Europlanet Science Congress 2022
Palacio de Congresos de Granada, Spain
18 – 23 September 2022
Europlanet Science Congress 2022
Palacio de Congresos de Granada, Spain
18 September – 23 September 2022

TP15

Astrobiology

Astrobiology is the study of whether present or past life exists elsewhere in the universe. To understand how life can begin in space, it is essential to know what organic compounds were likely available, and how they interacted with the planetary environment. This session seeks papers that offer existing/novel theoretical models or computational works that address the chemical and environmental conditions relevant to astrobiology on terrestrial planets/moons or ocean worlds, along with other theoretical, experimental, and observational works related to the emergence and development of Life in the Universe. This includes work related to prebiotic chemistry, the chemistry of early life, the biogeochemistry of life’s interaction with its environment, chemistry associated with biosignatures and their false positives, and chemistry pertinent to conditions that could possibly harbor life (e.g. Titan, Enceladus, Europa, TRAPPIST-1, habitable exoplanets, etc.). Understanding how the planetary environment has influenced the evolution of life and how biological processes have changed the environment is an essential part of any study of the origin and search for signs of life. Earth analogues experiments/instruments test and/or simulation campaigns and limits of life studies are included as well as one of the main topics of this session. Major Space Agencies identified planetary habitability and the search for evidence of life as a key component of their scientific missions in the next two decades. The development of instrumentation and technology to support the search for complex organic molecules/sings of life/biosignatures and the endurance of life in space environments is critical to define unambiguous approaches to life detection over a broad range of planetary environments.

Co-organized by OPS/SB/EXOA
Convener: Felipe Gómez | Co-conveners: Nuria Rodríguez-González, Sohan Jheeta, Frank Trixler, Rosanna del Gaudio
Orals
| Mon, 19 Sep, 10:00–11:30 (CEST), 15:30–18:30 (CEST)|Room Albéniz+Machuca
Posters
| Attendance Mon, 19 Sep, 18:45–20:15 (CEST)|Poster area Level 1

Orals: Mon, 19 Sep | Room Albéniz+Machuca

Chairpersons: Felipe Gómez, Nuria Rodríguez-González, Sohan Jheeta
10:00–10:20
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EPSC2022-254
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solicited
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MI
Juan Perez-Mercader

Experimental progress made during the last decade in dynamical self-assembly and its chemical implementation can be used to provide experimental examples of biochemistry-free autopoietic systems that emerge from homogeneous and isotropic solutions under selected environmental conditions. These simple emergent vesicular structures and systems self-assemble and, then in aqueous media, using conformational information, metabolize, self-reproduce, compete and evolve by adaptive or non-adaptive means. They also are chemo and phototactic. These systems can be implemented in the chemistry laboratory. They can be thought of as very primitive proto-cellular systems capable of evolving. Their information handling and metabolism use RAFT (Reversible Addition Fragmentation Transfer) polymerization chemistry, their reproduction is by sporular seeds and results from the combination of both environment induced degradation and hydrodynamic instability of the autonomously created amphiphiles and their metastable self-assembled membranes. Their evolution involves the adaptive interaction between environment, population and the feedback loops between the two highly selective chemistries that are combined in the system: “click chemistry” and (RAFT) polymerization induced self-assembly.

How to cite: Perez-Mercader, J.: From a Homogeneous Non-biochemical Soup to the Emergence of Fundamental Functions of Life, including Adaptation. Physics and Chemistry Working Together at micron scales, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-254, 2022.

10:20–10:35
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EPSC2022-141
Vassilissa Vinogradoff, Raphael Pepino, Vanessa Leyva, Lauryane Cazals, Coline Serra, Gregoire Danger, and Cornelia Meinert

 Introduction: Sugars are important molecules with high biological interest. Found in cometary-like analogs (Meinert et al., 2016), carbonaceous meteorites (Cooper et al., 2001; Furukawa et al., 2019), and likely on early Earth, sugars may have contributed as a source of molecules for the emergence of prebiotic systems on Earth. Hence, it is of prime importance to investigate their formation in conditions relevant to these environments, and particularly in the presence of minerals. For example, sugar formation is achieved through the formose reaction: the dimerization of formaldehyde, forming glycolaldehyde, which then by aldol reactions with another formaldehyde, will form successively higher sugar homologues. A catalyst is usually required for the first step, the formation of glycolaldehyde (typically calcium hydroxide). However, there is a lack of studies exploring the potential of minerals on the classical formose reaction (Gabel and Ponnamperuma, 1967; Haas et al., 2020) and in conditions representative of prebiotic environments. Here, we focus on the formation of sugars from formaldehyde via the formose reaction in aqueous solution using minerals, simulating conditions in which planetary surfaces could have evolved at the beginning of the Solar System.

Experiments and methods: Experiments took place in aqueous systems under anoxic atmosphere at 80 °C. We choose olivine as a model silicate, which is omnipresent in the solar system, and designed a series of experiments differing formaldehyde (F), glycolaldehyde (G), calcium hydroxide Ca(OH)2 (α) and olivine (O) compositions. We tested different combinations, O, F, FO, FG, FGO, Fα, FGα, for different durations up to 45 days. Formaldehyde (under the form of polyoxymethylene) was introduced with glycolaldehyde or calcium hydroxide at a weight ratio of 10/1 and olivine/formaldehyde also at a weight ratio of 10/1. The mixtures were loaded in closed cells under argon atmosphere in a glove box before being heated in an oven at 80 °C. We used Gas Chromatography-Mass Spectrometry (GC-MS) and GC×GC-TOFMS for the identification and quantification of sugars formed in the individual samples.

Results: Identification of sugars in the different samples was performed comparing retention times and relative mass spectra with those of reference standards (oses, polyols, sugar acids and deoxy sugars acids).

Abundance of sugars found in samples after 2 days of reaction are shown in figure 1. No sugars have been identified in samples F2, except minor contaminants from the derivatization protocol. In contrary, in the presence of olivine (sample FO2), 16 sugars have been identified and quantified based on reference standards, and many more peaks seen in the chromatograms are suspected polyolsbased on their mass spectra. We observed the same sugars in the FGO samples, while only a few of them are observed in the FG samples. Most importantly, olivine allowed the detection of C6 sugars after only 2 days of reaction, not observed in samples without olivine even after 45 days of hydrothermal reaction. When compared to experiments with the classical Ca(OH)2 catalyst, identical sugars are identified with olivine with highest abundances found for Ca(OH)2. For all samples, the diversity and quantity of sugars (mainly oses) decreased after 2 days of reactions, and mainly polyols remained in samples with olivine after 45 days.

Discussion: These experiments demonstrate that minerals may have played a crucial role in the chemical reactivity during evolution of chemical systems in aqueous environments. Here, sugars have been formed  through a mineral-assisted formose reaction leading to a high molecular diversity and sugar abundance after short reaction times, without any other classical catalyst. The silicate likely ensures the selection and stabilization of the C3-C4 sugars allowing rapid aldolisation to C6, unlike solutions without silicate. However, decomposition of sugars with time is inevitable; nonetheless, surprisingly polyol-sugars survive hydrothermal alteration with olivine on longer times. These experiments raise again the question of mineral impact on the organic evolution, even as simple as olivine, in conditions mimicking aqueous environments on planetary surfaces similar to prebiotic conditions on Earth (Vinogradoff et al., 2020).

References:   Cooper G. et al., (2001), Nature 414.

Furukawa Y. et al., (2019), Proc. Natl. Acad. Sci. 116.

Gabel N. W. and Ponnamperuma C. (1967), Nature 216.

Haas M. et al., (2020), Commun. Chem. 3.

Meinert C., et al., (2016), Science 352.

Vinogradoff V. et al., (2020) Geochim. Cosmochim. Acta 269.

 

How to cite: Vinogradoff, V., Pepino, R., Leyva, V., Cazals, L., Serra, C., Danger, G., and Meinert, C.: Mineral-catalyzed sugar synthesis under hydrothermal conditions, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-141, 2022.

10:35–10:50
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EPSC2022-86
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ECP
Elle Bethune, Charles S Cockell, Eleanor E.B Campbell, and Andrey Gromov

The appearance of the first microbial life on Earth coincided with the Late Heavy Bombardment, during which time a large amount of meteoritic material was accreted. A significant fraction of this material contained organic carbon of extra-terrestrial origin which likely survived atmospheric entry. It is therefore highly plausible these extra-terrestrial carbon compounds interacted with primitive microorganisms in some respect. Of the known extra-terrestrial carbon compounds found in meteorites, little is known about the effect of fullerenes and their derivatives on microbial communities. An anaerobic community is used in our studies as a model to infer how these compounds may have influenced the metabolic development of primitive microbes with respect to the environmental conditions on the early Earth.

Pristine high molecular weight fullerenes C60 and C70 appear to have no effect on the growth of anaerobic microorganisms when an additional carbon source is present. Community growth is significantly reduced when C60 is present as the sole carbon source and no intermediate breakdown products are detected with mass spectrometry. Some features observed with transmission electron microscopy indicate ingestion of small amounts of C60 may be occurring, however C60 and C70 remain to appear relatively inaccessible to anaerobic microbes.

The naturally occurring water-soluble C60 derivative, C60 fullerol, is inhibitory to the growth of this anaerobic community, particularly when exposed to ambient or short-wave UV light. The presence of these fullerene derivatives on the early Earth therefore may have had an inhibitory effect on the development of primitive microbes and added to the selection pressures driving metabolic evolution.

Current and future work focuses on simulating early Earth environmental conditions to produce naturally occurring fullerene breakdown products as potential sources of accessible carbon for primitive microorganisms. 

How to cite: Bethune, E., Cockell, C. S., Campbell, E. E. B., and Gromov, A.: Anaerobic Microbial Interactions with Fullerenes: Implications for the Use of Extra-terrestrial Organics by Life on Early Earth, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-86, https://doi.org/10.5194/epsc2022-86, 2022.

10:50–11:05
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EPSC2022-72
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ECP
Iva Vilovic, Dirk Schulze-Makuch, and René Heller

In our search for life in the Universe, it would be anthropocentric to assume that there are no planets more suitable for life than Earth. We call such planets ‘superhabitable’1. Some of the environmental conditions related to superhabitability are motivated astrophysically, while others are based on the varying habitability throughout Earth’s natural history2

Here we present our initial results in which we investigate potentially superhabitable conditions which, among other parameters, include K-dwarfs as host stars. To simulate the astrophysical condition of superhabitability, we obtained an LED solar simulator with a variable spectrum module which we adapted for our needs. As part of the theoretical preparations for our physical setup of the experiment in the lab chamber, we modeled the emission spectrum of a 4300 Kelvin K-dwarf star using the PHOENIX spectral library. We calculated the emission spectrum at the top of the planetary atmosphere of the hypothetical planet in the center of the star’s habitable zone, at a distance of ~0.44 AU, where it receives 0.6 times the solar effective flux, i.e. ~820 W/m2. Using Earth’s telluric spectrum we calculated for the first time the stellar spectrum of a K-dwarf star transmitted to the surface of a hypothetical habitable zone planet with an Earth-like atmosphere. We used this spectrum as a backbone for creating the LED spectral fit. As a test run, we built a small external-light-isolating chamber and are determining the responses of plant species (e.g. watercress) to the produced K-dwarf stellar spectrum in comparison to solar light.

At the same time we quantified the variations of habitability conditions during the natural history of Earth. Paleontological and geochemical records are key to the reconstruction of geological and atmospheric aspects that have affected Earth’s biosphere. We used these to understand how environmental tracers (e.g. surface temperatures, oxygen partial pressures and relative humidity) correlate with biological tracers (e.g. biomass production and biological diversity). Variations of the global average surface temperature in the Phanerozoic era have previously been demonstrated to be inversely correlated with biodiversity3,4. Here we show for the first time that periods with elevated oxygen partial pressures in the atmosphere correlate with increased biomass production but not biological diversity, whereas humid periods correlate strongly with biodiversity and to some extent with biomass. These results extend the previously established effect of surface temperature on biological diversity to a similar correlation with biomass, and stress the impact of oxygen and relative humidity on the biosphere. Our results help us to better understand how the modern biosphere could change in the future, especially in light of the rapid anthropogenic changes. Beyond that, such tracers could soon be measured on extrasolar planets with space-based observatories5–7, whose geo- or biological origin could be better interpreted using our results. 

Eventually we plan to apply theoretical climate-chemistry models to determine how life affects the biosignatures of a superhabitable planet around a K-dwarf host star by calculating synthetic transmission / emission spectra and atmospheric compositions, as it is vital to determine whether life that flourishes under such conditions can also be observable. These results will be used to provide a guide for space-based transit observations of extrasolar potentially habitable planets.

References

1. Heller, R. & Armstrong, J. Superhabitable Worlds. Astrobiology vol. 14 50–66 (2014).

2. Schulze-Makuch, D., Heller, R. & Guinan, E. In Search for a Planet Better than Earth: Top Contenders for a Superhabitable World. Astrobiology 20, 1394–1404 (2020).

3. Mayhew, P. J., Jenkins, G. B. & Benton, T. G. A long-term association between global temperature and biodiversity, origination and extinction in the fossil record. Proc. Biol. Sci. 275, 47–53 (2008).

4. Song, H. et al. Thresholds of temperature change for mass extinctions. Nat. Commun. 12, 4694 (2021).

4. Krissansen-Totton, J., Garland, R. & Irwin, P. Detectability of biosignatures in anoxic atmospheres with the James Webb Space Telescope: A TRAPPIST-1e case study. Astron. J. (2018).

5. The LUVOIR Team. The LUVOIR Mission Concept Study Final Report. arXiv [astro-ph.IM] (2019).

7. Scott Gaudi, B. et al. The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Final Report. arXiv [astro-ph.IM] (2020).

How to cite: Vilovic, I., Schulze-Makuch, D., and Heller, R.: Earth’s varying paleoenvironment and experimental tests provide insights into superhabitabitable conditions on exoplanets, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-72, https://doi.org/10.5194/epsc2022-72, 2022.

11:05–11:20
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EPSC2022-495
Nicoletta La Rocca, Mariano Battistuzzi, Riccardo Claudi, Lorenzo Cocola, and Luca Poletto

Recently discovered Earth-like exoplanets are orbiting the Habitable Zone of M-dwarf stars, the most abundant and long-lived stars known in the Milky Way. Such stars have different spectral characteristics respect to the Sun, being less luminous and generating a light spectrum with a major component in far-red and infrared, while emitting very low in the visible. Many researchers discussed the possibility of oxygenic photosynthesis in these worlds, as the characteristics of M-dwarf stars do not seem suitable for most oxygenic photosynthetic organisms evolved on Earth to absorb the only visible light. However, no experimental research has been done testing organisms under simulated M-dwarf spectra. At the university of Padova, a collaboration between the Department of Biology, the Astronomical Observatory (INAF) and the Institute of Photonics and Nanotechnology (IFN-CNR) led to the construction and the development of a new experimental tool. The setup is composed by two main components: a Star Light Simulator, able to generate different light intensities and spectra, including those of M-dwarf stars and an Atmosphere Simulator Chamber where different gas compositions can be set, allowing to grow photosynthetic organisms under selected non-terrestrial conditions. We initially focused on cyanobacteria as target microorganisms, due to their extraordinary capacities to withstand every kind of environment on the Earth as well as their ability to acclimate to Far-Red light. We are now testing the responses of different species of microalgae and mosses by analysing their ability to acclimate to Far-Red light and M-dwarf simulated spectra.

How to cite: La Rocca, N., Battistuzzi, M., Claudi, R., Cocola, L., and Poletto, L.: Responses of eukaryotic photosynthetic organisms to simulated M-dwarf star light. , Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-495, 2022.

11:20–11:30
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EPSC2022-70
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ECP
Silvana Pinna, Emilie Werner, and Joseph Moran

In modern metabolism, phosphorylated compounds play a key role[1]. The informational molecules RNA and DNA are composed of phosphorylated units (nucleotides), and phosphorylation is also used as an activation mechanism for many metabolic processes, particularly through the universal energy currency adenosine triphosphate (ATP).

The deeply conserved nature of this reaction suggests an early origin of phosphorylation to drive metabolism. However, the non-enzymatic transfer of a phosphate group is challenging in water. Additionally, the poor geochemical accessibility of phosphate constrains the plausibility of phosphorylated compounds at the origin of life that are biologically relevant and have an appropriate reactivity in aqueous conditions.

Here, I report the phosphorylation of several biologically relevant molecules by an active metabolite-metal species that uses the prebiotically plausible molecule acetyl phosphate[2–5] as phosphate donor. Occurring in aqueous solution under mild prebiotic conditions, this work furthers the notion that ATP is universally conserved across life likely due to its formation being chemically favoured in aqueous solution that has recently been suggested[6].

 

References: 

[1] Westheimer, F. Why nature chose phosphates over arsenates. Science (1987). 13(4793): 3601–3608.

[2] Lipmann, F., Tuttle, L.C. Acetyl phosphate: chemistry, determination, and synthesis. J. Biol. Chem. (1944). 153: 571–582.

[3] de Duve, C. Blueprint for a cell: the nature and origin of life. (1991). Neil Patterson Publishers, Burlington.

[4] Schönheit, P., Buckel, W., Martin, W.F. On the Origin of Heterotrophy. Trends Microbiol. (2016). 24: 12–25.

[5] Whicher, A., Camprubí, E., Pinna S, Herschy B, Lane N. Acetyl Phosphate as a Primordial Energy Currency at the Origin of Life. Orig. Life. Evol. Biosph. (2018). 48: 159–179.

[6] Pinna, S., Kunz, C., Harrison, S.A.,  Jordan, S.F., Ward, J., Werner, F., Lane, N. A prebiotic basis for ATP as the universal energy currency. bioRxiv. (2021).

How to cite: Pinna, S., Werner, E., and Moran, J.: Metabolites and metals as phosphate transfer catalysts, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-70, https://doi.org/10.5194/epsc2022-70, 2022.

Coffee break
Chairpersons: Felipe Gómez, Nuria Rodríguez-González, Rosanna del Gaudio
15:30–15:45
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EPSC2022-140
Sohan Jheeta

The amino acid condensation reaction on a heterogeneous mineral surface has been regarded as one of the important pathways for peptide bond formation. Keeping this in view, we have studied the oligomerization of the simple amino acids, glycine and alanine, on nickel ferrite (NiFe2O4), cobalt ferrite (CoFe2O4), copper ferrite (CuFe2O4), zinc ferrite (ZnFe2O4), and manganese ferrite (MnFe2O4) nanoparticles surfaces, in the temperature range from 50–120  oC for 1–35 days, without applying any wetting/drying cycles. Among the metal ferrites tested for their catalytic activity, NiFe2O4 produced the highest yield of products by oligomerizing glycine to the trimer level and alanine to the dimer level, whereas MnFe2O4 was the least efficient catalyst, producing the lowest yield of products, as well as shorter oligomers of amino acids under the same set of experimental conditions. It produced primarily diketopiperazine (Ala) with a trace amount of alanine dimer from alanine condensation, while glycine was oligomerized to the dimer level. The trend in product formation is in accordance with the surface area of the minerals used. A temperature as low as 50 oC can even favour peptide bond formation in the present study, which is important in the sense that the condensation process is highly feasible without any sort of localized heat that may originate from volcanoes or hydrothermal vents. However, at a high temperature of 120 oC, anhydrides of glycine and alanine formation are favoured, while the optimum temperature for the highest yield of product formation was found to be 90 oC.

How to cite: Jheeta, S.: Thermal Condensation of Glycine and Alanine on Metal Ferrite Surface: Primitive Peptide Bond Formation Scenario, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-140, 2022.

15:45–16:00
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EPSC2022-352
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ECP
Rita Severino, Moisés Maestro-Lópes, Jorge Cuéllar, José María Valpuesta, and Victor Parro

Astrobiology is the study of the origin, evolution, and distribution of life in the context of cosmic evolution, which includes habitability in the Solar System and beyond (Horneck et al., 2016). After NASA was established in 1958, the agency began an effort to learn how to look for the presence of life beyond Earth - both ancient and current. This began with the Viking landers in 1976, but it was not until the 2012 landing of Curiosity that another astrobiology (though not life detection) mission began. Today there is a growing multidisciplinary community that aims at answering the question: Is there life beyond Earth and, if so, how can we detect it? Mars, in particular, once had water, atmosphere, and volcanic activity, where life could have flourished. There is also a slim chance that microbial life exists on Mars today. But how can we detect Martian life? Our research focuses on biosignatures as facilitating life detection (Horneck et al., 2016; Neveu, Hays, Voytek, New, & Schulte, 2018). Particularly, the identification and detection of functional molecules (DNA, lipids, proteins), using antibodies and immunoassays, in natural samples. Antibodies targeting proteins obtained from crude environmental extracts, from extreme environments on Earth, have been used as antigens in our research, successfully (Fernández-Martínez et al., 2019; Sanchez-Garcia et al., 2019). Recently, we tested ancestral proteins, obtained through Ancestral Sequence Reconstruction techniques, as antigens, and tested several terrestrial environments (Severino et al., in preparation). Results were promising, as their presence could be traced back to terrestrial paleoenvironments (environments that retain ancestral characteristics), thus opening a new field in astrobiology. Molecular chaperones are one of the oldest protein families, and Hsp60 (chaperonins) is the oldest clan, whose origins can be traced back to the last common ancestor (Rebeaud, Mallik, Goloubinoff, & Tawfik, 2021). They are commonly identified in extreme environments, either by metaproteomics, or microarray immunoassays (Fernández-Martínez et al., 2019; Sanchez-García et al., 2019). Here, we report the ancestral sequence reconstruction and protein resurrection of this family of proteins (Figure 1) and discuss our findings in the light of biogeochemistry, systems-level paleoenvironments characterization, and astrobiological applications (Kaçar, Guy, Smith, & Baross, 2017).