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Mycetozoa Domain Eukarya Kingdom Protista Phylum Mycetozoa Looking Back at Bio 115 The Organism as a Unit of Life Cellular Structure (cell = unit of life)…one or many! Metabolism = Homeostasis (PSN, Resp, N2fix, ferment, etc.) Growth = irreversible change in size Reproduction…failure = extinction Acclimatization-short term responses = behavior Adaptation-long term responses = evolution Lumpers Shifting Kingdoms Plantae Fungi Protista Splitters 2 3 5 6 8 Bacteria Bacteria Bacteria Bacteria Bacteria Archaebacteria Archaebacteria Archaebacteria Archaebacteria Archaebacteria Archezoans Archezoans Archezoans Archezoans Archezoans Euglenoids Euglenoids Euglenoids Euglenoids Euglenoids Chrysophytes Chrysophytes Chrysophytes Chrysophytes Chrysophytes Green Algae Green Algae Green Algae Green Algae Green Algae Brown Algae Brown Algae Brown Algae Brown Algae Brown Algae Red algae Red algae Red algae Red algae Red algae Slime Molds Slime Molds Slime Molds Slime Molds Slime Molds True Fungi True Fungi True Fungi True Fungi True Fungi Bryophytes Bryophytes Bryophytes Bryophytes Bryophytes Tracheophytes Tracheophytes Tracheophytes Tracheophytes Tracheophytes Protozoans Protozoans Protozoans Protozoans Protozoans Myxozoans Myxozoans Myxozoans Myxozoans Myxozoans Multicellular Animals Multicellular Animals Multicellular Animals Multicellular Animals Multicellular Animals Extant How Many Kingdoms? Protista refined 8 Protista appears Still needs refining! 5 3 Extinct 2 1 Original Cell Mycetozoans • “True and Cellular Slime Molds” • Somewhere between protists and fungi Predatory amoeboid feeding upon bacteria, usually in decaying material Engulfing feeding Reproduction via spores • 500 species • Two Major Classes: 1. 2. Myxogastrea (True slime molds: Physarum) Dictyostelea (Cellular slime molds: Dictyostelium) Physarum polycephalum True Slime Mold Haploid (1N) spores germinate in rotting vegetation Flagellated gametes emerge and undergo syngamy Diploid (2N) zygote amoeboid cell feeds on bacteria Mitosis without cytokinesis makes multinucleate plasmodium Cytoplasm migrates by streaming Develops into fruiting body undergoing meiosis to make haploid spores http://botit.botany.wisc.edu:16080/images/332/Slime_molds_M_Ac_sl_so/Physarum_folder/Physarum_plasmodium_I_TJV.gif Physarum polycephalum True Slime Mold Food Vacuoles Nuclei http://bic.usuf1.usuhs.mil/Mark/Images/OgiharaEM01.jpg This portion of the plasmodium is showing the amoeboid movement of the cytoplasm. The plasmodium engulfs bacteria by endocytosis into food vacuoles for digestion The plasmodium is multinucleate, and each nucleus is diploid (2N). Physarum polycephalum True Slime Mold QuickTime™ and a Photo - JPEG decompressor are needed to see this picture. The plasmodium with all of those nuclei and food vacuoles, etc. shows amazingly active cytoplasmic streaming shown in this movie. The movement involves actinmyosin interactions between microfilaments of actin and myosin proteins bound to organelles. The movement relies upon Ca2+ and ATP availability. http://botit.botany.wisc.edu/courses/img/Botany_130/Movies/Slime_mold.mov Physarum polycephalum True Slime Mold Looking at this sporangium, can you figure out how the specific epithet was inspired? Sporangium Sporangiophore Spores http://www.botany.hawaii.edu/faculty/wong/Bot201/Myxomycota/Physarum_Sporangium.jpg http://www.bioimages.org.uk/MMWSt/PixM.7xs/2000/00-10/00-10-17/00J17E+E.jpg Physarum polycephalum True Slime Mold Spore Zygote Gametes http://www2.una.edu/pdavis/physamb.jpg The spores germinate, releasing flagellated gametes. The gametes unite in syngamy. The resulting zygote is amoeboid and begins feeding. Mitoses without cytokinesis enlarges the multinucleate zygote into a full plasmodium. Tipula oleraceae or T. paludosa Adults resemble mosquitoes because they are indeed relatives. adult Adults generally do not feed and live for only a few days. eggs The larval stages are aquatic in some species or lawn soil dwelling in other species. adult larva pupa http://whatcom.wsu.edu/cranefly/faq.htm Life Cycle of Physarum polycephalum isogametes swarm cells mitosis gametes zygote gametangia differentiation asexual reproduction mitosis plasmodium SYNGAMY Gametophyte differentiation mitosis germination 1N 2N germination mitosis no cytokinesis differentiation Sporophyte differentiation sporangium spores mitosis sporocyte MEIOSIS myxamoebae 4 meiospores This is basically the gametic shortcut… spores become gametes… if the mitosis of myxamoebae is not considered equivalent to the production of a multicellular gametophyte. sporocyte cytokinesis sporangium Dictyostelium discoideum Cellular Slime Mold This is the spore produced by the sporangium. Actin rods extend the length of the spore. It is released into the wind and carried to hopefully-better environments. There it germinates to produce amoebae. http://www.rinshoken.or.jp/org/EM/spore.jpg Dictyostelium discoideum Cellular Slime Mold The amoebae feed upon bacteria. When the bacterial supply is gone, one amoeba produces cAMP. This signals others to join together to form a multicellular pseudoplasmodium (“slug”). http://www.nigms.nih.gov/research/images/dicty.jpg Adenine NH2 N OO P O O O O N N N Ribose OH http://dicty.cmb.nwu.edu/chisholm/chisho2.jpg http://www.biologie.uni-hamburg.de/b-online/d27_10/agg290.jpg Dictyostelium discoideum Cellular Slime Mold http://www.axxon.com.ar/zap/208/MohoMucoso.jpg The pseudoplasmodium moves on a slime trail seeking more bacteria. If bacteria are not found, the plasmodium differentiates into sporangiophore and sporangium. http://csep10.phys.utk.edu/krogh_instructorCD/biology/ImageBank/Unlabeled/CH20/uFG20_10.jpg Dictyostelium discoideum Cellular Slime Mold The amoebae feed upon bacteria. When the bacterial supply is gone, one amoeba produces cAMP, signalling the others to join together to form a multicellular pseudoplasmodium (“slug”). The slug moves on a slime trail seeking more bacteria. http://www.bio.ic.ac.uk/research/tps/images/fig4.gif If bacteria are not found, the plasmodium differentiates into sporangiophore and sporangium. The spores are shed to the wind to disperse the species.
