Miller-Urey Research Articles

A Miller–Urey broth mirrors the mass density distribution of all Beilstein indexed organic molecules

The Miller–Urey experiment became a paradigm for spontaneous generation of biomolecules on the prebiotic Earth. In the experiment water, methane, ammonia and hydrogen gases are submitted to electric discharges. New molecules emerge and accumulate in liquid water to form a rich organic solution. Although many important biomolecules such as amino-acids have been isolated from a Miller–Urey broth, it is unclear how many different molecules the experiment is able to produce. Here we analyze the prebiotic broth by liquid chromatography and high-resolution mass spectroscopy. We find that the experimentally determined molecular mass density distribution from the Miller–Urey experiment reproduces the distribution of all organic molecules (regardless of their elemental composition) indexed in the Beilstein database. The observed mass density distribution exhibits paretian behavior: it closely follows a log-normal distribution except for its tails where it approaches a power-law. Simple growth models reproduce the experimentally observed mass distribution to a lesser extent than the Beilstein data. We conclude that molecular growth processes are unlikely to limit the experimental outcome, rather the Miller–Urey experiment seems to explore the entire range of prominent, stable masses of molecules that are part of the Beilstein/Reaxys database and made from the same atomic elements. We suspect that in principle the experiment can, at least statistically, produce any small organic molecule that exhibits sufficient stability as part of the broth.

Do aliens dream of offworld sheep?

AbstractThe Stanley Miller experiment suggests that amino acid-based life is ubiquitous in our universe, although its varieties will not have followed the particular, highly contingent and path-dependent, evolutionary trajectory found on Earth. Are many alien organisms likely to be individually conscious in ways we would recognize? Almost certainly. Will alien consciousness require a ‘sleep cycle’? A strong argument suggests it will. Can some species develop analogs to culture and high-order technology? Less likely, but still fairly probable. If so, will we be able to communicate with them? Only on a basic level, and only with profound difficulty. The reasoning is fairly direct and involves convolution of a learned heritage system with individual and collective consciousness.

Myth and fact in the origins of cellular life on Earth

Research into the origins of the first protocell is of a multidisciplinary nature. It draws evidence from what we know about the Earth’s early atmosphere and environment, and about the most ancient features of the cell’s structure and composition. Such data provides the input for the hypothesis generation and experimental reconstruction necessary to mimic steps in the formation of the first protocell. While research into the origins of the first protocell is condemned to focus upon laboratory experiments, it should be guided by a detailed study of real evidence pertaining to the environment on Earth 4 billion years ago. In this review, we take stock of the research that has been performed to date across the main disciplines of earth sciences, biochemistry, and molecular biology. We seek to identify the progress made in laying down a sequence for the events that led up to the first protocell. We also assess the strengths and weaknesses of the experimental designs and suggest some future approaches. While the field has made many important advances, from the original Stanley Miller experiment establishing ‘life from chemistry’ products such as amino acids, through to Deamer’s findings on fatty acid membranes and Szostack’s work on lipids, there is still a long and challenging journey ahead to understand how cellular life began. The experiments required to make more rapid progress in the field will likely be more elaborate, costly, and time consuming.

Seeds of Life in Space (SOLIS)

Context: Modern versions of the Miller-Urey experiment claim that formamide (NH$_2$CHO) could be the starting point for the formation of metabolic and genetic macromolecules. Intriguingly, formamide is indeed observed in regions forming Solar-type stars as well as in external galaxies. Aims: How NH$_2$CHO is formed has been a puzzle for decades: our goal is to contribute to the hotly debated question of whether formamide is mostly formed via gas-phase or grain surface chemistry. Methods: We used the NOEMA interferometer to image NH$_2$CHO towards the L1157-B1 blue-shifted shock, a well known interstellar laboratory, to study how the components of dust mantles and cores released into the gas phase triggers the formation of formamide. Results: We report the first spatially resolved image (size $\sim$ 9", $\sim$ 2300 AU) of formamide emission in a shocked region around a Sun-like protostar: the line profiles are blueshifted and have a FWHM $\simeq$ 5 km s$^{-1}$. A column density of $N_{\rm NH_2CHO}$ = 8 $\times$ 10$^{12}$ cm$^{-1}$, and an abundance (with respect to H-nuclei) of 4 $\times$ 10$^{-9}$ are derived. We show a spatial segregation of formamide with respect to other organic species. Our observations, coupled with a chemical modelling analysis, indicate that the formamide observed in L1157-B1 is formed by gas-phase chemical process, and not on grain surfaces as previously suggested. Conclusions: The SOLIS interferometric observations of formamide provide direct evidence that this potentially crucial brick of life is efficiently formed in the gas-phase around Sun-like protostars.

Formation of nucleobases in a Miller-Urey reducing atmosphere.

The Miller-Urey experiments pioneered modern research on the molecular origins of life, but their actual relevance in this field was later questioned because the gas mixture used in their research is considered too reducing with respect to the most accepted hypotheses for the conditions on primordial Earth. In particular, the production of only amino acids has been taken as evidence of the limited relevance of the results. Here, we report an experimental work, combined with state-of-the-art computational methods, in which both electric discharge and laser-driven plasma impact simulations were carried out in a reducing atmosphere containing NH3 + CO. We show that RNA nucleobases are synthesized in these experiments, strongly supporting the possibility of the emergence of biologically relevant molecules in a reducing atmosphere. The reconstructed synthetic pathways indicate that small radicals and formamide play a crucial role, in agreement with a number of recent experimental and theoretical results.

ChemInform Abstract: Emergence of the First Catalytic Oligonucleotides in a Formamide‐Based Origin Scenario

AbstractReview: 97 refs.

Emergence of the First Catalytic Oligonucleotides in a Formamide-Based Origin Scenario.

50 years after the historical Miller-Urey experiment, the formamide-based scenario is perhaps the most powerful concurrent hypothesis for the origin of life on our planet besides the traditional HCN-based concept. The information accumulated during the last 15 years in this topic is astonishingly growing and nowadays the formamide-based model represents one of the most complete and coherent pathways leading from simple prebiotic precursors up to the first catalytically active RNA molecules. In this work, we overview the major events of this long pathway that have emerged from recent experimental and theoretical studies, mainly concentrating on the mechanistic, methodological, and structural aspects of this research.

Primordial soup was edible: abiotically produced Miller-Urey mixture supports bacterial growth.

Sixty years after the seminal Miller-Urey experiment that abiotically produced a mixture of racemized amino acids, we provide a definite proof that this primordial soup, when properly cooked, was edible for primitive organisms. Direct admixture of even small amounts of Miller-Urey mixture strongly inhibits E. coli bacteria growth due to the toxicity of abundant components, such as cyanides. However, these toxic compounds are both volatile and extremely reactive, while bacteria are highly capable of adaptation. Consequently, after bacterial adaptation to a mixture of the two most abundant abiotic amino acids, glycine and racemized alanine, dried and reconstituted MU soup was found to support bacterial growth and even accelerate it compared to a simple mixture of the two amino acids. Therefore, primordial Miller-Urey soup was perfectly suitable as a growth media for early life forms.

Meteorite-catalyzed syntheses of nucleosides and of other prebiotic compounds from formamide under proton irradiation

Liquid formamide has been irradiated by high-energy proton beams in the presence of powdered meteorites, and the products of the catalyzed resulting syntheses were analyzed by mass spectrometry. Relative to the controls (no radiation, or no formamide, or no catalyst), an extremely rich, variegate, and prebiotically relevant panel of compounds was observed. The meteorites tested were representative of the four major classes: iron, stony iron, chondrites, and achondrites. The products obtained were amino acids, carboxylic acids, nucleobases, sugars, and, most notably, four nucleosides: cytidine, uridine, adenosine, and thymidine. In accordance with theoretical studies, the detection of HCN oligomers suggests the occurrence of mechanisms based on the generation of radical cyanide species (CN·) for the synthesis of nucleobases. Given that many of the compounds obtained are key components of extant organisms, these observations contribute to outline plausible exogenous high-energy-based prebiotic scenarios and their possible boundary conditions, as discussed.

Abiotic synthesis of amino acids and self-crystallization under prebiotic conditions.

Building on previous research on the origin and homochirality of life, this study focuses on analyses profiling important building blocks of life: the natural amino acids. The spark discharge variation of the iconic Miller experiment was performed with a reducing gas mixture of ammonia, methane, water and hydrogen. Amino acid analysis using liquid chromatography coupled with tandem mass spectrometry after pre-column derivatizaiton revealed the generation of several amino acids including those essential for life. Re-crystallization of the synthetic products and enantiomeric ratio analysis were subsequently performed. Results from liquid chromatography coupled with either fluorescent detector or tandem mass spectrometry after pre-column derivatization with chiral reagent revealed spontaneous and effective asymmetric resolution of serine and alanine. This work describes a useful analytical platform for investigation of hypotheses regarding the origin and homochirality of amino acids under prebiotic conditions. The formation of numerous amino acids in the electric discharge experiment and the occurrence of high enantiomeric ratios of amino acids in re-crystallization experiment give valuable implications for future studies in unraveling fundamental questions regarding origins and evolution of life.

Miller experiments in atomistic computer simulations.

The celebrated Miller experiments reported on the spontaneous formation of amino acids from a mixture of simple molecules reacting under an electric discharge, giving birth to the research field of prebiotic chemistry. However, the chemical reactions involved in those experiments have never been studied at the atomic level. Here we report on, to our knowledge, the first ab initio computer simulations of Miller-like experiments in the condensed phase. Our study, based on the recent method of treatment of aqueous systems under electric fields and on metadynamics analysis of chemical reactions, shows that glycine spontaneously forms from mixtures of simple molecules once an electric field is switched on and identifies formic acid and formamide as key intermediate products of the early steps of the Miller reactions, and the crucible of formation of complex biological molecules.

Influence on Crystallisation Process of Amino Acids from Solution

The famous Miller experiment to model the primordial soup demonstrated that amino acids can form spontaneously as the essential building blocks of life in solutions. It is, however, still an open question how self-recognition processes influence the transformation of these spontaneously formed amino acids in solvents into higher ordered structures in the solid state, thereby creating chiral materials and catalytically competent structures. The understanding of the first steps of molecular self-assembly processes in such environments will thus give important clues towards the understanding of biological evolution. Most of intermolecular interactions are not very strong and their formation is related to and affected by small changes in the molecular structure and the crystallisation conditions. Continuing our investigations on aggregation of substituted aromatic molecules in the solid state, we studied the influence and boundaries of weak directing substituents like deuterium on the aggregation of small molecules. Hydrogen/deuterium (H/D)-exchange, the smallest possible modification of a molecule, is generally seen as a non dominating parameter in the formation of crystal structures of chemical compounds. On the other hand, it could already be shown that the aggregation of molecules in the solid state of polymorphic N-heterocycle systems like pyridine-N-oxide or acridine can be very sensitive to small changes of the isotopic substitution pattern of the selected molecules. Within our project, the molecular aggregation of amino acids in solution with the formation of molecular aggregates and pre-nucleation clusters in deuterated and non-deuterated systems, and in particular the role of the solvent in these processes, will be studied in both experiment and theory.

Amino acids generated from hydrated Titan tholins: Comparison with Miller–Urey electric discharge products

Various analogues of Titan haze particles (termed ‘tholins’) have been made in the laboratory. In certain geologic environments on Titan, these haze particles may come into contact with aqueous ammonia (NH3) solutions, hydrolyzing them into molecules of astrobiological interest. A Titan tholin analogue hydrolyzed in aqueous NH3 at room temperature for 2.5years was analyzed for amino acids using highly sensitive ultra-high performance liquid chromatography coupled with fluorescence detection and time-of-flight mass spectrometry (UHPLC-FD/ToF-MS) analysis after derivatization with a fluorescent tag. We compare here the amino acids produced from this reaction sequence with those generated from room temperature Miller–Urey (MU) type electric discharge reactions. We find that most of the amino acids detected in low temperature MU CH4/N2/H2O electric discharge reactions are generated in Titan simulation reactions, as well as in previous simulations of Triton chemistry. This argues that many processes provide very similar mixtures of amino acids, and possibly other types of organic compounds, in disparate environments, regardless of the order of hydration. Although it is unknown how life began, it is likely that given reducing conditions, similar materials were available throughout the early Solar System and throughout the universe to facilitate chemical evolution.

REVIEW OF GRAVITATIONAL WAVE DETECTIONS: DYNAMICAL SPACE

This is a review of the numerous successful gravitational wave detections and the implications for the nature of space and time. The prevailing space time paradigm in physics was founded on the putative “null” results of the Michelson-Morley (MM) 1887 interferometer experiment to detect light speed anisotropy and which resulted in two different new relativity theories: Lorentz relativity (Lorentz, 1904) and special relativity (Einstein, 1905), with the later invoking the claimed reality of space time, in place of separate phenomena of space and time. Miller (1933) repeated the MM experiment in 1925/26 and obtained non-null quality data, resulting in the determination of light speed anisotropy and establishing the key sidereal effect. It is now understood, since 2002, that both of these experiments are consistent and that the MM 1887 experiment was never null: Michelson had used Newtonian physics to calibrate the interferometer. Using Lorentz Relativity, but not Special Relativity, it is now possible to analyse the data from these experiments and which shows that the Michelson interferometer has zero sensitivity unless operated with a dielectric present in the light paths; air in the MM1887 and Miller experiments. Since that 2002 analysis various older and new light speed anisotropy experiments have produced fully consistent results, using different experimental techniques. These have included: RF EM Speeds in coaxial cable, optical fiber Michelson Interferometer, optical fiber/RF coaxial cables, earth spacecraft flyby RF doppler shifts, 1st order dual RF coaxial cables. These are all classical phenomena detectors. However in 2013 nanotechnology quantum detectors were invented that use correlations between electron barrier tunnelling current fluctuations in spatially separated zener diodes. Not only do all of these experiments, spanning 125 years, give a consistent anisotropy velocity, with speed ∼500 km/s, RA ∼5 h, Dec. ∼80deg S, but all showed significant fluctuations in that velocity. A neo-lorentzian interpretation of these results is that a dynamical 3-space is passing the solar system and exhibits turbulence/wave effects. These wave effects produce gravitational forces and so the experimental data implies that the Michelson and Morley experiment not only detected light speed anisotropy but detected “gravitational waves”. These gravitational waves have properties that are not consistent with the general relativity predicted waves, which travel at the speed of light, are transverse polarised and are weak and only produced by distant major astronomical events. Gravitational waves with these properties have never been detected. The zener diode quantum detectors reveal that quantum fluctuations are not random and intrinsic to a quantum system, but are imposed by the passing space: This discovery has major implications for the interpretations of quantum theory and the quantum to classical transition, which profoundly creates our reality. The dynamical space theory also posses an intrinsic inflation epoch.

Analysis of vibroacoustics of trombone bells thanks to an adaptation of the Miller experiment

The influence of wall vibrations on the sound produced by a wind instrument is an open question. If it is clear that the vibrations of bells vibrations can be felt and measured, the influence of these vibrations on the radiated sound is more difficult to bring to light, because the fluid-structure couplings involved are particularly weak except when coincidence effects occur. We propose to study the case of a trombone bell, which is large and thin, favoring the vibrations of large amplitudes and thus the vibroacoustic coupling between the wall and the air column. For studying the light fluid-structure interaction in organ pipes, Miller [Science 29(735), 161–171 (1909)] developed one century ago an experiment consisting in blowing an organ pipe surrounded by water. A water tank can be filled progressively in order to modify the mechanical modes of the system in a continuous manner. We propose an adaptation of this experiment to the case of a trombone bell. The acoustic impedance, the acoustical and mechanical responses of a trombone bell excited by a loudspeaker or a shaker are measured for different levels of water allowing an analysis of the vibroacoustic couplings.

Cosmic rays and terrestrial life: A brief review

“The investigation into the possible effects of cosmic rays on living organisms will also offer great interest.” – Victor F. Hess, Nobel Lecture, December 12, 1936High-energy radiation bursts are commonplace in our Universe. From nearby solar flares to distant gamma ray bursts, a variety of physical processes accelerate charged particles to a wide range of energies, which subsequently reach the Earth. Such particles contribute to a number of physical processes occurring in the Earth system. A large fraction of the energy of charged particles gets deposited in the atmosphere, ionizing it, causing changes in its chemistry and affecting the global electric circuit. Remaining secondary particles contribute to the background dose of cosmic rays on the surface and parts of the subsurface region. Life has evolved over the past ∼3 billion years in presence of this background radiation, which itself has varied considerably during the period [1–3]. As demonstrated by the Miller–Urey experiment, lightning plays a very important role in the formation of complex organic molecules, which are the building blocks of more complex structures forming life. There is growing evidence of increase in the lightning rate with increasing flux of charged particles. Is there a connection between enhanced rate of cosmic rays and the origin of life? Cosmic ray secondaries are also known to damage DNA and cause mutations, leading to cancer and other diseases. It is now possible to compute radiation doses from secondary particles, in particular muons and neutrons. Have the variations in cosmic ray flux affected the evolution of life on earth? We describe the mechanisms of cosmic rays affecting terrestrial life and review the potential implications of the variation of high-energy astrophysical radiation on the history of life on earth.

Synthesis of Peptides in Prebiotic Environment: Implications for the Chemical Evolution

Since Miller's experiment in 1951, research on prebiotic chemistry has received much attention of chemists. However, there are a few lines of research with the focus directed to this science in Brazil. Therefore, the objective of this paper is to describe some of the research in this field, with emphasis on peptide synthesis under prebiotic conditions and the implication of these studies in the context of molecular enrichment on the primitive earth. We also want to encourage new researchers conducting research in this area as well as promoting scientific debate related to the topic of the origin of life.

Organic matter in the universe

1. History and introduction 2. The chemistry of organic matter 2.1 families of organic molecules 2.2 different forms of carbon 2.3 chains and rings 2.4 molecules of biological significance 3. Techniques of detecting organic molecules in space 3.1 Electronic structure of molecules 3.2 Rotational transitions 3.3 Vibrational transitions 3.4 Electronic transitions 3.5 Nuclear spin and hyperfine lines 3.6 Radical and molecular ions 3.7 Ground-based observations and spectroscopic observations from space 4. Organic molecules in the diffuse interstellar medium 5. Organic compounds in galaxies 6. Synthesis of organic compounds in the late stages of stellar evolution 6.1 nucleosynthesis of carbon 6.2 stellar winds and the late stages of stellar evolution 6.3 synthesis of gas-phase molecules and the condensation of solids 6.4 physical conditions of the stellar wind and chemical pathways of synthesis 6.5 emergence of aliphatic and aromatic compounds and their ejection into the interstellar medium 7. Organic compounds in the Solar System 7.1 meteorites 7.2 interplanetary dust particles 7.3 comets 7.4 asteroids 7.5 planetary satellites 8. Organic compounds as carriers of unsolved astronomical phenomena 8.1 unidentified infrared emission features 8.2 diffuse interstellar bands 8.3 the 217 nm feature 8.4 extended red emission 8.5 the 21 and 30 micron emission features 9. Chemical structures of organic matter in space 9.1 polycyclic aromatic hydrocarbons 9.2 hydrogenated amorphous carbon and carbon nanoparticles 9.3 quenched carbonaceous composites 9.4 kerogen and coal 9.5 tholin and HCN polymers 10. Laboratory simulations of molecular synthesis 10.1 Miller-Urey experiment 10.2 Ultraviolet photolysis of ices 11. Delivery of organic compounds in the early history of the Earth 11.1 isotopic signatures and the existence of presolar grains 11.2 crater records and the heavy bombardment phase in the early history of the Earth 12. Origin of life on Earth 12.1 endogenous and exogenous theories of origin of life 12.2 organic compounds and the first emergence of life 13. Outlook for the future 13.1 future astronomical facilities 13.2 future Solar System exploration missions 14. References 15. Glossary 16. Subject index 17. Object index

Constraint multi-objective automated synthesis for CMOS operational amplifier

A multi-objective evolution algorithm (MOEA) is presented to automatically determine the parameters in Op-Amp synthesis where the cost functions (e.g., minimizing the power dissipation and the chip area) and the constraint functions (e.g., the user-defined specifications) can be modeled as polynomials of the design variables. The proposed algorithm is based on MOEA which does not use weighting coefficients in converting multiple objectives into single objective. A constraint handling strategy without penalty parameters is proposed to avoid the difficulty of penalty parameter selection. Moreover, an elitist maintaining scheme is utilized to keep the evenness of the Pareto front. Simulations over several benchmark functions validate the efficiency of the proposed algorithm for the evenness of population distribution and the convergence to the Pareto front. Numerical experiments of a Miller compensated two-stage Op-Amp show that the proposed MOEA is able to achieve better performance than NSGA-II+PCH, GA+SPF and GA+PCH.

The Reception of Miller's Ether-Drift Experiments in the USA: The History of a Controversy in Relativity Revolution

Summary This paper analyses documents from several US archives in order to examine the controversy that raged within the US scientific community over Dayton C. Miller's ether-drift experiments. In 1925, Miller announced that his repetitions of the famous Michelson-Morley experiment had shown a slight but positive result: an ether-drift of about 10 kilometres per second. Miller's discovery triggered a long debate in the US scientific community about the validity of Einstein's relativity theories. Between 1926 and 1930 some researchers repeated the Michelson-Morley experiment, but no one found the same effect as Miller had. The inability to confirm Miller's result, paired with the fact that no other ether theory existed that could compete with special relativity theory, made his result an enigmatic one. It thus remained of little interest to the scientific community until 1954, when Robert S. Shankland and three colleagues reanalysed the data and proposed that Miller's periodic fringe shift could be attributed to temperature effects. Whereas most of the scientific community readily accepted this explanation as the conclusion of the matter, some contemporary anti-relativists have contested Shankland's methodology up to now. The historical accounts of Miller's experiments provide contradictory reports of the reaction of the US scientific community and do not analyse the mechanisms of the controversy. I will address this shortcoming with an examination of private correspondence of several actors involved in these experiments between 1921 and 1955. A complex interconnection of epistemic elements, sociological factors, and personal interests played a fundamental role in the closure of this experimental controversy in the early 1930s, as well as in the reception of Shankland's reanalysis in the 1950s.