Sponges: Chondroclada lampadglobus Size: up to 50 cm high with inflated spheres 3‐5 cm in diameter Distribu-on: East Pacific Rise (178S, 23°S, 13°N) Biolog y: rooted in sediments near vents or on pillow basalts but not near to the animals communiJes. Carnivorous mode of feeding
Abyssocladia sp. From Lau Back‐Arc Basin; also found on the East Pacific Rise(carnivorous, up to 40 mm high
Carnivorous sponge (Demospongiae) is 8‐10 cm high and found at 1000 m depth off of New Zealand along the Rim of Fire rooted on basalt. The lip‐shaped spicules covering the outside of the sponge are like sJcky Velcro and catch prey such as crustaceans that brush against them. Without a mouth or stomach, the cells of the sponge stream towards the prey and engulf its flesh, each cell digesJng a Jny part of the prey
41 st Saas‐Fee course from Planets to Life 3‐9 April 2011 Lecture 4: The “top down” approach to understanding the origin of life – cont. • Microbes in low nutrient environments (oligotrophic environments) • MulJcellular animal that grows in the absence of oxygen and in 36% brine – The nature of the mitochondria and related organelles • Origin of life 1
Heterotrophic life in low nutrients – oligotrophic organisms • The most common bacteria in the open ocean and in remote lakes (alpine) grow on microgram levels of organic nutrients (this group of microbes are the reason we are interested in Lake Vostok as an analoque environment to icy moons with liquid oceans) • There are other microbes that grow on CO, CH 4 and just recently a microbe was isolated that grows on hydrocarbons in the absence of oxygen
Examples of oligotrophic bacteria SAR11 now named Pelagibacter ubique is stained with DNA stains. P. ubique is the most numerous bacterial species in the Caulobacter crescentus dividing into world esJmated to be 10 28 cells . This a stalk daughter cell (top) and a bacterium grows on µM levels of organic mo6le daughter cell with a flagellum compounds and is inhibited by high (bo:om); Caulobacter and related concentraJons. It can eat DMSO and has a organisms grow in disJlled water proteorhodopsin (derives some energy agached to walls of the container from light) Scale bar is 1µm
The first anaerobic metazoan First – why do metazoans like oxygen? a) the mitochondria
Mitochondria A mitochondrion (plural mitochondria) is an organelle found in most eukaryoJc cells. Mitochondria are someJmes described as "cellular power plants," because their primary funcJon is to convert organic materials into energy in the form of ATP via Mitochondria structure: the process of oxidaJve phosphorylaJon. 1) Inner membrane Usually a cell has hundreds or thousands of 2) outer membrane mitochondria, which can occupy up to 25 3) Crista (internal percent of the cell's cytoplasm. compartments) 4) Matrix (matrix contains hundreds of enzymes, ribosomes, the mitochondrial genome, and the TCA cycle)
Biochemistry textbooks depict mitochondria as oxygen‐dependent organelles, but many mitochondria can produce ATP without any oxygen. In fact, several other types of mitochondria exist and they occur in highly diverse groups of eukaryotes‐ proJsts as well as metazoans – and possess an ooen overlooked diversity of pathways to deal with the electrons resulJng from carbohydrate oxidaJon. These anaerobically funcJoning mitochondria produce ATP with the help of proton‐pumping electron transport, but they do not need oxygen to do so. Recent advances in understanding of mitochondrial biochemistry provide many surprises and furthermore, give insights into the evoluJonary history of ATP‐ producing organelles.
Brine pool in the Gulf of Mexico Selected geochemical characteris-cs of the LocaJon of deep‐sea anoxic L’Atalante deep hypersaline anoxic basin hypersaline lakes in the Depth 3499 m Eastern Mediterranean Sea Brine layer depth 400 m Salinity 366 0 / 00 Temperature 14.3°C Hydrogen sulfide 2.9 mM Methane 0.52 mM Ammonium 3.0 mM
The phylum Loricifera Lorucufera (laJn, Lorica, corset + ferre , to Light microcopy image of an bear); small (100 µm‐1mm)marine sediment‐ undescribed species of dwelling animals with 22 described species in Spinoloricus that is living in the 8 genera and at least 100 more species not described. They agached themselves to anoxic L’Atalante basin in the sediments. The animals have a head, mouth Mediterranean Sea. Stained with and digesJve system. There is no circulatory Rose Bengal. Size bar is 50 µm system, and a relaJvely large brain. They have spiny heads, separate sexes and have a larval stage.
Evidence that the L’Atlante Loricifera grow in the absence of oxygen • Live stains • Electron microscopy and con‐focal microscopy – No mitochondria • Biochemical analyses • Isotope uptake (leucine)
No evidence of agached microbes – would be the case if the animals were dead
IncorporaJon of Cell‐Tracker Green CMFDA by loriciferans from the anoxic sediments of the L‐Atalante basin. Series of confocal laser microscipy images across different secJons of the body volume of the loriciferans. SecJons 1‐21 represent the progressive scanning of the loriciferans from the inner to the outer part of the body. (a) Cell‐ Tracker Green treated loriciferans, and (b) Loriciferans killed by freezing prior to Cell‐ Tracker Green treatment and used as the control (Danovaro et al., BMC Biol 2010)
Electron micrographs of the internal body of loriciferans from the deep hypersaline anoxic L’Atalante basin. Illustrated are (a) a hydrogenosome‐like organelle; (b) hydrogenosome‐like‐organelle with evidence of a marginal plate; (c) a field of hydrogenosome‐like organelles; (d) the proximity between a possible endosymbioJc prokaryote and hydrogenosome‐like organelles; (e‐f) the presence of possible endosymbioJc prokaryotes. Scale bars, 0.2 µm; H is hydrogenosome; P is possible endosymbioJc prokaryote; M is marginal plate
Mitochondria Hydrogenosomes Mitosomes
Model of ATP‐synthesis in hydrogenosomes Hydrogenosome is a membrane‐enclosed organelle of some anaerobic ciliates, trichomonads and fungi. The hydrogenosome of the trichomonads contain prokaryotes and produce hydrogen, acetate, carbon dioxide and ATP by the combined acJons of puruvate:ferredoxin oxido‐reductase, hydrogenase, acetate;succinate VoA transferase and succinate thiokinase. Superoxide dismutase, malate dehydrogenase, ferredoxin, adenylate kinase and NADH:ferredoxin oxido‐reductase are also localized in the hydrogenosome. This organelle is believed to have evolved from anaerobic archaea although this is not a segled issue.
Summary of “extreme” life • Only high (max temp. unknown) low temperatures (probably <‐20°C) and the absence of sufficient water, prevent growth of organisms • Microbes can uJlize a wide range of inorganic and organic compounds and elements as energy sources (with and without oxygen) • Microbes have adapted to grow in ultra low levels of key organic and inorganic nutrients • MulJ‐cellular animals have been shown to grow at 50°C and in the absence of oxygen (new findings) • It is very likely that there are planetary bodies, and parJcularly icy moons with oceans that can support Earth life – the quesJon is acquiring such life It is very likely that there are planetary bodies, and parJcularly icy moons with oceans that can support Earth life – the quesJon is acquiring such life
41 st Saas‐Fee course from Planets to Life 3‐9 April 2011 Lecture 4 ‐ Origin of Life and its Early EvoluJon on Earth
Outline • Some history • When and where did life originate? • How did life originate? • Would an understanding of the “when” and “how” quesJons help constrain the seungs (where) for the origin of life? • What did the earliest life look like?
The origin of life: A historical perspecJve • Spontaneous generaJon: Organic life could and does arise from inorganic mager (generally agributed to Anaximander (Milesian philosopher) in the 6 th and 5 th centuries before Christ. • Aristotle (384‐322 BC) life arose from the 4 elements: earth, air, fire and water. Since Aristotle denied that the universe, and the earth, had a beginning, life occurs all of the Jme. • The idea of spontaneous generaJon persisted into the 19 th century with mulJple recipes for making life (wheat and wet rags in an open jar will produce mice in 21 days) – lots of recipes for making maggots and other animals that like putrafaceous
The end of “spontaneous generaJon” or not? While there is a rich history of discussion of spontaneous generaJon in the 17 th to 19 th centuries, much of the ideas centered around the “abiogenesis” of animals. ScienJsts in the 17 th century (Francisco Redi) and 18 th century (Lazzaro Spallanzani and John Needham) performed experiments with open and closed containers showing that animals did not appear in the closed containers. The definiJve experiment was performed by Louis Pasteur in 1859. illustraJon of the Swan‐necked bogle used in Pasteur's experiments to disprove spontaneous generaJon
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