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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The mystery of why life uses molecules with specific orientations has deepened with a NASA-funded discovery that RNA — a key molecule thought to have potentially held the instructions for life before DNA emerged — can favor making the building blocks of proteins in either the left-hand or the right-hand orientation. Resolving this mystery could provide clues to the origin of life. The findings appear in research recently published in Nature Communications.
Proteins are the workhorse molecules of life, used in everything from structures like hair to enzymes (catalysts that speed up or regulate chemical reactions). Just as the 26 letters of the alphabet are arranged in limitless combinations to make words, life uses 20 different amino acid building blocks in a huge variety of arrangements to make millions of different proteins. Some amino acid molecules can be built in two ways, such that mirror-image versions exist, like your hands, and life uses the left-handed variety of these amino acids. Although life based on right-handed amino acids would presumably work fine, the two mirror images are rarely mixed in biology, a characteristic of life called homochirality. It is a mystery to scientists why life chose the left-handed variety over the right-handed one.
A diagram of left-handed and right-handed versions of the amino acid isovaline, found in the Murchison meteorite.NASA DNA (deoxyribonucleic acid) is the molecule that holds the instructions for building and running a living organism. However, DNA is complex and specialized; it “subcontracts” the work of reading the instructions to RNA (ribonucleic acid) molecules and building proteins to ribosome molecules. DNA’s specialization and complexity lead scientists to think that something simpler should have preceded it billions of years ago during the early evolution of life. A leading candidate for this is RNA, which can both store genetic information and build proteins. The hypothesis that RNA may have preceded DNA is called the “RNA world” hypothesis.
If the RNA world proposition is correct, then perhaps something about RNA caused it to favor building left-handed proteins over right-handed ones. However, the new work did not support this idea, deepening the mystery of why life went with left-handed proteins.
The experiment tested RNA molecules that act like enzymes to build proteins, called ribozymes. “The experiment demonstrated that ribozymes can favor either left- or right-handed amino acids, indicating that RNA worlds, in general, would not necessarily have a strong bias for the form of amino acids we observe in biology now,” said Irene Chen, of the University of California, Los Angeles (UCLA) Samueli School of Engineering, corresponding author of the Nature Communications paper.
In the experiment, the researchers simulated what could have been early-Earth conditions of the RNA world. They incubated a solution containing ribozymes and amino acid precursors to see the relative percentages of the right-handed and left-handed amino acid, phenylalanine, that it would help produce. They tested 15 different ribozyme combinations and found that ribozymes can favor either left-handed or right-handed amino acids. This suggested that RNA did not initially have a predisposed chemical bias for one form of amino acids. This lack of preference challenges the notion that early life was predisposed to select left-handed-amino acids, which dominate in modern proteins.
“The findings suggest that life’s eventual homochirality might not be a result of chemical determinism but could have emerged through later evolutionary pressures,” said co-author Alberto Vázquez-Salazar, a UCLA postdoctoral scholar and member of Chen’s research group.
Earth’s prebiotic history lies beyond the oldest part of the fossil record, which has been erased by plate tectonics, the slow churning of Earth’s crust. During that time, the planet was likely bombarded by asteroids, which may have delivered some of life’s building blocks, such as amino acids. In parallel to chemical experiments, other origin-of-life researchers have been looking at molecular evidence from meteorites and asteroids.
“Understanding the chemical properties of life helps us know what to look for in our search for life across the solar system,” said co-author Jason Dworkin, senior scientist for astrobiology at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and director of Goddard’s Astrobiology Analytical Laboratory.
Dworkin is the project scientist on NASA’s OSIRIS-REx mission, which extracted samples from the asteroid Bennu and delivered them to Earth last year for further study.
“We are analyzing OSIRIS-REx samples for the chirality (handedness) of individual amino acids, and in the future, samples from Mars will also be tested in laboratories for evidence of life including ribozymes and proteins,” said Dworkin.
The research was supported by grants from NASA, the Simons Foundation Collaboration on the Origin of Life, and the National Science Foundation. Vázquez-Salazar acknowledges support through the NASA Postdoctoral Program, which is administered by Oak Ridge Associated Universities under contract with NASA.
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Last Updated Nov 21, 2024 EditorWilliam SteigerwaldContactNancy N. Jonesnancy.n.jones@nasa.govLocationGoddard Space Flight Center Related Terms
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By NASA
Teams from NASA and ESA (European Space Agency), including NASA astronaut Stan Love (far right) and ESA astronaut Luca Parmitano (far left) help conduct human factors testing inside a mockup for the Gateway lunar space station. Thales Alenia Space Teams at NASA, ESA (European Space Agency), and Thales Alenia Space, including astronauts Stan Love and Luca Parmitano, came together in Turin, Italy, this summer for a test run of Gateway, humanity’s first space station to orbit the Moon.
The group conducted what is known as human factors testing inside a mockup of Lunar I-Hab, one of four Gateway modules where astronauts will live, conduct science, and prepare for missions to the Moon’s South Pole region. The testing is an important step on the path to launch by helping refine the design of spacecraft for comfort and safety.
Lunar I-Hab is provided by ESA and Thales Alenia Space and is slated to launch on Artemis IV. During that mission, four astronauts will launch inside the Orion spacecraft atop an upgraded version of the SLS (Space Launch System) rocket and deliver Lunar I-Hab to Gateway in orbit around the Moon.
ESA, CSA (Canadian Space Agency), JAXA (Japan Aerospace Exploration Agency), and the Mohammad Bin Rashid Space Centre of the United Arab Emirates are providing major hardware for Gateway, including science experiments, the modules where astronauts will live and work, robotics, and life support systems.
International teams of astronauts will explore the scientific mysteries of deep space with Gateway as part of the Artemis campaign to return to the Moon for scientific discovery and chart a path for the first human missions to Mars and beyond.
A mockup of ESA’s Lunar I-Hab module, one of four elements of the Gateway space station where astronauts will live, conduct science, and prepare for missions to the lunar South Pole Region.Thales Alenia Space An artist’s rendering of ESA’s Lunar I-Hab module in orbit around the Moon, one of four elements of the Gateway space station where astronauts will live, conduct science, and prepare for missions to the lunar South Pole Region.NASA/Alberto Bertolin, Bradley Reynolds Learn More About Gateway Share
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Last Updated Oct 22, 2024 EditorBriana R. ZamoraContactDylan Connelldylan.b.connell@nasa.govLocationJohnson Space Center Related Terms
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By NASA
3 min read
NASA Selects Two Teams to Advance Life Sciences Research in Space
NASA announced two awards Thursday to establish scientific consortia – multi-institutional coalitions to conduct ground-based studies that help address the agency’s goals of maintaining a sustained human presence in space. These consortia will focus on biological systems research in the areas of animal and human models, plants, and microbiology. When fully implemented, the awards for these consortia will total about $5 million.
Space biology efforts at NASA use the unique environment of space to conduct experiments impossible to do on Earth. Such research not only supports the health and welfare of astronauts, but results in breakthroughs on diseases such as cancer and neurodegenerative disorders to help protect humanity down on the ground.
The awards for the two consortia are for the following areas:
Studying space biosphere. The Biology in Space: Establishing Networks for DUrable & REsilient Systems consortium involves a collaborative effort between human/animal, plant, and microbial biologists to ensure an integrated view of the space flight biosphere by enhancing data acquisition, modeling, and testing. It will include participation of more than thirty scientists and professionals working together from at least three institutions. Led by Kristi Morgansen at the University of Washington in Seattle, Washington. Converting human waste into materials for in-space biomanufacturing. The Integrative Anaerobic Digestion and Phototrophic Biosystem for Sustainable Space Habitats and Life Supports consortium will develop an anaerobic digestion process that converts human waste into organic acids and materials that can be used for downstream biomanufacturing applications in space. It will include eight scientists from six different institutions in three different states, including Delaware and Florida. The consortium is led by Yinjie Tang at Washington University in St. Louis, Missouri. Proposals for these consortia were submitted in response to ROSES 2024 Program Element E.11 Consortium in Biological Sciences for a consortium with biological sciences expertise to carry out research investigations and conduct activities that address NASA’s established interests in space life sciences.
NASA’s Space Biology Program within the agency’s Biological and Physical Sciences division conducts research across a wide spectrum of biological organization and model systems to probe underlying mechanisms by which organisms acclimate to stressors encountered during space exploration (including microgravity, ionizing radiation, and elevated concentrations of carbon dioxide). This research informs how biological systems regulate and sustain growth, metabolism, reproduction, and development in space and how they repair damage and protect themselves from infection and disease.
For more information about NASA’s fundamental space-based research, visit https://science.nasa.gov/biological-physical
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Last Updated Oct 17, 2024 Contact NASA Science Editorial Team Location NASA Headquarters Related Terms
Biological & Physical Sciences For Researchers Research Opportunities in Space and Earth Sciences (ROSES) Science & Research View the full article
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