Cyanomorfologia_4

7/29/2019 Cyanomorfologia_4

1/10

1

Division: Cyanophyta(blue-green algae or cyanobacteria)

Single class: Cyanophyceae ~150 genera ~2000 species

2

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

3

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

4

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:


2/10

5

Nucleus?

Chloroplasts?

Pigments?

Carbon storage ?

Flagella?

Cyanobacteria Cellular Structure:

6

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

4

7

Cyanobacteria Cellular StructureNo complex organelles

Thyllakoids- photosystems I & II

Carboxisomes- bacterial microcompartments that contain enzymesinvolved in carbon fixation- concentrate CO2 for RuBisCo

8

Unicells in mucus envelope

Colonies

Filaments, Branched filaments most complicated form

Cellular Structure: microscopic


3/10

9

Cyanophyta Cellular Structure

vegetative cells- photsynthesize

spores- resting stages

heterocysts- specialized cells for fixing nitrogen

10

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:

11

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

12

Mucilaginous Sheath motion (gliding)-protection against desiccation- protection against UV irradiance

Sheath is often colored:Red = acidicBlue = basicYellow/Brown = high salt


4/10

13

False branching =

outgrowth of filamentsadjacent to dead orspecialized cells; filamentcurves

True branching =

outgrowth from cells thatchange their axis ofdivision, 90 degrees fromaxis of trichome

14

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

15

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

16

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


5/10

17

4. Hormogonia = short piece of trichome that detachesfrom parent filament and glides away

Separation disk or Necridium = funky dead cellwhere detachment occurs

Reproduction

18

Asexual ReproductionHormogonia short piece of trichome

found in filaments. It detaches fromparent filament and glides away

Hormogonia

19

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

20

Akinete

A - akineteH


6/10

21

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

22

Earliest evidence of Cyanophyta comes fromstromatolites : 3.5 BYA

Layered calcareous mounds that contain fossils of prokaryotesthat look like cyanobacteria

23

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)

24

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???


7/10

25

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

26

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)!

27

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

28

Class Cyanophyceae

O. Oscillatorialesfilamentous, nospecialized structures

O. Nostocalesfilamentous,specialized structures

O. Stigonematalesfilamentous, truebranching, specializedstructures

ClassificationDomain BacteriaClade Cyanophyta


8/10

29

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

30

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.

31

Class Cyanophyceae




ClassificationKingdom MoneraDivision Cyanophyta

32

Celebrity genera: Order Nostocales

Anabaena Produces neurotoxins that becomerelease when they are ingested byanimals Fixes nitrogen Has heterocysts


9/10

33


Callothrix Fixes nitrogen Has heterocysts, often atthe base of filaments Filaments taper at ends Found in the high intertidal

34


Tolypothrix Fixes nitrogen Has heterocysts Exhibits false branching

35


Cylindrospermum Produces neurotoxins that arereleased when they are ingested. Fixes nitrogen Has heterocyst at the base oflarge akinetes

36

ClassificationKingdom Monera

Class Cyanophyceae




Division Cyanophyta


10/10

37

Celebrity genera: Order Stigonematales

Stigonema - Has heterocysts- Exhibits True Branching- Often found as phycobiontin lichens

38

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

Cyanomorfologia_4

Documents

Transcript of Cyanomorfologia_4