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A
Ambler, RP, Macko SA, Sykes B, Griffiths JB, Bada J, Eglinton G.  1999.  Documenting the diet in ancient human populations through stable isotope analysis of hair - Discussion. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences. 354:75-76.Website
Ambler, RP, Bada JL, Finch P, Grocke DR, Eglinton G, Macko SA.  1999.  Preservation of key biomolecules in the fossil record: current knowledge and future challenges - Discussion. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences. 354:86-87.Website
Arrhenius, G, Bada JL, Joyce GF, Lazcano A, Miller S, Orgel LE.  1999.  Origin and ancestor: Separate environments. Science. 283:792-792.Website
Aubrey, AD, Cleaves HJ, Bada JL.  2009.  The Role of Submarine Hydrothermal Systems in the Synthesis of Amino Acids. Origins of Life and Evolution of Biospheres. 39:91-108.   10.1007/s11084-008-9153-2   AbstractWebsite

There is little consensus regarding the plausibility of organic synthesis in submarine hydrothermal systems (SHSs) and its possible relevance to the origin of life. The primary reason for the persistence of this debate is that most experimental high temperature and high-pressure organic synthesis studies have neglected important geochemical constraints with respect to source material composition. We report here the results of experiments exploring the potential for amino acid synthesis at high temperature from synthetic seawater solutions of varying composition. The synthesis of amino acids was examined as a function of temperature, heating time, starting material composition and concentration. Using very favorable reactant conditions (high concentrations of reactive, reduced species), small amounts of a limited set of amino acids are generated at moderate temperature conditions (similar to 125-175A degrees C) over short heating times of a few days, but even these products are significantly decomposed after exposure times of approximately 1 week. The high concentration dependence observed for these synthetic reactions are demonstrated by the fact that a 10-fold drop in concentration results in orders of magnitude lower yields of amino acids. There may be other synthetic mechanisms not studied herein that merit investigation, but the results are likely to be similar. We conclude that although amino acids can be generated from simple likely environmentally available precursors under SHS conditions, the equilibrium at high temperatures characteristic of SHSs favors net amino acid degradation rather than synthesis, and that synthesis at lower temperatures may be more favorable.

Aubrey, A, Cleaves HJ, Chalmers JH, Skelley AM, Mathies RA, Grunthaner FJ, Ehrenfreund P, Bada JL.  2006.  Sulfate minerals and organic compounds on Mars. Geology. 34:357-360.   10.1130/g22316.1   AbstractWebsite

Strong evidence for evaporitic sulfate minerals such as gypsum and jarosite has recently been found on Mars. Although organic molecules are often codeposited with terrestrial evaporitic minerals, there have been no systematic investigations of organic components in sulfate minerals. We report here the detection of organic material, including amino acids and their amine degradation products, in ancient terrestrial sulfate minerals. Amino acids and amines appear to be preserved for geologically long periods in sulfate mineral matrices. This suggests that sulfate minerals should be prime targets in the search for organic compounds, including those of biological origin, on Mars.

Aubrey, AD, Chalmers JH, Bada JL, Grunthaner FJ, Amashukeli X, Willis P, Skelley AM, Mathies RA, Quinn RC, Zent AP, Ehrenfreund P, Amundson R, Glavin DP, Botta O, Barron L, Blaney DL, Clark BC, Coleman M, Hofmann BA, Josset JL, Rettberg P, Ride S, Robert F, Sephton MA, Yen A.  2008.  The Urey instrument: An advanced in situ organic and oxidant detector for Mars exploration. Astrobiology. 8:583-595.   10.1089/ast.2007.0169   AbstractWebsite

The Urey organic and oxidant detector consists of a suite of instruments designed to search for several classes of organic molecules in the martian regolith and ascertain whether these compounds were produced by biotic or abiotic processes using chirality measurements. These experiments will also determine the chemical stability of organic molecules within the host regolith based on the presence and chemical reactivity of surface and atmospheric oxidants. Urey has been selected for the Pasteur payload on the European Space Agency's (ESA's) upcoming 2013 ExoMars rover mission. The diverse and effective capabilities of Urey make it an integral part of the payload and will help to achieve a large portion of the mission's primary scientific objective: "to search for signs of past and present life on Mars." This instrument is named in honor of Harold Urey for his seminal contributions to the fields of cosmochemistry and the origin of life.

B
Bada, JL, Shou MY, Man EH, Schroeder RA.  1978.  Decomposition of Hydroxy Amino-Acids in Foraminiferal Tests - Kinetics, Mechanism and Geochronological Implications. Earth and Planetary Science Letters. 41:67-76.   10.1016/0012-821x(78)90042-0   Website
Bada, J, Herman B, Payan IL, Man E.  1989.   Amino Acid Racemization in bone and boiling of the german emperor Lothar I. Applied Geochemistry. 4
Bada, JL, Miller SL, Zhao MX.  1995.  The Stability of Amino-Acids at Submarine Hydrothermal Vent Temperatures. Origins of Life and Evolution of the Biosphere. 25:111-118.   10.1007/bf01581577   AbstractWebsite

It has been postulated that amino acid stability at hydrothermal vent temperatures is controlled by a metastable thermodynamic equilibrium rather than by kinetics. Experiments reported here demonstrate that the amino acids are irreversibly destroyed by heating at 240 degrees C and that quasi-equilibrium calculations give misleading descriptions of the experimental observations. Equilibrium thermodynamic calculations are not applicable to organic compounds under high-temperature submarine vent conditions.

Bada, JL, Zhao MX, Steinberg S, Ruth E.  1986.  Isoleucine Stereoisomers on the Earth. Nature. 319:314-316.   10.1038/319314a0   Website
Bada, JL, Fegley B, Miller SL, Lazcano A, Cleaves HJ, Hazen RM, Chalmers J.  2007.  Debating evidence for the origin of life on Earth. Science. 315:937-938.Website
Bada, JL, Miller SL.  1970.  Kinetics and Mechanism of Reversible Nonenzymatic Deamination of Aspartic Acid. Journal of the American Chemical Society. 92:2774-&.   10.1021/ja00712a031   Website
Bada, JL.  2004.  How life began on Earth: a status report. Earth and Planetary Science Letters. 226:1-15.   10.1016/j.epsl.2004.07.036   AbstractWebsite

There are two fundamental requirements for life as we know it, liquid water and organic polymers, such as nucleic acids and proteins. Water provides the medium for chemical reactions and the polymers carry out the central biological functions of replication and catalysis. During the accretionary phase of the Earth, high surface temperatures would have made the presence of liquid water and an extensive organic carbon reservoir unlikely. As the Earth's surface cooled, water and simple organic compounds, derived from a variety of sources, would have begun to accumulate. This set the stage for the process of chemical evolution to begin in which one of the central facets was the synthesis of biologically important polymers, some of which had a variety of simple catalytic functions. Increasingly complex macromolecules were produced and eventually molecules with the ability to catalyze their own imperfect replication appeared. Thus began the processes of multiplication, heredity and variation, and this marked the point of both the origin of life and evolution. Once simple self-replicating entities originated, they evolved first into the RNA World and eventually to the DNA/Protein World, which had all the attributes of modern biology. If the basic components water and organic polymers were, or are, present on other bodies in our solar system and beyond, it is reasonable to assume that a similar series of steps that gave rise of life on Earth could occur elsewhere. (C) 2004 Elsevier B.V. All rights reserved.

Bada, J, Finkel R.  1983.  The upper pleistocene peopling of the New World: evidence derived from Radiocarbon, Amino acid racemization and Uranium serius dating. Quaternary coastline and marine archeology: towards the prehistory of land bridges and continental shelves. ( Masters PM, Flemming NC, Eds.).:463-479., London: Academic Press
Bada, JL, Protsch R.  1973.  Racemization Reaction of Aspartic-Acid and Its Use in Dating Fossil Bones - (Olduvai Gorge 5,000-70,000-Years-Old Range Hominids). Proceedings of the National Academy of Sciences of the United States of America. 70:1331-1334.   10.1073/pnas.70.5.1331   Website
Bada, JL.  1984.  Invivo Racemization in Mammalian Proteins. Methods in Enzymology. 106:98-115.Website
Bada, JL.  2013.  New insights into prebiotic chemistry from Stanley Miller's spark discharge experiments. Chem Soc Rev. 42:2186-96.   10.1039/c3cs35433d   Abstract

1953 was a banner year for biological chemistry: The double helix structure of DNA was published by Watson and Crick, Sanger's group announced the first amino acid sequence of a protein (insulin) and the synthesis of key biomolecules using simulated primordial Earth conditions has demonstrated by Miller. Miller's studies in particular transformed the study of the origin of life into a respectable field of inquiry and established the basis of prebiotic chemistry, a field of research that investigates how the components of life as we know it can be formed in a variety of cosmogeochemical environments. In this review, I cover the continued advances in prebiotic syntheses that Miller's pioneering work has inspired. The main focus is on recent state-of-the-art analyses carried out on archived samples of Miller's original experiments, some of which had never before been analyzed, discovered in his laboratory material just before his death in May 2007. One experiment utilized a reducing gas mixture and an apparatus configuration (referred to here as the "volcanic" apparatus) that could represent a water-rich volcanic eruption accompanied by lightning. Another included H(2)S as a component of the reducing gas mixture. Compared to the limited number of amino acids Miller identified, these new analyses have found that over 40 different amino acids and amines were synthesized, demonstrating the potential robust formation of important biologic compounds under possible cosmogeochemical conditions. These experiments are suggested to simulate long-lived volcanic island arc systems, an environment that could have provided a stable environment for some of the processes thought to be involved in chemical evolution and the origin of life. Some of the alternatives to the Miller-based prebiotic synthesis and the "primordial soup" paradigm are evaluated in the context of their relevance under plausible planetary conditions.

Bada, JL, Miller SL.  1969.  Kinetics and Mechanism of Nonenzymatic Reversible Deamination of Aspartic Acid. Journal of the American Chemical Society. 91:3946-&.   10.1021/ja01042a047   Website
Bada, JL, Lazcano A.  2003.  Prebiotic soup - Revisiting the Miller experiment. Science. 300:745-746.   10.1126/science.1085145   Website
Bada, JL, Schroede.Ra, Protsch R, Berger R.  1974.  Concordance of Collagen-Based Radiocarbon and Aspartic-Acid Racemization Ages. Proceedings of the National Academy of Sciences of the United States of America. 71:914-917.   10.1073/pnas.71.3.914   Website
Bada, J, Brown SE, Masters PM.  1980.  age determination of marine mammaks based on aspartic acid racemization in teeth and lens nucleus. Rep.International Whaling comisison (Special issue). 3:113-118.
Bada, JL, Ehrenfreund P, Grunthaner F, Blaney D, Coleman M, Farrington A, Yen A, Mathies R, Amudson R, Quinn R, Zent A, Ride S, Barron L, Botta O, Clark B, Glavin D, Hofmann B, Josset JL, Rettberg P, Robert F, Sephton M.  2008.  Urey: Mars Organic and Oxidant Detector. Space Science Reviews. 135:269-279.   10.1007/s11214-007-9213-3   AbstractWebsite

One of the fundamental challenges facing the scientific community as we enter this new century of Mars research is to understand, in a rigorous manner, the biotic potential both past and present of this outermost terrestrial-like planet in our solar system. Urey: Mars Organic and Oxidant Detector has been selected for the Pasteur payload of the European Space Agency's (ESA's) ExoMars rover mission and is considered a fundamental instrument to achieve the mission's scientific objectives. The instrument is named Urey in recognition of Harold Clayton Urey's seminal contributions to cosmochemistry, geochemistry, and the study of the origin of life. The overall goal of Urey is to search for organic compounds directly in the regolith of Mars and to assess their origin. Urey will perform a groundbreaking investigation of the Martian environment that will involve searching for organic compounds indicative of life and prebiotic chemistry at a sensitivity many orders of magnitude greater than Viking or other in situ organic detection systems. Urey will perform the first in situ search for key classes of organic molecules using state-of-the-art analytical methods that provide part-per-trillion sensitivity. It will ascertain whether any of these molecules are abiotic or biotic in origin and will evaluate the survival potential of organic compounds in the environment using state-of-the-art chemoresistor oxidant sensors.

Bada, JL, Bigham C, Miller SL.  1994.  Impact Melting of Frozen Oceans on the Early Earth - Implications for the Origin of Life. Proceedings of the National Academy of Sciences of the United States of America. 91:1248-1250.   10.1073/pnas.91.4.1248   AbstractWebsite

Without sufficient greenhouse gases in the atmosphere, the early Earth would have become a permanently frozen planet because the young Sun was less luminous than it is today. Several resolutions to this faint young Sun-frozen Earth paradox have been proposed, with an atmosphere rich in CO2 being the one generally favored. However, these models assume that there were no mechanisms for melting a once frozen ocean. Here we show that bolide impacts between about 3.6 and 4.0 billion years ago could have episodically melted an ice-covered early ocean. Thaw-freeze cycles associated with bolide impacts could have been important for the initiation of abiotic reactions that gave rise to the first living organisms.