lecture 24 slime molds
TRANSCRIPT
Plasmodial Slime Plasmodial Slime MoldsMolds
http://www.ucmp.berkeley.edu/chromista/chromistasy.html
Ribosomal RNA phylogenies place slime molds as unrelated, early branching eurkaryote lineages
Actin, elongation factor, and β-tubulin phylogenies place the plasmodial and cellular slime molds as a monophyletic group close to Animal + FungI
Baldauf and Doolittle, 1997. PNAS 94 (22): 12007-12012
ClassificationClassification
Mycetozoa = cellular, plasmodial slime Mycetozoa = cellular, plasmodial slime molds plus protostelidsmolds plus protostelids
Cellular slime molds and protostelids now Cellular slime molds and protostelids now placed in phylum Myxomycotaplaced in phylum Myxomycota
Names imply a fungal-like affinityNames imply a fungal-like affinity
MyxomycotaMyxomycota
Myxomycetes--5 orders, 13 families, 62 Myxomycetes--5 orders, 13 families, 62 genera, 800 speciesgenera, 800 species
Characterized by Characterized by plasmodiumplasmodium Engulfs bacteria, fungal spores, small pieces Engulfs bacteria, fungal spores, small pieces
of organic matterof organic matter
PhysarumPhysarum life cycle life cycle
macrocyst
karyogamy
meiosis
microcyst
Synchronous mitotic divisions
Stages in Life CycleStages in Life Cycle
Spores (2nSpores (2nn)n) 4-20 4-20 µmµm, pigmented , pigmented
ornamented; meiosis ornamented; meiosis in spore = 4 nuclei; 3 in spore = 4 nuclei; 3 degeneratedegenerate
Stages in Life CycleStages in Life Cycle
Myxamoebae (n)Myxamoebae (n) feed, divide, convert to feed, divide, convert to
swarm cells, function swarm cells, function as gametes; form as gametes; form microcysts under microcysts under adverse conditionsadverse conditions
www.uoguelph.ca/~gbarron/ MISCE2002/myxamo2.jpg
Stages in Life CycleStages in Life Cycle
Swarm cells (n)Swarm cells (n) 1-4 anterior whiplash 1-4 anterior whiplash
flagella, amoeboid flagella, amoeboid posterior; feed posterior; feed (absorption and (absorption and engulfment), function engulfment), function as gametesas gametes
can’t undergo cell can’t undergo cell divisiondivision
http://www.botany.hawaii.edu/faculty/wong/Bot201/Myxomycota/Swarm_Cells2.jpg
Stages in Life CycleStages in Life Cycle Zygote (2n)Zygote (2n)
Formed by fusion of myxamoebae or swarm Formed by fusion of myxamoebae or swarm cells; enlarges through synchronous nuclear cells; enlarges through synchronous nuclear divisiondivision
Plasmodium (2n)Plasmodium (2n) Multinucleate, wall-less protoplasmMultinucleate, wall-less protoplasm
Photo by Stephen Sharnoff
http://www.plant.uga.edu/mycology-herbarium/myxogal/Physros3.jpg
Stages in Life CycleStages in Life Cycle
Sporophore (2n)Sporophore (2n) Entire plasmodium is Entire plasmodium is
converted into converted into sporophore(s)sporophore(s)
Sclerotium or Sclerotium or macrocyst (2n)macrocyst (2n) Resistant stage Resistant stage
formed by plasmodiumformed by plasmodium
Types of plasmodiaTypes of plasmodia
PhaneroplasmodiumPhaneroplasmodium Conspicuous, often colored, with protoplasm Conspicuous, often colored, with protoplasm
forming veins with reversible streamingforming veins with reversible streaming AphanoplasmodiumAphanoplasmodium
With a network of fine, transparent threads With a network of fine, transparent threads and homogenous protoplasmand homogenous protoplasm
ProtoplasmodiumProtoplasmodium Microscopic, with homogenous protoplasm, Microscopic, with homogenous protoplasm,
giving rise to one sporophore giving rise to one sporophore
SporophoresSporophores
Mass of spores formed inside peridium, spores Mass of spores formed inside peridium, spores intermingled with:intermingled with: CapillitiumCapillitium
• threadlike, often ornamentedthreadlike, often ornamented ElatersElaters
• Threadlike, ornamented, not connected at endsThreadlike, ornamented, not connected at ends PseudocapillitiumPseudocapillitium
• Threads, bristles, membrane or platelike networkThreads, bristles, membrane or platelike network
Lime may be present on peridium, stalk, Lime may be present on peridium, stalk, columella or capillitium, or nodes of columella or capillitium, or nodes of pseudocapillitumpseudocapillitum
www.botany.hawaii.edu/.../Bot201/ Myxomycota/elaters.jpg
Capillitium (top left; photo by David Geiser)
Pseudocapillium (top right; photo from Fifth Kingdom)
Elaters (bottom left)
Sporocarp—stalked or sessileSporocarp—stalked or sessile
May have columella
AethaliumAethalium
Large, cushion-shaped Large, cushion-shaped sporophore, one per sporophore, one per plasmodiumplasmodium
PseudoaethaliumPseudoaethalium
Cluster of sporophores Cluster of sporophores grouped tightly grouped tightly togethertogether
Photo by David Geiser
PlasmodiocarpPlasmodiocarp
Sporophore developing Sporophore developing along veins of along veins of phaneroplasmodium; phaneroplasmodium; takes on reticulate takes on reticulate shape of veinsshape of veins
Photo by Stephen Sharnoff
Liceales-- Pale or brown spores, capillitium and lime absent, Liceales-- Pale or brown spores, capillitium and lime absent, pseudocapillitium may be presentpseudocapillitium may be present
Dictydium
Lycogala Photo by Stephen Sharnoff
Trichiales--Pale spores (yellow, orange or red) and abundant, Trichiales--Pale spores (yellow, orange or red) and abundant, conspicuous capillitium conspicuous capillitium
Trichia
Arcyria
Physarales--Purplish-brown spores, usually with abundant Physarales--Purplish-brown spores, usually with abundant and conspicuous lime on or in sporophoreand conspicuous lime on or in sporophore
Badhamia
FuligoLeocarpus
Stemonitales--Violet-brown spores, lime absentStemonitales--Violet-brown spores, lime absent
Diachea
Lamproderma
Stemonitis
Photo by Stephen Sharnoff
Ceratiomyxales--Exosporous sporophores; probably Ceratiomyxales--Exosporous sporophores; probably belongs in protostelids (one genus, belongs in protostelids (one genus, CeratiomyxaCeratiomyxa))
Photo by Stephen Sharnoff Photo by David Geiser
ProtostelidsProtostelids
Simplest known slime moldsSimplest known slime molds Discovered in 1970Discovered in 1970
Easily mistaken for mucoraceous fungi or Easily mistaken for mucoraceous fungi or deuteromycetesdeuteromycetes
In dead, attached plant parts, herbivore In dead, attached plant parts, herbivore dung or soil; feed on bacteria, yeast and dung or soil; feed on bacteria, yeast and fungal sporesfungal spores
14 genera and 32 species14 genera and 32 species
Protostelid Life CycleProtostelid Life Cycle
Amoeboid cells (filose pseudopodia) Amoeboid cells (filose pseudopodia) become one or more prespore cells that become one or more prespore cells that rise on stalk and encyst to form one to four rise on stalk and encyst to form one to four spores spores
Plasmodium and flagellated cells present Plasmodium and flagellated cells present in “complex” life cyclesin “complex” life cycles
Sexual reproduction not knownSexual reproduction not known
http://comp.uark.edu/~fspiegel/protist.html#sporocarp%20morphology
Life cycle of simple protostelid
http://comp.uark.edu/~fspiegel/protist.html#sporocarp%20morphology
Life cycle of complex protostelid
Images courtesy of Fred Spiegal, Univ. of Arkansas