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Abrevaya XC, Galante D, Tribelli PM, Oppezzo OJ, Nóbrega F, Araujo GG, Rodrigues F, Odert P, Leitzinger M, Ricardi MM, Varela ME, Gallo T, Sanz-Forcada J, Ribas I, Porto de Mello GF, Rodler F, Cerini MF, Hanslmeier A, Horvath JE. Protective Effects of Halite to Vacuum and Vacuum-Ultraviolet Radiation: A Potential Scenario During a Young Sun Superflare. ASTROBIOLOGY 2023; 23:245-268. [PMID: 36577046 DOI: 10.1089/ast.2022.0016] [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: 06/17/2023]
Abstract
Halite (NaCl mineral) has exhibited the potential to preserve microorganisms for millions of years on Earth. This mineral was also identified on Mars and in meteorites. In this study, we investigated the potential of halite crystals to protect microbial life-forms on the surface of an airless body (e.g., meteorite), for instance, during a lithopanspermia process (interplanetary travel step) in the early Solar System. To investigate the effect of the radiation of the young Sun on microorganisms, we performed extensive simulation experiments by employing a synchrotron facility. We focused on two exposure conditions: vacuum (low Earth orbit, 10-4 Pa) and vacuum-ultraviolet (VUV) radiation (range 57.6-124 nm, flux 7.14 W/m2), with the latter representing an extreme scenario with high VUV fluxes comparable to the amount of radiation of a stellar superflare from the young Sun. The stellar VUV parameters were estimated by using the very well-studied solar analog of the young Sun, κ1 Cet. To evaluate the protective effects of halite, we entrapped a halophilic archaeon (Haloferax volcanii) and a non-halophilic bacterium (Deinococcus radiodurans) in laboratory-grown halite. Control groups were cells entrapped in salt crystals (mixtures of different salts and NaCl) and non-trapped (naked) cells, respectively. All groups were exposed either to vacuum alone or to vacuum plus VUV. Our results demonstrate that halite can serve as protection against vacuum and VUV radiation, regardless of the type of microorganism. In addition, we found that the protection is higher than provided by crystals obtained from mixtures of salts. This extends the protective effects of halite documented in previous studies and reinforces the possibility to consider the crystals of this mineral as potential preservation structures in airless bodies or as vehicles for the interplanetary transfer of microorganisms.
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Affiliation(s)
- Ximena C Abrevaya
- Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, Pabellón IAFE, Ciudad Universitaria, Ciudad Autónoma de Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Ciudad Autónoma de Buenos Aires, Argentina
| | | | - Paula M Tribelli
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
- IQUIBICEN, CONICET, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
| | - Oscar J Oppezzo
- Comisión Nacional de Energía Atómica, Buenos Aires, Centro Atómico Constituyentes, Argentina
| | | | - Gabriel G Araujo
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Fabio Rodrigues
- Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Petra Odert
- Institute of Physics, University of Graz, Graz, Austria
| | | | - Martiniano M Ricardi
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIByNE-CONICET), Departamento de Fisiología y Biología Molecular y Celular (FBMC), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
| | - Maria Eugenia Varela
- Instituto de Ciencias Astronómicas de la Tierra y del Espacio (ICATE-CONICET), San Juan, Argentina
| | - Tamires Gallo
- Synchrotron Radiation Research, Lund University, Lund, Sweden
| | | | - Ignasi Ribas
- Institut de Ciències de l'Espai (ICE, CSIC), Campus UAB, Bellaterra, Spain
- Institut d'Estudis Espacials de Catalunya (IEEC), Barcelona, Spain
| | | | | | | | | | - Jorge E Horvath
- Instituto de Astronomía, Geofísica e Ciencias Atmosfericas (IAG), Universidade de Sao Paulo, Sao Paulo, Brazil
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Haroun B, Bahreini G, Zaman M, Jang E, Okoye F, Elbeshbishy E, Santoro D, Walton J, Al-Omari A, Muller C, Bell K, Nakhla G. Vacuum-enhanced anaerobic fermentation: Achieving process intensification, thickening and improved hydrolysis and VFA yields in a single treatment step. WATER RESEARCH 2022; 220:118719. [PMID: 35704979 DOI: 10.1016/j.watres.2022.118719] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 05/08/2022] [Accepted: 06/04/2022] [Indexed: 06/15/2023]
Abstract
This study assessed the feasibility of a novel vacuum-enhanced anaerobic digestion technology, referred to as IntensiCarbTM (IC), under mild vacuum pressure (110 mbar), compared to a control (conventional fermenter), and evaluated the impact of the vacuum on the activities of various microbial groups. Both fermenters (test and control) were operated with mixed (50% v/v) municipal sludge at solids concentrations of 2-2.5%, pH of 7.8-8.1, 40-45 °C, a theoretical solids retention time (SRT) of 3 days with different hydraulic retention times (HRT). The intensification factor (IF) of the IC, defined as SRT/HRT, was controlled at 1.3 and 2.0. Simultaneous thickening and fermentation intensification were achieved. Compared with the control, the IC, despite the shorter HRTs, achieved 29.5 to 90.2% increase in the VFA yield (79 to 116 mg ΔVFA/ g VSS vs 61 mg ΔVFA/ g VSS), and 16.2% to 56.4% increase (280 to 377 mg ΔsCOD/ g VSS vs 241 mg ΔsCOD/ g VSS), in the hydrolysis yield. Fermentate from the IC exhibited comparable specific denitrification rates to acetate. Further, the solids-free condensate contained low nutrient concentrations, and thus was far superior to a typical centrates from dewatering as a carbon source. No adverse effects of vacuum on the activity of fermentative bacteria and methanogens were observed. This study demonstrated that the IC can be deployed as an intensification technology for both fermentation and anaerobic digestion of biosolids with the additional significant advantage, i.e. elimination of sidestream ammonia treatment requirements.
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Affiliation(s)
- Basem Haroun
- Chemical and Biochemical Engineering, University of Western Ontario, Canada; Water Pollution Research Department, National Research Center, 33 El Bohoth St., P.O.12622, Dokki, Giza, Egypt
| | | | - Masuduz Zaman
- Chemical and Biochemical Engineering, University of Western Ontario, Canada
| | | | - Frances Okoye
- Civil Engineering Department, Ryerson University, Canada
| | | | | | | | | | | | | | - George Nakhla
- Chemical and Biochemical Engineering, University of Western Ontario, Canada; Civil and Environmental Engineering, University of Western Ontario, Canada.
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Pacelli C, Alessia C, Siong LM, Lorenzo A, Moeller R, Fujimori A, Igor S, Silvano O. Insights into the Survival Capabilities of Cryomyces antarcticus Hydrated Colonies after Exposure to Fe Particle Radiation. J Fungi (Basel) 2021; 7:495. [PMID: 34206448 PMCID: PMC8304246 DOI: 10.3390/jof7070495] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/14/2021] [Accepted: 06/15/2021] [Indexed: 11/30/2022] Open
Abstract
The modern concept of the evolution of Mars assumes that life could potentially have originated on the planet Mars, possibly during the end of the late heavy bombardment, and could then be transferred to other planets. Since then, physical and chemical conditions on Mars changed and now strongly limit the presence of terrestrial-like life forms. These adverse conditions include scarcity of liquid water (although brine solutions may exist), low temperature and atmospheric pressure, and cosmic radiation. Ionizing radiation is very important among these life-constraining factors because it damages DNA and other cellular components, particularly in liquid conditions where radiation-induced reactive oxidants diffuse freely. Here, we investigated the impact of high doses (up to 2 kGy) of densely-ionizing (197.6 keV/µm), space-relevant iron ions (corresponding on the irradiation that reach the uppermost layer of the Mars subsurface) on the survival of an extremophilic terrestrial organism-Cryomyces antarcticus-in liquid medium and under atmospheric conditions, through different techniques. Results showed that it survived in a metabolically active state when subjected to high doses of Fe ions and was able to repair eventual DNA damages. It implies that some terrestrial life forms can withstand prolonged exposure to space-relevant ion radiation.
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Affiliation(s)
- Claudia Pacelli
- Italian Space Agency, 00133 Rome, Italy;
- Department of Ecological and Biological Sciences, University of Tuscia, 01100 Viterbo, Italy; (A.L.); (O.S.)
| | - Cassaro Alessia
- Department of Ecological and Biological Sciences, University of Tuscia, 01100 Viterbo, Italy; (A.L.); (O.S.)
| | - Loke M. Siong
- Ludwig Maximilian University of Munich, 80336 Munich, Germany;
| | - Aureli Lorenzo
- Department of Ecological and Biological Sciences, University of Tuscia, 01100 Viterbo, Italy; (A.L.); (O.S.)
| | - Ralf Moeller
- Radiation Biology Department, Aerospace Microbiology, German Aerospace Center (DLR e.V.), Institute of Aerospace Medicine, 51147 Cologne (Köln), Germany;
- Department of Natural Sciences, University of Applied Sciences Bonn-Rhein-Sieg (BRSU), 53359 Rheinbach, Germany
| | - Akira Fujimori
- Molecular and Cellular Radiation Biology Group, Department of Basic Medical Sciences for Radiation Damages, NIRS/QST, Chiba 263-8555, Japan;
| | - Shuryak Igor
- Department of Radiation Oncology, Center for Radiological Research, Columbia University Irving Medical Center, New York, NY 10032, USA;
| | - Onofri Silvano
- Department of Ecological and Biological Sciences, University of Tuscia, 01100 Viterbo, Italy; (A.L.); (O.S.)
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Bywaters K, Stoker CR, Batista Do Nascimento N, Lemke L. Towards Determining Biosignature Retention in Icy World Plumes. Life (Basel) 2020; 10:life10040040. [PMID: 32316157 PMCID: PMC7235855 DOI: 10.3390/life10040040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 04/11/2020] [Accepted: 04/14/2020] [Indexed: 02/07/2023] Open
Abstract
With the discovery of the persistent jets of water being ejected to space from Enceladus, an understanding of the effect of the space environment on potential organisms and biosignatures in them is necessary for planning life detection missions. We experimentally determine the survivability of microbial cells in liquid medium when ejected into vacuum. Epifluorescence microscopy, using a lipid stain, and SEM imaging were used to interrogate the cellular integrity of E. coli after ejected through a pressurized nozzle into a vacuum chamber. The experimental samples showed a 94% decrease in visible intact E. coli cells but showed a fluorescence residue in the shape of the sublimated droplets that indicated the presence of lipids. The differences in the experimental conditions versus those expected on Enceladus should not change the analog value because the process a sample would undergo when ejected into space was representative. E. coli was selected for testing although other cell types could vary physiologically which would affect their response to a vacuum environment. More testing is needed to determine the dynamic range in concentration of cells expected to survive the plume environment. However, these results suggest that lipids may be directly detectable evidence of life in icy world plumes.
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Affiliation(s)
- Kathryn Bywaters
- SETI Institute, Moffett Field, CA 94043, USA
- Correspondence: (K.B.); (C.R.S.); Tel.: +1-650-604-2295 (K.B.); +1-650-604-6490 (C.R.S.)
| | - Carol R. Stoker
- NASA Ames Research Center, Space Science Division, Moffett Field, CA 94035, USA; (N.B.D.N.J.); (L.L.)
- Correspondence: (K.B.); (C.R.S.); Tel.: +1-650-604-2295 (K.B.); +1-650-604-6490 (C.R.S.)
| | | | - Lawrence Lemke
- NASA Ames Research Center, Space Science Division, Moffett Field, CA 94035, USA; (N.B.D.N.J.); (L.L.)
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Backhaus T, Meeßen J, Demets R, de Vera JP, Ott S. Characterization of Viability of the Lichen Buellia frigida After 1.5 Years in Space on the International Space Station. ASTROBIOLOGY 2019; 19:233-241. [PMID: 30742495 DOI: 10.1089/ast.2018.1894] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The lichen Buellia frigida was exposed to space and simulated Mars analog conditions in the Biology and Mars Experiment (BIOMEX) project operated outside the International Space Station (ISS) for 1.5 years. To determine the effects of the Low Earth Orbit (LEO) conditions on the lichen symbionts, a LIVE/DEAD staining analysis test was performed. After return from the ISS, the lichen symbionts demonstrated mortality rates of up to 100% for the algal symbiont and up to 97.8% for the fungal symbiont. In contrast, the lichen symbiont controls exhibited mortality rates of 10.3% up to 31.9% for the algal symbiont and 14.5% for the fungal symbiont. The results performed in the BIOMEX Mars simulation experiment on the ISS indicate that the potential for survival and the resistance of the lichen B. frigida to LEO conditions are very low. It is unlikely that Mars could be inhabited by this lichen, even for a limited amount of time, or even not habitable planet for the tested lichen symbionts.
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Affiliation(s)
- Theresa Backhaus
- 1 Institute of Botany, Heinrich Heine University, Duesseldorf, Germany
| | - Joachim Meeßen
- 1 Institute of Botany, Heinrich Heine University, Duesseldorf, Germany
| | - René Demets
- 2 European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Noordwijk, Netherlands
| | - Jean-Pierre de Vera
- 3 Research Group, Astrobiological Laboratories, Institute of Planetary Research, Management and Infrastructure, German Aerospace Center (DLR), Berlin, Germany
| | - Sieglinde Ott
- 1 Institute of Botany, Heinrich Heine University, Duesseldorf, Germany
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Visscher AM, Seal CE, Newton RJ, Frances AL, Pritchard HW. Dry seeds and environmental extremes: consequences for seed lifespan and germination. FUNCTIONAL PLANT BIOLOGY : FPB 2016; 43:656-668. [PMID: 32480494 DOI: 10.1071/fp15275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 01/24/2016] [Indexed: 06/11/2023]
Abstract
In the context of climate change, food security and long-term human space missions, it is important to understand which species produce seeds that can tolerate extreme environmental conditions. Here we consider dry seed survival of extreme conditions encountered in both natural and artificially controlled environments. Considerable overlap exists between the two: for example, ultra-dry and anoxic conditions can be artificially imposed during seed storage and also occur naturally in the vacuum of space environments. Aside from ultra-drying and anoxia, dry seeds of many species may experience extremely high temperatures due to heat from wildfires or when exposed to solar heat in biomes such as deserts. In addition, seeds can be irradiated by UV-A and UV-B at the surface of the Earth and by the shorter wavelengths of UV-C in outer space. We focus on the effects of these extreme environmental conditions on dry seed lifespan and germination. Although it is clear that seeds from particular plant species and families can tolerate exposures to ultra-drying, high temperatures (at least 32 families) or UV radiation with minimal consequences for subsequent germination ability, further research is needed to elucidate many of the mechanisms underlying extreme tolerance of these environmental conditions found on Earth or in space.
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Affiliation(s)
- Anne M Visscher
- Department of Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Ardingly, RH17 6TN, West Sussex, UK
| | - Charlotte E Seal
- Department of Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Ardingly, RH17 6TN, West Sussex, UK
| | - Rosemary J Newton
- Department of Conservation Science, Royal Botanic Gardens, Kew, Ardingly, RH17 6TN, West Sussex, UK
| | - Alba Latorre Frances
- Department of Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Ardingly, RH17 6TN, West Sussex, UK
| | - Hugh W Pritchard
- Department of Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Ardingly, RH17 6TN, West Sussex, UK
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Fajardo-Cavazos P, Waters SM, Schuerger AC, George S, Marois JJ, Nicholson WL. Evolution of Bacillus subtilis to enhanced growth at low pressure: up-regulated transcription of des-desKR, encoding the fatty acid desaturase system. ASTROBIOLOGY 2012; 12:258-270. [PMID: 22416764 DOI: 10.1089/ast.2011.0728] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The atmospheric pressure on Mars ranges from 1-10 mbar, about 1% of Earth pressure (∼1013 mbar). Low pressure is a growth-inhibitory factor for terrestrial microorganisms on Mars, and a putative low-pressure barrier for growth of Earth bacteria of ∼25 mbar has been postulated. In a previous communication, we described the isolation of a strain of Bacillus subtilis that had evolved enhanced growth ability at the near-inhibitory low pressure of 50 mbar. To explore mechanisms that enabled growth of the low-pressure-adapted strain, numerous genes differentially transcribed between the ancestor strain WN624 and low-pressure-evolved strain WN1106 at 50 mbar were identified by microarray analysis. Among these was a cluster of three candidate genes (des, desK, and desR), whose mRNA levels in WN1106 were higher than the ancestor on the microarrays. Up-regulation of these genes was confirmed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis. The des, desK, and desR genes encode the Des membrane fatty acid (FA) desaturase, the DesK sensor kinase, and the DesR response regulator, respectively, which function to maintain membrane fluidity in acute response to temperature downshift. Pressure downshift caused an up-regulation of des mRNA levels only in WN1106, but expression of a des-lacZ transcriptional fusion was unaffected, which suggests that des regulation was different in response to temperature versus pressure downshift. Competition experiments showed that inactivation of the des gene caused a slight, but statistically significant, loss of fitness of strain WN1106 at 50 mbar. Further, analysis of membrane FA composition of cells grown at 1013 versus 50 mbar revealed a decrease in the ratio of unsaturated to saturated FAs but an increase in the ratio of anteiso- to iso-FAs. The present study represents a first step toward identification of molecular mechanisms by which B. subtilis could sense and respond to the novel environmental stress of low pressure.
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Affiliation(s)
- Patricia Fajardo-Cavazos
- Department of Microbiology and Cell Science, University of Florida, Kennedy Space Center, 32899, USA
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Yang Y, Yokobori SI, Yamagishi A. Assessing Panspermia Hypothesis by Microorganisms Collected from The High Altitude Atmosphere. ACTA ACUST UNITED AC 2009. [DOI: 10.2187/bss.23.151] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Roles of the major, small, acid-soluble spore proteins and spore-specific and universal DNA repair mechanisms in resistance of Bacillus subtilis spores to ionizing radiation from X rays and high-energy charged-particle bombardment. J Bacteriol 2007; 190:1134-40. [PMID: 18055591 DOI: 10.1128/jb.01644-07] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The role of DNA repair by nonhomologous end joining (NHEJ), homologous recombination, spore photoproduct lyase, and DNA polymerase I and genome protection via alpha/beta-type small, acid-soluble spore proteins (SASP) in Bacillus subtilis spore resistance to accelerated heavy ions (high-energy charged [HZE] particles) and X rays has been studied. Spores deficient in NHEJ and alpha/beta-type SASP were significantly more sensitive to HZE particle bombardment and X-ray irradiation than were the recA, polA, and splB mutant and wild-type spores, indicating that NHEJ provides an efficient DNA double-strand break repair pathway during spore germination and that the loss of the alpha/beta-type SASP leads to a significant radiosensitivity to ionizing radiation, suggesting the essential function of these spore proteins as protectants of spore DNA against ionizing radiation.
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Diaz B, Schulze-Makuch D. Microbial survival rates of Escherichia coli and Deinococcus radiodurans under low temperature, low pressure, and UV-Irradiation conditions, and their relevance to possible Martian life. ASTROBIOLOGY 2006; 6:332-47. [PMID: 16689650 DOI: 10.1089/ast.2006.6.332] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Viability rates were determined for microbial populations of Escherichia coli and Deinococcus radiodurans under the environmental stresses of low temperature (-35 degrees C), low-pressure conditions (83.3 kPa), and ultraviolet (UV) irradiation (37 W/m(2)). During the stress tests the organisms were suspended in saltwater soil and freshwater soil media, at variable burial depths, and in seawater. Microbial populations of both organisms were most susceptible to dehydration stress associated with low-pressure conditions, and to UV irradiation. However, suspension in a liquid water medium and burial at larger depths (5 cm) improved survival rates markedly. Our results indicate that planetary surfaces that possess little to no atmosphere and have low water availability do not constitute a favorable environment for terrestrial microorganisms.
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Affiliation(s)
- Benjamin Diaz
- Program of Environmental Toxicology, Department of Microbiology, Cornell University, Ithaca, New York, USA
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Abstract
We present some results on the interaction of low energy atomic ions with DNA. Experiments consist of irradiation of dried DNA in vacuum with Ar ions at low keV energies for different time intervals. The DNA is placed back in solution and analysed by agarose gel electrophoresis. These experiments demonstrated the production of single and double strand breaks. The induction of these lesions could be due to several processes: direct collisions with DNA constituent atoms resulting in displacements, cascade recoil collisions of the constituent atoms, electron transfer processes between the ion and the DNA as well as breaks induced by molecular excitation and secondary electron interactions. Here we briefly discuss some aspects of direct and recoil collision processes.
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Affiliation(s)
- S Lacombe
- Laboratoire des Collisions Atomiques et Moléculaires, (Unité Mixte de Recherche CNRS-Université No 8625), Université Paris-Sud, Orsay 91405, France
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Douki T, Laporte G, Cadet J. Inter-strand photoproducts are produced in high yield within A-DNA exposed to UVC radiation. Nucleic Acids Res 2003; 31:3134-42. [PMID: 12799441 PMCID: PMC162242 DOI: 10.1093/nar/gkg408] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Far-UV irradiation of DNA leads to the dimerization of pyrimidine bases, resulting in the formation of cyclobutane type dimers and (6-4) photoproducts. In the dry state, an additional thymine dimeric photolesion, the spore photoproduct, is also generated. While most photoproducts are expected to be produced between adjacent pyrimidines, little attention has been paid to lesions involving bases located on different DNA strands. Using HPLC- mass spectrometry analysis of enzymatically digested DNA, we observed that, in the dry state, inter-strand dimeric photoproducts represented 30% of the total yield of dimeric thymine lesions. The major inter-strand damage was found to be the spore photoproduct. Formation of inter-strand lesions in significant yield could be obtained in solution upon modification of the DNA conformation as the result of the addition of large amounts of ethanol. In both cases, DNA is in the A-form, which is characterized by a high compaction, likely to favor inter-strand photoreactions. Since the latter DNA conformation is also predominant in bacterial spores, the formation and repair of dimeric photoproducts involving thymine bases located on different DNA strands may thus be relevant in terms of deleterious effects of UV radiation to the latter microorganisms.
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Affiliation(s)
- Thierry Douki
- Laboratoire 'Lésions des Acides Nucléiques', Service de Chimie Inorganique et Biologique, FRE 2600, CEA/DSM/Département de Recherche Fondamentale sur la Matière Condensée, CEA-Grenoble, 17 Avenue des Martyrs, 38054 Grenoble Cedex 9, France.
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Abstract
The field of study that deals with the origins of life does not have a consensus for a theory of life's origin. An analysis of the range of theories offered shows that they share some common features that may be reliable predictors when considering the possible origins of life on another planet. The fundamental datum dealing with the origins of life is that life appeared early in the history of the Earth, probably before 3.5 Ga and possibly before 3.8 Ga. What might be called the standard theory (the Oparin-Haldane theory) posits the production of organic molecules on the early Earth followed by chemical reactions that produced increased organic complexity leading eventually to organic life capable of reproduction, mutation, and selection using organic material as nutrients. A distinct class of other theories (panspermia theories) suggests that life was carried to Earth from elsewhere--these theories receive some support from recent work on planetary impact processes. Other alternatives to the standard model suggest that life arose as an inorganic (clay) form and/or that the initial energy source was not organic material but chemical energy or sunlight. We find that the entire range of current theories suggests that liquid water is the quintessential environmental criterion for both the origin and sustenance of life. It is therefore of interest that during the time that life appeared on Earth we have evidence for liquid water present on the surface of Mars.
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Affiliation(s)
- W L Davis
- Space Science Division, NASA Ames Research Center, Moffett Field, CA 94035-1000, USA
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Horneck G, Eschweiler U, Reitz G, Wehner J, Willimek R, Strauch K. Biological responses to space: results of the experiment "Exobiological Unit" of ERA on EURECA I. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1995; 16:105-118. [PMID: 11542695 DOI: 10.1016/0273-1177(95)00279-n] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Spores of different strains of Bacillus subtilis and the Escherichia coli plasmid pUC19 were exposed to selected conditions of space (space vacuum and/or defined wavebands and intensities of solar ultraviolet radiation) in the experiment ER 161 "Exobiological Unit" of the Exobiology Radiation Assembly (ERA) on board of the European Retrievable Carrier (EURECA). After the approximately 11 months lasting mission, their responses were studied in terms of survival, mutagenesis in the his (B. subtilis) or lac locus (pUC19), induction of DNA strand breaks, efficiency of DNA repair systems, and the role of external protective agents. The data were compared with those of a simultaneously running ground control experiment. The survival of spores treated with the vacuum of space, however shielded against solar radiation, is substantially increased, if they are exposed in multilayers and/or in the presence of glucose as protective, whereas all spores in "artificial meteorites", i.e. embedded in clays or simulated Martian soil, are killed. Vacuum treatment leads to an increase of mutation frequency in spores, but not in plasmid DNA. Extraterrestrial solar ultraviolet radiation is mutagenic, induces strand breaks in the DNA and reduces survival substantially; however, even at the highest fluences, i.e. 3 x 10(8) J m-2, a small but significant fraction of spores survives the insolation. Action spectroscopy confirms results of previous space experiments of a synergistic action of space vacuum and solar UV radiation with DNA being the critical target.
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Affiliation(s)
- G Horneck
- Deutsche Forschungsanstalt fur Luft-und Raumfahrt, Institut fur Luft- und Raumfahrtmedizin, Abteilung Strahlenbiologie, Koln, Germany
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Horneck G. Exobiology, the study of the origin, evolution and distribution of life within the context of cosmic evolution: a review. PLANETARY AND SPACE SCIENCE 1995; 43:189-217. [PMID: 11538433 DOI: 10.1016/0032-0633(94)00190-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The primary goal of exobiological research is to reach a better understanding of the processes leading to the origin, evolution and distribution of life on Earth or elsewhere in the universe. In this endeavour, scientists from a wide variety of disciplines are involved, such as astronomy, planetary research, organic chemistry, palaeontology and the various subdisciplines of biology including microbial ecology and molecular biology. Space technology plays an important part by offering the opportunity for exploring our solar system, for collecting extraterrestrial samples, and for utilizing the peculiar environment of space as a tool. Exobiological activities include comparison of the overall pattern of chemical evolution of potential precursors of life, in the interstellar medium, and on the planets and small bodies of our solar system; tracing the history of life on Earth back to its roots; deciphering the environments of the planets in our solar system and of their satellites, throughout their history, with regard to their habitability; searching for other planetary systems in our Galaxy and for signals of extraterrestrial civilizations; testing the impact of space environment on survivability of resistant life forms. This evolutionary approach towards understanding the phenomenon of life in the context of cosmic evolution may eventually contribute to a better understanding of the processes regulating the interactions of life with its environment on Earth.
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Affiliation(s)
- G Horneck
- Deutsche Forschungsanstalt für Luft- und Raumfahrt, Institut für Luft- und Raumfahrtmedizin, Köln, Germany
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Riklis E. Radiobiology and photobiology on Earth and in space: points of encounter and protection considerations. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1994; 14:285-293. [PMID: 11539963 DOI: 10.1016/0273-1177(94)90479-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
All radiations originate in space, and the spectrum of radiations reaching the troposphere is limited only because of their range and absorption by the ozone layer above the atmosphere. Ultraviolet-C and the very heavy ions are therefore produced on earth only artificially, by special lamps and in accelerators. The range of biological effects of the different UV radiations and low and high LET radiations have been studied extensively, yet only recently new facts such as the production of DNA strand breaks by long wave UV light were established, adding to the various points of encounter existing between ionizing and nonionizing radiations. There are some similarities in radiation products, and the resulting effects of insult by radiation on biological systems very often are similar, if not the same. A common phenomenon that exists in all healthy biological cells is the ability to repair damage to DNA and thus either survive or mutate, and although the specific mechanisms of repair are somewhat different, the end result is the same. Recently a mechanism of improved radioprotection was found to involve an effect of certain radioprotective compounds on DNA repair. It is suggested that improved, and nontoxic, modes of protection may be offered by employing such compounds as biological response modifiers and natural substances. Further research is needed and is under way.
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Affiliation(s)
- E Riklis
- Nuclear Research Center-Negev, Beer-Sheva, Israel
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Horneck G, Bucker H, Reitz G. Long-term survival of bacterial spores in space. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1994; 14:41-45. [PMID: 11539977 DOI: 10.1016/0273-1177(94)90448-0] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
On board of the NASA Long Duration Exposure Facility (LDEF), spores of Bacillus subtilis in monolayers (10(6)/sample) or multilayers (10(8)/sample) were exposed to the space environment for nearly six years and their survival was analyzed after retrieval. The response to space parameters, such as vacuum (10(-6) Pa), solar electromagnetic radiation up to the highly energetic vacuum-ultraviolet range (10(9) J/m2) and/or cosmic radiation (4.8 Gy), was studied and compared to the results of a simultaneously running ground control experiment. If shielded against solar ultraviolet (UV)-radiation, up to 80 % of spores in multilayers survive in space. Solar UV-radiation, being the most deleterious parameter of space, reduces survival by 4 orders of magnitude or more. However, up to 10(4) viable spores were still recovered, even in completely unprotected samples. Substances, such as glucose or buffer salts serve as chemical protectants. With this 6 year study in space, experimental data are provided to the discussion on the likelihood of "Panspermia".
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Affiliation(s)
- G Horneck
- DLR, Institute of Aerospace Medicine, Biophysics Division, Koln, Germany
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Horneck G, Brack A. Study of the origin, evolution and distribution of life with emphasis on exobiology experiments in earth orbit. ADVANCES IN SPACE BIOLOGY AND MEDICINE 1992; 2:229-62. [PMID: 1342246 DOI: 10.1016/s1569-2574(08)60023-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- G Horneck
- Institut für Flugmedizin, DLR, Köln, Germany
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Riklis E. Photoproducts in DNA irradiated in vitro and in vivo under extreme environmental conditions. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1989; 9:223-232. [PMID: 11537296 DOI: 10.1016/0273-1177(89)90441-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
UV-irradiated DNA forms different photoproducts in accordance with its state of hydration, and the environment in which the irradiation takes place. Photoproducts in addition to the well-known thymine dimer are produced, some of which probably not recognized due to being heat or acid labile, and milder methods for DNA hydrolysis are needed. The isolation, structure and properties of photoproducts which are formed in UV-irradiated frozen thymine solutions are described. Urea, n-propylurea and dihydrothymine are obtained as photolytic products by high radiation doses in low concentrations of thymine. The cyclobutane cis-anti thymine dimer is obtained at high concentrations of thymine, following several cycles of freezing, thawing and irradiations. A trimer is obtained with 290 nm UV light filtered through Pyrex. It reverts back to thymine dimer and thymine when reirradiated in solution. The cis-syn dimer is obtained at all concentrations of frozen thymine and in a dose dependent form. The adduct 5-hydroxy-6-4' (5'-methylpyrimid 2'-1) dihydrothymine is also obtained. In vacuum-dried thymine or DNA, other photoproducts are formed, including the spore-product, TDHT. Several solvent systems were used to develop chromatograms that allow separation of photoproducts.
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Affiliation(s)
- E Riklis
- Radiobiology Department, Nuclear Research Center-Negev, Beer-Sheva, Israel
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Horneck G, Bucker H, Dose K, Martens KD, Bieger A, Mennigmann HD, Reitz G, Requardt H, Weber P. Microorganisms and biomolecules in space environment experiment ES 029 on Spacelab-1. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1984; 4:19-27. [PMID: 11539627 DOI: 10.1016/0273-1177(84)90220-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Bacterial spores are proper test organisms for studying problems of space biology and exobiology. During the Spacelab 1 mission, studies on the limiting factors for survival of Bacillus subtilis spores in free space have been performed. An exposure tray on the pallet of Spacelab 1 accomodated 316 samples of dry spores for treatment with space vacuum and/or the following selected wavelengths of solar UV: > 170 nm, 220 nm, 240nm, 260nm and 280 nm. After recovery, inactivation, mutation induction, reparability, and photochemical damages in DNA and protein have been studied. The results contribute to the understanding of the mechanisms of increased UV sensitivity of bacterial spores in vacuo and to a better assessment of the chance of survival of resistant forms in space and of interplanetary transfer of life.
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Affiliation(s)
- G Horneck
- Biophysics Div., Institute for Aerospace Medicine, DFVLR, Koln, FRG
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Horneck G, Bucker H. Inactivation, mutation induction and repair in Bacillus subtilis spores irradiated with heavy ions. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1983; 3:79-84. [PMID: 11542759 DOI: 10.1016/0273-1177(83)90177-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Studies on the response of bacterial spores to accelerated heavy ions (HZE particles) help in understanding problems of space radiobiology and exobiology. Layers of spores of Bacillus subtilis strains, differing in repair capabilities, were irradiated with accelerated boron, carbon and neon ions of linear energy transfer (LET) values up to 14000 MeV cm2/g. Inactivation as measured by loss of colony forming ability and induction of mutations as measured by reversion to histidine prototrophy and resistance to 150 micrograms/ml sodium azide were tested, as well as the influence of repair processes on these effects. For inactivation, the cross-sectional values sigma plotted as a function of LET follow a saturation curve. The plateau, which is reached around a LET of 2000 MeV cm2/g, occurs at 2.5 x 10(-9) cm2, a value in good agreement with the dimensions of the spore protoplast. Lethal damage produced at LET values < 2000 MeV cm2/g is reparable. Recombination repair is more effective than excision repair. At higher LET values, lethal damage could not be reconstituted by the repair mechanisms studied. In addition, at these high LET values, the frequency of induced mutations was drastically decreased. The data support the assumption of at least two qualitatively different types of lesion, depending on the LET of the affecting heavy ion.
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Affiliation(s)
- G Horneck
- DFVLR, Institute fur Flugmedizin, Abt. Biophysik, Koln, FRG
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