Posted: Mar 12, 2010 2:35 pm
So, I submitted this list of steps in contemporary origin of life research :
It seems to me, from what I have gathered over the last 6-12 months of interest in the subject, that a number of steps have been presented as being abiotically plausible, and a number are undergoing active research. I will list them here and anyone is free to comment and tell me I misunderstood something:
As I understand the current model, scientists are trying to identify a number of abiotically plausible steps resulting in a protocell capable of undergoing Darwinian evolution. The protocell is basically a lipid bilayer vesicle(membrane of fatty acids) containing some form of simple genetic material. So, in order to demonstrate that this protocell can come about by natural means, scientists are working on showing how the individual constituents of the cell could naturally form and come together to form the final product.
As I understand it, the following steps have been demonstrated so far : (Steps in orange are subjects I haven't yet read much on and red are subjects which have not yet been satisfyingly demonstrated to occur under abiotic conditions).
1. Abiotic formation of fatty acids.
Initial indications of abiotic formation of hydrocarbons in the Rainbow ultramafic hydrothermal system, Mid-Atlantic Ridge, Nils G. Holma, , and Jean Luc Charloub.
2. Abiotic Fatty acid concentrating mechanics resulting in the formation of bilayer vesicles.
Extreme accumulation of nucleotides in simulated hydrothermal pore systems.
Philipp Baaske*, Franz M. Weinert*, Stefan Duhr*, Kono H. Lemke†, Michael J. Russell‡, and Dieter Braun*§
Formation of Protocell-like Vesicles in a Thermal Diffusion Column
Itay Budin,†,§ Raphael J. Bruckner,‡,§ and Jack W. Szostak*,§
Mineral Surface Directed Membrane Assembly
Martin M. Hanczyc & Sheref S. Mansy & Jack W. Szostak
3. Abiotic formation of Varying nucleotides * (Much depends on the type of nucleotides, I think the formation of Ribonucleotides have been pretty sufficiently demonstrated).
I'm not going to cite all the papers I have found on this, but propably most important is the classic contention that RNA cannot form because Ribose is not abiotically plausible. This has been demonstrated to be false:
Alkaline fluid circulation in ultramafic rocks and formation of nucleotide constituents: a hypothesis.
Nils G Holm*, Marion Dumont, Magnus Ivarsson and Cécile Konn.
4. Abiotic nucleotide concentrating mechanics resulting both in formation of oligomers and areas of high concentration of single nucleotides.
Extreme accumulation of nucleotides in simulated hydrothermal pore systems.
Philipp Baaske*, Franz M. Weinert*, Stefan Duhr*, Kono H. Lemke†, Michael J. Russell‡, and Dieter Braun*§
5. Ability of the bilayer vesicle to *ingest* nucleotides under abiotic conditions.
Semipermeable lipid bilayers exhibit diastereoselectivity favoring ribose.
M. G. Sacerdote* and J. W. Szostak†
Experimental Models of Primitive Cellular Compartments: Encapsulation, Growth, and Division
Martin M. Hanczyc,* Shelly M. Fujikawa,* Jack W. Szostak†
6. Ability of bilayer vesicle to grow/split under abiotic conditions.
Coupled Growth and Division of Model Protocell Membranes. Ting F. Zhu†,‡ and Jack W. Szostak*,†
Now this is where it gets intersting and where to my knowledge most of the research is being done today:
7. Demonstrate ability of nucleotide-containing vesicle to develop increasingly complex nucleotide polymers.
8. Demonstrate ability of nucleotide-polymers to evolve into self-replicators. This has not yet been demonstrated.
9. Demonstrate ability of nucleotide-containing vesicle to reproduce with copies of genetic polymer. So haven't this.
From what I have gathered reading the most recent of the Szostak lab's papers, they are currently exploring alternative nucleotides (ignoring their abiotic plausibility) like DNA, TNA and LNA in order to better understand what is required to reach the goal of an abiotically plausible self-replicator.
It seems to me, from what I have gathered over the last 6-12 months of interest in the subject, that a number of steps have been presented as being abiotically plausible, and a number are undergoing active research. I will list them here and anyone is free to comment and tell me I misunderstood something:
As I understand the current model, scientists are trying to identify a number of abiotically plausible steps resulting in a protocell capable of undergoing Darwinian evolution. The protocell is basically a lipid bilayer vesicle(membrane of fatty acids) containing some form of simple genetic material. So, in order to demonstrate that this protocell can come about by natural means, scientists are working on showing how the individual constituents of the cell could naturally form and come together to form the final product.
As I understand it, the following steps have been demonstrated so far : (Steps in orange are subjects I haven't yet read much on and red are subjects which have not yet been satisfyingly demonstrated to occur under abiotic conditions).
1. Abiotic formation of fatty acids.
Initial indications of abiotic formation of hydrocarbons in the Rainbow ultramafic hydrothermal system, Mid-Atlantic Ridge, Nils G. Holma, , and Jean Luc Charloub.
2. Abiotic Fatty acid concentrating mechanics resulting in the formation of bilayer vesicles.
Extreme accumulation of nucleotides in simulated hydrothermal pore systems.
Philipp Baaske*, Franz M. Weinert*, Stefan Duhr*, Kono H. Lemke†, Michael J. Russell‡, and Dieter Braun*§
Formation of Protocell-like Vesicles in a Thermal Diffusion Column
Itay Budin,†,§ Raphael J. Bruckner,‡,§ and Jack W. Szostak*,§
Mineral Surface Directed Membrane Assembly
Martin M. Hanczyc & Sheref S. Mansy & Jack W. Szostak
3. Abiotic formation of Varying nucleotides * (Much depends on the type of nucleotides, I think the formation of Ribonucleotides have been pretty sufficiently demonstrated).
I'm not going to cite all the papers I have found on this, but propably most important is the classic contention that RNA cannot form because Ribose is not abiotically plausible. This has been demonstrated to be false:
Alkaline fluid circulation in ultramafic rocks and formation of nucleotide constituents: a hypothesis.
Nils G Holm*, Marion Dumont, Magnus Ivarsson and Cécile Konn.
4. Abiotic nucleotide concentrating mechanics resulting both in formation of oligomers and areas of high concentration of single nucleotides.
Extreme accumulation of nucleotides in simulated hydrothermal pore systems.
Philipp Baaske*, Franz M. Weinert*, Stefan Duhr*, Kono H. Lemke†, Michael J. Russell‡, and Dieter Braun*§
5. Ability of the bilayer vesicle to *ingest* nucleotides under abiotic conditions.
Semipermeable lipid bilayers exhibit diastereoselectivity favoring ribose.
M. G. Sacerdote* and J. W. Szostak†
Experimental Models of Primitive Cellular Compartments: Encapsulation, Growth, and Division
Martin M. Hanczyc,* Shelly M. Fujikawa,* Jack W. Szostak†
6. Ability of bilayer vesicle to grow/split under abiotic conditions.
Coupled Growth and Division of Model Protocell Membranes. Ting F. Zhu†,‡ and Jack W. Szostak*,†
Now this is where it gets intersting and where to my knowledge most of the research is being done today:
7. Demonstrate ability of nucleotide-containing vesicle to develop increasingly complex nucleotide polymers.
8. Demonstrate ability of nucleotide-polymers to evolve into self-replicators. This has not yet been demonstrated.
9. Demonstrate ability of nucleotide-containing vesicle to reproduce with copies of genetic polymer. So haven't this.
From what I have gathered reading the most recent of the Szostak lab's papers, they are currently exploring alternative nucleotides (ignoring their abiotic plausibility) like DNA, TNA and LNA in order to better understand what is required to reach the goal of an abiotically plausible self-replicator.