NASA grant funds research for sunscreen on Mars


What do a fungus, a bacteria and an astronaut have in common? They all need protection from ultraviolet rays, especially if they live on Mars. Researchers at the University of Nevada at Reno, in collaboration with Henry Sun of the Desert Research Institute and Christopher McKay of the NASA Ames Research Center received a seed grant from the program established by NASA to Boost Competitive Research (EPSCoR) to study how they can mimic biology to make potent sunscreen.

Serious sunscreen

Lichens are the colorful, green moss-like growths found on rocks and trees in the Sierras (in fact, Tanzil Mahmud, a graduate student working on this project, hiked Oregon and collected 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 is too energetic, which is why these uniquely linked organisms have developed “sunscreen” to protect themselves.

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

Tanzil Mahmud is a graduate student of Christopher Jeffrey’s lab. He is pictured holding a lichen he collected for the lab while hiking in Oregon.

Billions of years ago, when Earth’s atmosphere was not as protective as it is today, cyanobacteria had to shield themselves from intense ultraviolet rays, the same radiation astronauts would be exposed to on Mars. The bacteria developed pigments which absorbed this aggressive radiation and protected the cells. These bacteria are thought to have also photosynthesized and produced oxygen, creating the ozone layer, which now protects us from the sun’s rays.

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

“The pigment is only present in the outer layer. I realized that the pigment has nothing to do with photosynthesis. It has to be related to UV protection, ”Sun said. It was then that he contacted Matthew Tucker, associate professor in the Department of Chemistry. Tucker suggested that he and Sun meet with associate professor Christopher Jeffrey, also in the chemistry department, and Sun’s curiosity about the pigment quickly spread. Researchers began to design an experiment to determine if and how the pigments evolved to protect the lichen from solar radiation.

Collect compounds … then explode them with radiation

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

A masked Christopher Jeffrey holds a vial containing a bright yellow crystalline powder labeled "vulpinic acid" in one hand and a blurry green lichen in the other, with two other individuals in the background.
Jeffrey is holding a vial of vulpinic acid isolated from lupus litharium, or wolf lichen. Wolf lichen is found in Nevada, and the sample from which they isolated vulpinic acid was collected during a camping trip to Yuba Pass. The pigment yield is relatively high because five percent of the lichen mass is composed of the pigment.

Jeffrey’s research will focus on isolating pigments from lichen and using synthetic chemistry techniques to produce larger amounts of pigment, as harvesting them from lichen does not necessarily produce a high yield of pigment. Then comes the question of ensuring that the pigments will withstand intense energy. This is 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 function as cameras with a shutter speed capable of picking up molecular motion and energy flow on this tiny timescale.

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

Once in Tucker’s lab, the pigments will be placed in the path of a laser guided by a series of mirrors that will allow 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 hit the pigment, but instead of letting light through, the pigment will dissipate that energy.

A green laser beam bounces off the mirrors of a rectangular device.
Tucker’s lab laser beam is powerful enough to burn your finger.

The evolution of pigments to work the way they do is impressive. Pigments prevent adverse chemical reactions from occurring inside cells resulting from absorption of ultraviolet light. Instead, the pigments dissipate energy quickly, safely and efficiently.

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

“And now, once you’ve got that protection sorted out, you can design plant life that way, now you can start growing plant life on Mars.” You can generate ozone possibilities and, at the end of the day, you don’t need all that UV protection, ”Tucker said.

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

Other applications of these pigments could be more commercial, such as a bridge paint that resists exposure to the sun for longer periods.

The researchers also hope to understand the structure of the sheath that contains the pigments. Typically, these carbohydrate sheaths are soluble in water, but the pigments do not disappear when it rains on the lichen. Sun says this indicates that the sheath is a “chemically perfect scaffold” for the pigment.

Earth’s first organisms like cyanobacteria are useful analogues for organisms that survive in harsh environments. Different organizations have solved the radiation problem in the same way.

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

Spanning disciplines

As these symbiotic lichens demonstrate, working together can lead to a beautiful thing, and Tucker is no stranger to the idea. He is currently a Co-Principal Investigator and is working with other professors on two large Department of Energy projects for $ 2.5 million and $ 2.6 million.

“These collaborations are essential to the success of the project and show how selfless cooperation between sciences benefits everyone,” said Associate Dean of the College of Sciences Vince Catalano.

This research is an intersection of biology, chemistry, and physics, which is right down Jeffrey’s alley. As a researcher at the Hitchcock Center for Chemical Ecology, Jeffrey knows how important it can be to overcome disciplinary divisions. The Hitchcock Center for Chemical Ecology is a University program funded by Mick Hitchcock who has developed a revolutionary treatment for HIV. The program is anchored in interdisciplinary research, particularly between biology, ecology and chemistry. Sun also stressed the importance of working in multiple areas.

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

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

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

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

The research team is also focusing on the production of a short documentary.

“The point of the documentary is to engage audiences in this way, because they could see the result of science, or the result of sending something to the moon, but often times they don’t see how it really takes a huge multidisciplinary group not only to have their expertise in their sciences but also to see the way that unites them all and to find how to work with each other to get a result, ”said Tucker.

“We want to train students to think broadly,” Sun said. “We are led to a narrow path of thought. This is the reason, I think, that this interdisciplinary idea has merit.


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