18 September 2017

The Summons Lab bids farewell to a talented lab member and welcomes several new mambers


Dr. Xiaolei Liu as been a postdoc associate and a research scientist in Roger’s lab for the last 3 years. Xiaolei received his PhD degree at the University of Bremen with Dr. Kai-Uwe Hinrichs. Afterwards, he continues his postdoc in the same lab. In 2014, he joined Summons Lab and since then, he has been working on several projects. Xiaolei has contributed significantly to this lab and has helped manage the lab since 2016. Xiaolei recently accepted the offer from the University of Oklahoma (OU) to be a tanure-track professor. http://www.ou.edu/mcee/geology/people/faculty/xiaolei_liu.html. Summons Lab wishes he all the best with his new career.



Dr. Xiaowen Zhang received her PhD in the summer, 2017. Right afterwards, she joined Summons’ Lab. For her PhD, she has been working on the permafrost thawing in the Arctic Alaska and the climatic feedback. She pioneered the use of compound specific radiocarbon analysis in tracking permafrost thawing in the past. For her postdoc research, she will primarily focus on the abiotic synthesis of lipid. Her research could potentially answer how the earliest lipids were synthesized on Earth



Angel Mojarro is a new PhD student coadvised by Summons Lab and Zuber/Carr Lab. His research is focused on the human exploration and search for life of Mars. In Summons Lab, he will analyze organic molecules from rock/soil samples and extract life information in them.


23 June 2017

Latest Summons Lab Research


The front cover of the latest issue of Journal Applied and Environmental Microbiology featured the research work from Summons Lab on the synthesis of methylated hopanoids by cyanobacterium Nostoc punctiforme ATCC 29133S. This work discovered that by deleting the hpnP gene, Nostoc Punctiforme is not able to synthesize all 2-methylhopanoids, however, it produces much higher levels of two bacteriohopanepentol isomers than the wild type. The ΔhpnP mutant was found to have decreased growth rates under both pH and osmotic stress, confirming a role for 2-methylhopanoids in stress tolerance. Evidence of elevated photosystem II yield and NAD(P)H-dependent oxidoreductase activity in the ΔhpnP mutant under stress conditions, compared to the wild type, suggested that the absence of 2-methylhopanoids increases cellular metabolic rates under stress conditions.

cover image

Cover photograph: Scanning electron micrograph of the cyanobacterium Nostoc punctiforme ATCC 29133S forming akinetes (resting cells that are larger and rounder in morphology) under conditions of phosphate deprivation. N. punctiforme has a complex life cycle, in which, based on environmental signals, vegetative cells can differentiate into N2-fixing heterocysts, akinetes, or motile hormogonia. N. punctiforme ATCC 29133 was originally isolated from a symbiotic association with the gymnosperm cycad Macrozamia sp.; the 29133S strain is a spontaneous mutant that grows more rapidly and homogenously in liquid, producing slow hormogonia. (See related article at e00777–17.) (Copyright © 2017 American Society for Microbiology. All Rights Reserved.)

15 March 2017

Summons Lab Latest Research Highlights


Summons Lab recent research features two publications in Nature and PNAS with funding support from the Simons Foundation Origins of Life Collaboration program.

Recently, David Gold published his paper entitled “Paleoproterozoic sterol biosynthesis and the rise of oxygen” in Nature. Sterol biosynthesis signals aerobic metabolic processes by eukaryotes. However, there has been debates on the earliest emergence of eukaryotes, with time ranging from Archean to meso-proterozoic. Here, he used a molecular clock approach to improve constrains on the evolution of sterol biosynthesis. He found the maximum marginal probability for eukaryal sterol biosynthesis genes is around 2.31 Gyr ago, in align with the evidence of the Great Oxidation Event. This study further indicated that the simple sterol biosynthesis existed well before the diversification of eukaryotes and is tied to the first widespread availability of molecular oxygen in the ocean-atmosphere system.



Gareth Izon published his work entitled “Biological regulation of atmosphere chemistry en route to planetary oxygenation” in PNAS and provided us evidence on the presence of organic-haze pre-GOE. It has been proposed that enhanced methane fluxes to Earth’s early atmosphere could have altered atmospheric chemistry, initiating a hydrocarbon-rich haze reminiscent of Saturn’s moon, Titan. In this study, he tested and refined the “haze hypothesis” to refine the structure and timing of haze development. The persistence of haze requires a sustained biological driver, with methane fluxes controlled by the relative availability of organic carbon and sulfate. This study implied that the presence of haze could have had a significant impact on the escape of hydrogen from the atmosphere, contributing to the terminal oxidation ~2.4 GYr ago.


11 March 2017

Summons Lab 2017 Retreat


Summons Lab group retreat was held in Jackson, NH. This lab retreat brought together most of current lab members and a former lab member, Shane O’Reilly. Everyone shared their on-going research, all with common objectives in attempting to better understand earth history. Topics were broad and spanned origin of life to modern biogeochemical processes. The group retreat was very successful and it was clear that all involved got insights and ideas from the presentations.


Ainara giving presentation on seeking new biomarkers to understand the role of gut microbiome in human evolution


Everyone is happy about the snow.

15 September 2016

The Summons Lab bids farewell to several talented and valuable lab members!


RossPicpdfDr. Ross Williams has been a PhD researcher in Roger’s lab for the last 5 years. Ross recently received his PhD degree in Geochemistry at MIT. His research focus has been on paleoenvironment reconstruction in extreme climates ranging from Early Cenozoic lignite deposits in India to modern day high elevation lakes of the Chilean Altiplano. Ross has recently accepted a Postdoctoral position through the Center for Research and Exploration in Space Science & Technology (CRESST) at NASA Goddard Space Flight Center in Maryland. There he will work on supporting the Sample Analysis at Mars (SAM) investigation on the Mars Science Laboratory (MSL). Ross has also recently welcomed a new family member into the world, his adorable son Hendrick Ross Williams. Ross, Hendrick, and his beautiful wife Christina are looking forward to the next chapter of their lives in Maryland. Ross has been a dedicated and valued colleague and friend, and he will be greatly missed by all!


Dr. Shane O’Reilly is a Postdoctoral Fellow who has been in Roger’s lab since 2014. Shane has received a competitive Marie Curie fellowship with a joint appointment with the University College in Dublin, where he will continue his research fellowship for an additional year after his tenure at MIT. Shane’s research involves the use of lipids and next generation sequencing approaches to study microbial communities associated with marine and terrestrial carbonate deposits and the fossil lipids that can be preserved within these carbonate over geologic time. These include ooids, tufa and pisoids. Shane has also been involved in a number of projects studying exceptional preservation of organic molecules in vertebrate fossils, including Messel birds and mammoth bones. He also contributed to astrobiology projects relating to the analog experiments to understand the Curiosity Rover’s detection of organic molecules on Mars. Shane has been an outstanding colleague and friend to all members of the Summons lab, and will be greatly missed!


Yongli Zhou is an undergraduate researcher from University of Science and Technology of China who has been in the Summons laboratory for a 3 month summer internship. Yongi has been a highly motivated and productive student, and his research has focused on characterizing fossilized plant lipids at an ancient site in Africa, and preserved functionalized lipids in mammoth bone fossils. Yongli will be considering graduate school opportunities in the future, and will have a bright and promising future in research. All members of the Summons lab have greatly enjoyed having Yongli in the lab during his visit, and he will be missed!

12 August 2016

GRC Organic Geochemistry meeting 2016 in Holderness, NH


The Gordon Research Conference Organic Geochemistry meeting was held at Holderness School in Holderness, New Hampshire from July 24th – July 29th, 2016. The conference was chaired by Anne Pearson, and Lloyd Snowdon served as the vice chair. Many who attend this meeting will agree that the quality of science and unique “campy” experience in Holderness makes this GRC one of the most pleasurable to attend. The conference is held every two years, and since 1970 has traditionally been held in the same venue. Holderness is located in the heart of New Hampshire’s Lakes Regions, and includes 600 acres of woodlands, open fields, trails, and a river. The afternoons are open during the conference to encourage recreational activities. This year, the meeting topics were focused on using advanced technologies to address current and future societal challenges. The itinerary was packed with fascinating talks and poster sessions from scientists across a breadth of disciplines in the field of organic geochemistry. Representatives from the Summons lab who participated included Roger, Xialei, Ainara, Emily, and Heather.


13 July 2016

Latest Summons Lab Research


From the origin’s of complex life to the timing of oxygen’s first appearance in the atmosphere, the Summons lab has published a number of exciting and important papers in recent weeks.

David recently published his combined biomarker and genomic study in PNAS. Here, he presented conclusive evidence that sea sponges were indeed the source of the unusual biomarkers in 640 million year old rocks. This ‘sponge biomarker hypothesis’ was first proposed by Roger and co-workers, and this new work provides further evidence that sea sponges were one of the earliest animals on the scene on Earth. Read more about this in a number of media outlets such as The Independent, Newser, Boston CBS, TechTimes and MIT News.

In May in Scientific Advances, Genming published evidence for a rapid oxygenation of Earth’s atmosphere 2.33 billion years ago and a precise constraint on the timing of the Great Oxidation Event (known as the GOE). Media coverage for this include the Air & Space Magazine published by the Smithsonian, Phys.org, and MIT News.

Xiaolei recently published two papers providing significant advances in our knowledge of the diagenetic fate and structural diversity of glycerol dialkyl glycerol tetraether lipids. He published his work in the journals Geochimica et Cosmochimica Acta and Rapid Communications in Mass Spectrometry. Xiaolei’s work involved collaborations with members of the Bosak Lab in MIT and the Hinrich’s Lab in Bremen.

In June, Shane published a paper in Geobiology studying ooids from The Bahamas. Ooids are accretionary carbonate grains that occur in many Precambrian and Phanerozoic rocks, and provide an insight into the environmental/depositional conditions and seawater chemistry in marine environments through time. However, the formation of these enigmatic grains is actively debated. In this paper, Shane demonstrates that the major source of organic matter within ooids is from benthic microbial biofilms. Organic matter bound within ooid grains is old and altered, having been subject to microbial decomposition, likely under reducing conditions. The association of bacteria and these molecular signals with ooid carbonate crystals suggests that these biological processes may contribute to ooid formation.

10 April 2016

Cambridge Science Festival!



The Cambridge Science Festival is fast approaching us! Starting on Friday April 15th, the festival is an annual 10-day celebration of science, technology, engineering, art and math in Cambridge and beyond. Collaborators for the festival include MIT, Harvard University, the City of Cambridge and the Museum of Science. Every spring, the festival makes science accessible, engaging and fun for everyone through a host of exhibitions, activities and multicultural events. This year the festival is celebrating its 10th anniversary, and it promises to be a memorable one. The Summons Lab will be actively involved, together with other members of MIT EAPS department and the NAI Astrobiology Team Foundations for Complex Life.

The Science Carnival & Robot Zoo will happen on Saturday, April 16. This is an action-packed free carnival with science and technology exhibitors from around the globe. The Summons Lab and the NASA Astrobiology Institute Foundations for Complex Life time will have two stands side by side. We will be inviting everyone to come along and take their shot at the recently developed app game ‘Earth History in 60 Seconds’. This is an exciting, fast-paced, multiplayer game testing your knowledge of major events in Earth’s long history in 60 seconds! The app is available for download on iTunes here. We will also be providing an interactive demonstration and discussion of the amazing science of ‘molecular fossils’. Roll your sleeves up and join us for a molecular fossil hunt! The carnival will be on at the Cambridge Rindge & Latin Field House, Cambridge Public Library, Broadway and Ellery Street. It will run from 12:00-4:00pm.

Christy Grettenberger will be leading guided tours of ‘A Walk Through Geologic Time’. Earth’s history stretches back over 4.567 billion years—how are we supposed to grasp such a vast number? We’ve shrunken it down to a third of a mile along the Charles River, and invite you to join us on a walk through time to tour the many incredible events during Earth’s long and storied history. The tours will run on April 15th & 16th at 5:30 pm, and on April 17th at 11 am and 5:30 pm. All tours will meet at the intersection of Mass. Ave. and Memorial Drive (MIT side), lasts approximately 45 minutes and are totally FREE!

Shane will be given a science outreach talk for CafeSci Boston (presented by NOVA). His talk is titled ‘Hunting for fossil fat in Earth’s History’. The event will be held at Le Laboratoire (650 East Kendall Street) on Tuesday 19th April from 7 to 8pm. The talk is free, informal and open to the public. Here is a link to the event on Eventbrite and Boston Calendar.

Check out the full list of events for the Cambridge Science Festival on the festival website and the blog. A detailed calendar of events is available here.

9 April 2016

GRC Geobiology meeting 2016 in Galveston


The GRC Geobiology meeting was held in early February in Galveston, Texas. The venue was the magnificent Hotel Galvez and was chaired by David Fike and Tanja Bosak. The meeting brought together a core group of experts from diverse fields, all with common objectives in attempting to answer some of the most important questions in Geobiology today. The meeting was attended by molecular biologists, microbial ecologists, geochemists, paleontologists, and geologists among others. Topics were broad and spanned life’s early beginnings to modern biogeochemical processes. The aim of this meeting was to also identify future research directions and to foster and encourage continued interest from the academic and industrial community. The Summons Lab was represented by Shane and Xiaolei, who both presented posters of their recent work. Many members of the Bosak lab were also in attendance, as well as former members of the Summons Lab.  The meeting was very successful and it was clear that all involved came away with much enthusiasm and ideas.

Image credit: Gordon Research Conferences

Image credit: Gordon Research Conferences



9 April 2016

The Summons Lab welcomes two recent additions to the group


The Summons Lab welcomes two new postdoctoral scientists – Ainara Sistiaga and Heather Throckmorton.

Ainara is no stranger to the Summons Lab and to MIT, as she spent time hereas a visiting student during her postgraduate studies. Ainara’s research is focused on exploiting the organic molecular information preserved in sediments, with particular emphasis on the paleodietary record. She combines organic geochemistry and paleolithic archaeology to provide greater insight into the dietary role of meat and plants during human evolution. One interesting aspect of her work involves the use of faecal biomarkers (sterols, bile acids and other potential novel indicators) as a source of paleodietary information. For an insight into Ainara’s work, check out this MIT news story on neanderthal diet.



Heather arrives from Los Alamos National Laboratory where she was a postdoctoral scientist. Heather studied  geology at the University of Southern Maine before headingwest to University of California, Davis where she received her doctorate. Heather has expertise in soil biogeochemistry and has previously studied the impacts of microbial biomass types on soil carbon stabilization (and how soil matrices effect the former), as well as pathways and fate of dissolved methane and inorganic carbon in Arctic tundra watersheds. She joins the group as an NAI-funded fellow and will be leading and collaborating in a diverse range of astrobiology projects.