1. Virus Fossils
James Laidler

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

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

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

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 nm
TMV

14. 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