Setting constraints on origins of life’ hypotheses. Example 1: thioester world and metabolism first in hydrothermal vents

When it comes to origins of life (Ool) hypotheses, we are often served with beautiful stories on how one event follows another and then you get life. But, the devil is always in the details and we want it to be out, to be known and to be addressed.

“Only when negative results are permitted and theories can be abandoned will science  progress in this area (OoL)”

-Robert Shapiro (1935 – 2011)

Here is a summary of my recent paper addressing a weakness in the metabolism first hypotheses in hydrothermal vents.

Thioesters, the prebiotic analogues of Acetyl coenzyme A is a linchpin organic compound in respiration processes in life. Its occurrences have been transposed into geochemical settings such as hydrothermal vents to form many metabolism first schemes for origins of life in the last 40 years or so. One glaring problem, despite the usual poised narration, is that, this hypothesis have survived so long without through investigations for that many years. Now, researchers at Earth-Life Science Institute (ELSI), an institute incepted to exclusively study the origins problem is doing just that, to set constrains on current OoL models and to produce more experimentally driven principles to understand the origins of life.

The open-source paper available in, has demonstrated that the accumulated concentration of thioesters in HT vents are too insignificant to launch any meaningful progression in metabolism first schemes. Additionally, thioester (like Acetyl-Co-A) has a very limited shelf life; the researchers measured the decay rate and concluded that, depending on thioesters speciation and physical conditions, they are unlikely to persist in hydrothermal vent conditions for long, thus constraining the metabolism first hypotheses.

p.s: We are extremely delighted to get this piece out in an open source journal.


Figure is showing the possible formation of thioacetic acids, in blue and thioesters (methyl thioacetic acid) , in pink in hydrothermal vent systems.


Authors: Kuhan Chandru, Alexis Gilbert, Christopher Butch, Masashi Aono and Henderson James Cleaves II

Title: The Abiotic Chemistry of Thiolated Acetate Derivatives and the Origins of Life

Journal: Scientific Reports, 2016

DOI: 10.1038/srep29883


Scribbles on the Gordon Research Conference (2016) for the Origins of Life

January is often a horrendous month for ELSI researchers; first we have our own in-house annual international symposium and then this is followed by our intense internal evaluation seminar, a two-day affair where all ELSI members present their work for the past twelve months. This year I decided to one up that schedule by attending the Gordon Research Conference on the Origins of Life in Galveston, Texas in between these two important events.


This was my first trip to the UNITED STATES OF AMERICA, and I was very excited about it before boarding the flight. After 15 hours of journey, I started to develop mixed feelings about this trip until I was shown to my room at the famously haunted Hotel Galvez (be sure to watch the video in youtube), where I slept for the next 15 hours. That is a personal record.

Here are some of my random observations during the GRC’s intense science program.

  1. You are forbidden to record electronically any of the talks or posters given by the presenters. Because of that very fact, we are ALLOWED to argue aggressively. Rumor has it that there was a legendary argument that took place in the past. When I say argument, I don’t mean light ones. But to my surprise nothing like that happened this time. This was probably because they wasn’t anyone trying to sell/convince you their version of OoL scenario (which usually happens in Origins kind of conferences). This GRC, in my opinion, was amazing since the focus was only in what we know, what we don’t know, and what the current evidence is showing. That was such a relieve for me after witnessing many sales pitches in the field in the past.
  2.  GRC likes placing their conferences in, sorry Galveston, remote areas to create an intimate group setting. This is something that didn’t go well with the enthusiastic foreigner like me who wants to spend some time off as well. But in any case, science always comes first, and I was immensely satisfied with what I have gained (talks and meeting people) and not to mention having the time-off to visit Johnson Space Center with some of my favorite people on board.
  3. The scientific talks were exclusively made for an interdisciplinary crowd, meaning that one never saw a physicist showing only equations and expecting the biologists and chemist to understand, as if it were “matter of fact” knowledge. I don’t mean this in an offensive way but it is really hard to be able to give a talk to an interdisciplinary crowd, something we do almost everyday at ELSI. The GRC Origins was good demonstration of this with few minor exceptions.
  4. The GRC starts from 9 to 12 pm, we then have a huge break until dinner, and talk resumes again from 7.30 to 9.30. This was thoughtful and pleasing as it helps the jet-lagged foreigner to sleep and feel refreshed for the sessions.

One glaring shift I noticed among some of the leading OoL workers in the field is that they are moving away from trying to only understand origins based on modern bio-molecules. This is good news, as we in ELSI are also having similar views and are working to explore new chemical domains within prebiotic chemistries and origins of life. I also noticed that the integration of theory and experiments are also coming into play more than before to understand this complex problem. In my opinion, interdisciplinarity between sciences cannot be forced upon but needs to grow organically. This puts ELSI in an amazing position with all the disciplines combining (sometimes clashing) to solve some of the pieces of the origins puzzle. In my world of complaints and criticisms (I’m an experimentalist), this is one of the best conference I have attended in this field, absolutely worth the jet-lag and crazy ELSI schedule of January.

kuhan2016-01-21 15.58.jpg

originally post on February 4, 2016 (ELSI blog)

38億年の時を 超え、 生体分子生成の瞬間に迫る

Researcher’s Eye 〜地球最大の謎に挑む研究者たち

Kuhan Chandru


kuhan01.jpg「日本での研究はスピードが速くて刺激的。その上、ELSIには第一線の研究者が集まっているから、知りたいことがあればすぐに聞きに行ける。この環境はとても貴重です」と話すのは、ELSI若手研究員 のクーハン・チャンドゥルー。「原始地球で、どのようにして生命誕生につながる生体分子ができたのか」に迫ろうと、自らが中心となって新たな実験を準備中だ。













Original interview appeared on February 2015 ELSI (Japanese) 

Kensei Kobayashi’s flow-reactor, the SCWFR, part 2

The SCWFR at Kensei Kobayashi's lab at Yokohama National University
The SCWFR at Kensei Kobayashi’s lab at Yokohama National University

Kensei Kobayashi’s group with the help of Takeo Kanaeko (a brilliant man) came up with another design where they named it Super Critical Water Flow Reactor (SCWFR) utilizing an infrared (IR) gold image furnace (Figure above). This enables the fluid in this system to heat up to 400 °C (or any desired temperature) within seconds (without pre-heating). This one specification is important as most autoclave and other flow reactors utilized an electrical heater which takes time to heat up to the desired temperature. This is undesirable as this “pre-heating” is also making the initial chemicals to react (or altered) to lower and rising temperature, which is not very realistic to a real vent. In other case, this is one of the slightly more realistic simulators i have worked to date.

Kobayashi’s ex-student, Nazrul Islam performed the survivability experiment using several amino acids (aspartic acid, threonine, serine, sarcosine, glutamic acid, α-aminobutyric acid, β- alanine, γ-aminobutyric acid, 5-aminovaleric acid and 6- aminohexanoic acid), 10 mM each) by heating them up at four different temperatures (250, 300, 350 and 400°C ) at 25 MPa for 2 min (that’s pretty fast). They showed that amino acids tend to show better recovery when it is hydrolyzed, suggesting some kind of aggregation and/or condensation is happening within the system. Additionally they also showed oligomerization of glycine (100mM) with the same temperature. At 400°C, no oligomerization was found. However, at 200-350°C, diketopiperazine, diglycine, triglycine and tetraglycine were formed. It was suggested that the glycine reactions in a supercritical fluid (300°C to 400°C) are quite different from those in the liquid phase (at 200–350°C). There were many other peaks of unknown compounds in all of the chromatograms of the unhydrolyzed products. Most of those peaks disappeared after acid hydrolysis. This particular findings however remains a mystery.

Another of Kensei’s sudent, Hironari Kurihara, used the SCWFR to test the stability of complex compounds produced from simulated primitive atmosphere (similar to Miller and Urey’s work). He then tested these compounds to assess the stability of some known amino acids. The complex-combined amino acids (from the primitive atmosphere simulation) preserved more amino acids (including amino acid precursors that give amino acids after acid hydrolysis) than free amino acids after heating in simulated SHS environments. In other words, these complex chemicals which could come from atmosphere (or space) could be better preserved if they are come into contact with the hot hydrothermal system which could have existed during the prebiotic-earth setting. This also hints that “clean or perfect” chemicals like amino acids used in many kinds of experiments are not necessarily showing the right picture when comes to chemical evolution on early earth. More on this in the future.

Many critics of hydrothermal vent simulators often argues that, simulators mentioned on this post and previous ones have a rather short flow-rate and short flow-length (showing low residence time, meaning how long the sample stays in the system). Critics usually cite studies that refer to residence time of fluids in axial hydrothermal environments range from years to decades, while those in lower temperature off-axis diffuse flow systems may be on the order of thousands of years. The problem with these studies about residential axial time of fluids is that, they’re are based on models and calculation only, no work has been done so far in regards to real time sampling or measuring the length of vent system (although, there are work in measuring the velocity of fluid emitting from a vent which looks promising for future measuring). Despite this limitation, i believe the future of simulators will be done using computer simulators, where experimental data from physical simulators (like the ones mentioned in this blog) could be used as parameters. The biggest advantage in this, is that, we do experiments on a larger scale which is could make the origin of life more complicated, interesting and not so straightforward, which I believe is a good problem to have in the future.

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The flow-reactor, a better hydrothermal vent simulator, part 1

flow-reactor (HCFR) build by Ei-ichi Imai at Nagaoka Institute of Technology.
flow-reactor (HCFR) build by Ei-ichi Imai at Nagaoka Institute of Technology.

In the previous post, i wrote about a conventional kind of submarine hydrothermal simulator (SHS) called the autoclave. In today’s post i will talk about the flow kind of reactor which is more realistic compared to the autoclave. Jack Corliss, the man who discovered a real SHS, came up with the notion that a flow-type reactor is essential for new origin of life experiments, as he argued that the quenching effect of the cold seawater is important to hold the short-lived intermediates (hydrogen cyanide, sugars and etc) or as he calls it “quasi-species” in prebiotic synthesis of bio-molecules. This essentially means that a flow kind of simulators are required to better represent a real SHS to  produce more reliable results than the autoclave.

Initial Schematics of Jack Corliss in his paper
Initial Schematics of Jack Corliss in his paper

Co-incidentally, Koichiro Matsuno, designed a principle idea of a flow reactor which could reflow the fluids repeatedly in heat and cold (i will name here-forth as hydrothermal circulation flow-reactor (HCFR) for convenience). Ei-Ichi Imai, Koichiro Matsuno and co-workers went on to build  (image above, schematics diagram below) the reactor and experimented using many bio-molecules.

Their first paper which made it to Nature (big thing for scientist), reported that oligomerization of glycine could occur at 200-250°C, where a monomer glycine solution was circulating for 2 hours or so. Oligomers up to Hexaglycine was reported when metal (Cu2+) and controlled pH was introduced. Without them, only oligomers up to triglycine could be obtained. They also tried the same experiment using  glycine and alanine. They observed oligomerzation products such as

Schematic diagram of the HCFR system from Nagaoka Institute of Technology
Schematic diagram of the HCFR system from Nagaoka Institute of Technology

diketopiperaxine, gly-ala, ala-gly, gly-ala-ala, ala-ala, ala-ala-ala and ala-ala-ala- ala was created when the solution was heated with similar conditions. What i described abover is a big thing in origin of life studies. This land-mark discovery, was the first to show that oligomerization (a shorter version of polymerization) could occur using basic amino acid (gly), without the help of DNA and RNA molecules which are crucial in making proteins in life.

In their other works, oligomerization of nucleotide up to trimers (basic monomer of DNA) was also observed when 20mM of adenosine monophosphate was used with 1mM ZnCl2 were reflowed at 110°C.

Despite the findings made by HCFR, the system is rather hypothetical, since we know that real live vents don’t really circulate in that manner (shown below) however, this kind of reactor is useful when it comes to monitor chemical changes in the system. In my next post, i will review another kind of flow-reactor in Japan which i have also worked on in the past.

HCFR mimicking a circulatory system in a real life vent.
HCFR mimicking a hypothetical circulatory system in a real life vent.

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Modus operandi in EARTH-LIFE SCIENCE INSTITUTE (ELSI), Japan – Day 0

This article appeared in the ELSI’s blog

1557567_10151911643485911_1948361252_nMay is a month where nothing really happens in Japan. It is the post-sakura season where everyone is done taking pictures of cherry blossoms and is getting ready for a humid and hot summer. I say this with tongue in cheek but there is some truth to the lull of May. People gear up for the new school and fiscal year beginning in April and slowly settle into the pattern of life by May, in relief. I joined ELSI in the beginning of May after going through their multiple interviews in January. Yes, I say multiple interviews to point to the unique way ELSI evaluates its potential newcomer, where you meet numerous people by whom you are not sure you are being judged or just having a scientific exchange. Or both. It is an unconventional way but it seemed to have worked for me much to my delight.

elsiDuring this time, I managed to get to know whom I will be working closely with and I feel lucky to be with people whom are my instant noodle expert (INE). INE are people who will be there to give you suggestions and ideas in an instant. Some of my colleagues may not be here all year long but they are nevertheless very insightful to have around when they are around. Within a few interactions, I realised how much more reading I needed to do and how I can reduce workflows in research. This I got within the first week of being here.

I was also impressed by how collaboration happens here, where fields are interrelated and you get to see the bigger picture. A young scientist often neglects the bigger picture, preferring to dig deeper. At ELSI, the bigger picture is often the talking point and this is how collaborations happen. It is slightly daunting in the beginning but it is exciting once you get it.

Right now I am facilitating in building the chemistry lab, which is almost like a “mansion” room. In Japan, a “one-room mansion” is the common term referring to a studio apartment. This is one of those Japanese terms that I have a hard time comprehending till this day. However, the limits in space will all change, as ELSI will have a new building by the end of next year. For now, we are dealing with making the best of space, which is manageable. Personally, the opportunity of building a lab is an exciting prospect to me, where we are sharing ideas on how to handle the logistics of instruments and materials in a small room. I hope that we will be fully operational by end of summer.

On the lighter note, what I find nice and admittedly a little weird is, the people at ELSI are like a family. We often have lunch together, meet for daily tea-time at 3, and we drink together every Friday. Yes, you could surmise that perhaps we don’t have many friends. However, friendless or not, some of the best discussions happen here. It is like a mix of getting to know some of the research staff and building a connection between them. We are planning to watch some of the World Cup matches together. My general advice is, don’t mix work and life together. But ELSI is an exception, I suppose.

Finally, I would like to convey my appreciation to the wonderful set of support staff we have at ELSI. They have made my registrations and other legal obligations amazingly easy since day 1. Moreover, they are always welcoming when you approach them in their office. They make a point to ask you personal questions (the nice ones), to be your friend and to make your time here a smooth one.

All is pretty good, until of course we find ourselves rooting for opposing teams when we watch the World Cup matches together as an ELSI family!

Making life in a pot

In the last few posts, i wrote about the basics of submarine hydrothermal vents (SHS), here i will be posting about the simulators that we use in the lab to recreate this environment. This is useful as we can use many kinds of basic chemicals to test how they react when directed to massive heat and pressure similar to SHS. Today’s post will be about the most basic of simulator, we call it the autoclave; I will be also describing some of the experiments done in an autoclave system to date.; which literally a boiling pot.

Autoclave at Kensei Kobayashi lab at Yokohama National University, Japan
Autoclave at Kensei Kobayashi lab at previous university, Yokohama National University, Japan

When the hypothesis that life could have started at SHS was proposed; Miller and Bada was one of the first to come with real experimental simulations. They  argued that biomolecules decompose at high temperature and pressure, thus making SHS an unreliable spot for origins. They carried out the experiment at 250°C and 26 Mpa for about 6 hours, and adjusted the pH to neutral of amino acids, leucine, alanine, serine and aspartic acid. The experiment was conducted in an autoclave; a device conventionally used to sterilize equipment and supplies by subjecting them to high pressure and temperature (figure on the left and below, you can’t miss it!!). They showed that aspartic acid and serine decomposed rapidly, and the half life of leucine was about 15-20 min; and alanine appears to be much stable than the rest. Glycine, which was not part of the starting material, was produced during the course of the experiments. From this experiment, They went on to conclude that SHS is not ideal for origin of life, because amino acid being an monomer to proteins will be destroyed at high heat and pressure.

This finding, however received much criticism, some scientists mentioned that the duo did not control the redox conditions in their simulations, and started at a neutral pH; this is very much unlikely in a real situation hence, their results are not very realistic. Kohara and and his buddies showed that if a reducing condition (adding hydrogen) is introduced to an autoclave (similar to a real SHS), amino acid are better conserved up to 300°C. The stability of amino acids was dependent on the fugacity of hydrogen in the system compared to inert conditions shown by Miller and Bada. This is shown in Kohara and co workers’ work, that hydrolyzed samples exhibits higher recovery compared to the non-hydrolyzed ones.

Schemetic diagram of a simple autoclave
Schemetic diagram of a simple autoclave

Moving on, in 1992, RJC Hennet and friends managed to show that by using some basic chemicals found in the ocean (KCN with NH4CL and HCHO together with pyrite, pyrrhotite and magnetite to be precise) at 150°C, could form a variety of amino acids in an autoclave. Similarly, David Marshall also showed how amino acids and amines could be formed using aqueous NH4HCO3 solutions were reacted with gaseous C2H2, H2, and O2 at 200-275°C for 0.2-2 hours. These experiments seems to be supporting that bio-molecules especially amino acids (so far), could be formed in such conditions which could have existed on early earth.

Now on the cons of autoclave. Despite being robust and proven useful, the autoclaves severely lacks a cooling device. Conventionally, once the heating vessel is removed from the furnace of an autoclave, a fan is usually placed to cool it down for a few hours. This is not exactly how a real SHS will function, one could easily imagine that the hot fluids emitted by the vents will be rapidly cooled down by the near freezing water of the ocean. This limitation made researchers to come with a more dynamic system, which i will write about in the next post.

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Lost City hydrothermal field, an unique hydrothermal vent system

In 2000, a completely new kind of vent system was discovered at mid-Atlantic ocean that differ significantly from black-smokers and never seen before chemical enviroment. They are characterized by carbonate chimneys that rise up to 60 meters (picture below). The system, named Lost City hydrothermal field (LCHF) could also be a spot for origins. They are also located a few kilometers away from the spreading

Typical morphology of active chimney at Lost City showing multiple, delicate pinnacles of young carbonate material. (NOAA website)
Typical morphology of active chimney at Lost City showing multiple, delicate pinnacles of young carbonate material. (NOAA website)
Diagrammatic sketch showing geologic and tectonic relationships at Lost City. Hydrothermal structures are located on a faulted down-dropped block of variably altered and deformed crust composed predominantly of serpentinite; taken from Kelley, D. S, Karson, J. A, Früh-Green, G. L, Yoerger, D. R, Shank, T. M, Butterfield, D. (2005) A serpentinite-hosted ecosystem: the Lost City hydrothermal field. Science, 307(5714), 1428–1434
Diagrammatic sketch showing geologic and tectonic relationships at Lost City. Hydrothermal structures are located on a faulted down-dropped block of variably altered and deformed crust composed predominantly of serpentinite; taken from Kelley, D. S, Karson, J. A, Früh-Green, G. L, Yoerger, D. R, Shank, T. M, Butterfield, D. (2005) A serpentinite-hosted ecosystem: the Lost City hydrothermal field. Science, 307(5714), 1428–1434

zone. They fluids are heated up a ~ 200°C, but they are not in close contact with the magma chamber like a black-smoker. Instead they are fueled by chemical reactions between mantle rocks and seawater. The rocks contain large amounts of olivine (a Mg-Fe silicate) which reacts with seawater at temperatures ~200°C and forms serpentine minerals (hydrous Mg-silicates) and magnetite. This process, referred to as serpentinization makes the system highly alkaline (pH 9–11). An interesting fact is that, serpentinization have been producing geological H2 for as long as there has been water on the Earth. This new system, has yet to get an experimental focus for origin of life studies, although i do think they are researchers whom are looking in this idea. Do keep an eye on this.

In the next post i will be reviewing some of the hydrothermal vent simulators i have used in the past for origin of life based experiments.

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From Russia with love: another meteorite explosion

A meteorite like object lit up the skies at the wee hours at Murmansk, Russia (check the video footage out). There is a possibility that the object is part of the Lyrid meteor shower which happens annually when it’s nearing its peak. I find this amazing as this is the second time this is happening in Russia (northern hamisphere??). In February 2013, a surprise asteroid about 20 metres and 5,000 kilograms came across the sky over Chelyabinsk, Russia. The blast from its explosion was worth millions of euros worth of damages and injured over 1,000 people. Nobody saw it coming. I am aware that almost every day the Earth gets hit with hundreds of tons of material from space, most of them ranges from the size of a grain of sand to something of an object the size of a sim card. This kind of meteorite strikes (for the second time) kinda scares me a little, its like a sign that every now and then a meteorite or asteroid can hit us and exterminate life as we know it. Gosh, I am thinking about the extincted dinosaurs now, or worst, aliens rising from them.