Geiser
- 26. Protostelids Simplest known slime molds Discovered in 1970 Easily mistaken for mucoraceous fungi or deuteromycetes In dead, attached plant parts, herbivore dung or soil; feed on bacteria, yeast and fungal spores 14 genera and 32 species
- 27. Protostelid Life Cycle Amoeboid cells (filose pseudopodia) become one or more prespore cells that rise on stalk and encyst to form one to four spores Plasmodium and flagellated cells present in “complex” life cycles Sexual reproduction not known
- 28. Life cycle of simple protostelid http://comp.uark.edu/~fspiegel/protist.html#sporocarp%20morphology
- 29. Life cycle of complex protostelid http://comp.uark.edu/~fspiegel/protist.html#sporocarp%20morphology
- 30. Images courtesy of Fred Spiegal, Univ. of Arkansas
Editor's Notes
- #3: Illustrated tree of crown eukaryotes