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, N 2 fix, ferment, etc.) Growth = irreversible change in size Reproduction…failure = extinction Acclimatization-short term responses = behavior Adaptation-long term responses = evolution
Shifting Kingdoms Bacteria Archaebacteria Archezoans Euglenoids Chrysophytes Green Algae Brown Algae Red algae Slime Molds True Fungi Bryophytes Tracheophytes Protozoans Myxozoans Multicellular Animals Lumpers Splitters PlantaeFungiProtista
How Many Kingdoms? Multicellular Animals MyxozoansProtozoans Tracheophytes Bryophytes True Fungi Slime Molds Red algae Brown Algae Green Algae Chrysophytes EuglenoidsArchezoans Archaebacteria Bacteria Original Cell Extant Extinct Long Time with Prokaryotes only Protista appears Protista refined Still needs refining!
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.Myxogastrea (True slime molds: Physarum) 2.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
Physarum polycephalum True Slime Mold This portion of the plasmodium is showing the amoeboid movement of the cytoplasm. The plasmodium engulfs bacteria by endocytosis into food vacuoles for digestion Food Vacuoles Nuclei The plasmodium is multinucleate, and each nucleus is diploid (2N).
Physarum polycephalum True Slime Mold The plasmodium with all of those nuclei and food vacuoles, etc. shows amazingly active cytoplasmic streaming shown in this movie. The movement involves actin- myosin interactions between microfilaments of actin and myosin proteins bound to organelles. The movement relies upon Ca 2+ and ATP availability.
Physarum polycephalum True Slime Mold Looking at this sporangium, can you figure out how the specific epithet was inspired? Sporangium Sporangiophore Spores
Spore Zygote Gametes Physarum polycephalum True Slime Mold 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. Adults generally do not feed and live for only a few days. The larval stages are aquatic in some species or lawn soil dwelling in other species. adult eggs larva pupa adult
Life Cycle of Physarum polycephalum plasmodium sporangium cytokinesis SYNGAMY MEIOSIS zygote SporophyteGametophyte sporangium sporocyte spores gametangia gametes germination mitosis differentiation mitosis germination mitosis differentiation mitosis 1N 2N 4 meiospores myxamoebae isogametes swarm cells differentiation no cytokinesis asexual reproduction mitosis 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
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.
Dictyostelium discoideum Cellular Slime Mold The amoebae feed upon bacteria. OHO O O-O- O O O P N NH 2 N N N Adenine Ribose When the bacterial supply is gone, one amoeba produces cAMP. This signals others to join together to form a multicellular pseudoplasmodium (slug).
Dictyostelium discoideum Cellular Slime Mold The pseudoplasmodium moves on a slime trail seeking more bacteria. If bacteria are not found, the plasmodium differentiates into sporangiophore and sporangium.
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. If bacteria are not found, the plasmodium differentiates into sporangiophore and sporangium. The spores are shed to the wind to disperse the species.