Oceanic protection of prebiotic organic compounds from UV radiation

Cleaves, H. James; Miller, Stanley L.

doi:10.1073/pnas.95.13.7260

Cited by 115 publications

(107 citation statements)

References 46 publications

(46 reference statements)

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“…Microbial mats scatter light such that the lower levels have only 1% of incident light at 0.5mm depth, and subsurface community hosting layers of sandstone reduce light levels to 0.005% of incidence (Cockell 1999;Garcia-Pichel et al 1994;Nienow & Friedmann 1993;Nienow et al 1988). As well, prebiotic organic polymers and dissolved inorganic ions may provide sufficient protection from UV degradation in as little as 2mm of ocean water (Cleaves & Miller 1998). Fig.…”

Section: Results: Uv Fluxes For Planets Orbiting Fgkm Starsmentioning

confidence: 99%

Uv Surface Environment of Earth-Like Planets Orbiting FGKM Stars Through Geological Evolution

Rugheimer

Segura

Kaltenegger

et al. 2015

ApJ

126

253

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The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars at the 1AU equivalent distance for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present day levels at 2.0 Gyr ago, 0.8 Gyr ago and modern Earth (following Kaltenegger et al. 2007). In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern EarthSun levels. A pre-biotic Earth orbiting GJ 581 (M3.5V) receives 300 times less biologically effective radiation, about 2 times modern Earth-Sun levels. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet orbiting a range of stars. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments.

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Section: Results: Uv Fluxes For Planets Orbiting Fgkm Starsmentioning

confidence: 99%

Uv Surface Environment of Earth-Like Planets Orbiting FGKM Stars Through Geological Evolution

Rugheimer

Segura

Kaltenegger

et al. 2015

ApJ

126

253

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“…All three types of biopolymers are formed via condensation polymerization, producing a single water molecule per bond formed. Water is the solvent of life, and geologists predict that a significant ocean volume existed on the prebiotic Earth [3]. However, polymerization reactions in aqueous media drive the polymerization reaction toward the reactants, via hydrolysis, since water is a product of the reaction.…”

Section: Glycine%mentioning

confidence: 99%

“…UV irradiation is also expected to have played a significant role in prebiotic chemistry. The ozone layer was not yet developed on the prebiotic Earth, so significant UV irradiation may have contributed to photocatalysis [28,61] as well as photodegradation [3]. Mineral surfaces may have also catalyzed early reactions [62] prior to the emergence of protein catalysts.…”

Section: Monomersmentioning

confidence: 99%

A Chemical Engineering Perspective on the Origins of Life

Grover

Hsieh

et al. 2015

Processes

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Atoms and molecules assemble into materials, with the material structure determining the properties and ultimate function. Human-made materials and systems have achieved great complexity, such as the integrated circuit and the modern airplane. However, they still do not rival the adaptivity and robustness of biological systems. Understanding the reaction and assembly of molecules on the early Earth is a scientific grand challenge, and also can elucidate the design principles underlying biological materials and systems. This research requires understanding of chemical reactions, thermodynamics, fluid mechanics, heat and mass transfer, optimization, and control. Thus, the discipline of chemical engineering can play a central role in advancing the field. In this paper, an overview of research in the origins field is given, with particular emphasis on the origin of biopolymers and the role of chemical engineering phenomena. A case study is presented to highlight the importance of the environment and its coupling to the chemistry.

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“…For example, peptides were synthesized under the conditions of high salt content (85,93), catalyzed by copper ions; also, the hydrolytic stability of RNA is reported to increase with a high salt content (4). The salts in the early oceans also provided UV protection to amino acids (13). It has been suggested, however, that life could not have started in salty oceans because the colloidal stability of fatty acid soap vesicles is poor in such solutions (18,71): it is sensitive to pH and high ionic strength and to small amounts of divalent metal ions which precipitate insoluble salts and agglomerate such vesicles.…”

Section: Hadean Evolution the Salty Oceanmentioning

confidence: 99%

The Role of Biomacromolecular Crowding, Ionic Strength, and Physicochemical Gradients in the Complexities of Life's Emergence

Spitzer¹,

Poolman

2009

Microbiol Mol Biol Rev

130

168

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SUMMARY We have developed a general scenario of prebiotic physicochemical evolution during the Earth's Hadean eon and reviewed the relevant literature. We suggest that prebiotic chemical evolution started in microspaces with membranous walls, where external temperature and osmotic gradients were coupled to free-energy gradients of potential chemical reactions. The key feature of this scenario is the onset of an emergent evolutionary transition within the microspaces that is described by the model of complex vectorial chemistry. This transition occurs at average macromolecular crowding of 20 to 30% of the cell volume, when the ranges of action of stabilizing colloidal forces (screened electrostatic forces, hydration, and excluded volume forces) become commensurate. Under these conditions, the macromolecules divide the interior of microspaces into dynamically crowded macromolecular regions and topologically complementary electrolyte pools. Small ions and ionic metabolites are transported vectorially between the electrolyte pools and through the (semiconducting) electrolyte pathways of the crowded macromolecular regions from their high electrochemical potential (where they are biochemically produced) to their lower electrochemical potential (where they are consumed). We suggest a sequence of tentative transitions between major evolutionary periods during the Hadean eon as follows: (i) the early water world, (ii) the appearance of land masses, (iii) the pre-RNA world, (iv) the onset of complex vectorial chemistry, and (v) the RNA world and evolution toward Darwinian thresholds. We stress the importance of high ionic strength of the Hadean ocean (short Debye's lengths) and screened electrostatic interactions that enabled the onset of the vectorial structure of the cytoplasm and the possibility of life's emergence.

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Oceanic protection of prebiotic organic compounds from UV radiation

Cited by 115 publications

References 46 publications

Uv Surface Environment of Earth-Like Planets Orbiting FGKM Stars Through Geological Evolution

Uv Surface Environment of Earth-Like Planets Orbiting FGKM Stars Through Geological Evolution

A Chemical Engineering Perspective on the Origins of Life

The Role of Biomacromolecular Crowding, Ionic Strength, and Physicochemical Gradients in the Complexities of Life's Emergence

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