Presentation on theme: "Fungi and Protists. Endosymbiotic Origin of Eukaryotes Schimper in 1883 and Mereschcowsky proposed that chloroplasts are cyanobacteria living inside plant."— Presentation transcript:
Fungi and Protists
Endosymbiotic Origin of Eukaryotes Schimper in 1883 and Mereschcowsky proposed that chloroplasts are cyanobacteria living inside plant cells Andreas Franz Wilhelm Schimper ( , Germany) Konstantin Sergeevich Mereschcowsky ( , Russia)
Ivan Emanuel Wallin Rejected cytoplasmic origin of mitochondria Considered them to be microbes living in the cytoplasm Claimed to have cultured isolated mitochondria as proof of their microbial nature , USA
Endosymbiosis Proposed with explanation by Lynn Margulis ( , USA) in 1967 based on her work and drawing on the works of Konstantin Merezhkovsky ( , Russia) and Ivan Wallin ( , USA). Figure from Margulis (1970); note the figure illustrates endosymbiosis and the origin of the 5 kingdoms.
Archaezoa Hypothesis Autogenous theory (Archezoa Hypothesis- Cavalier-Smith 1983) Organelles evolved within the cell by progressive compartmentalization HOWEVER, Roger (1999)- all extant eukaryotes have mitochondrial genes in their nuclear DNA Later, Cavalier-Smith accepted endosymbiosis Thomas Cavalier-Smith (1942, Britain)
Evidence that these organelles have prokaryotic traits: Mitochondria and chloroplasts – Circular DNA – Synthesize proteins – Divide by fission – Mutate SSU rDNA phylogeny
a larger prokaryote (or perhaps early eukaryote) engulfed or surrounded a smaller prokaryote (permanent resident) some 1.5 billion to 700 million years ago
endomembrane system evolved from inward folds of the plasma membrane of a prokaryotic cell DNA Plasma membrane Cytoplasm Ancestral prokaryote Endoplasmic reticulum Nuclear envelope Nucleus Cell with nucleus and endomembrane system
Serial Endosymbiosis Theory Max F.J.R. Taylor (1939, South Africa and Canada); eukaryote created following endosymbiosis with mitochondrial bacterium. Further developed Margulis Endosymbiosis Serial endosymbiotic theory (SET ( )) organelles are the result of successive engulfments…
Photosynthetic eukaryotic cell Photosynthetic prokaryote (Some cells) Chloroplast Mitochondrion Aerobic heterotrophic prokaryote endosymbiosis generated mitochondria and chloroplasts Aerobic cells use oxygen to release energy from organic molecules by cellular respiration -Proteobacteria Cyanobacteria
Insights from recent results: Reduce the number of secondary losses of mitochondrial – Group together many amitochondriate lineages – Find evidence of very reduced mitochondria – Mitochondrial monophyly? – (discoid, flattened, and tubular cristae) Reduce the number of secondary endosymbioses (photosynthetic eukaryote being engulfed by another eukaryote) – Group together branches with chloroplast surrounded by four membranes The initial endosymbiotic events were rare and most diversity through secondary endosymbioses
Eukaryotic Domains Tree of Life generated by Sandra Baldauf of Uppsala University using multigene analyses
Supergroup Unikonta A group defined by Cavalier-Smith Includes Amoebozoa, Animalia, and Fungi Unikonta means one to move by. The reference is to motile cells having a single flagellum.
Amoebozoa Two major groups: 1.Most free-living amoebae 2.Slime molds ?
Amoebozoa Unicellular Heterotrophic Most are free-living, a few are important parasites
Excavates Unicellular Most are heterotrophs, commensals, a few are parasites No sexual reproduction known Mitochondria absent (lost them)
Euexcavata Trichonympha is a common symbiont in the gut of termites and is a good representative of the upper clade. The lower clade includes free-living cells that typically have only 2 flagella.
Discicristates Some photosynthetic (secondary endosymbiosis) Some are free-living heterotrophs Some are important parasites
Supergroup Chromalveolata Supergroup contains some of the most important organisms in the oceans Range in form from simple single cells to complex multicellular taxa Vary from heterotrophs to parasites to autotrophs Includes 4 kingdoms: – Heterokontae – Alveolatae – Rhizariae – Hacrobiae
Heterokontae United by same type of motile cell Very diverse
Phaeophyta (the Brown Algae)
Alveolatae All unicellular Many with complex life histories Free-living and symbionts Photosynthetic, heterotrophic, commensals, parasitic United by type of cell covering
Rhizaria Usually unicellular When they make pseudopods, they are long and frequently anastomose Taxa are free-living and symbiotic Many have mineralized internal cytoskeletons
Generally multicellular with complex life histories Include: mushrooms, molds, and yeasts Sister group to the animals Generally are decomposers; some are parasitic and cause disease, particularly in plants
Penicillium, common mold
Mushroom Life History
Prototaxites Silurian to Devonian. Gigantic fungus, largest terrestrial organism until advent of trees at the end of the Devonian. Evidence of symbiotic algae in the trunk-like structures, making them lichens.
Honey Mushrooms Armillaria ostoyae years old Covers 2,384 acres in Malhur National Forest of the Blue Mountains in Eastern Oregon.
Lichens Foliose Fruticose Crustose Symbiotic structures made of algae and fungi The fungus is the primary biotic partner and enslaves the alga. The lichen form is different from either the fungus or the alga and can live in habitats that neither one can inhabit alone.