BIO 4320 – marine algers systematikk og biologi Division ”CHLOROPHYTA”

Origin of chloroplast Chlorophyta

Phylogeny of Chlorophyta sensu lato

Chlorophyta sensu lato 5-10 classes Freshwater 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 flagella

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 UTC clade = Ulvophyceae-Trebouxiophyceae Chlorophyceae Chlorodendrales moved from Prasinophyceae to Chlorophyta Prasinophyceae may be split into several classes

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

Flagellar apparatues Ulvophyceae CW Trebouxiophyceae CCW DO Cruciate UTC-clade (a-c) Ulvophyceae CW Trebouxiophyceae CCW Prasinophyceae DO Chlorophyceae MLS Charophyceae Prasinophyceae multilayered structure

Chlorophyceae cruciate and clock wise flagellar bases from van den Hoek et al. 1995

Chlamydomonas reinhardtii flagellar bases and roots Clockwise: 1 o’clock – 7 o’clock type (connective fibres omitted) from van den Hoek et al. 1995

Chlamydomonas reinhardtii flagellar bases and roots upper striated connective connective fibres with centrin lower striated connective from van den Hoek et al. 1995

Chlamydomonas reinhardtii rhizoplast Contraction/relaxation contracted relaxed connective fibres rhizoplast nucleus from van den Hoek et al. 1995

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)

clade U T C Present in brackish water

Cell wall Cells are naked with cell wall or covered with organic scales

Cell division Cytokinesis 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