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Bada, JL, Luyendyk BP.  1971.  Route to Late Cenozoic Temperature History. Science. 172:503-&.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.

Schroeder, RA, Bada JL.  1976.  Review of Geochemical Applications of Amino-Acid Racemization Reaction. Earth-Science Reviews. 12:347-391.   10.1016/0012-8252(76)90011-8   Website
Botta, O, Glavin DP, Kminek G, Bada JL.  2002.  Relative amino acid concentrations as a signature for parent body processes of carbonaceous chondrites. Origins of Life and Evolution of Biospheres. 32:143-163.   10.1023/a:1016019425995   AbstractWebsite

Most meteorites are thought to have originated from objects in the asteroid belt. Carbonaceous chondrites, which contain significant amounts of organic carbon including complex organic compounds, have also been suggested to be derived from comets. The current model for the synthesis of organic compounds found in carbonaceous chondrites includes the survival of interstellar organic compounds and the processing of some of these compounds on the meteoritic parent body. The amino acid composition of five CM carbonaceous chondrites, two CIs, one CR, and one CV3 have been measured using hot water extraction-vapor hydrolysis, OPA/NAC derivatization and high-performance liquid chromatography (HPLC). Total amino acid abundances in the bulk meteorites as well as the amino acid concentrations relative to glycine = 1.0 for beta-alanine, alpha-aminoisobutyric acid and D-alanine were determined. Additional data for three Antarctic CM meteorites were obtained from the literature. All CM meteorites analyzed in this study show a complex distribution of amino acids and a high variability in total concentration ranging from similar to15 300 to similar to5800 parts per billion (ppb), while the CIs show a total amino acid abundance of similar to4300 ppb. The relatively (compared to glycine) high AIB content found in all the CMs is a strong indicator that Strecker-cyanohydrin synthesis is the dominant pathway for the formation of amino acids found in these meteorites. The data from the Antarctic CM carbonaceous chondrites are inconsistent with the results from the other CMs, perhaps due to influences from the Antarctic ice that were effective during their residence time. In contrast to CMs, the data from the CI carbonaceous chondrites indicate that the Strecker synthesis was not active on their parent bodies.

Chen, RF, Bada JL, Suzuki Y.  1993.  The Relationship between Dissolved Organic-Carbon (Doc) and Fluorescence in Anoxic Marine Porewaters - Implications for Estimating Benthic Doc Fluxes. Geochimica Et Cosmochimica Acta. 57:2149-2153.   10.1016/0016-7037(93)90102-3   AbstractWebsite

Fluorescence and dissolved organic carbon (DOC) measurements of porewaters from the Santa Barbara Basin, the Guaymas Basin, and the upper sections of the Nankai Trough suggest that ultraviolet fluorescence (lambda(ex) = 325 nm, lambda(em) = 450 nm) may be used as a first order estimate of DOC in anoxic marine porewaters. The majority of porewater organic carbon appears to be fluorescent, while a constant approximately 1 mM DOC, probably the low molecular weight compounds, is not fluorescent. These data are consistent with a model in which low molecular weight compounds dissolved in porewater act as the common intermediate between labile sedimentary organic matter and remineralization or polymerization products. Fluorescence may also be used to sensitively estimate benthic DOC fluxes to the overlying water column. Results from the Santa Barbara Basin, if representative of global anoxic oceanic regions, indicate that DOC release from anoxic sediments is not a major source of oceanic DOC when compared to internal recycling rates, but may be comparable to external input or permanent removal processes.

Brinton, KLF, Bada JL.  1996.  A reexamination of amino acids in lunar soils: Implications for the survival of exogenous organic material during impact delivery. Geochimica Et Cosmochimica Acta. 60:349-354.   10.1016/0016-7037(95)00404-1   AbstractWebsite

Using a sensitive high performance liquid chromatography technique, we have analyzed both the hot water extract and the acid hydrolyzed hot water extract of lunar soil collected during the Apollo 17 mission. Both free amino acids and those derived from acid labile precursors are present at a level of roughly 15 ppb. Based on the D/L amino acid ratios, the free alanine and aspartic acid observed in the hot water extract can be entirely attributed to terrestrial biogenic contamination. However, in the acid labile fraction, precursors which yield amino acids are apparently present in the lunar soil. The amino acid distribution suggests that the precursor is probably solar wind implanted HCN. We have evaluated our results with regard to the meteoritic input of intact organic compounds to the moon based on an upper limit of less than or equal to 0.3 ppb for alpha-aminoisobutyric acid, a non-protein amino acid which does not generally occur in terrestrial organisms and which is not a major amino acid produced from HCN, but which is a predominant amino acid in many carbonaceous chondrites. We find that the survival of exogenous organic compounds during lunar impact is less than or equal to 0.8%. This result represents an example of minimum organic impact survivability. This is an important first step toward a better understanding of similar processes on Earth and on Mars, and their possible contribution to the budget of prebiotic organic compounds on the primitive Earth.

Cleaves, HJ, Chalmers JH, Lazcano A, Miller SL, Bada JL.  2008.  A reassessment of prebiotic organic synthesis in neutral planetary atmospheres. Origins of Life and Evolution of Biospheres. 38:105-115.   10.1007/s11084-007-9120-3   AbstractWebsite

The action of an electric discharge on reduced gas mixtures such as H(2)O, CH(4) and NH(3) (or N(2)) results in the production of several biologically important organic compounds including amino acids. However, it is now generally held that the early Earth's atmosphere was likely not reducing, but was dominated by N(2) and CO(2). The synthesis of organic compounds by the action of electric discharges on neutral gas mixtures has been shown to be much less efficient. We show here that contrary to previous reports, significant amounts of amino acids are produced from neutral gas mixtures. The low yields previously reported appear to be the outcome of oxidation of the organic compounds during hydrolytic workup by nitrite and nitrate produced in the reactions. The yield of amino acids is greatly increased when oxidation inhibitors, such as ferrous iron, are added prior to hydrolysis. Organic synthesis from neutral atmospheres may have depended on the oceanic availability of oxidation inhibitors as well as on the nature of the primitive atmosphere itself. The results reported here suggest that endogenous synthesis from neutral atmospheres may be more important than previously thought.

Glavin, DP, Matrajt G, Bada JL.  2004.  Re-examination of amino acids in Antarctic micrometeorites. Space Life Sciences: Steps toward Origin(S) of Life. 33( Bernstein MP, Kress M, NavarroGonzalez R, Eds.).:106-113., Kidlington: Pergamon-Elsevier Science Ltd   10.1016/j.asr.2003.02.011   Abstract

The delivery of amino acids by micrometeorites to the early Earth during the period of heavy bombardment (4.5-3.5 Ga) could have been a significant source of the Earth's prebiotic organic inventory. Antarctic micrometeorites (AMMs) in the 100-200 mum size range represent the dominant mass fraction of extraterrestrial material accreted by the Earth today. However, one problem is that these 'large' micrometeorite grains can be heated to very high temperatures (1000 to 1500 degreesC) during atmospheric deceleration, causing the amino acids to decompose. In this study, we have analyzed the acid-hydrolyzed, hot water extracts from 455 AMMs for the presence of amino acids using high performance liquid chromatography. For comparison, a 5 mg sample of the CM meteorite Murchison was also investigated. In the Murchison sample we found high levels (similar to3-4 parts-per-million, ppm) of alpha-aminoisobutyric acid (AIB) and isovaline, two non-protein amino acids that are extremely rare on Earth and are characteristic of amino acids of apparent extraterrestrial origin. In contrast, we were unable to detect any AIB above the 0.1 ppm level in the AMM samples studied. Only in one AMM sample from a previous study has AIB been detected (similar to300 ppm). To date, more than 600 AMMs have been analyzed for extraterrestrial amino acids. Although our results indicate that less than 5% of all AMMs contain detectable levels of AIB, we cannot rule out the possibility that AIB can be delivered to the Earth intact by a small percentage of AMMs that escaped extensive heating during atmospheric entry. (C) 2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

Kminek, G, Bada JL, Pogliano K, Ward JF.  2003.  Radiation-dependent limit for the viability of bacterial spores in halite fluid inclusions and on Mars. Radiation Research. 159:722-729.   10.1667/0033-7587(2003)159[0722:rlftvo];2   AbstractWebsite

When claims for the long-term survival of viable organisms are made, either within terrestrial minerals or on Mars, considerations should be made of the limitations imposed by the naturally occurring radiation dose to which they have been exposed. We investigated the effect of ionizing radiation on different bacterial spores by measuring the inactivation constants for B. subtilis and S. marismortui spores in solution as well as for dry spores of B. subtilis and B. thuringiensis. S. marismortui is a halophilic spore that is genetically similar to the recently discovered 2-9-3 bacterium from a halite fluid inclusion, claimed to be 250 million years old (Vreeland et al, Nature 407, 897-900, 2000). B. thuringiensis is a soil bacterium that is genetically similar to the human pathogens B. anthracis and B. cereus (Helgason et al., Appl. Environ. Microbiol 66, 2627-2630, 2000). To relate the inactivation constant to some realistic environments, we calculated the radiation regimen in a halite fluid inclusion and in the Martian subsurface over time. Our conclusion is that the ionizing dose of radiation in those environments limits the survival of viable bacterial spores over long periods. In the absence of an active repair mechanism in the dormant state, the long-term survival of spores is limited to less than 109 million years in halite fluid inclusions, to 100 to 160 million years in the Martian subsurface below 3 m, and to less than 600,000 years in the uppermost meter of Mars. (C) 2003 by Radiation Research Society.

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, 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, 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
Boehm, MF, Bada JL.  1984.  Racemization of Aspartic-Acid and Phenylalanine in the Sweetener Aspartame at 100-Degrees-C. Proceedings of the National Academy of Sciences of the United States of America-Physical Sciences. 81:5263-5266.   10.1073/pnas.81.16.5263   Website
Bada, JL.  1982.  Racemization of Amino-Acids in Nature. Interdisciplinary Science Reviews. 7:30-46.Website
Bada, JL, Kvenvold.Ka, Peterson E.  1973.  Racemization of Amino-Acids in Bones. Nature. 245:308-310.   10.1038/245308a0   Website
Bada, JL.  1990.  Racemization Dating. Science. 248:539-540.   10.1126/science.248.4955.539   Website