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Virus Fossils

Virus Fossils. James Laidler. History of Prokaryotic Fossils. Walcott 1915 - Pre-Cambrian cyanobacteria (~ 600 - 700 Mya) Tyler and Barghoorn 1954 - Pre-Cambrian cyanobacteria (~ 1.9 Gya) Schopf and Packer 1987 Early Archaean (3.3 - 3.5 Gya) Oldest rocks - 3.85 Gya

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Virus Fossils

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  1. Virus Fossils James Laidler

  2. History of Prokaryotic Fossils • Walcott 1915 - Pre-Cambrian cyanobacteria (~ 600 - 700 Mya) • Tyler and Barghoorn 1954 - Pre-Cambrian cyanobacteria (~ 1.9 Gya) • Schopf and Packer 1987 Early Archaean (3.3 - 3.5 Gya) • Oldest rocks - 3.85 Gya • Earth cool enough for liquid water - ~4 Gya

  3. Schopf JW (2006) Fossil evidence of Archaean life. Phil. Trans. R. Soc. B. 361:869-885

  4. Schopf JW (2006) Fossil evidence of Archaean life. Phil. Trans. R. Soc. B. 361:869-885

  5. History of Viral Fossils

  6. Can Viruses Fossilize? • Viruses used as templates • Metalization • Mineralization • Form recognizable tubes • Carbon from virus detectable by EDXS • No environmental examples…yet

  7. Silicate Reactions • Polymerization occurs at neutral pH and higher • Bind strongly to amine groups at low pH - enhanced by proton pump activity • Al and Fe accelerate the process • Other metals (Pb, Cd, Cr, Cu, Zn) also accelerate the process

  8. Silicate Reactions with Organic Matter Phosphate residues R - PO3 - OH + Si(OH)4 = R - PO3 - O - SiO2 - OH + H2O Carboxyl residues R - COOH + Si(OH)4 = R - CO - O - Si(OH)3 + H2O Alcohol residues R - CH2 - OH + Si(OH)4 = R - CH2 - O - Si(OH)3 + H2O

  9. Experimental Plan:Benchside • Incubate TMV and SIRV in neutral silicate solution • Incubate TMV and SIRV in acidic silicate solution in presence of Fe and/or other metals • Examine for silicified virus particles by TEM • Imbed and section specimens and examine with EDXS for carbon signature

  10. Why TMV and SIRV? • Both TMV and SIRV are uniform in size and shape (TMV is used as a size standard) • Simple shapes (cylinders) not seen in nature • TMV is widely used for a template in nanotechnology • SIRV is found in acidic hot springs • No good candidate (yet!) for neutral hot springs (most are head-tail phages)

  11. 23nm 830nm SIRV1

  12. 18nm 300-310nm TMV

  13. Experimental Plan:Fieldwork • Collect silicate sinter at high-silica, low pH hot springs (e.g. BSL) • Collect silicate sinter at high-silica, neutral pH hot springs (e.g. MHS/GHS) • Examine under TEM for formations suggestive of viruses • Section and examine for carbon and phosphorus signature by EDXS • Publish the world’s oldest known viral fossils

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