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Brief history of photosynthetic organisms on earth

Division: Cyanobacteria 3.45 bya = Cyanobacteria appear and introduce photosynthesis

blue-green algae 1.5 bya = first Eukaryotes appeared (nuclear envelope and ER thought to come from invagination of plasma membrane)

0.9 bya = first multicellular algae (Rhodophyta - Red algae)

800 mya = earliest Chlorophyta (Green algae)

400-500 mya = plants on land – derived from Charophyceae

250 mya = earliest Heterokontophyta (Brown algae)

100 mya = earliest seagrasses (angiosperms)

• Single : Cyanophyceae • ~150 genera • ~4037 1 2

DOMAIN Groups () 1.Bacteria- cyanobacteria (blue green algae) Domain Bacteria- unicellular, lacking a nucleus, ribosomes, tRNA,

2.Archae peptoglycan in the cell wall 3.Eukaryotes 1. Alveolates- dinoflagellates Low-GC Gram-positive- staph infections & antrax 2. Stramenopiles- diatoms, heterokonyophyta Phylum High GC- Gram-positive- tuberculosis & antibiotics Phylum Hyperthermophilic bacteria- live at high temperatures 3. Rhizaria- unicellular amoeboids Phylum Hadobacteria-live at high temps, consume nuclear waste Phylum Cyanobacteria- blue green algae, origin of the chloroplast 4. Excavates- unicellular flagellates Phylum Spirochetes- syphilis & lime disease

5. Plantae- rhodophyta, chlorophyta, seagrasses Phylum Chlamydias- intercellular parasites Phylum Proteobacteria- pathogens, nitrogen fixers, autotrophs, 6. Amoebozoans- slimemolds origin of mitochondria

7. Fungi- heterotrophs with extracellular digestion

8. Choanoflagellates- unicellular

9. Animals- multicellular heterotrophs

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1 Cyanobacteria Cellular Structure: Cyanobacteria are important because: •Nucleus?

• Cyanobacteria are modern representatives of the very first photosynthetic organisms on Earth. •Chloroplasts?

•First organisms to have 2 photosystems and to produce organic material and to give off O2 as a biproduct. • Pigments?

•Instrumental in transforming early earths atmosphere to an oxidizing one  the oxygen revolution • Carbon storage?

• Most common algal group in terrestrial systems and symbiotic relationships • Flagella?

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Cyanobacteria Cellular Structure Cellular Structure: microscopic No complex organelles • Unicells in mucus envelope Thyllakoids- photosystems I & II

Carboxisomes- bacterial microcompartments that contain enzymes involved in carbon fixation • Colonies - concentrate CO2 for RuBisCo

• Filaments, Branched filaments most complicated form

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2 Cyanophyta Cellular Structure

vegetative cells- photsynthesize “facultative chemoautotropes”

•Many spp have the ability to photosynthesize under both aerobic spores- resting stages and anaerobic conditions

heterocysts- specialized cells for fixing nitrogen Difference is where the electrons come from:

Aerobic conditions? Electron donor is Water O2 produced

C0 2 + H20 CH2O + O2

Anaerobic conditions? Electron donor is Hydrogen sulfide  Water is produced

2H2S + CO2 CH2O + 2S + H2O

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Mucilaginous Sheath – Morphology of Cyanophyta –motion (gliding) • Cell wall made of peptidoglycan, polymer consisting of sugars and amino acids (not cellulose), similar to gram-negative bacteria -protection against desiccation - protection against UV irradiance • Trichome- Row of cells

• Filament- Trichome within a mucilaginous sheath Sheath is often colored: • Mucilaginous Sheath- layer of mucilage outside of cell wall Red = acidic

Blue = basic

• Possible to have > 1 trichome within a filament Yellow/Brown = high salt

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3 False branching = True branching = Movement

outgrowth of filaments outgrowth from cells that adjacent to dead or change their axis of 1. ”Gliding” against a solid substrate -no change in shape or obvious specialized cells; filament division, 90 degrees from curves axis of trichome pushing; no ability to steer, sometimes trichome rotates within sheath, and sheath is left behind as the trichome moves forward

2. Jet propulsion = excrete mucus

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

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Buoyancy: Reproduction: Cells contain gas vesicles or gas vacuole = hollow cylinders made of protein  No sexual reproduction  some DNA transfer has been observed, not conjugation per se. •low light? Decreased Ps  metabolism of polysaccharides  increase in gas vacuoles  float upward  Asexual reproduction through: •high light? Increased Ps  Accumulation of polysaccharides  cell pressure increases  gas vacuoles shrink  sink 1-Binary fission – dividing in two

2-Fragmentation of colonies

3-Endospores/exospores

4-Hormogonia

5-Akinetes

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4 Reproduction Asexual Reproduction

Hormogonia – short piece of trichome 4. Hormogonia = short piece of trichome that detaches from parent filament and glides away found in filaments. It detaches from parent filament and glides away

Separation disk or “Necridium” = funky dead cell 17 18 where detachment occurs Hormogonia

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

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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, , gymnosperms, angiosperms • Layered calcareous mounds that contain fossils of cyanobacteria that 21 look like Oscillatoria 22

Stromatolites Another big reason Cyanobacteria are cool and • Stromatolites are produced by successive deposition ecologically important: Nitrogen fixation 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: NH4+) using enzyme nitrogenase movement coarse gain sediments and laminates it to 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 numbers of days This is a trick, because O2 inactivates nitrogenase

•Also they grow up toward the sun and are directional How do they do it??? toward the sun (=can document annual motion of sun)

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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 categories except: hollow looking 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

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Domain Bacteria- unicellular, lacking a nucleus, ribosomes, tRNA, The dark side of cyanobacteria? peptoglycan in the cell wall

Phylum Cyanobacteria- 4037 species

Class Cyanophyceae- 4037 species, 7 orders Cyanobacterial blooms = death and destruction

Swimmer’s itch = Lyngbia  releases chemicals Chroococcales- 954 species filamentous, no specialized structures Cyanotoxins: released by animal ingestion  neurotoxins (e.g.

Anabaena, Oscillatoria) and hepatotoxins (e.g. Microcystis, Nostoc) (death to mammals, birds, fishes , no known human Order Oscillatoriales –926 species filamentous, no specialized structures deaths)

Order Nostocales- 1,297 species filamentous, specialized structures, may have true branching

27 28 Oscillatoria

7 Order Chroococcales Domain Bacteria- unicellular, lacking a nucleus, ribosomes, tRNA, peptoglycan in the cell wall 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 Chroococcales- filamentous, no specialized structures • 52 species

Order Oscillatoriales -filamentous, no specialized structures

Order Nostocales- filamentous, specialized structures, may have true branching

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Order Oscillatoriales Order Oscillatoriales - Unbranched filaments Genus Oscillatoria -No readily identifiable sheath, but is present -No specialized cells GenusTrichodesmium -Fix nitrogen -Early precambrian fossil stromatolites -Planktonic, form mats on mud, stone, sand, in - Important marine N fixer freshwater, brachish, marine -137 species - Segregates N fixing within colonies (lacks heterocysts) - More Phycoerythrin than Phycocyanin  Red color, gave the Red Sea its name - Strictly planktonic- marine & fresh water -10 species

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8 Domain Bacteria- unicellular, lacking a nucleus, ribosomes, tRNA, Order Nostocales peptoglycan in the cell wall

Phylum Cyanobacteria- blue green algae, origin of the chloroplast • Fixes nitrogen Genus Nostoc • Has heterocysts in the middle of Class Cyanophyceae- filaments •Akinates midway between heterocysts Order Chroococcales- filamentous, no specialized structures •94 species •Freshwater

Order Oscillatoriales -filamentous, no specialized structures

Order Nostocales- filamentous, specialized structures, may have true branching

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Order Nostocales Order Nostocales • Fixes nitrogen • Has heterocysts, often at the Genus Anabaena Genus Calothrix base of filaments • Produces neurotoxins that become release • Filaments taper at ends when they are ingested by animals • Periphytic on algae, aquatic plants, • Fixes nitrogen stone, wood, high intertidal • Has heterocysts in the middle of filaments •132 species • Akinates adjacent to heterocysts • Planktonic, or periphytic, benthic, soils, • 117 species

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9 Order Nostocales Order Nostocales • Fixes nitrogen Cylindrospermum GenusTolypothrix • Has heterocysts • Produces neurotoxins that are • Exhibits false branching released when they are ingested. • 60 species • Fixes nitrogen •Mainly submerged, also aerophytic • Has heterocyst at the base of habitats large akinetes •Periphytic or soils •49 species

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Order Nostocales

- Has heterocysts - Exhibits True Branching Stigonema - Often found as phycobiont in lichens, terrestrial & soil, freshwater - 62 species

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