Export 204 results:
Sort by: [ Author  (Asc)] Title Type Year
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 
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
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
Arrhenius, G, Bada JL, Joyce GF, Lazcano A, Miller S, Orgel LE.  1999.  Origin and ancestor: Separate environments. Science. 283:792-792.Website
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.

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.

Bada, JL.  1972.  Kinetics of Racemization of Amino-Acids as a Function of Ph. Journal of the American Chemical Society. 94:1371-&.   10.1021/ja00759a064   Website
Bada, J.  1985.   Racemization of Amino Acid . Chemistry and biochemistry of the amino acids. ( Barrett GC, Ed.).:399-414., London: Chapman and Hall
Bada, JL, Sephton MA, Ehrenfreund P, Mathies RA, Skelley AM, Grunthaner FJ, Zent AP, Quinn RC, Josset JL, Robert F, Botta O, Glavin DP.  2005.  New strategies to detect life on Mars. Astronomy & Geophysics. 46:26-27. AbstractWebsite

The quest to determine whether life existed, or still exists, on Mars continues with several missions planned for the red planet by both the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA) in the next few decades. One instrument designed for these missions is the Mars Organic Detector (MOD), which uses a new approach to achieve exceptionally high detection sensitivities and analysis capabilities for key bio-organic compounds. MOD is scheduled to fly in the ESA ExoMars mission early next decade and will attempt to answer the question of whether we are alone in the solar system. Here the MOD team explains why we have reason to be optimistic about uncovering the organic secrets of Mars.

Bada, JL, Miller SL.  1968.  Equilibrium Constant for Reversible Deamination of Aspartic Acid. Biochemistry. 7:3403-&.   10.1021/bi00850a014   Website
Bada, JL, Schoeninger MJ, Schimmelmann A.  1989.  Isotopic Fractionation During Peptide-Bond Hydrolysis. Geochimica Et Cosmochimica Acta. 53:3337-3341.   10.1016/0016-7037(89)90114-2   Website
Bada, JL.  1982.  Racemization of Amino-Acids in Nature. Interdisciplinary Science Reviews. 7:30-46.Website
Bada, JL.  2009.  Enantiomeric excesses in the Murchison meteorite and the origin of homochirality in terrestrial biology. Proceedings of the National Academy of Sciences of the United States of America. 106:E85-E85.   10.1073/pnas.0906490106   Website
Bada, J.  1974.  Details of amino acid racemization dating. McGraw-Hill yearbook of science and technology. :212-213.
Bada, JL, Cronin JR, Ho MS, Kvenvolden KA, Lawless JG, Miller SL, Oro J, Steinberg S.  1983.  On the Reported Optical-Activity of Amino-Acids in the Murchison Meteorite. Nature. 301:494-496.   10.1038/301494a0   Website
Bada, JL.  1995.  Cold Start. Sciences-New York. 35:21-25.Website
Bada, JL, Protsch R, Schroede.Ra.  1973.  Racemization Reaction of Isoleucine Used as a Paleotemperature Indicator. Nature. 241:394-395.   10.1038/241394a0   Website
Bada, JL, Gillespie R, Gowlett JAJ, Hedges REM.  1984.  Accelerator Mass-Spectrometry Radiocarbon Ages of Amino-Acid Extracts from Californian Paleoindian Skeletons. Nature. 312:442-444.   10.1038/312442a0   Website
Bada, JL.  1990.  Racemization Dating. Science. 248:539-540.   10.1126/science.248.4955.539   Website
Bada, J, Shou MY.  1980.  Kinetics and mechanics of amino acid racemization in aqueous solution and bones. Biogeochemistry of amino acids. Ed: Hare, P. E, Hoering, T. C, King, K.
Bada, JL, Schroede.Ra.  1972.  Racemization of Isoleucine in Calcareous Marine Sediments - Kinetics and Mechanism. Earth and Planetary Science Letters. 15:1-&.   10.1016/0012-821x(72)90022-2   Website