May 26 Please submit a question about your presentation Division: Cyanobacteria to me electronically. blue-green algae May 28, June 2 & 4 -Student Presentations Powerpoint Presentation 7-9 minutes. Both people must speak during the presentation. Intro, Material & Methods, Results & Discussion May 29Turn in herbarium early- 10 points extra credit Mastocarpus papillatus species complex (C. Agardh) Lindstrom Ulotricales/Ulvales-3 June 4/5- Lab practical, Notebooks & pressings due! June 11- Final 8:00-11:00am Single class: Cyanophyceae ~4,484 species 1 2 Algal Evolution: DOMAIN Groups (Kingdom) 1.Bacteria- cyanobacteria (blue green algae) 3.9 bya = Cyanobacteria appear and introduce photosynthesis 2.Archae 3.Eukaryotes 1. Alveolates- dinoflagellates 2.5 bya = Eukaryotes appeared (nuclear envelope and ER thought to come from invagination of plasma membrane) 2. Stramenopiles- diatoms, heterokonyophyta 1.6 bya = Multicellular algae -Rhodophyta (Red algae) &Chlorophyta 3. Rhizaria- unicellular amoeboids (Green algae) 4. Excavates- unicellular flagellates 900 mya= Dinoflagellates & Invertebrates appear 5. Plantae- rhodophyta, chlorophyta, seagrasses 490 mya = Phaeophyceae (Brown algae) & land plants & coralline algae & 6. Amoebozoans- slimemolds crustaceans & mulluscs 7. Fungi- heterotrophs with extracellular digestion 408mya= Insects & Fish 8. Choanoflagellates- unicellular 362 mya = Coccolithophores & Amphibians & Reptiles 9. Animals- multicellular heterotrophs 290mya- Gymnosperms 4 145 mya = Diatoms & Angiosperms 1 Domain Bacteria- unicellular, lacking a nucleus, ribosomes, tRNA, peptoglycan in the cell wall Cyanobacteria are important because: Phylum Low-GC Gram-positive- staph infections & antrax Phylum High GC- Gram-positive- tuberculosis & antibiotics • Cyanobacteria are modern representatives of the very Phylum Hyperthermophilic bacteria- live at high temperatures Phylum Hadobacteria-live at high temps, consume nuclear waste first photosynthetic organisms on Earth. Phylum Cyanobacteria- blue green algae, origin of the chloroplast Phylum Spirochetes- syphilis & lime disease •First organisms to have 2 photosystems and to produce Phylum Chlamydias- intercellular parasites orggganic material and to give off O2 as a biproduct. Phylum Proteobacteria- pathogens, nitrogen fixers, autotrophs, origin of mitochondria •Instrumental in transforming early earths atmosphere to an oxidizing one the oxygen revolution • Most common algal group in terrestrial systems and symbiotic relationships 5 6 Cyanobacteria Cellular Structure Cyanobacteria Cellular Structure •Nucleus ? – none, circular DNA, lack histones No complex organelles Thyllakoids- photosystems I & II •Chloroplasts? – no complex organelles Carboxisomes- bacterial microcompartments that contain enzymes Thylakoids- single or paired involved in carbon fixation -concentrate CO2 for RuBisCo •Pigments?– Chl a, b, d carotenoids- B carotene phycobiliproteins- phycoerythrin, phycocyanin, allophycocyanin •Carbon storage? - Cyanophycean starch •Flagella ? –none •Life History? Asexual reproduction 7 8 4 2 Cyanophyta Cellular Structure Cellular Structure: microscopic vegetative cells- photsynthesize • Unicells in mucus envelope spores- resting stages • Colonies heterocysts- specialized cells for fixing nitrogen • Filaments, Branched filaments most complicated form 9 10 “facultative chemoautotropes” Morphology of Cyanophyta • Cell wall made of peptidoglycan, polymer consisting of sugars and •Many spp have the ability to photosynthesize under both aerobic amino acids (not cellulose), similar to gram-negative bacteria and anaerobic conditions • Trichome- Row of cells Difference is where the electrons come from: • Filament- Trichome within a mucilaginous sheath Aerobic conditions? Electron donor is Water O2 produced • MiliMucilaginous ShhSheath- layer of mucilage outside of cell wall C02 + H20 CH2O + O2 • Possible to have > 1 trichome within a filament Anaerobic conditions? Electron donor is Hydrogen sulfide Water is produced CO2 +2H2S CH2O + 2S + H2O 11 12 3 Mucilaginous Sheath – False branching = True branching = –motion (gliding) outgrowth of filaments outgrowth from cells that -protection against desiccation adjacent to dead or change their axis of - protection against UV irradiance specialized cells; filament division, 90 degrees from curves axis of trichome Sheath is often colored: Red = acidic Blue = basic Yellow/Brown = high salt 13 14 Buoyancy: Movement Cells contain gas vesicles or gas vacuole = hollow cylinders made of protein 1. ”Gliding” against a solid substrate -no change in shape or obvious pushing; no ability to steer, sometimes trichome rotates within •low light? Decreased Ps metabolism of polysaccharides sheath, and sheath is left behind as the trichome moves forward increase in gas vacuoles float upward 2. Jet propulsion = excrete mucus •high light? Increased Ps Accumulation of polysaccharides cell pressure increases gas vacuoles shrink sink 3. Helical species (e.g. Spirulina), use waves of contraction 4. Swimming? No idea how they do this, but evidence of chemotaxis and phototaxis. 5. Changing buoyancy 15 16 4 Reproduction: Reproduction 4. Hormogonia = short piece of trichome that detaches from parent filament and glides away No sexual reproduction some DNA transfer has been observed, not conjugation per se. Asexual reproduction through: 1-Binary fission – dividing in two HiHormogonia 2-Fragmentation of colonies Separation disk or “Necridium” = funky dead cell where detachment occurs 3-Endospores/exospores 4-Hormogonia 5-Akinetes 17 18 Reproduction Akinete 5. Akinetes = thick-walled resting spores. Packed with energy reserves; dense = sink to the bottom when released. Triggered by unfavorable conditions, can remain viable for years. H A - akinete 19 20 5 Earliest evidence of Cyanobacteria comes from stromatolites: Wide Range of Habitats Precambrian- 3.5 BYA •Freshwater lakes •Terrestrial soils hotsprings at Yellowstone Park • Marine systems (intertidal, open ocean) • Extreme environments (e.g. salt flats, hot springs, glaciers, etc.) • Endosymbiotic: diatoms, sponges, tunicates, lichens, polar bear fur, bryophytes, gymnosperms, angiosperms • Layered calcareous mounds that contain fossils of cyanobacteria that 21 look like Oscillatoria 22 Stromatolites Nitrogen fixation • Stromatolites are produced by successive deposition through “grain trapping” or calcification: • Mucilaginous sheath of cyanos physically blocks the Many are able to fix nitrogen = convert atmospheric N2 (N N) to a usable form (Ammonium: NH +) using enzyme nitrogenase movement coarse gain sediments and laminates it to 4 the surface of the stromatolite N can be limiting; necessary for the production of amino acids • Attract and bind Ca ions to negatively charged sites •Locations :hypersaline seas (Shark Bay,western Aus.), frozen lakes (Antarctic), hot springs (Yellowstone), the Only cyanobacteria and proteobacteria can fix N; Caribbean BUT cyanobacteria also produce O2 during photosynthesis •Most cyano’s active during the day= layers count the This is a trick, because O inactivates nitrogenase numbers of days 2 •Also they grow up toward the sun and are directional How do they do it??? toward the sun (=can document annual motion of sun) 23 24 6 1. Spatial separation of functions: 2. Temporal separation of functions: Heterocyst = special cells for N fixation. • Fix N in the dark, Ps in the daytime; • Thick-walled, and larger than other vegetative cells; Every N-fixing cyanobacteria fits into these two hollow looking categories except: Trichodesmium = marine, colonial species; fix nitrogen • Not capable of dividing under aerobic conditions in the light through division of labor among cells within a filament (no heterocysts)! • Not photosynthetic, so no CO2 fixation or O2 production • Microplasmedesmata connect to other cells in filament 25 26 Domain Bacteria- unicellular, lacking a nucleus, ribosomes, tRNA, The dark side of cyanobacteria? peptidoglycan in the cell wall Phylum Cyanobacteria- 4484 species Cyanobacterial blooms = death and destruction Class Cyanophyceae- 4484 species, 10 orders Swimmer’s itch = Lyngbia seaweed dermatitus Order Spirulinales- 57 species filamentous, no specialized structures Cyanotoxins: released by animal ingestion leads to death in birds, mammals, & fish Order Oscillatoriales –1,290 species neurotoxins (e.g. Anabaena, Oscillatoria) filamentous, no specialized structures hepatotoxins (e.g. Microcystis, Nostoc) Order Nostocales- 1,365 species filamentous, specialized structures, may have true branching Oscillatoria 27 28 7 Order Spirulinales Domain Bacteria- unicellular, lacking a nucleus, ribosomes, tRNA, peptoglycan in the cell wall Genus Spirulina • Filament is spiral •Major food source for flamingos Phylum Cyanobacteria- blue green algae, origin of the chloroplast • Commercial food source • No heterocysts or akinetes Class Cyanophyceae- • benthic or plantonic, freshwater, thermal & mineral springs, coastal & brackish waters Order Spirulinales- filamentous, no specialized structures • 52 species Order Oscillatoriales -filamentous, no specialized structures Order Nostocales- filamentous, specialized structures, may have true branching 29 30 Order Oscillatoriales Order Oscillatoriales - Unbranched filaments GenusTrichodesmium -No readily identifiable sheath, but is present Genus Oscillatoria -No specialized cells - Important marine N fixer -Fix nitrogen - Segregates N fixing within colonies -Early precambrian fossil stromatolites (lacks heterocysts) -Planktonic, form