Special Issue "Frontiers of Astrobiology"

A special issue of Life (ISSN 2075-1729). This special issue belongs to the section "Astrobiology".

Deadline for manuscript submissions: 15 October 2020.

Special Issue Editor

Prof. Dr. Manasvi Lingam
Website
Guest Editor
Department of Aerospace, Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901, USA
Interests: astrobiology; habitability; exoplanets; origin of life; space science; ecology; biophysics; extraterrestrial intelligence

Special Issue Information

Dear Colleagues,

Astrobiology is a famously transdisciplinary field that encompasses the "origin, evolution, distribution, and future of life in the Universe", as described by NASA. This endeavor encompasses fields as diverse as physics and astronomy on the one hand and microbiology, biochemistry, and geobiology on the other. It comes as no surprise, therefore, that astrobiology has witnessed many seminal advances over the past decade, such as the discovery of a temperate planet orbiting the star closest to the Earth, detection of complex organic molecules on several worlds inside our Solar system, breakthroughs in our understanding of prebiotic chemistry and how life may have been initiated on Earth, and noteworthy advances in our understanding of extremophiles and their capacity to survive the harsh environment of outer space.

The next decade appears equally (if not more) promising for astrobiology, with a number of major missions slated to carry out surveys of potentially habitable worlds within and outside the Solar system. Furthermore, the development of more sophisticated laboratory experiments, analytical methods, and numerical models is expected to continue apace. Hence, when viewed collectively, we find ourselves in a better position than ever before to answer that age-old and oft-quoted question, "Are we alone?", and thereby assess the prevalence of life in the Universe.

The objective of this Special Issue is to cover all realms of astrobiology, thus reflecting the inherent diversity of this field. Hence, we welcome all manner of papers—spanning both the physical and biological sciences, and ranging from experimental analyses to theoretical models—that are rigorous, comprehensive, and embody the latest developments in the field. In addition to regular research articles, review papers and hypothesis articles are also solicited for this Special Issue.

Prof. Dr. Manasvi Lingam
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Life is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • origin of life
  • evolution
  • exoplanets
  • extreme environments
  • biogeochemistry
  • prebiotic chemistry
  • habitable worlds
  • limits of life
  • space missions

Published Papers (5 papers)

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Research

Open AccessArticle
Rocket Science: The Effect of Spaceflight on Germination Physiology, Ageing, and Transcriptome of Eruca sativa Seeds
Life 2020, 10(4), 49; https://doi.org/10.3390/life10040049 - 24 Apr 2020
Abstract
In the ‘Rocket Science’ project, storage of Eruca sativa (salad rocket) seeds for six months on board the International Space Station resulted in delayed seedling establishment. Here we investigated the physiological and molecular mechanisms underpinning the spaceflight effects on dry seeds. We found [...] Read more.
In the ‘Rocket Science’ project, storage of Eruca sativa (salad rocket) seeds for six months on board the International Space Station resulted in delayed seedling establishment. Here we investigated the physiological and molecular mechanisms underpinning the spaceflight effects on dry seeds. We found that ‘Space’ seed germination vigor was reduced, and ageing sensitivity increased, but the spaceflight did not compromise seed viability and the development of normal seedlings. Comparative analysis of the transcriptomes (using RNAseq) in dry seeds and upon controlled artificial ageing treatment (CAAT) revealed differentially expressed genes (DEGs) associated with spaceflight and ageing. DEG categories enriched by spaceflight and CAAT included transcription and translation with reduced transcript abundances for 40S and 60S ribosomal subunit genes. Among the ‘spaceflight-up’ DEGs were heat shock proteins (HSPs), DNAJ-related chaperones, a heat shock factor (HSFA7a-like), and components of several DNA repair pathways (e.g., ATM, DNA ligase 1). The ‘response to radiation’ category was especially enriched in ‘spaceflight-up’ DEGs including HSPs, catalases, and the transcription factor HY5. The major finding from the physiological and transcriptome analysis is that spaceflight causes vigor loss and partial ageing during air-dry seed storage, for which space environmental factors and consequences for seed storage during spaceflights are discussed. Full article
(This article belongs to the Special Issue Frontiers of Astrobiology)
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Open AccessArticle
Possible Transfer of Life by Earth-Grazing Objects to Exoplanetary Systems
Life 2020, 10(4), 44; https://doi.org/10.3390/life10040044 - 17 Apr 2020
Abstract
Recently, a 30-cm object was discovered to graze the Earth’s atmosphere and shift into a Jupiter-crossing orbit. We use the related survey parameters to calibrate the total number of such objects. The number of objects that could have exported terrestrial microbes out of [...] Read more.
Recently, a 30-cm object was discovered to graze the Earth’s atmosphere and shift into a Jupiter-crossing orbit. We use the related survey parameters to calibrate the total number of such objects. The number of objects that could have exported terrestrial microbes out of the Solar System is in the range 2 × 10 9 3 × 10 11 . We find that 10 7 10 9 such objects could have been captured by binary star systems over the lifetime of the Solar System. Adopting the fiducial assumption that one polyextremophile colony is picked up by each object, the total number of objects carrying living colonies on them upon capture could be 10– 10 3 . Full article
(This article belongs to the Special Issue Frontiers of Astrobiology)
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Open AccessArticle
Defining Lyfe in the Universe: From Three Privileged Functions to Four Pillars
Life 2020, 10(4), 42; https://doi.org/10.3390/life10040042 - 16 Apr 2020
Abstract
Motivated by the need to paint a more general picture of what life is—and could be—with respect to the rest of the phenomena of the universe, we propose a new vocabulary for astrobiological research. Lyfe is defined as any system that fulfills all [...] Read more.
Motivated by the need to paint a more general picture of what life is—and could be—with respect to the rest of the phenomena of the universe, we propose a new vocabulary for astrobiological research. Lyfe is defined as any system that fulfills all four processes of the living state, namely: dissipation, autocatalysis, homeostasis, and learning. Life is defined as the instance of lyfe that we are familiar with on Earth, one that uses a specific organometallic molecular toolbox to record information about its environment and achieve dynamical order by dissipating certain planetary disequilibria. This new classification system allows the astrobiological community to more clearly define the questions that propel their research—e.g., whether they are developing a historical narrative to explain the origin of life (on Earth), or a universal narrative for the emergence of lyfe, or whether they are seeking signs of life specifically, or lyfe at large across the universe. While the concept of “life as we don’t know it” is not new, the four pillars of lyfe offer a novel perspective on the living state that is indifferent to the particular components that might produce it. Full article
(This article belongs to the Special Issue Frontiers of Astrobiology)
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Open AccessArticle
Semipermeable Mixed Phospholipid-Fatty Acid Membranes Exhibit K+/Na+ Selectivity in the Absence of Proteins
Life 2020, 10(4), 39; https://doi.org/10.3390/life10040039 - 14 Apr 2020
Abstract
Two important ions, K+ and Na+, are unequally distributed across the contemporary phospholipid-based cell membrane because modern cells evolved a series of sophisticated protein channels and pumps to maintain ion gradients. The earliest life-like entities or protocells did not possess [...] Read more.
Two important ions, K+ and Na+, are unequally distributed across the contemporary phospholipid-based cell membrane because modern cells evolved a series of sophisticated protein channels and pumps to maintain ion gradients. The earliest life-like entities or protocells did not possess either ion-tight membranes or ion pumps, which would result in the equilibration of the intra-protocellular K+/Na+ ratio with that in the external environment. Here, we show that the most primitive protocell membranes composed of fatty acids, that were initially leaky, would eventually become less ion permeable as their membranes evolved towards having increasing phospholipid contents. Furthermore, these mixed fatty acid-phospholipid membranes selectively retain K+ but allow the passage of Na+ out of the cell. The K+/Na+ selectivity of these mixed fatty acid-phospholipid semipermeable membranes suggests that protocells at intermediate stages of evolution could have acquired electrochemical K+/Na+ ion gradients in the absence of any macromolecular transport machinery or pumps, thus potentially facilitating rudimentary protometabolism. Full article
(This article belongs to the Special Issue Frontiers of Astrobiology)
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Open AccessArticle
A Possible Primordial Acetyleno/Carboxydotrophic Core Metabolism
Life 2020, 10(4), 35; https://doi.org/10.3390/life10040035 - 07 Apr 2020
Abstract
Carbon fixation, in addition to the evolution of metabolism, is a main requirement for the evolution of life. Here, we report a one-pot carbon fixation of acetylene (C2H2) and carbon monoxide (CO) by aqueous nickel sulfide (NiS) under hydrothermal [...] Read more.
Carbon fixation, in addition to the evolution of metabolism, is a main requirement for the evolution of life. Here, we report a one-pot carbon fixation of acetylene (C2H2) and carbon monoxide (CO) by aqueous nickel sulfide (NiS) under hydrothermal (>100 °C) conditions. A slurry of precipitated NiS converts acetylene and carbon monoxide into a set of C2–4-products that are surprisingly representative for C2–4-segments of all four central CO2-fixation cycles of the domains Bacteria and Archaea, whereby some of the products engage in the same interconversions, as seen in the central CO2-fixation cycles. The results suggest a primordial, chemically predetermined, non-cyclic acetyleno/carboxydotrophic core metabolism. This metabolism is based on aqueous organo–metal chemistry, from which the extant central CO2-fixation cycles based on thioester chemistry would have evolved by piecemeal modifications. Full article
(This article belongs to the Special Issue Frontiers of Astrobiology)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Methanogens capable of using Mars-relevant clays as sole nutrient sources
Authors: R.L. Mickol, P.I. Craig, C.L Marnocha, P.D. Archer and T.A. Kral

Title: Can temperature and trace elements explain the rise and fall in stromatolite abundances?
Authors: Indrani Mukherjee, Ross Corkrey, Ross Large and Leonid Danyushevsky
Abstract: The occurrence of stromatolites date from 3.485 Ga and display varying diversity and abundance over time, with both rising to peaks at ~1.35-1.0 Ga, followed by declines. From the Cambrian
onwards their distribution has been limited to refugia associated with intertidal-supratidal zones, saline regions, and high energy environments, thought to exclude metazoan grazers and burrowers. Metazoa are classified within the Eukarya Domain.

Title: Life in the Nth Dimension: A Modeling Perspective
Authors: Adrian Lenardic

Title: On the Availability/Distribution of Amino Acids and Peptides throughout the Solar System
Authors: Chris J. Bennett
Affiliation: UCF Physics Department

Title: On the astrobiological relevance of Canary Islands (Spain): scientific models, instrumentation testing and outreach
Authors: Jesús Martínez-Frías
Affiliation: Instituto de Geociencias, IGEO (CSIC-UCM), C/ Del Doctor Severo Ochoa 7, Edificio Entrepabellones 7 y 8, 28040 Madrid, Spain

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