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Chaouche-Mechidal N, Stalport F, Caupos E, Mebold E, Azémard C, Szopa C, Coll P, Cottin H. Effects of UV and Calcium Perchlorates on Uracil Deposited on Strontium Fluoride Substrates at Mars Pressure and Temperature. ASTROBIOLOGY 2023; 23:959-978. [PMID: 37672714 DOI: 10.1089/ast.2022.0137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
Organic matter is actively searched on Mars with current and future space missions as it is a key to detecting potential biosignatures. Given the current harsh environmental conditions at the surface of Mars, many organic compounds might not be preserved over a long period as they are exposed to energetic radiation such as ultraviolet light, which is not filtered above 190 nm by the martian atmosphere. Moreover, the presence of strong oxidizing species in the regolith, such as perchlorate salts, might enhance the photodegradation of organic compounds of astrobiological interest. Because current space instruments analyze samples collected in the upper surface layer, it is necessary to investigate the stability of organic matter at the surface of Mars. Previous experimental studies have shown that uracil, a molecule relevant to astrobiology, is quickly photolyzed when exposed to UV radiation under the temperature and pressure conditions of the martian surface with an experimental quantum efficiency of photodecomposition (φexp) of 0.30 ± 0.26 molecule·photon-1. Moreover, the photolysis of uracil leads to the formation of more stable photoproducts that were identified as uracil dimers. The present work aims to characterize the additional effect of calcium perchlorate detected on Mars on the degradation of uracil. Results show that the presence of calcium perchlorate enhances the photodecomposition of uracil with φexp = 12.3 ± 8.3 molecule·photon-1. Although some of the photoproducts formed during these experiments are common to those formed from pure uracil only, the Fourier transformation infrared (FTIR) detection of previously unseen chemical functions such as alkyne C ≡ C or nitrile C ≡ N has shown that additional chemical species are formed in the presence of calcium perchlorate in the irradiated sample. This implies that the effect of calcium perchlorate on the photolysis of uracil is not only kinetic but also related to the nature of the photoproducts formed.
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Affiliation(s)
- N Chaouche-Mechidal
- Univ Paris Est Creteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, France
| | - F Stalport
- Université Paris Cité and Univ Paris Est Creteil, CNRS, LISA, F-75013 Paris, France
| | - E Caupos
- Univ Paris Est Creteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, France
- Ecole des Ponts, LEESU, F-77455 Champs-sur-Marne, France
| | - E Mebold
- Univ Paris Est Creteil, CNRS, OSU-EFLUVE, F-94010 Créteil, France
| | - C Azémard
- Univ Paris Est Creteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, France
| | - C Szopa
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, 78280 Guyancourt, France
| | - P Coll
- Université Paris Cité and Univ Paris Est Creteil, CNRS, LISA, F-75013 Paris, France
| | - H Cottin
- Univ Paris Est Creteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, France
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Gerakines PA, Qasim D, Frail S, Hudson RL. Radiolytic Destruction of Uracil in Interstellar and Solar System Ices. ASTROBIOLOGY 2022; 22:233-241. [PMID: 34672795 DOI: 10.1089/ast.2021.0053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Uracil is one of the four RNA nucleobases and a component of meteoritic organics. If delivered to the early Earth, uracil could have been involved in the origins of the first RNA-based life, and so this molecule could be a biomarker on other worlds. Therefore, it is important to understand uracil's survival to ionizing radiation in extraterrestrial environments. Here we present a study of the radiolytic destruction kinetics of uracil and mixtures of uracil diluted in H2O or CO2 ice. All samples were irradiated by protons with an energy of 0.9 MeV, and experiments were performed at 20 and 150 K to determine destruction rate constants at temperatures relevant to interstellar and Solar System environments. We show that uracil is destroyed much faster when H2O ice or CO2 ice is present than when these two ices are absent. Moreover, destruction is faster for CO2-dominated ices than for H2O-dominated ones and, to a lesser extent, at 150 K compared with 20 K. Extrapolation of our laboratory results to astronomical timescales shows that uracil will be preserved in ices with half-lives of up to ∼107 years on cold planetary bodies such as comets or Pluto. An important implication of our results is that for extraterrestrial environments, the application of laboratory data measured for the radiation-induced destruction of pure (neat) uracil samples can greatly underestimate the molecule's rate of destruction and significantly overestimate its lifetime, which can lead to errors of over 1000%.
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Affiliation(s)
- Perry A Gerakines
- Astrochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Danna Qasim
- Astrochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Department of Physics and Astronomy, Howard University, Washington, District of Columbia, USA
- Center for Research and Exploration in Space Science and Technology, NASA/GSFC, Greenbelt, Maryland, USA
| | - Sarah Frail
- Astrochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | - Reggie L Hudson
- Astrochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
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Lai W, Wang H. Detection and Quantification of UV-irradiation-induced DNA Damages by Liquid Chromatography-Mass Spectrometry and Immunoassay †. Photochem Photobiol 2021; 98:598-608. [PMID: 34679215 DOI: 10.1111/php.13546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 10/11/2021] [Accepted: 10/13/2021] [Indexed: 11/29/2022]
Abstract
Solar ultraviolet (UV)-induced DNA lesions are associated with skin carcinogenesis. The detection of these DNA lesions is important to understand their genotoxicity and health effects. However, sunlight exposure-relevant DNA damage measurement is still a challenge. Here, we summarize our recent progresses on the related analytical techniques, including synthesis of dimeric lesions, the optimization of procedures for ultrahigh performance liquid chromatography-coupled mass spectrometry (UHPLC-MS/MS), and the maturation of anti-T(6-4)T photoproduct antibodies and their potential applications for immunoassay.
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Affiliation(s)
- Weiyi Lai
- The State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China
| | - Hailin Wang
- Environment School, Institute for Advanced Study, UCAS, Hangzhou, China.,University of Chinese Academy of Sciences, Beijing, China
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