Post on 04-Apr-2018
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Division: Cyanophyta(blue-green algae or cyanobacteria)
Single class: Cyanophyceae ~150 genera ~2000 species
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Adapted from Sadava2007
Chromalvaeolates
Plantae
Excavates
Rhizaria
Unikonts
SpirochetesChlamydiasCyanophytaProteobacteria
ApicomplexansDinoflagellatesCiliates
Heterokontophyta
DiatomsOomycetesHaptophytes
Glaucophytes
Rhodophyta
ChlorophytesLand PlantsCharophytes
DiplomonadsParabasalids
HeteroloboseansEuglenidsKinetoplastids
CercozoansForaminiferans
Radiolarians
FungiChoanoflagellatesAnimals
Loboseans
Slime moldsSlime molds
Bacteria
Archaea
Eukaryotes
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Domain Bacteria- unicellular, lacking a nucleus, ribosomes, tRNA,peptoglycan in the cell wall
Clade Spirochetes- syphilis & lime diseaseClade Chlamydias- intercellular parasitesClade High GC- Gram-positive- tuberculosis & antibioticsClade Cyanophyta- cyanobacteria, blue green algaeClade Low-GC Gram-positive-staph infections & antraxClade Proteobacteria- pathogens, nitrogen fixers, autotrophs
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Cyanophyta are modern representatives of the veryfirst photosynthetic organisms on Earth.
First organisms to have 2 photosystems and to produceorganic material and to give off O2 as a biproduct.
Instrumental in transforming early earths atmosphereto an oxidizing one the oxygen revolution
Most common algal group in terrestrial systems andsymbiotic relationships
Cyanobacteria are important because:
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Nucleus?
Chloroplasts?
Pigments?
Carbon storage ?
Flagella?
Cyanobacteria Cellular Structure:
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Nucleus ? none, circular DNA, lack histones
Chloroplasts? no complex organellesThylakoids- single or paired
Pigments? Chl a, b, dcarotenoids- B carotenephycobiliproteins- phycoerythrin, phycocyanin, allophycocyanin
Carbon storage? - Cyanophycean starch
Flagella ? none
Life History?
Cyanobacteria Cellular Structure
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Cyanobacteria Cellular StructureNo complex organelles
Thyllakoids- photosystems I & II
Carboxisomes- bacterial microcompartments that contain enzymesinvolved in carbon fixation- concentrate CO2 for RuBisCo
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Unicells in mucus envelope
Colonies
Filaments, Branched filaments most complicated form
Cellular Structure: microscopic
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Cyanophyta Cellular Structure
vegetative cells- photsynthesize
spores- resting stages
heterocysts- specialized cells for fixing nitrogen
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2H2S + CO2 CH2O + 2S + H2O
C02 + H20 CH2O + O2
Aerobic conditions? Electron donor Water (O2 produced)
Anaerobic conditions? Electron donor Hydrogen sulfide (no O2 produced)
facultative chemoautotropesMany spp have the ability to photosynthesize under both aerobicand anaerobic conditions
Difference is where the electrons come from:
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Morphology of Cyanophyta
Cell wall made of peptidoglycan (not cellulose), similar to gram-negative bacteria (more complex cell wall than gram-positive)
Trichome - Row of cells
Filament - Trichome within a mucilaginous sheath
Mucilaginous Sheath- layer of mucilage outside of cell wall
Possible to have > 1 trichome within a filament
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Mucilaginous Sheath motion (gliding)-protection against desiccation- protection against UV irradiance
Sheath is often colored:Red = acidicBlue = basicYellow/Brown = high salt
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False branching =
outgrowth of filamentsadjacent to dead orspecialized cells; filamentcurves
True branching =
outgrowth from cells thatchange their axis ofdivision, 90 degrees fromaxis of trichome
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Movement
1. Gliding against a solid substrate -no change in shape or obviouspushing; no ability to steer, sometimes trichome rotates withinsheath, 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 ofchemotaxis and phototaxis.
5. Changing buoyancy
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Buoyancy:Cells contain gas vesicles or gas vacuole (all vesicles) = hollowcylinders made of protein
low light? decreased Ps metabolism of polysaccharides increase in gas vacuoles float upward
high light? Increased Ps Accumulation ofpolysaccharides cell pressure increases gas vacuolesshrink sink
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Reproduction:
9 No sexual reproduction some DNA transfer has beenobserved, not conjugation per se.
9 Asexual reproduction through:
1) Binary fission dividing in two
2) Fragmentation of colonies
3) Endospores/exospores
4) Hormogonia5) Akinetes
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4. Hormogonia = short piece of trichome that detachesfrom parent filament and glides away
Separation disk or Necridium = funky dead cellwhere detachment occurs
Reproduction
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Asexual ReproductionHormogonia short piece of trichome
found in filaments. It detaches fromparent filament and glides away
Hormogonia
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5. Akinetes = thick-walled resting spores.
Packed with energy reserves; dense = sink to the bottomwhen released.
Triggered by unfavorable conditions, can remain viablefor years.
Reproduction
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Akinete
A - akineteH
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Wide Range of Habitats
Freshwater lakes
Terrestrial soils
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
hotsprings at Yellowstone Park
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Earliest evidence of Cyanophyta comes fromstromatolites : 3.5 BYA
Layered calcareous mounds that contain fossils of prokaryotesthat look like cyanobacteria
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Stromatolites Stromatolites are produced by successive depositionthrough grain trapping or calcification:
Mucilaginous sheath of cyanos physically blocks thephysically blocks themovementmovement coarse gain sediments and laminates it tothe surface of the stromatolite Attract and bind Ca ions to negatively charged sitesAttract and bind Ca ions to negatively charged sites
Locations : hypersalinehypersaline seasseas (Shark Bay,western Aus.),frozen lakesfrozen lakes (Antarctic), hot springshot springs (Yellowstone), theCaribbeanMost cyanos active during the day= layers count thenumbers of daysAlso they grow up toward the sun and are directionaltoward the sun (=can document annual motion of sun)
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Another big reason Cyanophyta are cool andecologically important: Nitrogen fixationMany are able to fix nitrogen = convert atmospheric N 2 (N N)to a usable form (Ammonium: NH 4+) using enzyme nitrogenase
N can be l imiting; necessary for the production of amino acids
Only cyanophyta and prokaryotic bacteria can fix N; BUT cyanophyta also produce O 2 during photosynthesis
This is a trick, because O 2 inactivates nitrogenase
How do they do it???
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1. Spatial separation of functions:
Heterocyst = special cells for N fixation.
Thick-walled, and largerthan other vegetative cells;hollow looking
Not capable of dividing
Not photosynthetic, so noCO2 fixation or O 2 production
Microplasmedesmataconnect to other cells infilament
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2. Temporal separation of functions:
Fix N in the dark, Ps in the daytime;
Every N-fixing cyanobacteria fits into these twocategories except:
Trichodesmium = marine, colonial species; fix nitrogenunder aerobic conditions in the light through division oflabor among cells within a filament (no heterocysts)!
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The dark side of cyanobacteria?
Cyanobacterial blooms = death and destruction
Swimmers itch = Lyngbia releases chemicals
Cyanotoxins: released by animal ingestion neurotoxins (e.g.Anabaena, Oscillatoria ) and hepatotoxins (e.g. Microcystis,Nostoc ) (death to mammals, birds, fishes , no known humandeaths)
Oscillatoria
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Class Cyanophyceae
O. Oscillatorialesfilamentous, nospecialized structures
O. Nostocalesfilamentous,specialized structures
O. Stigonematalesfilamentous, truebranching, specializedstructures
ClassificationDomain BacteriaClade Cyanophyta
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Spirulina
Celebrity genera: Order Oscillatoriales Filament is spiral Common in lake with high pH Major food source for flamingos Commercial food source No heterocysts or akinetes
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Celebrity genera: Order Oscillatoriales
Trichodesmium
- Important marine N fixer- Segregates N fixing within colonies
(lacks heterocysts)- More Phycoerythrin than Phycocyanin
Red color, gave the Red Seaits name.
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Class Cyanophyceae
O. Oscillatorialesfilamentous, nospecialized structures
O. Nostocalesfilamentous,specialized structures
O. Stigonematalesfilamentous, truebranching, specializedstructures
ClassificationKingdom MoneraDivision Cyanophyta
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Celebrity genera: Order Nostocales
Anabaena Produces neurotoxins that becomerelease when they are ingested byanimals Fixes nitrogen Has heterocysts
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Celebrity genera: Order Nostocales
Callothrix Fixes nitrogen Has heterocysts, often atthe base of filaments Filaments taper at ends Found in the high intertidal
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Celebrity genera: Order Nostocales
Tolypothrix Fixes nitrogen Has heterocysts Exhibits false branching
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Celebrity genera: Order Nostocales
Cylindrospermum Produces neurotoxins that arereleased when they are ingested. Fixes nitrogen Has heterocyst at the base oflarge akinetes
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ClassificationKingdom Monera
Class Cyanophyceae
O. Oscillatorialesfilamentous, nospecialized structures
O. Nostocalesfilamentous,specialized structures
O. Stigonematalesfilamentous, truebranching, specializedstructures
Division Cyanophyta
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Celebrity genera: Order Stigonematales
Stigonema - Has heterocysts- Exhibits True Branching- Often found as phycobiontin lichens
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A cool poem O, I have labourd late and long
Researching in phycology,
And I must sing in simple song
My ladye, Chlorophyceae
O green algae absorb the light
Replete with Chlorophylls a and b
And green algae are my delight --
My ladye, Chlorophyceae
- Ralph A. LewinThe Biology of Algae andDiverse Other Verses