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Bada, JL.  1985.  Aspartic-Acid Racemization Ages of California Paleoindian Skeletons. American Antiquity. 50:645-647.   10.2307/280327   Website
Bada, JL, Miller SL.  1968.  Ammonium Ion Concentration in Primitive Ocean. Science. 159:423-&.   10.1126/science.159.3813.423   Website
Bada, JL, Mitchell E, Kemper B.  1983.  Aspartic-Acid Racemization in Narwhal Teeth. Nature. 303:418-420.   10.1038/303418a0   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, Schroeder RA.  1975.  Amino-Acid Racemization Reactions and Their Geochemical Implications. Naturwissenschaften. 62:71-79. AbstractWebsite
Bada, JL.  1985.  Amino-Acid Racemization Dating of Fossil Bones. Annual Review of Earth and Planetary Sciences. 13:241-268.   10.1146/   Website
Bada, JL, Brown SE.  1980.  Amino-Acid Racemization in Living Mammals - Biochronological Applications. Trends in Biochemical Sciences. 5:R3-R5.   10.1016/s0968-0004(80)80800-0   AbstractWebsite
Bada, J.  1984.  Application of Amino Acid Racemization Dating of Fossil Bones and Teeth in problems of paleoanthropology. McGraw-Hill yearbook of science and technology. :87-89.
Bada, JL, McDonald GD.  1995.  Amino-Acid Racemization on Mars - Implications for the Preservation of Biomolecules from an Extinct Martian Biota. Icarus. 114:139-143.   10.1006/icar.1995.1049   AbstractWebsite

Using kinetic data, we have estimated the racemization half-lives and times for total racemization of amino acids under conditions relevant to the surface of Mars. Amino acids from an extinct martian biota maintained in a dry, cold (<250 K) environment would not have racemized significantly over the lifetime of the planet. Racemization would have taken place in environments where liquid water was present even for time periods of only a few million years following biotic extinction. The best preservation of both amino acid homochirality and nucleic acid genetic information associated with extinct martian life would be in the polar regions. (C) 1995 Academic Press, Inc.

Bada, JL.  1991.  Amino-Acid Cosmogeochemistry. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences. 333:349-358.   10.1098/rstb.1991.0084   AbstractWebsite

Amino acids are ubiquitous components of living organisms and as a result they are widely distributed on the surface of the Earth. Whereas only 20 amino acids are found in proteins, a much more diverse mixture of amino acids has been detected in carbonaceous meteorites. Amino acids in living organisms consist exclusively of the L-enantiomers, but in meteorites, amino acids with chiral carbons are present as racemic mixtures. Protein amino acids undergo a variety of diagenetic reactions that produce some other amino acids but not the unique amino acids present in meteorites. Nevertheless, trace quantities of meteoritic amino acids may occur on the Earth, either as a result of bolide impact or from the capture of cosmic dust particles. The ensemble of amino acids present on the early Earth before life existed was probably similar to those in prebiotic experiments and meteorites. This generates a question about why the L-amino acids on which life is based were selected.

Bada, JL, Helfman PM.  1975.  Amino-Acid Racemization Dating of Fossil Bones. World Archaeology. 7:160-&. AbstractWebsite
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, Wang XS, Poinar HN, Paabo S, Poinar GO.  1994.  Amino-Acid Racemization in Amber-Entombed Insects - Implications for DNA Preservation. Geochimica Et Cosmochimica Acta. 58:3131-3135.   10.1016/0016-7037(94)90185-6   AbstractWebsite

DNA depurination and amino acid racemization take place at similar rates in aqueous solution at neutral pH. This relationship suggests that amino acid racemization may be useful in accessing the extent of DNA chain breakage in ancient biological remains. To test this suggestion, we have investigated the amino acids in insects entombed in fossilized tree resins ranging in age from <100 years to 130 million years. The amino acids present in 40 to 130 million year old amber-entombed insects resemble those in a modern fly and are probably the most ancient, unaltered amino acids found so far on Earth. In comparison to other geochemical environments on the surface of the Earth, the amino acid racemization rate in amber insect inclusions is retarded by a factor of > 10(4). These results suggest that in amber insect inclusions DNA depurination rates would also likely be retarded in comparison to aqueous solution measurements, and thus DNA fragments containing many hundreds of base pairs should be preserved. This conclusion is consistent with the reported successful retrieval of DNA sequences from amber-entombed organisms.

Bada, J.  1983.  Amino Acid Racemization dating of fossil bones from Zhouk. China Excahnge News. 11:4-6.
Bada, JL, Hoopes E, Darling D, Dungworth G, Kessels HJ, Kvenvolden KA, Blunt DJ.  1979.  Amino-Acid Racemization Dating of Fossil Bones .1. Inter-Laboratory Comparison of Racemization Measurements. Earth and Planetary Science Letters. 43:265-268.   10.1016/0012-821x(79)90210-3   AbstractWebsite
Brinton, KL, Bada JL.  1995.  Aspartic-Acid Racemization and Protein Diagenesis in Corals over the Last 350 Years - Comment. Geochimica Et Cosmochimica Acta. 59:415-416.Website
George, JC, Bada J, Zeh J, Scott L, Brown SE, O'Hara T, Suydam R.  1999.  Age and growth estimates of bowhead whales (Balaena mysticetus) via aspartic acid racemization. Canadian Journal of Zoology-Revue Canadienne De Zoologie. 77:571-580.   10.1139/cjz-77-4-571   AbstractWebsite

A total of 48 eye globes were collected and analyzed to estimate ages of bowhead whales using the aspartic acid racemization technique. In this technique, age is estimated based on intrinsic changes in the D and L enantiomeric isomeric forms of aspartic acid in the eye lens nucleus. Age estimates were successful for 42 animals. Racemization rate (k(Asp)) for aspartic acid was based on data from earlier studies of humans and fin whales; the estimate used was 1.18 x 10(-3)/year. The D/L ratio at birth ((D/L)(0)) Was estimated using animals less than or equal to 2 years of age (n = 8), since variability in the D/L measurements is large enough that differences among ages in this range are unmeasurable. The (D/L)(0) estimate was 0.0285. Variance of the age estimates was obtained using the delta method. Based on these data, growth appears faster for females than males, and age at sexual maturity (age at length 12-13 m for males and 13-13.5 m for females) occurs at around 25 years of age. Growth slows markedly for both sixes at roughly 40-50 years of age. Four individuals (all males) exceed 100 years of age. Standard error increased with estimated age, but the age estimates had lower coefficients of variation for older animals. Recoveries of traditional whale-hunting tools from five recently harvested whales also suggest life-spans in excess of 100 years of age in some cases.

Glavin, DP, Bada JL, Brinton KLF, McDonald GD.  1999.  Amino acids in the Martian meteorite Nakhla. Proceedings of the National Academy of Sciences of the United States of America. 96:8835-8838.   10.1073/pnas.96.16.8835   AbstractWebsite

A suite of protein and nonprotein amino acids were detected with high-performance liquid chromatography in the water- and acid-soluble components of an interior fragment of the Martian meteorite Nakhla, which fell in Egypt in 1911. Aspartic and glutamic acids, glycine, alanine, beta-alanine, and gamma-amino-n-butyric acid (gamma-ABA) were the most abundant amino acids detected and were found primarily in the 6 M HCl-hydrolyzed, hot water extract, The concentrations ranged from 20 to 330 parts per billion of bulk meteorite. The amino acid distribution in Nakhla, including the D/L ratios (values range from <0.1 to 0.5), is similar to what is found in bacterially degraded organic matter. The amino acids in Nakhla appear to be derived from terrestrial organic matter that infiltrated the meteorite soon after its fall to Earth, although it is possible that some of the amino acids are endogenous to the meteorite. The rapid amino acid contamination of Martian meteorites after direct exposure to the terrestrial environment has important implications for Mars sample-return missions and the curation of the samples from the time of their delivery to Earth.

Glavin, DP, Dworkin JP, Aubrey A, Botta O, Doty JH, Martins Z, Bada JL.  2006.  Amino acid analyses of Antarctic CM2 meteorites using liquid chromatography-time of flight-mass spectrometry. Meteoritics & Planetary Science. 41:889-902. AbstractWebsite

Amino acid analyses of the Antarctic CM2 chondrites Allan Hills (ALH) 83100 and Lewis Cliff (LEW) 90500 using liquid chromatography-time of flight-mass spectrometry (LC-ToF-MS) Coupled with UV fluorescence detection revealed that these carbonaceous meteorites contain a suite of indigenous amino acids not present in Antarctic ice. Several amino acids were detected in ALH 83100, including glycine, alanine, beta-alanine, gamma-amino-n-butyric acid (gamma-ABA), and alpha-aminoisobutyric acid (AIB) with concentrations ranging from 250 to 340 parts per billion (ppb). In contrast to ALH 83 100, the CM2 meteorites LEW 90500 and Murchison had a much higher total abundance of these amino acids (440-3200 ppb). In addition, ALL! 83 100 was found to have lower abundances of the alpha-dialkyl amino acids AIB and isovaline than LEW 90500 and Murchison. There are three possible explanations for the depleted amino, acid content in ALH 83100: 1) amino acid leaching from ALH 83100 during exposure to Antarctic ice meltwater, 2) a higher degree of aqueous alteration on the ALH 83 100 parent body, or 3) ALH 83 100 originated on a chemically distinct parent body from the other two CM2 meteorites. The high relative abundance of epsilon-amino-n-caproic acid (EACA) in the ALH 83100 meteorite as well as the Antarctic ice indicates that Nylon-6 contamination from the Antarctic sample storage bags may have occurred during collection.

Helfman, PM, Bada JL.  1976.  Aspartic-Acid Racemization in Dentin as a Measure of Aging. Nature. 262:279-281.   10.1038/262279b0   Website