bio 4320 – marine algers systematikk og biologi division ”chlorophyta”
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BIO 4320 – marine algers systematikk og biologi
Division ”CHLOROPHYTA”
Chlorophyta
Origin of chloroplast
Phylogeny of Chlorophyta sensu lato
Chlorophyta sensu lato
5-10 classesFreshwater and marine;ca. 5000 species
Division characteristics
morphology
• Flagellates, colonies• Filaments • Parenchymatic
Ulva Dunaliella
Division characteristics• Isokont swarmers• ”smooth” flagella or covered by scales• Stellate transition zone (flagella apparatues)• Dobble chloroplast membrane• Chloroplasts with 2-6 thylakoids, grana• Green chloroplast with:
chlorophyll a og b
β-karoten and xanthophyls• Some have pyrenoid (in chloroplast)• Storage product: starch (in chloroplast)
Bloom on the Southern coast of
Norway
Chloroplast pigments
chlorophyll a + b
carotenoids
• β-karoten
Xanthophylls
• lutein
• violaxanthin
• neoxanthin
flagella
”smooth” in Chlorophyceae
with organic scales in Prasinophyceae
Flagellar transition zone
from van den Hoek et al. 1995
sheding of flagella
from van den Hoek et al. 1995
flagellar roots of UTC
UTC clade = Ulvophyceae-Trebouxiophyceae Chlorophyceae
Chlorodendrales moved from Prasinophyceae to Chlorophyta
Prasinophyceae may be split into several classes
UTC clade
Microtubular roots of UTC
Microtubular roots run beneath the cell membrane to the posterior part of the cell
• anchor the flagella to the cell
• constitute a tubular cytoskeleton
4 flagellar roots:
• 2 consist of 2 microtubuli
• 2 consist of 4 (usually) microtubuli
Microtubular roots of UTC
Microtubular roots run in oppsite directions forming a cross-like pattern in apical view
3 principal arrangements can be distinguished based on displacement of basal bodies
Characterized as cruciate (three types)• clockwise • opposite• counterclockwise
multilayered structure
Cruciate
UTC-clade (a-c) CW
CCW
DO
MLS
Ulvophyceae
Chlorophyceae
Trebouxiophyceae
Charophyceae
Prasinophyceae
Prasinophyceae
Flagellar apparatues
Chlorophyceae cruciate and clock wise flagellar bases
from van den Hoek et al. 1995
2 flagella
4 flagella
Chlamydomonas reinhardtii flagellar bases and roots
from van den Hoek et al. 1995
(connective fibres omitted)
1 o’clock – 7 o’clock type
Clockwise:
Chlamydomonas reinhardtii flagellar bases and roots
from van den Hoek et al. 1995
upper striated connective
lower striated connective
connective fibres with centrin
Chlamydomonas reinhardtii rhizoplast
from van den Hoek et al. 1995
rhizoplast
nucleus
connective fibres
Contraction/relaxation
contracted
relaxed
Mitosis
• open; nuclear membrane disperse during metaphase (Charophyceae)
• closed; nuclear membrane is persistent (many UTC)
• Trebouxiophyceae; closed mitosis with metacentric spindle
(see fig 16.8)
U
T
C
clade
Present in brackish water
Cell wall
Cells are
• naked
• with cell wall
• or covered with organic scales
Cell divisionCytokinesis• by furrowing (Prasino-,Trebouxiophyceae)
• by phycoplast-furrowing (chlorophyceae)
Mode of division of systematical importance
Mitosis and cell division
8 different modes have been distinguished
occurrence
• freshwater, brackish water, salt water• rock pools, ponds and snow• humid soil, tree trunks, stones
• Tropical, temperate and polar milieu
diversity
• Cell size from < 1 μm to 20-30 cm
• Flagellates, coccoids, colony forming, filamentous and parenchymatic