NASA grant funds research for sunscreen on Mars

NASA grant funds research for sunscreen on Mars

NASA grant funds research for sunscreen on Mars

December 30, 2021
RENO, NEV.

By Michelle Werdann, UNR

NASA
Mars
Sunscreen

Above: Vulpinic acid sits on a lab bench next to several lichen species.

Credit: UNR

High radiation on Mars is one of the many reasons the Red Planet seems inhospitable. Two chemistry professors from the University are using solutions from early Earth to solve that problem on Mars.

Reposted from University of Nevada, Reno – https://www.unr.edu/nevada-today/news/2021/sunscreen-for-mars

What do a fungus, a bacterium and an astronaut all have in common? They all need protection from ultraviolet radiation, especially if they’re living on Mars. Researchers at the University of Nevada, Reno in collaboration with Henry Sun of the Desert Research Institute and Christopher McKay of the NASA Ames Research Center received a NASA Established Program to Stimulate Competitive Research (EPSCoR) seed grant to study how they can mimic biology to make some powerful sunscreen.

Serious sunscreen

Lichens are the colorful green moss-like growths found on rocks and trees throughout the Sierras (in fact, Tanzil Mahmud, a graduate student working on this project, went on a hike in Oregon and collected some lichen for the lab). While they appear to be a single organism, lichens are the result of a symbiotic relationship between bacteria and fungi forming a composite organism. Ultraviolet radiation can be harmful to plants if it’s too energetic, so these uniquely bonded organisms evolved a “sunscreen” to protect themselves.

The “sunscreen” is a pigment that is produced by either the bacteria or the fungi. Different species evolved the pigment on their own, suggesting that they were vital to survival in early Earth’s atmosphere. The researchers hypothesize that the absorbed radiation is dissipated in the pigment and transferred into vibrational energy, which dissipates to the environment as heat.

Tanzil Mahmud with lichen sample

Tanzil Mahmud is a graduate student in Christopher Jeffrey’s lab. He is shown holding a lichen he collected for the lab on a hiking trip in Oregon. 

Credit: UNR

Billions of years ago, when Earth’s atmosphere wasn’t as protective as it is now, cyanobacteria had to protect themselves from intense ultraviolet radiation—the same radiation astronauts would be exposed to on Mars. The bacteria evolved pigments that absorbed that harsh radiation and protected the cells. It is believed that these bacteria also photosynthesized and produced oxygen, thus building the ozone layer, which now protects us from the sun’s harsh radiation.

The idea of microbial sunscreens came from Sun. Sun is a molecular microbiologist and an expert on life found in extremely harsh conditions. He noticed the lichen in places like Florida or the Amazon have very green coloration, but that lichens in the desert have different colors. This led Sun to wonder what the pigments did for the lichen.

“The pigment is only in the outer layer. I came to the realization that the pigment has nothing to do with photosynthesis. It must be related to shielding the UV,” Sun said. That’s when he reached out to Matthew Tucker, an associate professor in the Department of Chemistry. Tucker suggested he and Sun meet with associate professor Christopher Jeffrey, also from the Department of Chemistry, and Sun’s curiosity about the pigment spread quickly. The researchers started to design an experiment to determine if and how the pigments evolved to shield the lichen from the sun’s radiation.

Harvesting compounds…then blasting them with radiation

Jeffrey studies the diversity of secondary metabolites, which can perform many different functions in an organism and are often very specific to a species. And as Jeffrey emphasizes, they’re not secondary because they’re unimportant. Using synthetic chemistry and analytical tools, Jeffrey studies secondary metabolites, such as the pigments, with the goal of understanding their relationship to other molecules and to the organism itself.

 

Wolf lichen sample

Jeffrey holds a vial of vulpinic acid isolated from lupus litharium, or Wolf lichen. Wolf lichen is found in Nevada, and the sample they isolated the vulpinic acid from was collected on a camping trip at Yuba Pass. The yield for the pigment is relatively high because five percent of the lichen’s mass is composed of the pigment.

Credit: UNR

Jeffrey’s research will focus on isolating the pigments from the lichen and using synthetic chemistry techniques to produce larger quantities of the pigments, because harvesting them from the lichen doesn’t necessarily produce a high yield of pigment. Then comes the matter of making sure the pigments will hold up to intense energy. That’s where Tucker’s lab comes in.

Tucker’s lab specializes in femtosecond laser spectrometry. A femtosecond is a millionth of a billionth of a second, and ultra-fast lasers can work like cameras with a shutter speed that can catch molecular movement and energy flow at that tiny time scale.

“I’m interested in understanding structural dynamics and the relationships to biological systems using laser spectroscopy,” said Tucker. He studies how energy can flow in an environment, or in this case, within the pigments and their environment.

Once in Tucker’s lab, the pigments will be placed in the path of a laser that is guided by a series of mirrors that will allow the researchers to determine exactly when the laser hits the pigment, which happens at the speed of light. The equipment in Tucker’s lab is precise enough to account for the time difference generated by the mirrors. The laser beam will strike the pigment, but instead of letting the light through, the pigment will dissipate that energy.

 

Laser beam

The laser beam in Tucker’s lab is powerful enough to burn your finger.

Credit: UNR

The evolution of the pigments to work as they do is impressive. The pigments prevent unfavorable chemical reactions from happening inside the cells that result from the absorption of ultraviolet light. Instead, the pigments dissipate the energy quickly and a most safe and effective way.

Utilizing their findings, researchers hope to develop a supplement that can be consumed by astronauts that will give them the same protective effects that the lichens have, like a sunscreen that protects you from the inside.

“And now, once you have this protection sorted out, you can engineer plant life in that way, now you can start to grow plant life on Mars. You can generate some ozone possibilities and ultimately you don’t need all that UV protection,” Tucker said.

Sun said the bacteria have moved a lethal problem (the radiation) to a manageable chemical problem (oxidation), but that because the bacteria have to deal with the oxidation, they may contain useful antioxidants that can be synthesized in labs like Jeffrey’s.

Other applications of these pigments might be more commercial, such as a deck paint that withstands sun exposure for longer periods of time.

Researchers also hope to understand the structure of the sheath that contains the pigments. Typically, these carbohydrate sheaths are water-soluble, but the pigments don’t wash away when it rains on the lichen. Sun says this indicates the sheath is a “chemically perfect scaffold” for the pigment.

Early Earth organisms like cyanobacteria are useful analogs for organisms surviving in harsh environments. Different organisms have solved the radiation problem in the same way.

“There may not be life on Mars, but it’s not because of the radiation,” Sun said. “If other conditions are conducive to life, the radiation would be an easy problem to solve.”

Credit: UNR

Spanning the disciplines

As these symbiotic lichens demonstrate, working together can lead to a beautiful thing, and Tucker is no stranger to that idea. He is currently a co-principal investigator working with other faculty on two large Department of Energy projects for $2.5 million and $2.6 million.

“These collaborations are essential for the project’s success and show how unselfish cooperativity amongst the sciences benefits everyone,” Associate Dean of the College of Science Vince Catalano said.

This research is an intersection of biology, chemistry and physics, which is right up Jeffrey’s alley. As a researcher in the Hitchcock Center for Chemical Ecology, Jeffrey knows how important it can be to reach across the discipline divide. The Hitchcock Center for Chemical Ecology is a program at the University funded by Mick Hitchcock, who developed a groundbreaking treatment for HIV. The program is rooted in interdisciplinary research, particularly between biology, ecology and chemistry. Sun also emphasized the importance of working across fields.

“I’m not a chemist,” Sun said. “So, like the lichen this partnership is mutually beneficial.”

“NASA relies heavily on outside scientists to define the science goal of missions and to analyze the data and put the results in the broad scientific context,” said McKay. “Because missions are interdisciplinary (they usually involve several instruments and several science objectives) the interdisciplinary projects are very important to this process.”

The purpose of the NASA ESPSCoR grant is to bring a wider range of fields into aerospace research activities and apply those fields. Jeffrey has partnered with faculty at Nevada State College (NSC) to develop an interdisciplinary STEM internship program that will bring NSC students to the University campus. This summer internship program will allow those students to gain real research experience in chemistry, biology and physics.

“With the undergraduate interns they get exposure to how the sciences work together, which is important for job and workforce development,” Jeffrey said.

The research team is also focused on producing a short documentary.

“The goal of the documentary is to engage the public that way, because they might see the outcome of science, or the outcome of sending something to the Moon, but often they don’t see how it really takes a huge multi-disciplinary group to not only have their expertise in their sciences, but see the pathway that unites all of those together, and figure out how to work with each other to deliver an outcome,” Tucker said.

“We want to train students to think broadly,” Sun said. “We’re led to a narrow path of thinking. That’s the reason, I think, this interdisciplinary idea has merit.”

Meet Charlotte van der Nagel, Graduate Researcher

Meet Charlotte van der Nagel, Graduate Researcher

Meet Charlotte van der Nagel, Graduate Researcher

DECEMBER 6, 2021
LAS VEGAS, NEV.

Geoscience
Ecohydrology
Ecosystem Sciences

Above: Charlotte van der Nagel during sunrise at Reflection Canyon, Utah.

Credit: Charlotte van der Nagel.

Charlotte van der Nagel is a graduate research assistant with the Division of Earth and Ecosystems Sciences at DRI in Las Vegas and a Ph.D. student in the Geoscience program at University of Nevada, Las Vegas. Learn more about Charlotte and her graduate research in this interview with DRI’s Behind the Science blog!

DRI: What brought you to DRI?

van der Nagel: I am originally from the Netherlands. I worked with Dr. Henry Sun at DRI for half a year in 2020 as part of the research for my master’s thesis. This time allowed me to get to know DRI – and Nevada as a whole – and I sure liked it a lot! So, when a Ph.D. position became available that continued the research I had already started the year before, I didn’t doubt for a single second and applied for it, which brought me back to DRI and Las Vegas in August 2021.

DRI: What are you studying?

van der Nagel: The main focus of my study is ecohydrology. This discipline focuses on the interaction between water and ecology. I am particularly interested in how the desert ecosystem can support life with such limited water availability.

Van Der Nagel moapa

Charlotte van der Nagel in the field digging a hole to bury multiple TDR sensors to monitor soil moisture distribution over depth and time in Arrow Canyon near Moapa, NV.

Credit: Charlotte van der Nagel.

DRI: What research projects are you working on? And who at DRI are you working with?

van der Nagel: I work with my Ph.D. advisor Dr. Henry Sun. My main project is a study that focuses on the occurrence of barren circles of on average 13ft in diameter, surrounding a central ant nest. These circles are found throughout most of the western U.S. and are even visible from satellite images. Ants keep the circles barren by cutting down any seedling that wants to establish inside of the circle, yet ants depend on these plants for their food source. By keeping the circle barren, the ants take away their nearest food source, which does not make sense from a biological viewpoint. In this study, we will try to find the driving force for ants to display this disk clearing behavior.

Another project I recently started working on involves regional die-back of Screwbean Mesquite trees. As these trees are of high ecological significance, there is a lot of interest from different agencies to study the die-back and find possible causes to explain and possibly revert this die-back. For this study, I will be looking at soil moisture conditions, N15 and O18 isotopes of the trees, and sulfide concentrations and redox conditions in the groundwater.

van der nagel ant nests

Charlotte van der Nagel is working with her advisor, Dr. Henry Sun, to study ants nests found within barren circles in the Great Basin and other western ecosystems. Ants keep the circle barren by cutting down vegetation that grows inside the circle, but scientists do not yet understand the reason for this behavior.

Credit: Charlotte van der Nagel.

DRI: What are your short-term and long-term goals while at DRI?

van der Nagel: As I just started my Ph.D. program a couple of months ago, my short-term goal would be to get both my projects up and running, so that I will start getting results in. In the meantime, I am planning on learning as much as I can about the various topics my research includes.

In the long-term, I want to engage in more cross-disciplinary research. Often, a research problem is not easily classified as one field of work. For example, my ant circle study requires not only knowledge of hydrology, but also of ecology and biology. If you exclusively look at one of those disciplinaries, you will inevitably miss a lot of potentially important findings in the other fields. I therefore want to extend my area of focus and I feel like DRI would be a great place for this.

DRI: Tell us about yourself. What do you do for fun?

van der Nagel: Coming from a country that is flat and very densely populated, I love spending all my free time out of the city, enjoying the vastness of the desert. You can find me every weekend out hiking, climbing, camping, kayaking or off-roading – the more remote, the better.  I really like that Las Vegas is close to so many great national parks and try to make every weekend into an adventure. One of the most amazing things I have done so far was driving 2 hours on a rough off-road, then hiking 10 miles with a heavy backpack to camp on the edge of Reflection Canyon, Utah. The most rewarding hike I have ever done!

Van Der Nagel in Zion

Charlotte van der Nagel hiking Angels Landing in Zion National Park, Utah.

Credit: Charlotte van der Nagel.

Additional Information:

For more information on graduate programs at DRI, please visit: https://www.dri.edu/education/graduate-programs/.

Meet Henry Sun, Ph.D.

Meet Henry Sun, Ph.D.

Henry Sun, Ph.D., is an associate research professor of microbiology with the Division of Earth and Ecosystem Sciences at the Desert Research Institute in Las Vegas. Henry specializes in the study of microscopic organisms that live in extreme environments, often using specimens from here on earth to learn about possibilities for life on Mars. He is originally from China and has a bachelor’s degree in botany and master’s degree in phycology (the study of algae) from Nanjing University. He also holds a Ph.D. in microbiology from Florida State University and completed a post-doc in astrobiology (the study of life in the universe) at the Jet Propulsion Lab in Pasadena, CA. Henry has been a member of the DRI community since 2004. In his free time, he enjoys playing pickup basketball with friends in Las Vegas, and spending time with his wife and two kids.

DRI: What do you do here at DRI?HS: I do quite a few things, all centered around the study of life in extreme environments – places that are in one way or another similar to Mars. We are studying what we call analog environments, trying to understand whether there’s life in these places that are comparable to Mars, learning how to go about detecting life and organisms, and developing ideas for reliable instruments that we can send to Mars to look for life there.

DRI: How did you become interested in this line of work?
HS: It started in graduate school, when I was given the opportunity to go to Antarctica, to a place called the Dry Valleys, to do my dissertation work. Until 1976, this was a place thought to be devoid of all life. But my former adviser, Imre Friedmann, extrapolating from his work in the hot deserts in the southwestern U.S., discovered thriving communities of microalgae and cyanobacteria in the pore spaces in the Antarctic sandstone. Sandstone is translucent, so sunlight can penetrate the first few millimeters. The stone holds onto water in the pore spaces so it doesn’t dry out right away. And that’s all you need to support life. I fell in love with these organisms on my very first trip there.

Henry Sun at work in Antarctica, January 2005.

Henry Sun at work in Antarctica, January 2005.

DRI: What did you learn from studying those organisms?
HS: Probably the most remarkable thing we have learned about these organisms is that they have a very slow growth rate. We have monitored a few rocks closely over the last 50 years and never saw any appreciable signs of growth. In fact, they are so long-lived that their age can be determined by radiocarbon decay. In other words, if you look at their radiocarbon content, you would think they are dead, fossilized organisms. But we know they are alive because as soon as we thaw them to a normal temperature they start to breathe, taking up carbon dioxide and releasing oxygen. And because they start to grow and reproduce when we put them in a petri dish and incubate at more favorable temperature conditions.

That said, we still have a lot to learn about these organisms, and the opportunity for a serious study presented itself this year. When my former advisor passed away in 2007, he left behind a large collection of thousands of rocks from Antarctica, amassed over his career, in a walk-in -30oC freezer at Florida State University in Tallahassee, Florida. Last year, Florida State decided to decommission that building, and the samples were about to be thrown out. This past June, with a little help from DRI and NASA, we raised some money and purchased three freezers. I drove to Florida and hauled all of the samples back in a cargo van full of coolers and dry ice. I moved the entire collection to Las Vegas without them ever being thawed, so now they are sitting at DRI waiting to be studied.

An outcrop of Antarctic sandstone at one of Henry Sun's field sites.

An outcrop of Antarctic sandstone at one of Henry Sun’s field sites.

DRI: What are you planning to do with these samples?
HS: Inside of the freezers, the samples are kept at temperatures of -30oC (-22oF) and in complete darkness, but the microbes are still alive. As I said, we have thousands of samples. Only two samples have been studied using modern-day DNA analysis. So, the first thing we want to is a comprehensive molecular study and find out what lives in these samples.

We are also working with colleagues at the NASA Ames Research Center to look for cyanobacteria that can grow not using the visible light, but using the infrared. Visible light, which photosynthetic organisms prefer, is filtered out by the sandstone. But the infrared is still present. It is not as good as the visible, but that is all the organisms at the bottom of the colonized zone have. We speculate that they may subsist on the infrared.

Closeup of one of Henry Sun's Antarctic rock samples, home to unknown species of microorganisms.

Closeup of one of Henry Sun’s Antarctic rock samples, home to unknown species of microorganisms.

DRI: What do you like best about what you do?
HS: I feel most rewarded when we engage school teachers and their students in what we do. We do this through a program called Spaceward Bound, which was created by Chris McKay, DRI’s Nevada Medalist from two years ago. The goal is to train the next generation of space explorers in remote but scientifically interesting places that are analogous to the moon or Mars. The reason why we need to start this now is because the first human mission to Mars may happen as early as the 2030s. The scientists who will go to Mars to study its environment are still in school today. We have done several Spaceward Bound expeditions in the Mojave and Death Valley area with teachers and students from Nevada. To me, there is no greater reward than to see children get inspired by the work we do so that one day they may become scientists themselves and continue to push back the frontier of knowledge.

Henry Sun talks with a student at DRI's 2018 'May Science Be With You' event in Las Vegas.

Henry Sun talks with a student at DRI’s 2018 ‘May Science Be With You’ event in Las Vegas.

For more information on Henry Sun and his research, continue to his research page: https://www.dri.edu/directory/4764-henry-sun

Saving the Desert’s Upper Crust

To a casual observer, desert lands may appear a barren vista of sand and soil, sparsely dotted with shrubbery and cacti but, in reality, they are lush with microscopic plants: lichens, mosses, and cyanobacteria. There isn’t an inch of soil that is without these organisms.

“These organisms are a critical component of the desert ecosystem: they stabilize soils against erosion and provide essential nutrients to plants,” says NEXUS scientist Dr. Henry Sun, a research microbiologist at the Desert Research Institute (DRI).

These coverings-known as cryptogamic crusts-while providing essential ecosystem services, are also very fragile. Both the installation of solar farms and regular maintenance activities can disturb and remove this biological layer. “Such activities can destroy the crusts and result in increased dust emission,” Sun says. “And, once destroyed, they take decades to recover.”

Consequently, Sun and his graduate student, Lynda Burns, are trying to understand the impacts that large scale solar farms will have on this component of desert ecosystems and how to develop mitigation strategies to help prevent, or remediate any damage. “The goal of our research is to know the vulnerabilities of the organisms that build these protective crusts and to use the information to guide future restoration mitigation efforts in the context of solar plant impacts,” Sun says.

Banking Biology

The presence of these non-flowering plants is a key indicator of a healthy desert ecosystem. As well as forming a protective soil crust, and a barrier to erosion, they also provide nutrients to plants, mediate the transfer of water and provide a base for seed germination and plant growth.  In addition, the cyanobacteria can convert the nitrogen in the atmosphere into compounds that act as fertilizers for other plants, via a process called nitrogen fixation. “So you fix nitrogen using solar energy into a form that is available to plants,” Sun says.

Recognizing the importance of these crusts, and also their vulnerabilities, scientists have been investigating how to protect them. One suggested approach has been to harvest the crusts prior to a disturbance such as the installation of a solar farm, and save them. Once the construction is complete, the researchers’ suggestion is then to use the preserved crusts to inoculate the soil and aid in restoring the new crust.

The desert can prove a harsh environment for plants with temperatures and rainfall fluctuating between extremes. Also, a process called photochemical oxidation, facilitated by the sun’s ultraviolet rays can result in reactive oxygen species that are extremely damaging to life. “For this strategy to be effective, we need to know if the organisms lose vitality during storage, how long they would survive, and how to help them survive and thrive once they’ve been re-introduced to the desert habitat,” Sun says.

The scientific community does not yet know the answers to such questions and it was a knowledge gap that the NEXUS team set out to close. They began by collecting and saving the organisms in the soil crust and set about trying to understand how long those samples could survive and whether they could be successfully reintroduced to the desert environment. “There were two questions we’re trying to answer,” Sun says. “One, whether you can store the organisms and, two, when you reintroduce them what can we do to help them re-establish?”

Putting Crusts to the Test

In the lab, the scientists started their investigations by storing lichen samples from the Mojave Desert for different periods of time. In their natural habitat the lichens in the crusts alternate between drying out and hydration. During the desiccation process, they suffer from cellular damage but once they are hydrated repair and growth is possible. In their experiments, the researchers watered the stored samples and then monitored their recovery. “Healthy specimens become active within a minute of watering and compromised lichens go through a period of repair before they become productive,” Sun says. The researchers assumed that those lichens that showed no activity after 8 hours were dead.

Using this methodology, the scientists found that lichens can be stored dry at room temperature in ambient air for up to a year without any significant decline in vitality.  One-year old samples showed similar behavior to fresh samples: once they were given water they were ready to use light energy and photosynthesize.  Three and even ten-year-old samples were weaker and it would take them between 25 and 200 minutes to restore photosynthesis after the addition of water.

The scientists then attempted to determine how ultraviolet (UV) rays would impact the lichens when they were reintroduced back into the desert. The crust lichens protect themselves from UV light by synthesizing compounds that create a screen that blocks the harsh rays.  Even when the researchers put intense UV source as close as 25 centimeters away for one week the lichens suffered only minor damage. “It was well within their ability to repair,” Sun says. “This level of ionizing radiation resistance is unparalleled in the microbial world.”

The scientists did find, however, that the lichens were vulnerable to high concentrations of ozone. Fumigation in ozone for long periods caused photochemical oxidation, killing Collema, a cyanobacterial lichen, and severely damaging Placidium, a green algal lichen. Previous studies on the stress tolerance of crust-forming organisms considered only the impacts of UV radiation and desiccation. “Our work showed that photochemical oxidation presents a more severe stress than UV and desiccation,” Sun says. “And this has implications for crust storage and restoration.”

Given the evidence that the crust lichens are primarily vulnerable to oxidation, Sun recommends that the samples be stored in a non-oxidizing gas, such as nitrogen, instead of ambient atmosphere, to minimize oxidative stress.  In the field, amending the soil with antioxidants could protect the newly restored “seed” organisms from oxidation and thereby help them grow faster.  Both the ability of the organisms to be stored and their ability to survive typical desert conditions bodes well for the future, Sun says. “The research suggests that crust restoration is feasible and should be considered by land managers and solar companies,” Sun says.


This story was written by Jane Palmer and was originally published by the Solar-Energy-Water-Environment Nexus Project. For more information about the Nexus Project, visit: https://solarnexus.epscorspo.nevada.edu/

The Desert Research Institute (DRI) is a recognized world leader in investigating the effects of natural and human-induced environmental change and advancing technologies aimed at assessing a changing planet. For more than 50 years DRI research faculty, students, and staff have applied scientific understanding to support the effective management of natural resources while meeting Nevada’s needs for economic diversification and science-based educational opportunities. With campuses in Reno and Las Vegas, DRI serves as the non-profit environmental research arm of the Nevada System of Higher Education. For more information, visit www.dri.edu.