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1 Fossils of Cyanobacteria in CI1 Carbonaceous Meteorites Hoover, R.B., Journal of Cosmology, 2011, Vol 13 Talk by Essl Noah on May. 6, 2011 in the Seminar "Schwerpunktseminar Astrobiologie: Habitabilitätskriterien von (Exo-)planeten" 1 Carbonaceous Chondrites - CI Group Or Ivuna-like, Ivuna, Tanzania; 1938 Apperance: → „Small, black, friable, tarlike, looks like charcoal“ Components: → Contain water, carbon, Mg/Si ratio near solar values → Complete absence of chondrules and refractory inclusions → ~20% indigenious water, hydration on parent bodies (t<50°C) → crystals of olivine, pyroxene, elemental iron, presolar diamonds, graphite, insoluble organic matter similar to kerogen Facts: → Extremely rare, 9 out of ~35.000 Meteorites → 5 observed falls, collected directly after fall 1 Falls Name Alais Orgueil Ivuna Date 3/15/1806 5/14/1864 12/16/1938 Mass Weak Biomarkers Strong Biomarkers 6kg Carbon, Water, Clay Minerals, Organic Matter, humus and liguite with Odor of Bitumen, SulphHydrocarbhons, Petroleum like Hydrocarbons, Aliphatic and Aromatic Hydrocarbons, PAH Porphyrins, Pristane, NorPristane, Phytane, Nitrogen Heterocycles and Nucleobases – Purines and Pyrimidines, Filamentous Microfossils, Trichomic Prokaryotes and Cyanobacteria Organic Matter, humus, peat and liguite coal and clay minerals, Amino Acids, Normal Alkanes, „Orgenized Elements“, Microvessicles Long-Chain Fatty Acids, Isoprenoids, Kerogen, Porphyrins, Pristane, NorPristane, Phytane,Protein Amino Acids with Enantiomeric Excess, Nitrogen Heterocycles and Nucleobases – Purines and Pyrimidines, Filamentous Microfossils, Trichomic Prokaryotes and Cyanobacteria Petroleum like Hydrocarbons, Aliphatic and Aromatic Hydrocarbons, PAH Porphyrins, Pristane, NorPristane, Phytane,Protein Amino Acids with Enantiomeric Excess, Nitrogen Heterocycles and Nucleobases – Purines and Pyrimidines, Filamentous Microfossils, Trichomic Prokaryotes and Cyanobacteria 14kg 705g 1 Alais Orgueil J.J. Berzelius (1836): „I was so suspicious, because the meteorite containes water that I was about to throw away my sample.“ „in water it disintegrates instantaneously to a greyish-green powder which has an odor reminding one of fresh hay“ Ivuna δ¹³C aprox. +60 per mil. = unlike any terrestrial C Excludes contamination M. Leymerie(1864): „the broken surface reveals a dark charcoal colored substances so soft that it can be easily cut with a knife. Fragments placed in water disintergrate immediately.“ Tonk & Revelstroke No data yet been published about organic chemistry, only mineralogic research so far 1 Methods Used: FESEM – Field Emission Scanning Electron Microscopy Resolution down to 1,5 nm ESEM - Environmental Scanning Electron Microscope For vacuum instabile samples EDS - Energy Dispersive X-Ray Spectroscopy Requirements: → uncoated, freshly fractured, interior surfaces → all tool, sample holders, stubs were flame sterilized → samples sealed at -80°C → all solvents, acids or liquids avoided 1 Images and EDS-Spectra of Filaments in Ivuna CI1: FESEM-Image of thin unserate filament, flattend on the left, zylindrical in the lower part, embedded in the meteorites matrix → Rich in C, Mg and S, depleted in N → Enceased with carbonacous sheath → EDS-Data for (1) and (3) ← Permineralized remains of ensheathed trichomic Prokaryote Similar bacteria: Spirulina subtilissima Spirulina laxissima Chloroflexus aurantiacus 1 Images and EDS-Spectra of Filaments in Ivuna CI1: → length, diameter and spiral form also found in FESEM images of Titanospirillum Velox → extremophile, genus not yet validly Published Bacteriological Code Rules: Procaryotic microorganisms must be isolated and grown in pure culture in two international culture collections and two different countries 1 Sheath 1 EDS-Spectra of Ivuna CI1 Mineral matrix 1 Images and EDS-Spectra of Filaments in Orgueil CI1: Numbers 1 – 12 are fossil filaments Nr.7 is the only one with N (1%) and P (0,8%) EDS-Spectra from all filaments and the meteorite matrix 1 Relative concentration Bright in O, C, Mg, S dark in Si, Fe, Ni Shows the elemental Abundance SED-Image → Secondary Electron Detection BSED-Images → BackScattered Electron Detection 1 Images and EDS-Spectra of Filaments in Orgueil CI1: Filament 1 & 2: → Sheaths with longitudinal strations → characteristics of multiseriate trichomic prokaryotic filaments → attached or physically embedded in the stones matrix → bundles of parallel trichomes → CW: cross-wall strictions, indicate cell size of ~4µm → interpretations constist with morphotypes of undifferentiated filamentous cyanobacteria (Oscilliatoriacea) 1 Images and EDS-Spectra of Filaments in Orgueil CI1: Filament 3 & 4 may be interpreted as Trichocoleus Agnostidis Filament 4: → hookshaped, 2µm diameter, narrowed terminus → several species of Trichocoleus match this criteria 1 Images and EDS-Spectra of Filaments in Orgueil CI1: 9: collapsed 10: hollow, flattened, twisted and folded sheath Spiral coil near the base of Nr. 10 is similar to Phormidium Stagninum Often seen in other Cyanobacteria → No diagnostic feature www.cyanodb.cz/ db/Phormidium/ Phormidium.jpg 1 Images and EDS-Spectra of Filaments in Orgueil CI1: Filament 11: tapered and hooked form, cell or calyptra in the apex 1 Images and EDS-Spectra of Filaments in Orgueil CI1: 1 Filaments in Orgueil with differentiated heterocysts: → Heterocysts used by several cyanobacteria of Nostocales and Stignometales for Nitrogen fixation → unambiguous biological process that is crucial to life on Earth → reduces nitrogen molecules (N2) to ammonia, nitrates or nitrogendioxide → higly specialized cells to encapsulate the nitrogenase enzyme in thick-walled protective heterocysts → only found in Nostocales and Stigonematales 1 Filaments in Orgueil with differentiated heterocysts: 1 Filaments in Orgueil CI1 → modern cyanobacteria do not actively grow in dry state → Orgueil meteorite is destroyed when put in water → no Orguiel meteorite sample was in a pool of liquid water needed for growth of large photoautotriphic cyanobacteria → interpreted as indigenious remains of microfossils that were present on the meteorite rock when it entered Earths atmosphere → living and dead cyanobacteria are usually damaged by the FESEM-Beam, but Orgueil filaments were not. → C/N and C/S ratio similar to fossiled material and kerogen but different from living biologic matter 1 Nitrogen in fossils and living bacteria → Meteorites depleted in N → Living forms: 2% - 15% → even detectable in mummys and pleistocene mammoths → trilobites and cyanobacteria fossils also do not show Nitrogen 1 Amino Acids In Living Bacteria, Fossils And Meteorites 1 Comets as parent bodies Possible sources: → CI1 are jet black and contain extraterestrial water → same as many comets → comet temperature: - IKS-Vega data → nucleous of Halley at 420 +/- 60K at 0,8 AU - nucleous of 19P/Borelly at ~345K → cometary outflow: ISO found that Halle-Bopp released water vapor, carbon monoxide and carbon dioxide at a rate of 2 x 10⁹ kg/sec 1 Comments from other scientists - No logic reason nor proof that life started on Earth - there is definitely no contamination - Wickramasinghe: cometary particles found in atmosphere with fossils and even living bacteria - between first planets in universe and formation of earth lies 6 Gyr with higher SNe rate. Cyanobacteria can resist higher radiation then present on earth. - At 81P (Comet) were found PAH, Olivine and CAI (Ca-Al-Inclusions) => great mixing of material in protoplanetary disk - not only CI and CM bur even normal chondrites were sampled 1 Comments from other scientists - we should concentrate research the origin of the structure - the paper itself is rich in information, but it is not presented well - existing pictures that would have prooven the facts better were not used - life will not have evolved from a single cell (on Earth) and Archea and Eukaryotes must have come from space too - possibly a remnant of prior impact on earth - focus on thermosynthesis and temperatur gradients - CI1 and ALH84001 have same isotopic ratio → CI1 from Mars as well? - Nitrogen can not be seen really good with SED, maybe use other instruments? (contamination argument) 1 Comments from other scientists - In terms of morphology, several structures could be said to resemble abiogenic ambient inclusion trails (AITs), commonly mistaken for cyanobacterial microfossils, including by Hoover and his colleagues. Such AITs are formed by the forward projection of minerals under gaseous pressure through a solid or liquid medium. Schwerpunktseminar Astrobiologie: Habitabilitätskriterien von (Exo-)planeten Questions? X