Phaeophyta - West Chester...
Transcript of Phaeophyta - West Chester...
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Phaeophyta!
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Phaeophyte Characteristics:!1) Pigments?
2) Chloroplast structure?
3) Storage product?
4) Flagella?
Division: Stramenopiles!Many classes, mostly unicellular or colony of unicells:!!• class: Chrysophyta!
• class: Bacillariophyta!
• class: Pyrrhophyta!
• class: Euglenophyta!
• class: Phaeophyceae*** !
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Phaeophyte Morphology!
stipe
holdfast
blade
thallus
sori
Pneumatocysts- !!- large float containing gas found!! !
!!- O2, CO2, CO!
Cystoseria !! ! !Sargassum !Catenate ! ! ! !singly!
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Midrib
Undaria sp.!
Fucus!
Laminaria!
- complex multicellular thalli, adults never unicellular!- simplest forms = branching filaments!- differentiation into cortex (outer pigmented cells) and medulla (inner non-pigmented cells)! !- may grow large ! over 40 meters long!
Phaeophyceae Thallus Morphology:!
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Phaeophyte Cell Wall Morphology!Two main components:!!1. Cellulose ! microfibrils (1-10% of thallus dry weight)!
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2. Alginic acid ! surrounds the microfibrills (35% of thallus dry weight)!
- Ice-cream!!
- Frosting!!
- Paints!
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!- Food = �kombu� in Japan; dried and shredded laminarians!
Human Uses for Alginates!
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Plasmodesmata = connections between adjacent cells, formed during cell division = cell-to-cell transport of photosynthetic products and cell communication !
Microscopic Phaeophyte Morphology!Only alga to transport sugar/photosynthate in sieve elements!
Transport in Plants vs. Algae!Independent Evolutionary Origins!
Plants!- water and sugar conducting cells!
- xylem = non-living!
- sieve elements = alive!
- sieve elements lack!organelles!
- companion cells!
Algae!- conduct sugars and some nutrients!
- all cells living!
- sieve elements = alive!
- sieve elements w/o organelles except mitochondria!
- no companion cells!
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Now, why are the Phaeophytes the only algae that contain sieve elements?!
Phaeophyte Metabolites:!Tannins: (a.k.a. polyphenolic compounds and terpenes)!- protective, defense system!- stored in special vesicles called physodes in the cytoplasm!
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More Phaeophyte Storage Products:!
- Laminarin and Mannitol are most abundant!- always sugars!- storage products in cytoplasmic vacuoles (no special name); not associated with chloroplasts or pyrenoids !!
Mannitol function != sugar alcohol – originally from flowering ash!- important in osmoregulation- algae make more
mannitol to use up ions!- transporting organic material to different parts of
the thallus in large species!- lowers freezing point!
Laminarin function!- storage glucan = polymer of glucose!- used as additive for pork patties!- main form of food storage in brown algae!
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Phaeophyte Reproduction:!
Unilocular = spores/gametes produced in a single compartment!!�unangia�!
Plurilocular = many small chambers (locules); one spore/gamete per chamber!!�plurangia�!
Gametangia = structure where gametes are formed !Sporangia = structure !where spores are formed !
uniseriate multiseriate
attached laterally, never apically!!Anterior �flimmer flagellum�!- movement!- long flagellum with �mastigoneme�!!!Posterior �whiplash flagellum�!- steering!- short, smooth flagellum!- contains flavin!!!an eyespot acts a shading structure or light reflector!
Phaeophyte Flagella:!
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How do the male gametes find the female ones?
Pheromones = chemicals produced to elicit a specific behavioral or physiological response Phaeophyceans produce sexual pheromones = chemically similar (unsaturated hydrocarbons = high cross-reactivity Male gametes are VERY sensitive to pheromones = low concentration will elicit a response
Functional Anisogamy
Mostly marine (or at least brackish water)!Intertidal and subtidal!Dominate colder waters = Northern hemisphere: !
# of red species > # of brown species!# of red individuals << # of brown individuals !
Phaeophyte Habitat!
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12 orders within the Phaeophyta
Our focus will be on the following 4 orders:
Class Phaeophyceae
Chordariales Ectocarpales Laminariales Fucales
Distinguishing among orders based on
1. Life History and Reproduction - isomorphic/heteromorphic alternation of generations - isogamous, anisogamous, oogamous
2. Macrothallus Construction
3. Growth - diffuse, apical, intercalary, trichothallic, meristodermal (a surface layer of cells (epidermis) that is capable of dividing = is meristematic)
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Celebrity genus: Ectocarpus
Class Phaeophyceae
Desmarestiales Ectocarpales Laminariales Fucales
- mostly epiphytic
- uniseriate filaments
- opportunistic = excellent colonizers - Female gametes releases pheromone ectocarpene, hormosirene
Life History of Ectocarpales:!
meiosis!
Asexual reporduction by plurilocular sporangia = sporophyte!Sexual reproduction is dioecious and anisogamous!
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Thallus Morphology and Growth!Body is macroscopic, multicellular, filamentous!!Prostrate system - irregularly branched, uniseriate and attached!!Lateral branching , series of elongated cells!!Cells uninucleate with discoid chromoplasts!!Distribution generally is cold oceans!!Growth apical though no specialized apical cells!
- Saxicolous
- Low intertidal to subtidal
- �Acid weed�
Celebrity genus: Desmarestia
Class Phaeophyceae
Desmarestiales Ectocarpales Laminariales Fucales
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Life History of Desmarestiales Heteromorphic life history, sphorophyte, macroscopic gametophyte!
Morphology variable within the genus - subtidal = high light (abundant if disturbance has removed canopy, e.g. El Nino, or urchin grazing)
- disappears with kelp growth due to canopy = shading - �Acid weed�: cells accumulate sulfate ions from seawater + water = sulfuric acid or malic acid, stored in vacuoles
=ANTIHERBIVORY, pH 0.8-1.8, bleaches other algae
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Desmarestia Growth!Trichothallic growth = tips, sides and main axis have a fringe along the margins !!Trichothallic growth filaments!
Class Phaeophyceae
Desmarestiales Ectocarpales Laminariales Fucales
- saxicolous - sporangia always unilocular
- most have sieve cells/elements - pheromone released by female gametes lamoxirene
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Life History of Laminariales Diplohaplontic Alternation of Generations: organism having a separate multicellular diploid sporophyte and haploid gametophyte stage, flagellated sperm
Laminariales General Morphology
stipe
holdfast
blade
sorus (pl: sori)
haptera
sporophylls
Sorus/sporophyll - sporangia!!Hapteran holdfast = always submerged, multiple �branches�!! !
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Microscopic gametophytes
Intercalary growth
- growth in both directions (away from meristem) - between stipe and blade (or blade and pneumatocyst)
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Meristoderm/outer cortex – !Inner cortex – !Medulla – !Meristodermal growth gives thallus girth (mostly), mostly periclinal cell division!
Meristodermal Growth!
Periclinal and Anticlinal cell division:!!
- periclinal = cell division parallel to the plane of the meristoderm = girth!
- anticlinal = cell division perpendicular to the plane of the meristoderm = length!
Transport sieve elements, sieve cells!- transport photosynthetic products!- outgrowths of cortex cells grow into the medulla!- sieve plates = specialized plasmodesmata between the sieve
elements that allow transport of sugars between cells!
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Class Phaeophyceae
Desmarestiales Ectocarpales Laminariales Fucales
Celebrity genera: Fucus, Silvetia, Pelvetiopsis, Sargassum, Cystoseira
- usually saxicolous - unattached in few cases - unilocular gametangia
Life History of Fucales
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Conceptacles - chambers where the gametes are stored
Receptacle - swollen tips of fucoids where meiosis occurs - terminal portion of a branch bearing numerous embedded conceptacles
Oogonia-
Conceptacles
Antheridia-
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Fucus Silvetia Pelvetiopsis
Midrib Playdough stipe Flattened stipe
8 eggs per oogonium 2 eggs per oogonium 1 egg per oogonium
Sargasso Sea in the Atlantic Gulf Stream, North Atlantic, Canary and Equatorial!!home to Sargassum natans and fluitans!
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Growth and Construction at a Glance!Order Construction
(Macrothallus) Growth (Macrothallus)
Isomorphic Ectocarpales
Heteromorphic Desmarestiales
Laminariales
Diplontic Fucales