Have a listen to an interview I did for the Naked Scientists, a BBC Radio Cambridgeshire podcast about our recent Nature Ecology and Evolution paper. This piece featured on BBC Radio and ABC Radio National Australia.
(Ignore the transcript below, I think it was generated automatically and didn’t like my accent!)
Here is our latest paper about protocell formation at the origin of life in alkaline hydrothermal vents. You can also check out my “Behind the Paper” piece below.
The following is a piece I wrote for the Nature Ecology and Evolution community “Behind the Paper” series. See the original here.
An origin of life in deep sea hydrothermal vents has been deemed problematic due to the inability to form lipid vesicles in saline solutions. Our latest research suggests this may not be as difficult as we once thought.
An alkaline vent at the Lost City hydrothermal field
We noticed that one common theme of these experiments was that they all used a combination of 1-3 SCAs to form vesicles. This seemed at odds with the Fischer-Tropsch-type synthesis which can produce up to around 40 different SCAs, with the most abundant chain lengths in the region of 10-15 carbon atoms, under hydrothermal conditions. So we decided to try using slightly more complex mixtures of SCAs whilst keeping the molecules themselves very simple. This is arguably more representative of the actual conditions on the early Earth. In our recent Nature Ecology and Evolution paper we show that using mixtures of 12 fatty acids and alcohols at low concentrations under alkaline hydrothermal vent-like conditions (i.e. 70 °C and pH ~12) we were able to form vesicles in sea water concentrations of sodium chloride, magnesium, or calcium. Straight away we had observed the benefits of increasing the number of SCAs in a mix. Unfortunately, in a solution containing all these salts together, vesicles became aggregated. Around this time we had been discussing the idea of isoprenoids at the origin of life. These form the tails of archaeal phospholipids, the position taken by fatty acids in bacterial phospholipids. Phylogenetics suggests that the last universal common ancestor (LUCA) had the capability to synthesise both of these lipid types. It is possible then that isoprenoid acids and alcohols could have played a role in membrane formation at the origin of life, yet very little work has been done on vesicle formation with isoprenoids. So we added geranic acid and geraniol, both C10 isoprenoid molecules, to our 12 SCA mixture. These 14 component vesicles formed readily in the most extreme hydrothermal mixtures of salts and were stable enough to encapsulate fluorescent dyes over 24 hours.
Confocal microscope image of mixed SCA vesicles in alkaline fluid.
They key point here is that vesicles can and do form in oceanic conditions. For the mixtures we used the alkaline vent conditions were actually essential. Below temperatures of about 60-70 °C or pH 11-12 vesicles did not form – but once formed under these conditions they can persist at lower temperatures and pH. However, there are myriad SCAs simple enough to have been available for vesicle formation at the origin of life. It is likely that with continuing research we will find combinations that could provide bilayer membranes in almost any environment. The idea that vesicle formation from simple SCA mixtures should lead researchers to cast aside a theory for the origin of life is clearly unreasonable. We hope that this work will encourage others to increase the complexity of mixtures of various prebiotically plausible molecules to expand our understanding of how the first protocells might have formed and behaved at the origin of life.
The Lane Lab contributed two research articles to this issue including one in which I was the lead author. This paper is the culmination of some really interesting discussions between Nick and myself followed by some long hours in the lab trying to follow up on our ideas. We shed some light on the potential for protocell membranes to contain both fatty acids and isoprenoids, possible precursors to bacterial and archaeal membrane lipids respectively. We look at the some of the possible pros and cons of this and how these may have contributed to an early lipid divide! There is a lot more to do on this topic and hopefully this will be the first of several publications probing this aspect of protocell membranes more deeply.
See the whole issue here, check out the protocell paper here, and read our paper on CO2 reduction here!
I am delighted to have this new paper out. This is a culmination of a real multidisciplinary team effort arising from our time onboard the RV Celtic Explorer in 2014. The work involved researchers from Dublin City University, National University of Ireland Maynooth, the Geological Survey of Ireland, the British Geological Survey, Géoazur in France, and the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale in Italy.
After a rush through rough seas to escape from the tail end of a hurricane on the Celtic Shelf, we sheltered in Bantry Bay. Work on a research vessel never stops, so we took this as an opportunity and did some multibeam scanning of the seabed. When we came across a pockmark field, shallow craters dotted across the seafloor, we decided to investigate further. We took sediment cores throughout the bay and analysed the gas and porewater chemistry as well as the organic signatures of microbial communities back in the lab.
The results shed light on methane gas, a powerful greenhouse gas, below the seafloor throughout Bantry Bay which probably formed the pockmarks observed there. They also suggest that the microbes in the sediment are probably consuming this gas and preventing it from escaping the seafloor and potentially reaching the atmosphere. There are other similar locations to this around the coast of Ireland, which may have implications for future climate change. Hopefully we’ll see some more research in these areas over the coming years.
Have a read of the full article here:
https://www.sciencedirect.com/science/article/pii/S0272771419301040
DOI: 10.1016/j.ecss.2019.05.014
It was great to play a part in this exciting research and I am delighted to see it published.
Well worth a read!
https://www.nature.com/articles/s41598-017-04934-9
DOI:10.1038/s41598-017-04934-9
It is great to get this work published. This was arguably my favourite research project from my PhD, using lipid biomarkers in a unique bog setting to interpret Irish palaeoclimate conditions during the Holocene.
http://www.sciencedirect.com/science/article/pii/S0146638016302339
DOI: 10.1016/j.orggeochem.2017.02.004
I am delighted to have been a part of this new publication from Eloi Camprubi et al. with my new research group in here in UCL.
DOI: 10.1002/iub.1632
When I first began work on soil samples from the Italian Alps I didn’t realise the significance of the question that I was endeavouring to answer. Whilst determining the exact route taken by Hannibal of Carthage across the Alps to invade Italy in 218 BC won’t exactly change the way we live our lives, it is certainly of great interest to archaeologists, historians, and anyone with an interest in history. In fact, I believe people are always captivated by others who take great risks and embark on seemingly impossible journeys. Just how they manage to succeed in these extreme feats grasps the attention of everyone with an inquisitive mind.
Prof. Bill Mahaney of York University, Toronto certainly knew of the importance of this work as he had been fascinated by Hannibal’s great endeavour for many years. After thorough examination of the relevant literature from both ancient and modern historians, he was impressed by Sir Gavin De Beer’s inclusion of environmental factors in his suggestion of a particular passage through the Col De La Traversette. Prof. Mahaney had to see this for himself and so travelled the route and applied his expertise in geological techniques to investigate whether this really could be Hannibal’s chosen path. The results of this historical and geological analysis are presented in part 1 of our recent publication in Archaeometry.
Knowing that this evidence was not sufficient, Prof. Mahaney contacted his colleagues around the world to provide further analytical approaches using their own expertise. The project had now become a major multidisciplinary investigation involving researchers from Canada, Ireland, the USA, Estonia, Portugal, the UK, and France. My supervisor in Dublin City University, Dr. Brian Kelleher, was contacted to enquire about conducting chemical analysis of soils along the route. When an army of 30,000 troops, 15,000 horses, and 37 elephants travels through an area they are sure to leave some mark. In this case it was faecal biomarkers, chemical compounds in excrement that remain in the environment for 1000s of years.
Along the route there is a large body of water in the Guil Valley, an obvious place to rest for any traveller and perfect for a large army. Whilst sampling soil from an adjacent mire it was discovered that a layer of the soil was noticeably ‘churned-up’. The soil was disturbed in such a way as to suggest that there must have been significant activity at this point in history. Radiocarbon dating of this layer placed it spectacularly close to the date of Hannibal’s epic journey. Soil samples from this spot and other parts of the valley were analysed by myself and colleagues here in the OGRe lab in DCU, Dr. Shane O’Reilly and Dr. Brian Murphy. We detected significant levels of faecal sterols and bile acids, compounds produced during digestion, in this churned-up layer but not in any other location.
These chemical biomarkers are rarely present naturally in the environment and high concentrations such as those observed here are almost certainly due to faecal deposition. Microbiologists at Queen’s University, Belfast isolated gut bacteria from this soil as well, supporting the evidence of faecal deposition. These results are published in part 2 of our paper in the journal Archaeometry.
So far, along a route which matches well with historical accounts, we have identified a layer of disturbed soil with significantly increased levels of animal and/or human faeces which dates to the same time period of Hannibal’s crossing of the Alps. The media response to these findings has been brilliant, beginning with excellent articles written in The Guardian and The Irish Times. Since then the story has been covered by the BBC, CNN, The Huffington Post, Science Magazine and many others. In the past few days over 100 articles have emerged from publications across the globe, an overwhelming response. Whilst some media reports have claimed the age-old question has been answered, this is certainly not case closed. It is, however, very compelling evidence which requires further investigation to solve this mystery once and for all.
Hopefully some archaeological work in the near future will uncover items left by Hannibal’s army. Maybe there will be skeletal remains of soldiers, horses, or even elephants buried along the route. Until then, I am happy to have helped pave the way for this future research which may prove once and for all that this was the path chosen by Hannibal to conduct one of the most daring military journeys in history.
The second of a two-part paper on tracing Hannibal of Carthage’s route through the Alps to invade Italy in 218 BC using a combination of geological, geochemical, and microbiological techniques.
http://onlinelibrary.wiley.com/doi/10.1111/arcm.12228/abstract
DOI: 10.1111/arcm.12228
Sean F Jordan 