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Book Chapter
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.

Journal Article
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
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.

Rosa, C, Zeh J, George JC, Botta O, Zauscher M, Bada J, O'Hara TM.  2013.  Age estimates based on aspartic acid racemization for bowhead whales (Balaena mysticetus) harvested in 1998-2000 and the relationship between racemization rate and body temperature. Marine Mammal Science. 29:424-445.   10.1111/j.1748-7692.2012.00593.x   AbstractWebsite

Fifty-two eyes were collected and analyzed to estimate ages of 42 bowhead whales using the aspartic acid racemization aging technique. Between-eye and within-eye variance components for the ratio of the D and L optical isomers (D/L ratio) were estimated via analysis of variance using multiple measurements from nine whales with both eyes sampled and analyzed. For whales with more than one (D/L)(act) value, an inverse variance weighted average of the values was used as (D/L)(act) for the whale. Racemization rate (k(Asp)) and D/L ratio at birth (D/L)(0) were estimated using (D/L)(act) from 27 bowhead whales with age estimates based on baleen or ovarian corpora data and two term fetuses. The estimates were k(Asp) = 0.977x10(-3)/yr and (D/L)(0) = 0.0250. The nonlinear least squares analysis that produced these estimates also estimated female age at sexual maturity as ASM=25.86yr. SE(age) was estimated via a bootstrap that took into account the SE of (D/L)(act) and the variances and covariance of k(Asp) and (D/L)(0). One male exceeded 100yr of age; the oldest female was 88. A strong linear relationship between k(Asp) and body temperature was estimated by combining bowhead data with independent data from studies of humans and fin whales. Using this relationship, we estimated k(Asp) and ASM for North Atlantic minke whales.

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.

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.

Kminek, G, Botta O, Glavin DP, Bada JL.  2002.  Amino acids in the Tagish Lake meteorite. Meteoritics & Planetary Science. 37:697-701. AbstractWebsite

High-performance liquid chromatography (HPLC) based amino acid analysis of a Tagish Lake meteorite sample recovered 3 months after the meteorite fell to Earth have revealed that the amino acid composition of Tagish Lake is strikingly different from that of the CM and Cl carbonaceous chondrites. We found that the Tagish Lake meteorite contains only trace levels of amino acids (total abundance = 880 ppb), which is much lower than the total abundance of amino acids in the Cl Orgueil (4100 ppb) and the CM Murchison (16 900 ppb). Because most of the same amino acids found in the Tagish Lake meteorite are also present in the Tagish Lake ice melt water, we conclude that the amino acids detected in the meteorite are terrestrial contamination. We found that the exposure of a sample of Murchison to cold water lead to a substantial reduction over a period of several weeks in the amount of amino acids that are not strongly bound to the meteorite matrix. However, strongly bound amino acids that are extracted by direct HCl hydrolysis are not affected by the leaching process. Thus even if there had been leaching of amino acids from our Tagish Lake meteorite sample during its 3 month residence in Tagish Lake ice and melt water, a Murchison type abundance of endogenous amino acids in the meteorite would have still been readily detectable. The low amino acid content of Tagish Lake indicates that this meteorite originated from a different type of parent body than the CM and CI chondrites. The parent body was apparently devoid of the reagents such as aldehyldes/ketones, HCN and ammonia needed for the effective abiotic synthesis of amino acids. Based on reflectance spectral measurements, Tagish Lake has been associated with P- or D-type asteroids. If the Tagish Lake meteorite was indeed derived from these types of parent bodies, our understanding of these primitive asteroids needs to be reevaluated with respect to their potential inventory of biologically important organic compounds.

Grew, ES, Bada JL, Hazen RM.  2011.  Borate Minerals and Origin of the RNA World. Origins of Life and Evolution of Biospheres. 41:307-316.   10.1007/s11084-010-9233-y   AbstractWebsite

The RNA World is generally thought to have been an important link between purely prebiotic (>3.7 Ga) chemistry and modern DNA/protein biochemistry. One concern about the RNA World hypothesis is the geochemical stability of ribose, the sugar moiety of RNA. Prebiotic stabilization of ribose by solutions associated with borate minerals, notably colemanite, ulexite, and kernite, has been proposed as one resolution to this difficulty. However, a critical unresolved issue is whether borate minerals existed in sufficient quantities on the primitive Earth, especially in the period when prebiotic synthesis processes leading to RNA took place. Although the oldest reported colemanite and ulexite are 330 Ma, and the oldest reported kernite, 19 Ma, boron isotope data and geologic context are consistent with an evaporitic borate precursor to 2400-2100 Ma borate deposits in the Liaoning and Jilin Provinces, China, as well as to tourmaline-group minerals at 33003450 Ma in the Barberton belt, South Africa. The oldest boron minerals for which the age of crystallization could be determined are the metamorphic tourmaline species schorl and dravite in the Isua complex (metamorphism between ca. 3650 and ca. 3600 Ma). Whether borates such as colemanite, ulexite and kernite were present in the Hadean (>4000 Ma) at the critical juncture when prebiotic molecules such as ribose required stabilization depends on whether a granitic continental crust had yet differentiated, because in its absence we see no means for boron to be sufficiently concentrated for borates to be precipitated.

Parker, ET, Cleaves JH, Burton AS, Glavin DP, Dworkin JP, Zhou MS, Bada JL, Fernandez FM.  2014.  Conducting Miller-Urey experiments. Jove-Journal of Visualized Experiments.   10.3791/51039   AbstractWebsite

In 1953, Stanley Miller reported the production of biomolecules from simple gaseous starting materials, using an apparatus constructed to simulate the primordial Earth's atmosphere-ocean system. Miller introduced 200 ml of water, 100 mmHg of H-2, 200 mmHg of CH4, and 200 mmHg of NH3 into the apparatus, then subjected this mixture, under reflux, to an electric discharge for a week, while the water was simultaneously heated. The purpose of this manuscript is to provide the reader with a general experimental protocol that can be used to conduct a Miller-Urey type spark discharge experiment, using a simplified 3 L reaction flask. Since the experiment involves exposing inflammable gases to a high voltage electric discharge, it is worth highlighting important steps that reduce the risk of explosion. The general procedures described in this work can be extrapolated to design and conduct a wide variety of electric discharge experiments simulating primitive planetary environments.

Glavin, DP, Schubert M, Botta O, Kminek G, Bada JL.  2001.  Detecting pyrolysis products from bacteria on Mars. Earth and Planetary Science Letters. 185:1-5.   10.1016/s0012-821x(00)00370-8   AbstractWebsite

A pyrolysis/sublimation technique was developed to isolate volatile amine compounds from a Mars soil analogue inoculated with similar to 10 billion Escherichia coli cells. In this technique, the inoculated soil is heated to 500 degreesC for several seconds at Martian ambient pressure and the sublimate, collected by a cold finger, then analyzed using high performance liquid chromatography. Methylamine and ethylamine, produced from glycine and alanine decarboxylation, were the most abundant amine compounds detected after pyrolysis of the cells. A heating cycle similar to that utilized in our experiment was also used to release organic compounds from the Martian soil in the 1976 Viking gas chromatography/mass spectrometry (GC/MS) pyrolysis experiment. The Viking GC/MS did not detect any organic compounds of Martian origin above a level of a few parts per billion in the Martian surface soil. Although the Viking GC/MS instruments were not specifically designed to search for the presence of living cells on Mars, our experimental results indicate that at the part per billion level, the degradation products generated from several million bacterial cells per gram of Martian soil would not have been detected. (C) 2001 Elsevier Science B.V. All rights reserved.

Skelley, AM, Scherer JR, Aubrey AD, Grover WH, Ivester RHC, Ehrenfreund P, Grunthaner FJ, Bada JL, Mathies RA.  2005.  Development and evaluation of a microdevice for amino acid biomarker detection and analysis on Mars. Proceedings of the National Academy of Sciences of the United States of America. 102:1041-1046.   10.1073/pnas.0406798102   AbstractWebsite

The Mars Organic Analyzer (MOA), a microfabricated capillary electrophoresis (CE) instrument for sensitive amino acid biomarker analysis, has been developed and evaluated. The microdevice consists of a four-wafer sandwich combining glass CE separation channels, microfabricated pneumatic membrane valves and pumps, and a nanoliter fluidic network. The portable MOA instrument integrates high voltage CE power supplies, pneumatic controls, and fluorescence detection optics necessary for field operation. The amino acid concentration sensitivities range from micromolar to 0.1 nM, corresponding to part-per-trillion sensitivity. The MOA was first used in the lab to analyze soil extracts from the Atacama Desert, Chile, detecting amino acids ranging from 10-600 parts per billion. Field tests of the MOA in the Panoche Valley, CA, successfully detected amino acids at 70 parts per trillion to 100 parts per billion in jarosite, a sulfate-rich mineral associated with liquid water that was recently detected on Mars. These results demonstrate the feasibility of using the MOA to perform sensitive in situ amino acid biomarker analysis on soil samples representative of a Mars-like environment.

Glavin, DP, Schubert M, Bada JL.  2002.  Direct isolation of purines and pyrimidines from nucleic acids using sublimation. Analytical Chemistry. 74:6408-6412.   10.1021/ac0259663   AbstractWebsite

A sublimation technique was developed to isolate purines and pyrimidines directly from lambda-deoxyribonucleic acid (lambda-DNA) and Escherichia coli cells. The sublimation of adenine, cytosine, guanine, and thymine from lambda-DNA was tested under reduced pressure (similar to 0.5 Torr) at temperatures of > 150 degreesC. With the exception of guanine, approximately 60-75% of each base was sublimed directly from the lambda-DNA and recovered on a coldfinger of the sublimation apparatus after heating to 450 T. Several nucleobases including adenine, cytosine, thymine, and uracil were also recovered from E. coli bacteria after heating the cells to the same temperature, although some thermal decomposition of the bases also occurred. These results demonstrate the feasibility of using sublimation to isolate purines and pyrimidines from native E. coli DNA and RNA without any chemical treatment of the cells.

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
Onstott, TC, Magnabosco C, Aubrey AD, Burton AS, Dworkin JP, Elsila JE, Grunsfeld S, Cao BH, Hein JE, Glavin DP, Kieft TL, Silver BJ, Phelps TJ, van Heerden E, Opperman DJ, Bada JL.  2014.  Does aspartic acid racemization constrain the depth limit of the subsurface biosphere? Geobiology. 12:1-19.   10.1111/gbi.12069   AbstractWebsite

Previous studies of the subsurface biosphere have deduced average cellular doubling times of hundreds to thousands of years based upon geochemical models. We have directly constrained the in situ average cellular protein turnover or doubling times for metabolically active micro-organisms based on cellular amino acid abundances, D/L values of cellular aspartic acid, and the in vivo aspartic acid racemization rate. Application of this method to planktonic microbial communities collected from deep fractures in South Africa yielded maximum cellular amino acid turnover times of similar to 89years for 1km depth and 27 degrees C and 1-2years for 3km depth and 54 degrees C. The latter turnover times are much shorter than previously estimated cellular turnover times based upon geochemical arguments. The aspartic acid racemization rate at higher temperatures yields cellular protein doubling times that are consistent with the survival times of hyperthermophilic strains and predicts that at temperatures of 85 degrees C, cells must replace proteins every couple of days to maintain enzymatic activity. Such a high maintenance requirement may be the principal limit on the abundance of living micro-organisms in the deep, hot subsurface biosphere, as well as a potential limit on their activity. The measurement of the D/L of aspartic acid in biological samples is a potentially powerful tool for deep, fractured continental and oceanic crustal settings where geochemical models of carbon turnover times are poorly constrained. Experimental observations on the racemization rates of aspartic acid in living thermophiles and hyperthermophiles could test this hypothesis. The development of corrections for cell wall peptides and spores will be required, however, to improve the accuracy of these estimates for environmental samples.

Parker, ET, Cleaves HJ, Callahan MP, Dworkin JP, Glavin DP, Lazcano A, Bada JL.  2011.  Enhanced Synthesis of Alkyl Amino Acids in Miller's 1958 H2S Experiment. Origins of Life and Evolution of Biospheres. 41:569-574.   10.1007/s11084-011-9253-2   AbstractWebsite

Stanley Miller's 1958 H2S-containing experiment, which included a simulated prebiotic atmosphere of methane (CH4), ammonia (NH3), carbon dioxide (CO2), and hydrogen sulfide (H2S) produced several alkyl amino acids, including the alpha-, beta-, and gamma-isomers of aminobutyric acid (ABA) in greater relative yields than had previously been reported from his spark discharge experiments. In the presence of H2S, aspartic and glutamic acids could yield alkyl amino acids via the formation of thioimide intermediates. Radical chemistry initiated by passing H2S through a spark discharge could have also enhanced alkyl amino acid synthesis by generating alkyl radicals that can help form the aldehyde and ketone precursors to these amino acids. We propose mechanisms that may have influenced the synthesis of certain amino acids in localized environments rich in H2S and lightning discharges, similar to conditions near volcanic systems on the early Earth, thus contributing to the prebiotic chemical inventory of the primordial Earth.

Ehrenfreund, P, Glavin DP, Botta O, Cooper G, Bada JL.  2001.  Extraterrestrial amino acids in Orgueil and Ivuna: Tracing the parent body of Cl type carbonaceous chondrites. Proceedings of the National Academy of Sciences of the United States of America. 98:2138-2141.   10.1073/pnas.051502898   AbstractWebsite

Amino acid analyses using HPLC of pristine interior pieces of the Cl carbonaceous chondrites Orgueil and Ivuna have found that beta -alanine, glycine, and gamma -amino-n-butyric acid (ABA) are the most abundant amino acids in these two meteorites, with concentrations ranging from approximate to 600 to 2,000 parts per billion (ppb). Other alpha -amino acids such as alanine, alpha -ABA, alpha -aminoisobutyric acid (AIB), and isovaline are present only in trace amounts (<200 ppb). Carbon isotopic measurements of -alanine and glycine and the presence of racemic (D/L approximate to 1) alanine and beta -ABA in Orgueil suggest that these amino acids are extraterrestrial in origin. In comparison to the CM carbonaceous chondrites Murchison and Murray, the amino acid composition of the Cls is strikingly distinct, suggesting that these meteorites came from a different type of parent body, possibly an extinct comet, than did the CM carbonaceous chondrites.

Glavin, DP, Aubrey AD, Callahan MP, Dworkin JP, Elsila JE, Parker ET, Bada JL, Jenniskens P, Shaddad MH.  2010.  Extraterrestrial amino acids in the Almahata Sitta meteorite. Meteoritics & Planetary Science. 45:1695-1709.   10.1111/j.1945-5100.2010.01094.x   AbstractWebsite

Amino acid analysis of a meteorite fragment of asteroid 2008 TC(3) called Almahata Sitta was carried out using reverse-phase liquid chromatography coupled with UV fluorescence detection and time-of-flight mass spectrometry (LC-FD/ToF-MS) as part of a sample analysis consortium. LC-FD/ToF-MS analyses of hot-water extracts from the meteorite revealed a complex distribution of two- to seven-carbon aliphatic amino acids and one- to three-carbon amines with abundances ranging from 0.5 to 149 parts-per-billion (ppb). The enantiomeric ratios of the amino acids alanine, beta-amino-n-butyric acid, 2-amino-2-methylbutanoic acid (isovaline), and 2-aminopentanoic acid (norvaline) in the meteorite were racemic (d/l similar to 1), indicating that these amino acids are indigenous to the meteorite and not terrestrial contaminants. Several other nonprotein amino acids were also identified in the meteorite above background levels including alpha-aminoisobutyric acid (alpha-AIB), 4-amino-2-methylbutanoic acid, 4-amino-3-methylbutanoic acid, and 3-, 4-, and 5-aminopentanoic acid. The total abundances of isovaline and alpha-AIB in Almahata Sitta are approximately 1000 times lower than the abundances of these amino acids found in the CM carbonaceous chondrite Murchison. The extremely low abundances and unusual distribution of five-carbon amino acids in Almahata Sitta compared to CI, CM, and CR carbonaceous chondrites may reflect extensive thermal alteration of amino acids on the parent asteroid by partial melting during formation or subsequent impact shock heating. It is also possible that amino acids were synthesized by catalytic reactions on the parent body after asteroid 2008 TC(3) cooled to lower temperatures, or introduced as a contaminant from unrelated meteorite clasts and chemically altered by alpha-decarboxylation.

Elsila, JE, Glavin DP, Dworkin JP, Martins Z, Bada JL.  2012.  Inconclusive evidence for nonterrestrial isoleucine enantiomeric excesses in primitive meteorites. Proceedings of the National Academy of Sciences of the United States of America. 109:E3288-E3288.   10.1073/pnas.1213261109   Abstract

Pizzarello et al. (1) recently described the soluble organic content of eight Antarctic Renazzo-type (CR) carbonaceous chondrites and reported large enantiomeric excesses (ee) of l-isoleucine and d-alloisoleucine. The reported values of ee decrease with inferred increases in aqueous alteration. We believe the conclusions presented in the paper are not fully justified and the data are potentially flawed.

Potential terrestrial contamination of meteoritic amino acid data must always be considered. The manuscript states that “terrestrial contamination levels… were evaluated based on the presence of proteinogenic amino acids’ l-excesses and accounted for when needed,” but this “accounting” is not described. A wide range of l-proteinogenic amino acid excesses was measured …

Glavin, DP, Bada JL.  1998.  Isolation of amino acids from natural samples using sublimation. Analytical Chemistry. 70:3119-3122.   10.1021/ac9803784   AbstractWebsite

Amino acids have appreciable vapor pressures above 150 degrees C and will sublime under partial vacuum at elevated temperatures without any racemization or decomposition. The recoveries of several amino acids including aspartic acid, serine, glycine, alanine, ol-aminoisobutyric acid, and valine were optimized by varying the temperature and duration of sublimation. Sublimation has been shown to be a rapid and effective technique for the isolation of amino acids from natural samples for enantiomeric analyses and a good substitute for conventional cation-exchange desalting techniques.

Hutt, LD, Glavin DP, Bada JL, Mathies RA.  1999.  Microfabricated capillary electrophoresis amino acid chirality analyzer for extraterrestrial exploration. Analytical Chemistry. 71:4000-4006.   10.1021/ac9903959   AbstractWebsite

Chiral separations of fluorescein isothiocyanate-labeled amino acids have been performed on a microfabricated capillary electrophoresis chip to explore the feasibility of using such devices to analyze for extinct or extant life signs in extraterrestrial environments. The test system consists of a folded electrophoresis channel (19.0 cm long x 150 mu m wide x 20 mu m deep) that was photolithographically fabricated in a 10-cm-diameter glass wafer sandwich, coupled to a laser-excited confocal fluorescence detection apparatus providing subattomole sensitivity. Using a sodium dodecyl sulfate/gamma-cyclodextrin pH 10.0 carbonate electrophoresis buffer and a separation voltage of 550 V/cm at 10 degrees C, baseline resolution was observed for Val, Ala, Glu, and Asp enantiomers and Gly in only 4 min. Enantiomeric ratios were determined for amino acids extracted from the Murchison meteorite, and these values closely matched values determined by HPLC. These results demonstrate the feasibility of using microfabricated lab-on-a-chip systems to analyze extraterrestrial samples for amino acids.

Johnson, AP, Cleaves HJ, Dworkin JP, Glavin DP, Lazcano A, Bada JL.  2008.  The Miller volcanic spark discharge experiment. Science. 322:404-404.   10.1126/science.1161527   Website
Kminek, G, Bada JL, Botta O, Glavin DP, Grunthaner F.  2000.  MOD: an organic detector for the future robotic exploration of Mars. Planetary and Space Science. 48:1087-1091.   10.1016/s0032-0633(00)00082-9   AbstractWebsite

Searching for extinct or extant life on Mars is part of the future NASA surveyor class missions. Looking for key organic compounds that are essential for biochemistry as we know it or indicative of extraterrestrial organic influx is the primary goal of the Mars Organic Detector (MOD). MOD is able to detect amino acids, amines and PAHs with at least 100 times higher sensitivity than the Viking GCMS experiment. MOD is not capable of identifying specific organic molecules but can assess the organic inventory of amines and PAHs on the planet. MOD can also quantify adsorbed and chemisorbed water and evolved carbon dioxide in a stepped heating cycle to determine specific carbon-bearing minerals. All that comes with no sample preparation and no wet chemistry. The organics can be isolated from the carrier matrix by heating the sample and recovering the volatile organics on a cold finger. This sublimation technique can be used for extracting amino acids, amines and PAHs under Mars ambient conditions. The detection of amino acids, amines and PAHs is based on a fluorescence detection scheme. The MOD concept has functioned as a laboratory breadboard since 1998. A number of natural samples including shells, clays, bones, lambda -DNA and E.-coli bacteria have been used and organic molecules have been extracted successfully in each case. The first prototype of MOD is operational as of early fall of 1999. MOD has been selected for the definition phase of the NASA-MSR 2003 mission. (C) 2000 Elsevier Science Ltd. All rights reserved.

Glavin, DP, Cleaves HJ, Schubert M, Aubrey A, Bada JL.  2004.  New method for estimating bacterial cell abundances in natural samples by use of sublimation. Applied and Environmental Microbiology. 70:5923-5928.   10.1128/aem.70.10.5923-5928.2004   AbstractWebsite

We have developed a new method based on the sublimation of adenine from Escherichia coli to estimate bacterial cell counts in natural samples. To demonstrate this technique, several types of natural samples, including beach sand, seawater, deep-sea sediment, and two soil samples from the Atacama Desert, were heated to a temperature of 500degreesC for several seconds under reduced pressure. The sublimate was collected on a cold finger, and the amount of adenine released from the samples was then determined by high-performance liquid chromatography with UV absorbance detection. Based on the total amount of adenine recovered from DNA and RNA in these samples, we estimated bacterial cell counts ranging from similar to10(5) to 10(9) E. coli cell equivalents per gram. For most of these samples, the sublimation-based cell counts were in agreement with total bacterial counts obtained by traditional DA-PI (4,6-diamidino-2-phenylindole) staining.