1. What is adaptation? Noun vs. verb (vs. acclimation) Noun: “…[A] feature is an adaptation for some function if it has become prevalent or is maintained in a population… because of natural selection for that function” (Futuyma, p.355) “… the good fit of organisms to their environment” (Gould & Lewontin, 1979) What adaptation is not: Necessary, perfect, progress, harmonious, moral BIOL E-127 – 9/24/07

2. Origin of life Definition?: Conditions of early earth?:

3. Origin of life Needed components of first organism?:

4. First metabolism? Oparin Ocean scenario:

5. First metabolism? Autocatalytic cycles (Kauffman): (Eigen, 1971)

6. First genetics? Ultimate chicken & egg… Potential answer?

7. How get enclosure, metabolism & inheritance together? One scenario: Lipid world (Segrè & Lancet)

8. Experimental protocells Multiple groups addressing plausibility (Szostak, Rasmussen, Deamer, Luisi) Example: RNA adsorbed to clay & encapsulated into myristoleate vesicles Can replication provide drive for enlargement? (Chen et al., 2004) (Hanczyc et al., 2003)

9. Early history of life Constrained by ~4.6 Gya age of planet (or not?) Types of evidence?

10. Chemical evidence of life Isotopic enrichment in organic matter Banded iron formations (BIFs) (Madigan & Martenko, 2006)

11. New metabolisms with O 2 Global analysis of potential of collective biosphere (Raymond & Segrè, 2006) (Raymond & Segrè, 2006)

12. Sedimentary textures Stromatolites

13. Fossil evidence of life Microfossils in stromatolites: (Schopf, 1983)

14. Fossil evidence of life Microfossils in stromatolites: (Schopf, 1983) Nostoc

15. Fossil evidence of life Microfossils in stromatolites: (Brasier et al., 2002 )

16. Fossil evidence of life Microfossils in stromatolites: (Garcia-Ruiz et al., 2003) (Schopf, 2002)

17. Fossil evidence of life?: ALH84001 (McKay et al., 1996)

18. Molecular fossil evidence of life Eryops OH FOSSIL SKELETON H carbon skeleton with modified stereochemistry membrane biochemical

19. Who is it from?

20. Example molecular fossil: steranes & hopanoids Extract & run on GC-MS Sterols are eukaryotic specific 2-methylhopanoids common in Cyanobacteria (Brocks et al., 1999; Summons et al., 1999)

21. Extra references Brock Biology of Microorganisms, Ch. 11 Brocks et al., 1999. Science 285:1033-1036. Hanczyc et al., 2003. Science 618-622. Huber et al., 2003. Science 301:938-940. McKay et al., 1996. Science 273:924-930. Nisbet & Sleep, 2001. Nature 409:1083-1091. Raymond & Segrè, 2006. Science 311:1764-1767. Segrè et al., 2000. PNAS 97:4112-4117. Summons et al., 1999. Science 400:554-557. Smith & Morowitz, 2004. PNAS 101:13168-13173.

22. When: Wednesday Evening 6:00pm Where: Second floor lounge of Maxwell-Dworkin, 33 Oxford St. On the Harvard Campus Website: http://www.seas.harvard.edu/projects/weitzlab/squishy.html http://www.seas.harvard.edu/projects/weitzlab/squishy.html -------------------------------------------------------------------------------- Sept 26 Irene Chen, Harvard University: Lipid vesicles during the origin of life