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Marek Mentel Prednáška , Gymnázium GJH, marec 2012

Marek Mentel Prednáška , Gymnázium GJH, marec 2012. Are eukaryotes all about oxygen? ...and what Earth history has to do with it?. Marek Mentel Prednáška , Gymnázium GJH, marec 2012. Lecture content. What are eukaryotes - eukaryotes specific features. Eukaryotes origin theories.

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Marek Mentel Prednáška , Gymnázium GJH, marec 2012

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  1. Marek MentelPrednáška, Gymnázium GJH, marec 2012

  2. Are eukaryotes all about oxygen? ...and what Earth history has to do with it? Marek MentelPrednáška, Gymnázium GJH, marec 2012

  3. Lecture content • What are eukaryotes - eukaryotes specific features • Eukaryotes origin theories • Mitochondria types i.e. aerobic and anaerobic mitochondria hydrogenosomes mitosomes (cryptons) aerobic • Energetic metabolism of individual mitochondria forms i.e. respiration anaerobic fermentation chemolithotrophy • Mitochondria origin in the context of Earth geochemistry changes

  4. Cytology - Prokaryotic & Eukaryotic cells comparison

  5. Cytology - Eukaryotic cells specific features Nucleus/EndoMembrane system/ Golgi apparatus Cytoskeleton /Flagella & Cilia Endocytosis e.g. Phagocytosis Mitosis Sex – Meiosis & Fertilization Mitochondria Plastids Peroxisome Linear chromosomes (centromere, telomere, telomerase) Spliceosome (spliceosomal Introns splicing-mRNA export coupling)

  6. Habitats and Energetics - Prokaryotic & Eukaryotic cells versatility comparison anaerobic respiration aerobic respiration !! not true for eukaryotes !!

  7. Eukaryotic cells origin theories review Phagocytosis first / Mitochondria late view Mitochondria first/ Phagocytosis late view

  8. Eukaryotic cells origin theories - prokaryotes within prokaryotes plausibility Mealybug Planococcus citri endosymbiotic γ-proteobacteria within ß-proteobacteria

  9. Eukaryotic cells origin theories - ox-tox hypothesis

  10. Eukaryotic cells origin theories- hydrogen hypothesis

  11. Aerobic mitochondria • Biosynthetic pathways: Heme synthesis Fe-S synthesis Ubiquinone synthesis • Metabolism: Amino acids Carbohydrates Nucleotide & Krebs cycle Lipid • Energetics: aerobic respiration– oxidative phosphorylation aerobic respiration

  12. (facultative) Anaerobic mitochondria • Unicellular protists & Metazoa: Ciliates nitrate, nitrite • Fungi nitrate, nitrite, sulfur • Nematodes fumarate • Plathelminthsfumarate • Snails fumarate • Bivalves fumarate • anaerobic respiration Chemolithotrophic mitochondria • Metazoa: Bivalves • Polychaete worm • Crustaceans • chemolithotrophy – inorganic electron donor (S2-, HS-, H2S)

  13. Hydrogenosomes and Mitosomes (Crypton) - MLOs • Unicellular anaerobes: • Parabasalids(Trichomonas) • Ciliates (Nyctotherus) • Chytridiomycete fungi (Neocallimastix) • Amoeboflagellate(Psalteriomonas) • Stramenopile (Blastocystis) fermentation – substrate-level phosphorylation Hydrogenosome Diplomonads(Giardia) Entamoebids(Entamoeba) Microsporidia (Encephalitozoon) Apicomplexan (Cryptosporidium) no energy metabolism Mitosome • Mitochondria, Hydrogenosomes, Mitosomescommon features: double membrane protein targeting / import iron-sulfur clusters synthesis mitochondrial carrier family proteins

  14. Hydrogenosomes and Mitosomes structure hydrogenosome with cristae - N.ovalis mitosome - Giardia & Methanogen mitochondria hydrogenosome without cristae & EReticulum mitosome - Cryptosporidium Neocallimastix patriciarum

  15. (facultative) Anaerobic mitochondria – Fasciola hepatica

  16. Anaerobic mitochondria / Hydrogenosome – Nyctotherusovalis

  17. Hydrogenosome – Piromycessp. E2

  18. Mitosome – Giardia intestinalis

  19. Earth history - Geological TimeScales eukaryotes origin P - Pleistocene Holocene

  20. Geochemical history of Earth – atmosphere oxygenation eukaryotes origin

  21. Earth history – significant lag in oceans oxygenation & Canfield oceans chemistry slight atmosphere oxygenation continents weathering sulfate-reducing bacteria radiation

  22. Geochemical history of Earth – significant lag in oceans oxygenation & Canfield oceans eukaryotes origin Anbar & Knoll, 2002

  23. Earth history – significant lag in oceans oxygenation & Canfield oceans eukaryotes origin

  24. Eukaryotic anaerobes & Proterozoic ocean chemistry Dietrich, 2006 Mentel & Martin, 2008

  25. Origins of mitochondria, hydrogenosomes and mitosomes Glycolysis - backbone of energy metabolism in Eukaryotes Martin, 2001

  26. Metabolically flexible mitochondria – Arenicola marina

  27. Take home messages: O • EukaryotesandMitochondria 2 • Mitochondria: aerobic anaerobic chemolithotrophic hydrogenosomes – not uniform mitosomes oxidative phosphorylation • genome • cristae substrate-level phosphorylation no energy metabolism • Anaerobic mitochondria& eukaryotic anaerobes make sense in light of Proterozoic ocean chemistry Obligate aerobes like ourselves seems to represent specialized adaptation to recently oxygenated habitats

  28. Take home messages: • geochemical Earth history (changing Earth) what makes mitochondria an essential compartment for eukaryotic cell – where is the limit for its reduction ? & interconnection Eukaryotes evolution • mitosomes • cryptic mitochondria (Cryptosporidium parvum) • not energy metabolism • mitosomes (Giardia intestinalis (syn. lamblia)) • cryptic mitochondria (Cryptosporidium parvum) • mitochondria (yeast) • iron-sulfur cluster biosynthesis

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