Marek Mentel Prednka Gymnzium GJH marec 2012 Are

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 • Mitochondria types i. e. aerobic and anaerobic mitochondria hydrogenosomes mitosomes (cryptons) • Energetic metabolism of individual mitochondria forms i. e. respiration aerobic anaerobic fermentation chemolithotrophy • Mitochondria origin in the context of Earth geochemistry changes

Cytology - Prokaryotic & Eukaryotic cells comparison

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

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

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

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

Eukaryotic cells origin theories - ox-tox hypothesis

Eukaryotic cells origin theories - hydrogen hypothesis

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

(facultative) Anaerobic mitochondria • Unicellular protists & Metazoa: Ciliates nitrate, nitrite Fungi nitrate, nitrite, sulfur Nematodes fumarate Plathelminths fumarate Snails fumarate Bivalves fumarate anaerobic respiration Chemolithotrophic mitochondria • Metazoa: Bivalves Polychaete worm Crustaceans chemolithotrophy – inorganic electron donor (S 2 -, HS-, H 2 S)

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

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

(facultative) Anaerobic mitochondria – Fasciola hepatica

Anaerobic mitochondria / Hydrogenosome – Nyctotherus ovalis

Hydrogenosome – Piromyces sp. E 2

Mitosome – Giardia intestinalis

Earth history - Geological Time. Scales eukaryotes origin P - Pleistocene Holocene

Geochemical history of Earth – atmosphere oxygenation eukaryotes origin

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

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

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

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

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

Metabolically flexible mitochondria – Arenicola marina

Take home messages: • Eukaryotes and Mitochondria • Mitochondria: O 2 aerobic oxidative phosphorylation anaerobic chemolithotrophic hydrogenosomes – not uniform mitosomes • 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

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