Jobar

I was talking to a woman who I have known since we were both in first grade, a loooong time ago. She is a fundie, and happened to see a book by Carl Sagan on my desk; she commenced to bad-mouthing him as "that scientist fellow who is always talking about evolution, and saying there is no God." Needless to say, she was quite shocked when I told her I had been an atheist for most of our lives, and was a moderator here.

After the gasping, the self-righteous anger, and me assuring her that no I *wasn't* bullshitting her, she starts asking me many predictable questions, one of which was how evolution explained that life began. So I tried to explain about abiogenesis, and realized that aside from the classic Miller-Urey experiment, I am woefully ignorant of any modern work on the subject. In hopes of alleviating this lack, I ask the many experts here- what is the present status of abiogenesis research? Are there any projects using some type of energy input other than electrical discharges? Has anyone tried a much bigger reaction vessel than Miller used, and let it run for much longer? It seems to me that something like this would be a sure path to scientific fame, if it was pursued correctly.

Doubting Didymus

Here is a talkorigins post of the month outlining some current developments in abiogenesis. It's not very specific, but it's a good start.

WinAce

What's the lowdown on Sydney Fox's protocells? I haven't seen any scientific mention of them outside of a few webpages referred to by lucaspa on ChristianForums, one of the most scientific posters. Then again, creationists seem to avoid them like the plague =)

Doubting Didymus

Slap me roughly if i'm wrong, but I think protocells need RNA, or DNA, as a starting point? Because of that, a lot of abiogenesis research has focused on the origins of RNA, particularly trying to get RNA to replicate.

NOTE: these statements are made tentatively and do not neccessarily represent the IIDB or its administrators.

Darwin's Beagle

SLAP Actually Fox's point was that metabolism does not require a genome.

Fox showed that amino acids could form polymers (he actually referred to them as "proteinoids") which would form cell-like structures. These protocells would take up other amino acids and grow. Once they reached a certain size, they would bud off from the mother protocell to form daughter protocells. These protocells would catalyze certain reactions and would even fire action potentials like nerve cells.

Thus, Fox claimed to have produced cells that grew, had a metabolism, reproduced and responded to environmental stimuli. Some textbooks use just these criteria to define life and I guess if you do use that definition then life HAS been created in the test-tube.

I would not get too excited about it however, since it's definitely NOT life as we know it. There is absolutely nothing in these protocells that functions in an analogous manner as does DNA.

There Fox's work has stalled. The problem is how to get genetic material into these protocells. However, some groups have had some promising resuts with PNAs (peptide nucleic acids). I believe they have shown some PNAs can act as templates.

Doubting Didymus

Thank you, may I have another?

I didn't think they did. RNA is hardly a genome when it isnt encoding anything. I just thought that these protocells were what you got when RNA grows itself that little lipid membrane. I may be off the mark.

Hmm. Problem there is that they wouldn't really replicate. That is, the "child" protocell is not going to be an exact copy of the parent protocell. That would make mutation accumulation a bit tricky.

Yes? Templates for what? Do you have any references?

Darwin's Beagle

DD==

quote:
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Actually Fox's point was that metabolism does not require a genome.
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I didn't think they did. RNA is hardly a genome when it isnt encoding anything. I just thought that these protocells were what you got when RNA grows itself that little lipid membrane. I may be off the mark.

DB=

A little off the mark. Fox was one of the first "protein firsters". He believed that it was proteins (or more correctly, proteinoids) NOT nucleic acids were the first important molecules in living systems.


DD==
Hmm. Problem there is that they wouldn't really replicate. That is, the "child" protocell is not going to be an exact copy of the parent protocell. That would make mutation accumulation a bit tricky.

DB=
You are correct in that the child protocells would be not have any sequence similarity beyond the fact that amino acids are used in both cases. Yet the protocells as they "grow" (ie. take up and incorportate new amino acids), new protocells do bud off. Actually, since there is no fidelity in replication, mutations would build up VERY rapidly. My personal opinion is that selection would be for molecules that have the longest survival time.

quote:
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There Fox's work has stalled. The problem is how to get genetic material into these protocells. However, some groups have had some promising resuts with PNAs (peptide nucleic acids). I believe they have shown some PNAs can act as templates.
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Yes? Templates for what? Do you have any references?

DB=
Uh-oh, the problems of doing posts from memory. Let me check a few things

Here is a good site in which Fox summarizes his work.

Going through my reference list I find the following to be of probable interest:

Bohler C, Nielsen PE, Orgel LE. (1995). Template switching between PNA and RNA oligonucleotides. Nature. 376(6541):578-81.

and

Nelsen PE. (1993). Peptide nucleic acid (PNA): a model structure for the primordial genetic material? Orig Life Evol Biosph. 23(5-6):323-7.

Hope this helps you get started.

DB

mfaber

I'm not an expert biochemist, but here's my two centavos worth. Hope it helps.....

Here is what abiogenesis or spontaneous creation (it was an "RNA world") is all about in this animated lecture series from the School of Chemistry, University of Oxford, England: {You will need plug-ins for viewing animations and molecules..... can get by without it, but that's up to the reader}

Abiogenesis/The Prebiotic World and the Evidence(Oparin/Haldane Theory)

The RNA-World/Oparin-Haldane Theory

RNA is the only known macromolecule that can both encode genetic information and also act as a biocatalyst. RNA molecules that perform enzymatic functions (biocatalysts) are called ribozymes. One of the most interesting of these ribozymes was discovered by Tom Cech when he discoved a self-splicing RNA in the single celled organism Tetrahymena thermophila. This RNA splice out it's own introns WITHOUT the assistance of proteins.

A demonstration of Cech's ribozyme go to this WEBSITE and click on the links under the subsection entitled Group I Intron Splicing

HERE (pdf file) is Cech's lecture to the Nobel Laureate Committees on this discovery (Nobel Prize for chemistry 1989)that gives both a diagram of the splicing and his original research.

The observation of the above forms the basis for the 'RNA world' model which suggests that both the genetic and enzymatic components of early cells were RNA molecules. There are some problems with the "RNA-world":

• Making the sugar ribose under prebiotic conditions is problematic (it is unstable, in equilibrium with other anomeric forms, etc.) .
• Prebiotic conditions make it difficult to make nucleosides
• The phosphate chemistry utilized to activate RNA nucleotides in present-day living systems is not viewed as feasible under the primitive conditions of the pre-biotic world. However, nucleotide activation can also be based on imidazole chemistry, so this is not an insoluble problem.
• The 4 bases have to be joined to the sugar ribose, which under natural conditions is unstable. As of now, the only techniques discovered for joining the bases to ribose result in low yields, something unsuitable for the RNA world scenario.
• Polymerization of the nucleotides into RNA would have been a problem (assembling them so that they actually contained "information").
• The temperature of a primitive Earth would have made it difficult for RNA (once assembled) to remain stable.

Does this mean "curtains" for the RNA world scenario? NO. RNA could have "evolved" from other molecules better able to have withstood the harsh conditions of the prebiotic world. Here are a couple of articles on likely candidates for the "Pre-RNA world".......

1. Leslie Orgel--PNAs as Precursors to an RNA World Orgel and his group at the Salk Institute, studied a compound known as peptide nucleic acid (PNA). PNA has the ability to replicate itself and catalyze reactions but is much simpler than RNA. Orgel et al. demonstrated that PNA can act as a template both for its own replication and for the formation of RNA from its subcomponents. (Orgel, Leslie E. The Origin of Life on the Earth p 77-83 Scientific American, October 1994.)

2. A TNA World? (Synthesis of a chemical relative of RNA as a Possible Candidate for the First Self-Assembling, Self-Replicating Molecules)

IMO, the following quote from Quetzal, on the Self-replicating molecules thread from the EvC forum summed up the situation as it stands for the "Pre-RNA World.......
Anyway, the Oparin-Haldane Theory (the "chemistry" of prebiotic
Earth) , proposed by Oparin and Haldane in 1920 and extensively modified in the 1980s, also made the following predictions:

BASED on the geological evidence documenting the early earth environment, IF the organism referred to as the Universal or Common Ancestor had the following characteristics

• it would have been anaerobic
• t would have been hyperthermophilic and halophilic
• it would have been a chemolithoautotroph, obtaining both energy and carbon from inorganic sources, using H2 or reduced sulfur compounds as electron donors and CO2 or oxidized sulfur as electron acceptors to provide energy and fixing CO2 as their carbon source.

THEN organisms possessing the above characteristics would be found in environments (this planet or other extraterrestrial environments like a early earth--Europa?) similiar to that of early biotic Earth.

Has this prediction been verified (thus verifying the chemical spontaneous generation scenario????--->YES, by discovery of organisms inhabiting "extreme" environments HERE, NOW, on EARTH!!!-->Modern Chemolithoautotrophs

MODERN CHEMOLITHOAUTOTROPHS
These organisms are called "extremophiles" and here are more sites that describe some of them:

Other Extreme Earth Life
"Extremophilic" Archaea

• http://users.rcn.com/jkimball.ma.ult...A/Archaea.html
• http://www.firstscience.com/SITE/ARTICLES/volcano.asp
• http://www.space.com/searchforlife/l...ne_020116.html
  ----Samples of the archaea Sulfolobus shibatae, which lives in environments containing sulfuric acid and magnesium sulfate salts were obtained along with the highly radiation-resistant extremophile Deinococcus radiodurans'

Barotolerant(pressure resistant)organisms in deep sea enviroments (NOTE:75% of all ocean waters are deeper than 1000 meters)

Barotolerant Bacteria Isolated from the Mariana Trench (11,000 meters!) pdf

The existence of these organisms is seen as further evidence for the validity of abiogenesis.

Other Useful Sites:

Quetzal===>Abiogenesis-Or Better Living Through Chemistry (Summary of different hypotheses from EvC Forum)

Revolutionary New Theory For Origins Of Life On Earth(the iron-sulphide crystal hypothesis presented earlier on this forum)

Borel's Law and the Origin of Many Creationist/IDist Probabilities

Lies, #$%@!! Lies, and Statistics, and the Probability of Abiogenesis

THE ORIGIN OF LIFE: ABIOTIC SYNTHESIS OF ORGANIC MOLECULES (simple explanations of the chemistry)

THE ORIGIN OF LIFE: ABIOTIC SYNTHESIS OF ORGANIC MOLECULES

ORIGIN OF LIFE (powerpoint)

Test-Tube RNA

Reflections on a Warm Little Pond

Secular Pinoy

I'm currently debating abiogenesis in another board, and I'd like to ask for some pointers. My xian friend thinks that molecular oxygen in the atmosphere and the appearance of life happened simultaneously (which happened because his god chose to do it). I know that signatures of life can be found to about 3.8 bya, while the so-called oxygen revolution started about 2 bya. Can anyone help me provide evidences for these? Thanks.

bya=billion years ago

DNAunion

DNAunion: Exactly, Sidney Fox's proteinoid microspheres are low down on the list of theories for the origin of life!

The majority of contemporary OOL scientists are dismissive of Fox's exaggerated claims (no wonder he didn't win the Nobel Prize even after his "buddy" nominated him year after year), and they no longer work on proteinoids or proteinoid microspheres - that's why you won't find many recent articles on them.

Proteinoid microspheres don't grow, reproduce, or metabolize in a biological sense. They grow by accretion - when in a saturated solution of proteinoid, free proteinoids (which are created and supplied by the researchers, since neither proteinoids nor proteinoid microspheres can synthesize them) accrete on the proteinoid microspheres and they increase in size (this is unlike cells which manufacture their own constituents and grow from within). Once the proteinoid microspheres get too large, they simply split in two (just like soap bubbles do) or "bud" (don't be fooled by the term - the budding of microspheres is entirely different than the process of budding that yeasts and some other living organisms undergo). And whatever catalytic abilities proteinoids had they were weak, and as far as I know, no one has ever generated a closed metabolism when using only proteinoids (some researchers have ADDED preexisting enzymes to microspheres, but obviously, such experiments are irrelevant to the question of whether or not proteinoids or proteinoid microspheres themselves have a metabolism).

Proteionoid microspheres also lack genetic continuity, so evolution (which some regard as being a required characteristic of life) would be difficult or "impossible".

Finally, any claims that proteinoid microspheres are actual living cells are unfounded and in error.