Search for Alternative Life Forms on Earth
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00:00
NobeliumWasserwelle <Haarbehandlung>ThermoformingDeterrence (legal)Lecture/Conference
00:34
NobeliumDNS-SchädigungNobelpreis für ChemieDNS-SyntheseSystemic therapyRadioactive decayBase (chemistry)GesundheitsstörungEnzymeButter (2011 film)Hope, ArkansasLecture/Conference
01:58
TanninNobeliumChemistryProcess (computing)LactitolLecture/ConferenceMeeting/Interview
02:56
Silicon Integrated SystemsNobeliumToll-like receptorRiver sourceOrigin of replicationAzo couplingWine tasting descriptorsFunctional groupLecture/ConferenceMeeting/Interview
04:29
NobeliumOrigin of replicationDiatomics-in-molecules-MethodeCell (biology)PatentSpawn (biology)Bottling lineAbiogenesisLecture/ConferenceMeeting/Interview
05:00
MedroxyprogesteroneNobeliumDiatomics-in-molecules-MethodeMedical historyOrigin of replicationStockfishPeriodateErdrutschAbiogenesisNobeliumNecking (engineering)Sodium carbonateRNATelomerisationLecture/ConferenceMeeting/Interview
06:27
NobeliumCell (biology)WaterOrganische ChemieSaltAageRNASolventSolutionNucleic acidAlkaliNucleic acid double helixAcidAntifreezeDNAGlykolsäureSodium chlorideGrowth mediumDNS-SyntheseAzo couplingColourantFreezingClick chemistryNeutralization (chemistry)CHARGE syndromeLecture/ConferenceMeeting/Interview
07:48
Diatomics-in-molecules-MethodeLymphangioleiomyomatosisNobeliumMethyl iodideBET theoryOrigin of replicationDNS-SyntheseCHARGE syndromeChemical structureGlykolsäureWaterHuman body temperatureAbiogenesisStop codonOrigin of replicationFiningsLecture/ConferenceMeeting/Interview
08:58
Origin of replicationLambicStickstoffatomMethaneCobaltoxideDNS-SyntheseRNACell (biology)Cell fusionExplosionMetalProcess (computing)CondensationPH indicatorSystemic therapyTool steelMeeting/Interview
09:56
Origin of replicationNobeliumAlumColumbia RecordsStickstoffatomMethaneCobaltoxideRNADNS-SyntheseCell (biology)Cell fusionBallistic traumaOrganische ChemieProlineDNS-SyntheseProteinLecture/ConferenceMeeting/Interview
10:30
NobeliumOrigin of replicationLymphangioleiomyomatosisAlumColumbia RecordsMedroxyprogesteroneTrace elementCobaltoxideMethanisierungCarbon (fiber)ThermoformingBase (chemistry)ErdrutschGesundheitsstörungStickstoffatomCarbon dioxideWaterLecture/Conference
11:03
Origin of replicationLambicStickstoffatomCobaltoxideMethaneDNS-SyntheseRNACell fusionCell (biology)Cell (biology)Anaerobic organismCobaltoxideBase (chemistry)Organische ChemieWine tasting descriptors
11:36
AlumNobeliumOrigin of replicationGemstoneAmino acidCommon landRadical (chemistry)KohlenhydratchemieNucleic acidNucleotideActive siteMeteoriteRiboseDNS-SyntheseGesundheitsstörungMetalStop codonRubbleTool steelLecture/ConferenceMeeting/Interview
13:42
Mill (grinding)NobeliumOrigin of replicationColumbia RecordsOrganische ChemiePhotosynthesisAbiogenesisCobaltoxideOrigin of replicationLecture/Conference
14:13
Origin of replicationLambicStickstoffatomMethaneCobaltoxideRNADNS-SyntheseCell (biology)Cell fusionOrganische ChemieMan pageCell fusionPrecursor (chemistry)CobaltoxideCell (biology)Maskierung <Chemie>ZunderbeständigkeitElectronic cigaretteConcentrate
16:16
NobeliumOrigin of replicationThin filmSurface scienceLambicPhotosynthesisOrganische ChemieChemical plantMorse-PotenzialLecture/Conference
16:54
LambicOrganische ChemieTopicityThermoformingAttitude (psychology)GenklonierungSurface scienceRock (geology)Intergranular corrosionWine tasting descriptorsBiochemistryNucleic acid sequenceAnaerobic organismSeleniteDNS-SyntheseDeep seaAnaerobic exerciseLecture/ConferenceMeeting/Interview
18:53
RadiumOrigin of replicationNobeliumDNS-SyntheseNucleic acid sequenceRNANucleic acidFreies ElektronIonenbindungAreaLecture/Conference
19:30
RNAIngredientDNS-SyntheseKohlenhydratchemieAreaMeeting/Interview
20:07
NobeliumOrigin of replicationSpawn (biology)Azo couplingLecture/Conference
20:45
SpeciesSpawn (biology)Spawn (biology)WaterDeep seaIslandProcess (computing)Azo couplingProanthocyanidinMeeting/Interview
22:22
NobeliumSpawn (biology)VerwitterungAreaDeathFreezingPH indicatorWhiskyLecture/ConferenceMeeting/Interview
23:39
NobeliumHydro TasmaniaGrowth mediumCell growthGlycerinFormamidMethanolRiver sourceAnaerobic organismHuman body temperatureGesundheitsstörungDiolTurbidityEmission spectrumBase (chemistry)Organische ChemieErdrutschCell (biology)SolventLakeAreaFormamidConcentrateErgussgesteinBiosynthesisSodiumDeep seaGrowth mediumNucleic acidChemical compoundGlykolsäureCell growthGesundheitsstörungDNS-SyntheseRiver sourceIngredientActive siteDNS-abhängige-DNS-PolymerasenSolutionDeterrence (legal)RNAInhibitorLipid bilayerHuman body temperatureWaterfallFreies ElektronCuring (food preservation)HydroxyharnstoffChemistCell membraneBearing (mechanical)Chemical structureSystemic therapyRevenueProteinActivity (UML)Lecture/ConferenceMeeting/Interview
28:21
SolventNobeliumHydro TasmaniaGrowth mediumGesundheitsstörungWine tasting descriptorsAnaerobic organismFormaldehydeColumbia RecordsWaterSetzen <Verfahrenstechnik>Carbon (fiber)SolventDNS-SyntheseSolutionLecture/ConferenceMeeting/Interview
29:21
GraphiteinlagerungsverbindungenPondNobeliumThylakoidMutilationDNS-SyntheseThermoformingLecture/ConferenceMeeting/Interview
29:54
UreaNobeliumSolventChain (unit)Lamb and muttonChiralität <Chemie>ThermoformingAssetDeterrence (legal)Lecture/ConferenceMeeting/Interview
30:34
NobeliumLactoseAlumThermoformingSense DistrictLecture/Conference
31:06
Alkoholische GärungGesundheitsstörungThermoformingLecture/ConferenceMeeting/Interview
31:53
NobeliumColumbia RecordsIceHomocysteineNapalmTrace elementGesundheitsstörungFaserplatteLecture/Conference
32:28
ErdrutschSunscreenOrganische ChemieDNS-SyntheseLecture/ConferenceMeeting/Interview
32:59
NobeliumDNS-SyntheseMethylgruppeFunctional groupProteinElektronentransferCysteineResidue (chemistry)ChemistryStorage tankLactitolActivity (UML)Base (chemistry)MutagenFunctional groupEnzymeMethylgruppeResidue (chemistry)Set (abstract data type)CysteineDeterrence (legal)Active siteSunscreenAbiogenesisDNS-SyntheseBiochemistrySetzen <Verfahrenstechnik>Cell (biology)Systems biologyDNS-SchädigungProteinSystemic therapyGemstoneAgeingMutageneseStress (mechanics)NeotenyLecture/Conference
35:15
NobeliumFatty acid methyl esterPasteur, LouisDNS-SyntheseRNA splicingSense DistrictExciter (effect)Lecture/ConferenceMeeting/Interview
36:25
NobeliumCarbon (fiber)River sourceThermoformingMineral explorationDNS-SyntheseChemistryLecture/Conference
37:06
NobeliumThermoformingCarbon (fiber)Inclusion (mineral)Lecture/ConferenceMeeting/Interview
Transcript: English(auto-generated)
00:14
Hello everyone. Can you hear me in the back? Please wave. Okay, great.
00:21
I don't know how many of you were in the previous session here, a wonderful starting session, but a rather general theme on science. And we will go from the general to the rather more specific search for alternative life forms on Earth. And our Agora talker is Professor Thomas Lindahl.
00:42
And he was awarded the Nobel Prize in Chemistry in 2015, together with Paul Modrich and Asis Sankar, for mechanistic studies of DNA repair. To put this in perspective a little bit, in the early 70s, most people believed that DNA was highly stable under physiological conditions.
01:05
Thomas Lindahl had a different hypothesis, which he tested, and he proved that DNA was indeed very unstable, and there was a decay rate that ought to have made it impossible to develop life on Earth, at least DNA-based life.
01:21
And from that he went on to hypothesize that there should be a repair system for decaying DNA, and he discovered the enzymes of the base excision repair system. And I guess this general interest for very early life is the theme that we are going to discuss today.
01:41
And the session will be done in the following way. Professor Lindahl will speak for about 20-25 minutes, show some slides, and then we have the last 15 minutes as an interactive session, where I hope that all of you will ask questions. I have a few prepared, but I'm hoping for you also. Okay? Please.
02:03
Thank you. I hope you can hear me, otherwise wave. I sometimes get targeted questions from students, and I'm sure the same is true for my fellow laureates here.
02:21
How do you do a really important discovery? That will give me a job and perhaps make me a candidate for a major scientific prize. Well, the answer to that is usually just continue what you are doing.
02:42
If you have had a reasonable mentor and are already working in the field of science, where you can do productive work, publishable work, it's up to you to do something really interesting. But to be really original, you need luck and talent,
03:02
and nobody can say ahead of time how that goes. The strategy I and many of my colleagues have used is that you continue working on what you actually are interested in
03:20
and has been the basis of your career so far, and produce work there which allows you to have a functional laboratory. But what you can do on the side is occasionally little experiments, not big expensive experiments, but things where you just try something on
03:42
because you have an idea. And you have to be aware of that those experiments usually don't work. If you have an original idea, it's original because other people have already tried it and ruled it out as a rule.
04:00
So that is not something you can bet your whole career on, but it's worth trying something on the side, and this is what I've been doing over the years. A couple of times I've actually been lucky and done something that has been of great help to my own career. Other times you struggle with something for a while,
04:22
and then you quietly drop it, and it's important not to be so stubborn that you never drop anything. So that is the kind of project I'll talk about today, sort of an interesting side project. I should perhaps say from the start we don't have any new,
04:43
absolutely spectacular results, so this is a little bit earlier than you usually hear scientific presentations, which you keep relatively quiet about what you are doing until you can come out with some publishable or patentable discoveries.
05:01
I don't have that on the origin of life, but there are things that can be done. So as a background, I've given three references here. If you want to check on where I get this information from, there is a new book that came out just months ago by a historian,
05:22
which I think is pretty good, which is not usual in history. You focus in detail on some important historical period, and what David Christian has done rather successfully, I think, is write a history of everything that has happened. So in my next slide, for example, I show some dates,
05:45
and they come from that book. There is also an online version of that book, which I have put together with Bill Gates. I haven't seen it, but it's supposed to be good. The next reference is to Jack Szostak, who you probably know,
06:04
who had a Nobel Prize with Liz Blackburn for his work on telomeres. He's not here today, but he's a leading scientist, and he has had great interest in the origin of life, especially what happened in the so-called RNA world.
06:25
What we think about life is that it started relatively easily, but as an RNA world, and then it became more complex, and I'll say something about that.
06:42
And the final reference is my own interest in this, something, some old work I did as a graduate student, actually, that I've come back to in recent years, DNA being dissolved in other solvents than water. And there isn't much of a choice,
07:01
because you can't retain the secondary double helical structure of DNA in strong acids or alkali or, obviously, corrosive solvents. It's not a good idea, but there are a couple of solvents where you can actually dissolve DNA and study it. I've done some work on glycol,
07:21
which may be familiar to you as an antifreeze in your car. And that is a solvent you can study, nucleic acids in glycol solution. And what is important when I say glycol solution, water solution, DNA is a salt, so you do need some salt in your medium.
07:42
But sodium chloride is very soluble in both water and in glycol, so that's not the problem. You'll have to neutralize the charges. And I can also say about DNA in glycol, it's stable, the double helical structure is stable up to about 30 degrees,
08:02
which is much less than in water solution, where it's stable up to about 85 degrees. But that means you can work with DNA in glycol at room temperature or in cold room or at lower temperatures, if you so wish. There have been rather few studies on that, actually.
08:24
So let me move on to say something about original life, what we know about it, and just give you some dates here. This is the next slide.
08:43
Let's see. No? One back, I think. Yeah. Original, yeah, fine. Okay, so we start with a big bang. The definition I like is that in the beginning,
09:04
there was nothing which exploded. And then that can lead to a discussion of what you mean by nothing, but we don't have time for that now. And then there was condensation of dust generated in this explosion,
09:26
and the metals were formed, and they then further condensed to our present solar system and many, many other solar systems. And this process was probably completed about 4,500 million years ago.
09:48
And soon after that, surprisingly soon after that, are the first indications of simple life on Earth. So one extrapolation from that result
10:03
is that perhaps life can originate fairly easily because it came up very soon after Earth became a total habitat. On the other hand, we only know about one life form on Earth,
10:20
which is, as you know, DNA instructs RNA, which then codes for protein. And this is the lifestyle that we have. So if there is other forms of life, we don't know about them. What we know is that life originated in an atmosphere
10:48
essentially devoid of oxygen. You can see that on the slide, the nitrogen, carbon dioxide, and traces of methane and water, but there was no oxygen.
11:01
And that's how life arose. So if you want to look for early life forms, it's probably a good idea to do it under anaerobic conditions, which is fairly straightforward. If you have some basic training in microbiology, you can grow cells by the same techniques,
11:23
isolate anaerobic microorganisms like tetanus in the microbiology lab. You just evacuate out the oxygen from the incubator you use.
11:41
So all the experiments I'll talk about have been done in an essentially oxygen-free environment. And then to create life, you need some building stones. And most building stones of life are surprisingly simple to make.
12:02
The common amino acids have been found, or most common amino acids have been found in meteorites. They are out there in space. And the same holds true for the simple basis that you find in nucleic acids in DNA and RNA.
12:22
Sugars are a little trickier, but ribose can form under simple conditions. So you can have an RNA-based world. If you want a DNA-based world, that's much more difficult because deoxyribose, although it looks very similar to ribose,
12:44
is actually something that doesn't occur in nature except in DNA. And the way you can make DNA is only by reducing ribose on the nucleotide stage by a very complicated and interesting enzyme, ribonucleotide reductase,
13:02
which among other features has a stable free radical. That's an active site. That's very rare, but that's the only way you can make deoxyribose. And I would like to mention in passing here that the discovery of ribonucleotide reductase,
13:24
which opened up our understanding to how DNA is created, was Peter Reichert, among many other more important achievements, was one of my mentors at the Karadinska Institute in Stockholm.
13:41
Peter Reichert died last week. He was a great scientist. Okay, let me get on with things here and say something briefly about what happened after the origin of life,
14:00
some milestones that I'll mention briefly in my talk here. Next thing is photosynthesis, which has been called the largest environmental catastrophe ever because oxygen is a quite reactive gas. And it's generally believed that extrapolating from what we know
14:24
about so-called anaerobic microorganisms, that most of life that occurred at that point was killed by increasing the oxygen concentration in the atmosphere from less than 1% to 15, 20% like we have today.
14:45
So when you talk about environmental catastrophes, that may be ranked as number one. You could cope with that gradually by developing into eukaryotes,
15:02
which happened again by an unusual fusion by two microorganisms. And then those cells over many years would form aggregates and develop into multicellular organisms. And then you started getting large life on Earth.
15:22
So 100 million years ago, the Earth was ruled by dinosaurs. There were some other animals, precursors to fish, and even precursors to mammals, probably mouse-like creatures that were small and nocturnal.
15:43
They couldn't come out in daylight because then they would get eaten by a dinosaur. So those are our precursors, and it was our lucky break that then there was a major environmental catastrophe again, probably an asteroid impact that killed all the dinosaurs.
16:01
And some other small nocturnal mammals survived. And as you see on this kind of scale, man has been around for a very short time, 200,000 years. Now, what about life on other planets?
16:22
We don't know anything about that, but we can say today that if there were developments on other planets, like on Mars, for example, with multicellular organisms, or even photosynthesis with plants, we would probably know about it by now.
16:43
What we don't know is on the first part here, first life on Earth, other bacteria-like creatures, other simple monocellular organisms on Mars living under the surface.
17:00
It won't be so easy to detect those by sending a rocket there. Otherwise, if you want to know about alternative life forms, if they can be retrieved, the general attitude has been that of big science. Build a rocket, load it full of sensitive instruments,
17:20
and send it to Mars or the Moon to send data back. And that's obviously not something you can contemplate to do in your own lab very easily. What has been done much less is to say, is there anything on Earth already that hasn't been studied? What about anaerobic bacteria or simple creatures?
17:46
Well, they have mainly been studied as possible pathogens like tetanus, but we know very little about the anaerobic world on Earth. Now, with deep DNA sequencing and cloning and so on,
18:03
we can take some Earth and retrieve all kinds of organisms from it to get an idea of what's there. But the techniques to do that is all based on cloning and handling DNA. If there are other little organisms there that work in a slightly different way, we will miss them.
18:22
So one has to go back to more old-fashioned biochemical techniques to even look for something like that, if it exists. Now, so what can we do about this? Well, there's no point in being influenced by science fiction
18:40
and start looking for little green men or something like that. If there is alternative life, it's some very simple one-celled kind of organism, or perhaps even something simpler than that, something representing the so-called RNA world.
19:01
And why has the RNA world been replaced by DNA world? Well, that touches on my own area of interest, that nucleic acids are not as stable as you might think the carrier of genetic information should be,
19:20
and DNA has to be repaired, but that's nothing compared to RNA because the phosphodiester bonds in RNA are relatively labile. They will certainly be there for days and weeks, but not for many years.
19:41
So it's difficult to see how you could very slowly accumulate pieces of RNA that gradually fuse together to something interesting. And because of that, it's guessed by many scientists who are interested in this area that there was something in between RNA and DNA, something with a more stable sugar than RNA,
20:01
but something that has been replaced by DNA by deoxyribose, which, as I told you, is a very unique and rare ingredient. So that's where we are with that, and I'll take a couple of minutes to show you something
20:21
that inspired me and my coworkers here, which is this discovery of a living fossil, and that is Latimeria.
20:43
This is a fish-like creature, something in between a reptile and a fish that existed at the same time as the dinosaurs 100 million years ago. The amazing thing is that this fish or this creature still exists
21:04
in the deep waters outside Madagascar and also outside Indonesia, though it's a rare creature. I'll take a couple of minutes to tell you the story of how this was discovered
21:21
because perhaps you find that inspiring. A lady called Miss Latimer took a job as a teacher on an island outside Madagascar because she was interested in zoology.
21:42
This was in the 1930s. I apologize if you know this story better than I do. But she told local fishermen on the island that if they found some unusual, really unusual fish, she would be interested in buying it or seeing it.
22:03
And nothing happened for a long time, and then one day the fishermen came with a creature looking like this, and she had never seen anything like this, perhaps because it usually lives on 200 meters depth.
22:24
And she had a friend who was a professional professor in zoology who had promised to help her. So she got in touch with him. He was on vacation for a long time. And in the meantime, the weather was hot,
22:42
and she didn't have a deep freeze on her island, so the fish was going to get spoiled. So on her own initiative, she filled a bathtub with whiskey and put the fish in that so it could be preserved for some time until the professor came back from his vacation.
23:01
And when he came back, he immediately realized that, fortunately he was an expert in this area, that this was a living fossil. This was an amazing, alive animal from the time of the dinosaurs. And so they do exist.
23:21
And I think, I like to think of it, what are we trying to do or learn something about? We are looking for living fossils that are 30 times older than this creature. But perhaps that's not unreasonable. Something like that might have survived in some ecological niche. You won't find it unless you look for it.
23:42
So that's the basis of what we are trying to do, and I can tell you what kind of preliminary things we do about it. So let's have the next slide here. So the problem with looking for living fossils
24:04
is that our DNA-dependent life has penetrated just about every niche on Earth that has any reasonable life quality to it. Even in the Dead Sea, it's not dead at all. There are halophilic microorganisms that grow very happily
24:22
at high concentrations of sodium chloride, and they have the same DNA and RNA as we have in ourselves. But there are some solvents where you can actually have DNA and RNA without destroying their covalent structure, but where life presumably can't exist.
24:45
And that is in high concentrations of glycol, glycerol, and also with higher concentrations of formamide and mesanol. We don't have lakes on any of these solvents, but they are very common chemicals,
25:01
and they occur in volcanic areas and so on, so it's not impossible that there could be an ecological niche with solvent like that, which would allow a niche for an organism or a life form that's different from what we are usually dealing with.
25:22
So how do you look for this? You have to have some basic training in microbiology, but you don't need a lot of money. This is very simple science. It's like trying to grow bacteria in the laboratory. You have a medium energy source.
25:41
Look at room temperature and use these different solvents, and then you have to have an inoculum. And what do you inoculate with? We don't know. We go into, we try to find material through deep volcanic areas or underground areas as a possible source of material
26:03
that could grow under unusual conditions. And how do you know something is happening? Well, if it's single-cell organism at some early stage, you would really predict it would have developed some kind of simple phospholipid membrane
26:21
to keep all the ingredients from floating away. So you can look for cell turbidity, the way you measure bacterial growth. But you also look by spectrophotometry, DNA, RNA, protein, as you know,
26:41
and show characteristic absorption between 220 and 320 nanometers, which you can easily detect in spectrophotometer, and you can see if anything happens with these kind of compounds. Another related line of research, which we have started more recently,
27:03
is to see if you can find some more direct evidence for an RNA world. Same idea of having a medium but supplemented with ribonucleotides and try to prevent DNA synthesis. And one way you can prevent DNA synthesis, for example, is by using hydroxyurea, which is a specific inhibitor of DNA polymerase.
27:27
DNA polymerase, it interacts with free radical at the active site of ribonucleotide reductase. So it shouldn't interfere with the RNA world. So we are trying these various recipes here,
27:43
and where we are so far. We have had various kinds of muds, and inoculates sitting in salt-containing glycol solutions for the better part of a year, and so far nothing has happened. And it may well be that this is as far as we are going to get with this project.
28:00
But we are not giving up yet. We are actually just starting. And it's one of these projects where you have to be prepared for that. It most likely won't work. But if it does, it's really an interesting finding. And it would be nice to know if there is an alternative life or one else. Thank you.
28:29
Thank you very much, Thomas. In the previous session, one of the young researchers asked a question. What about all the results, or the experiments that do not give positive results and are never published?
28:41
And here's one of them that you can try yourself. We are prepared to take questions on this from the audience. I can go first with one. I think Carl Sagan said once that I am a carbon chauvinist and a water chauvinist, meaning that carbon, he thought that carbon-based life was essential,
29:04
and that water was the essential solvent. And later he changed his mind, and he said, perhaps I'm not a water chauvinist. And you're clearly not a water chauvinist because you're looking in different types of solutions, right? But you're a DNA chauvinist?
29:20
You believe that it must be DNA-based? No, I don't think it will be DNA at all. As I try to say, DNA is something that developed, should have developed fairly rarely. We don't know how life was created. There is only one form of it on us. So you can have all kinds of religious ideas about this. But most likely DNA developed as an alternative to other,
29:46
more sophisticated alternative to other life forms many years after the creation of an RNA-like work. Questions? Please, yes. I wanted to ask you about the chirality of life.
30:03
So do you think mirror life forms can exist? Rather than, you know, we're left with L-amino acids and D-sugars, but is this just an accident, or is that something specific? I don't know. You can argue that the form that exists
30:25
is presumably the predominant one, but I see no reason why you couldn't have a mirror image exist. Yes, over here. Thank you very much for a very informative talk.
30:41
I just have a question that, how do you think that knowing the alternative early life forms, how does it benefit the current science or the modern day science? If I understood correctly, how does the possible existence of alternative life forms, how would that affect modern science?
31:02
Why do you study this? That's the question. I think that's a good question. I think there is a philosophical argument that I'm interested in. If there are alternative life forms, we should know about them. A more practical aspect is if there are alternative forms of life
31:22
that can proliferate like under conditions where the life that we are familiar with doesn't do so well, it probably can be used for commercial fermentation and so on.
31:42
I'm sure that if there is an alternative form of life, it would also be of commercial interest in some way, but that's much further down the line. If you say there was an alternative between R and A world and D and A world,
32:04
where would you look for traces of that? Would you look in us? For example, the R and A world is still preserved in viruses or something. So are there traces of this intermediate thing? The question is if there was an intermediate between the R and A world and the D and A world,
32:22
how do you trace it? How do you look for it? I've already told you that we are trying to find conditions where DNA containing organisms wouldn't proliferate and see if something else grows up.
32:41
And that might be a very naive approach, but at least it's an experiment. And an important factor every time you think about some odd idea like this, what does it cost? Well, these experiments are actually quite inexpensive. And I have one more slide I must show here.
33:03
This is Monica. Monica Olson. We worked together when I was in Gothenburg 35 years ago. And she has stayed there and we keep in contact. And she does most of the experiments on this Origin of Life project I've been telling you about.
33:24
Monica has just reached retirement age, but the department is very keen to keep her on because she has the unusual talent that she is exceptionally good at purifying active proteins and enzymes in active form. And she can show the young people in the department how to do this.
33:44
So she's the one that does the experiments. And I should mention there's a reference here to a new kind of DNA repair enzyme we found 35 years ago, which was quite unexpected.
34:04
If you treat a cell or DNA with a mutagen like methyl naturals urea or MNNGs, strong lab mutagens, the reason that it's a mutagenic change is usually due to the formation of O6 methylguanin.
34:24
It's a site that's never otherwise methylated. And it's a very mutagenic base. And this is a constant set. So all organisms, we and bacterians, have a specific repair factor that deals with O6 methylguanin
34:42
and directly demethylate it by moving the methyl group over to a cysteine residue in a protein. And that was the first time cysteine had been found in a biological system. So that work was done by Monica and it has been confirmed many times since then.
35:02
So she knows what she's doing. I think it's important if you try to do something unusual that you're confident with biochemical lab techniques and you know what you're doing. Yes? I would like to go back to the introduction of this talk where you talked about how to achieve a big finding.
35:27
And the first thing you named was Luck and I find that rather curious. And I would like to ask you to which extent you believe that you can manipulate Luck. Is it rather something you find or does it find you? Somewhere in between there is a famous quote from Louis Pasteur that Luck favors the prepared mind.
35:50
There are probably quite a few people who have done interesting experiments and the results didn't make sense to them so they dropped it. And that can be very dangerous if a colleague then comes along and shows that you have all the data
36:05
to show something new and exciting in science. Splicing of DNA for example. Many people missed it but fortunately there were also one or two prepared minds who were willing to say that that unlikely outcome or the results must mean what it means.
36:26
We will soon wrap up. We have time for one more question from the floor I think. Yes, over there. Hi, thanks for the very nice talk. So you mentioned that you think that DNA might not be the only source of life.
36:44
So I wonder what's life definition for you? Is it carbon? Is it energy? Or when we for example go explore other forms of life in the solar system, are we just looking for DNA or are we looking for carbon? So do you think that there's something like another form than energy or carbon that we might be missing
37:01
and that's why we cannot really find different forms of life? Well, everything is possible but I think what we are thinking about is various kinds of carbon-based chemistry. So you don't think that there's different forms of life that does not include carbon?
37:22
Well, if you think along those lines you have to do some experiments and see if you can find something else. Okay, I had another question but I think I will refrain from putting that one because your question there which was essentially was what is life?
37:40
I think that's a good one to end this session with. Thank you very much, Thomas, and thank you very much to the audience.