ABSTRACT: The report by McKay et al. that the Martian meteorite ALH84001 contains evidence for life on Mars remains controversial. Of central importance is whether ALH84001 and other Antarctic Martian meteorites contain endogenous organic compounds. In any investigation of organic compounds possibly derived from Mars it is important to focus on compounds that play an essential role in biochemistry as we know it and that have properties such as chirality which can be used to distinguish between biotic versus abiotic origins. Amino acids are one of the few compounds that fulfill these requirements. Previous analyses of the Antarctic Martian meteorites ALH84001 and EETA79001 have shown that these meteorites contain low levels of terrestrial amino acid contamination derived from Antarctic ice meltwater. Here we report preliminary amino acid investigations of a third Antarctic Martian meteorite MIL03346 which was discovered in Antarctica during the 2003-04 ANSMET season. Additional information is included in the original extended abstract
ABSTRACT: Detection of life on Mars requires definition of a suitable biomarker
and development of sensitive yet compact instrumentation capable of
performing in situ analyses. Our studies are focused on amino acid
analysis because amino acids are more resistant to decomposition than
other biomolecules, and because amino acid chirality is a well-defined
biomarker. Amino acid composition and chirality analysis has been
previously demonstrated in the lab on microfabricated capillary
electrophoresis (CE) chips (1, 2). To analyze amino acids in situ, we
have developed the Mars Organic Analyzer (MOA), a portable analysis
system that consists of a compact instrument and a novel multi-layer CE
microchip. The heart of the MOA is the microchip that contains the CE
separation channels as well as microfabricated valves and pumps (3) for
sample handling. The pneumatic microfabricated valves are created by
combining an etched displacement chamber, an actuated PDMS membrane
layer, and a discontinuous fluidic channel structure. A microfabricated
pump is created by combining three individually-addressable valves in
series. These membrane valves and pumps are integrated with the glass
separation channel using a novel multilayer design in which sample
enters the top fluidic layer for routing and is directed to the bottom
glass layers for CE separation and analysis. The microfabricated device
is operated by the portable instrument which contains solenoids for
controlling fluidic valves, electronics, a 15 mW 400 nm diode laser,
confocal detection optics, and a fiber-optic coupled photomultiplier for
fluorescence detection. Limits of detection of fluorescamine-labeled
amino acids are in the nM to pM range corresponding to
part-per-trillion sensitivities in soil samples (4). The portable CE
instrument, in combination with the Mars Organic Detector (MOD) (5), was
recently successfully field tested on soil samples rich in jarosite from
Panoche Valley, CA. Jarosite has recently been detected on Mars and is
a key mineral indicating that liquid water was once present on the
planet's surface. Amino acids from jarosite samples were sublimed by
MOD and deposited onto a fluorescamine-coated cold finger. The
microfabricated pumps were used to direct buffer through the MOA sipper
to dissolve the sample, and then to return the sample for analysis. The
jarosite sample was found to contain low levels of methyl and ethylamine
(5 ppb), alanine/serine (0.4 ppb), glycine (0.2 ppb), glutamic (0.07
ppb) and aspartic (0.1 ppb) acid as well as a higher concentration of
valine ( ˜100 ppb). These results clearly demonstrate that amines
and amino acids can be extracted from sulfate-rich acidic soils such as
jarosite and analyzed using the MOA (http://astrobiology.berkeley.edu).
References 1. Hutt, L. D., Glavin, D. P., Bada, J. L. & Mathies, R.
A. (1999) Anal. Chem. 71, 4000-4006. 2. Skelley, A. M. & Mathies, R.
A. (2003) J. Chromatogr. A 1021, 191-199. 3. Grover, W. H., Skelley, A.
M., Liu, C. N., Lagally, E. T. & Mathies, R. A. (2003) Sens.
Actuators B 89, 325-323. 4. Skelley, A. M., Scherer, J. R., Aubrey, A.
D., Grover, W. H., Ivester, R. H. C., Ehrenfreund, P., Grunthaner, F.
J., Bada, J. F. & Mathies, R. A. (2004) Proc. Natl. Acad. Sci. USA,
manuscript in preparation. 5. Kminek, G., Bada, J. L., Botta, O.,
Glavin, D. P. & Grunthaner, F. (2000) Planetary & Space Science
AGU Fall Meeting Abstracts. 11/2004; -1:0916.
ABSTRACT: The exploration of the possible emergence and duration of life on Mars from landed platforms requires attention to the quality of measurements that address these objectives. In particular, the potential impact of terrestrial contamination on the measurement of reduced carbon with sensitive in situ instruments must be addressed in order to reach definitive conclusions regarding the source of organic molecules. Following the recommendation of the Mars Exploration Program Analysis Group (MEPAG) at its September 2003 meeting [MEPAG, 2003], the Mars Program Office at NASA Headquarters chartered the Organic Contamination Science Steering Group (OCSSG) to address this issue. The full report of the six week study of the OCSSG can be found on the MEPAG web site . The study was intended to define the contamination problem and to begin to suggest solutions that could provide direction to the engineering teams that design and produce the Mars landed systems. Requirements set by the Planetary Protection Policy in effect for any specific mission do not directly address this question of the potential interference from terrestrial contaminants during in situ measurements.
ABSTRACT: The origin of life on Earth, and possibly on other planets such as Mars, would have required the presence of liquid water and a continuous supply of prebiotic organic compounds. The exogenous delivery of organic matter by asteroids, comets, and carbonaceous meteorites could have contributed to the early Earth s prebiotic inventory by seeding the planet with biologically important organic compounds. A wide variety of prebiotic organic compounds have previously been detected in the Murchison CM type carbonaceous chondrite including amino acids, purines and pyrimidines. These compounds dominate terrestrial biochemistry and are integral components of proteins, DNA and RNA. Several purines including adenine, guanine, hypoxanthine, and xanthine, as well as the pyrimidine uracil, have previously been detected in water or formic acid extracts of Murchison using ion-exclusion chromatography and ultraviolet spectroscopy. However, even after purification of these extracts, the accurate identification and quantification of nucleobases is difficult due to interfering UV absorbing compounds. In order to reduce these effects, we have developed an extraction technique using sublimation to isolate purines and pyrimidines from other non-volatile organic compounds in Murchison acid extracts.
ABSTRACT: The conditions on Mars are thought to have been more conducive for life during its early history, about 3 billion years ago. If life ever evolved on Mars, would it be possible to see the remnants of a long-extinct biosphere today? Or even more interesting, would it be possible to find Martian bacterial spores that survived for billions of years on Mars?
ABSTRACT: One of the primary objectives of the 1976 Viking missions was to determine whether organic compounds, possibly of biological origin, were present in the Martian surface soils. The Viking gas chromatography mass spectrometry (GCMS) instruments found no evidence for any organic compounds of Martian origin above a few parts per billion in the upper 10 cm of surface soil, suggesting the absence of a widely distributed Martian biota. However, it is now known that key organic compounds important to biology, such as amino acids, carboxylic acids and nucleobases, would likely have been missed by the Viking GCMS instruments. In this study, a Mars soil analogue that was inoculated with approx. 10 billion Escherichia coli cells was heated at 500 C under Martian ambient pressure to release volatile organic compounds from the sample. The pyrolysis products were then analyzed for amino acids and nucleobases using high performance liquid chromatography (HPLC) and GCMS. 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 by the Viking GCMS instruments. Upcoming strategies for Mars exploration will require in-situ analyses by instruments that can assess whether any organic compounds, especially those that might be associated with life, are present in Martian surface samples.
ABSTRACT: Recent advances in microfabricated "lab-on-a-chip" technologies have
dramatically enhanced the capabilities of chemical and biochemical
analyzers. The portability and sensitivity of these devices makes them
ideal instruments for in situ chemical analysis on other planets. We
have focused our initial studies on amino acid analysis because amino
acids are more chemically resistant to decomposition than other
biomolecules, and because amino acid chirality is a well-defined
biomarker . Previously, we developed a prototype electrophoresis
chip, detection system and analysis method where the amino acids were
labeled with fluorescein using FITC and then electrophoretically
analyzed using g-cyclodextrin as the chiral resolution agent .
Extracts of the Murchison meteorite were analyzed, and the D/L ratios
determined by microchip CE closely matched those from HPLC and GCMS and
exhibited greater precision. Our microchip analyzer has now been further
improved by establishing the capability of performing amino acid
composition and chirality analyses using fluorescamine rather than FITC
. Fluorescamine is advantageous because it reacts more rapidly than
FITC, and because excess reagent is hydrolyzed to a non-fluorescent
product. Furthermore, the use of fluorescamine facilitates interfacing
with the Mars Organic Detector (MOD) . Fluorescamine-amino acids are
separated using similar conditions as the FITC-aa, resulting in similar
separation times and identical elution orders. Fluorescamine-aa are
chirally resolved in the presence of hydroxy-propyl-b-cyclodextrin, and
typical limits of detection are ˜ 50 nM. This work establishes
the feasibility of combining fluorescamine labeling of amino acids with
microfabricated CE devices to develop low-volume, high-sensitivity
apparatus for extraterrestrial exploration. The stage is now set for the
development of the Mars Organic Analyzer (MOA), a portable analysis
system for amino acid extraction and chiral analysis that will combine
the capabilities of microchip CE with the previously developed
extraction capabilities of MOD . Amino acids are first extracted from
soil by sublimation to a cold finger coated with fluorescamine for solid
phase labeling. Sample transfer between MOD and the CE device is
achieved through a capillary sipper driven by microfabricated valves and
pumps . The construction of a portable MOA instrument will facilitate
in situ studies of amino acids in Mars analog sites such as the Atacama
Desert in Chile. Preliminary chiral analyses of Atacama soil extracts on
the microfabricated CE device have shown amino acid detection down to
low ppb concentrations. Future field tests in the Atacama Desert will
explore the feasibility of the portable CE device for performing in situ
amino acid analysis. This work will provide the technology base for the
development the Mars Organic Laboratory (MOL), a portable device that
will analyze a broad suite of biomolecules, including nucleobases,
sugars, and organic acids and bases . J.L. Bada, G.D. McDonald,
Icarus 114 (1995) 139. L.D. Hutt, D.P. Glavin, J.L. Bada, R.A.
Mathies, Anal. Chem. 71 (1999) 4000. A.M. Skelley, R.A. Mathies, J.
Chromatogr. A (2003) in press. G. Kminek, J.L. Bada, O. Botta, D.P.
Glavin, F. Grunthaner, Planet. Space Sci. 48 (2000) 1087. W.H.
Grover, A.M. Skelley, C.N. Liu, E.T. Lagally, R.A. Mathies, Sens.
Actuators B 89 (2003) 325. A.M. Skelley, F.J. Grunthaner, J.F. Bada,
R.A. Mathies, in SPIE: Proceedings of the In-Situ Instrument
Technologies Meeting, Pasadena, CA, 2002.
AGU Fall Meeting Abstracts. 11/2003; -1:07.
ABSTRACT: Asteroids, comets, meteorites and IDPS, are generally believed to have
contributed to the volatile inventory of the terrestrial planets. About
1 weight-% of carbonaceous meteorites, which are thought to be fragments
of asteroids, can be extracted with solvents in the form of separable
compounds. Some of these compound might have been important starting
materials for the chemical evolution of the early Earth (and potentially
Mars). Interplanetary dust particles (IDPs), sub-millimeter sized
particles that contain up to 40% organic carbon, are associated with
comets and are thought to have contributed a large fraction to the
inventory of volatiles found on the terrestrial planets. We sumamrize
the organic composition of carbonaceous chondrites, asteroids and comets
may have played in the delivery of these organic compounds to the early
Earth and other solar system bodies.
ABSTRACT: A Mars soil analogue inoculated with E. coli was heated at 500°C
under Martian ambient pressure to isolate volatile amine compounds from
the cells. Our results suggest that ~30 million bacterial cells per gram
of Martian soil would not have been detected by the Viking GC/MS
ABSTRACT: 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 CI 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 CI 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 fiom 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 fiom 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.
Meteoritics and Planetary Science Supplement. 08/2001; 36:26.
ABSTRACT: Amino acid analyses using HPLC of pristine interior pieces of the CI 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 approximately 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 beta-alanine and glycine and the presence of racemic (D/L approximately 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 CIs 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.
Proceedings of the National Academy of Sciences 03/2001; 98(5):2138-41. · 9.68 Impact Factor
ABSTRACT: An overview of the amino acid composition of all carbonaceous chondrites
analyzed in our lab will be presented, including the CMs Murchison,
Murray, Nogoya, the CIs Orgueil and Ivuna, the CR Renazzo and the CV3
ABSTRACT: Integration of a micro-chip capillary electrophoresis analyzer with a sublimation-based extraction technique, as used in the Mars Organic Detector (MOD), for the in-situ detection of amino acids and their enantiomers on solar system bodies. Additional information is contained in the original extended abstract.
Proceedings of the National Academy of Sciences 02/2001; 98(3):797-800. · 9.68 Impact Factor
ABSTRACT: The delivery of amino acids by micrometeorites to the early Earth during the period of heavy bombardment could have been a significant source of the Earth's prebiotic amino acid inventory provided that these organic compounds survived atmospheric entry heating. To investigate the sublimation of amino acids from a micrometeorite analog at elevated temperature, grains from the CM-type carbonaceous chondrite Murchison were heated to 550 degrees C inside a glass sublimation apparatus (SA) under reduced pressure. The sublimed residue that had collected on the cold finger of the SA after heating was analyzed for amino acids by HPLC. We found that when the temperature of the meteorite reached approximately 150 degrees C, a large fraction of the amino acid glycine had vaporized from the meteorite, recondensed onto the end of the SA cold finger, and survived as the rest of the grains heated to 550 degrees C. alpha-Aminoisobutryic acid and isovaline, which are two of the most abundant non-protein amino acids in Murchison, did not sublime from the meteorite and were completely destroyed during the heating experiment. Our experimental results suggest that sublimation of glycine present in micrometeorite grains may provide a way for this amino acid to survive atmospheric entry heating at temperatures > 550 degrees C; all other amino acids apparently are destroyed.
Astrobiology 01/2001; 1(3):259-69. · 2.15 Impact Factor
ABSTRACT: The Mars Organic Detector (MOD) was recently selected for the definition phase of the HEDS '05 (originally scheduled for '03) lander instrument package for fundamental biology and in situ resource utilization. MOD is designed to detect organic compounds in rock and soil samples directly on the surface of Mars in order to assess the biological potential of the planet. In addition, a MOD Tunable Diode Laser Spectrometer (TDLS) will provide information on desorption and decomposition temperatures, as well as the release rates and quantities of water and carbon dioxide that can be liberated from regolith samples, thereby providing the parameters needed for the design of systems for the future large-scale in situ extraction of valuable consumable resources. A MOD TDLS will also measure the atmospheric water and carbon dioxide content, as well as the atmospheric carbon dioxide isotopic composition, in order to determine whether there is an isotopic offset between atmospheric and surface carbon.
ABSTRACT: The MOD (Mars Organic Detector) instrument which has selected for the definition phase of the BEDS package on the 2005 Mars Explorer Program spacecraft is designed to simply detect the presence of amino acids in Martian surface samples at a sensitivity of a few parts per billion (ppb). An additional important aspect of amino acid analyses of Martian samples is identifying and quantifying which compounds are present, and also distinguishing those produced abiotically from those synthesized by either extinct or extant life. Amino acid homochirality provides an unambiguous way of distinguishing between abiotic vs. biotic origins. Proteins made up of mixed D- and L-amino acids would not likely have been efficient catalysts in early organisms because they could not fold into bioactive configurations such as the a-helix. However, enzymes made up of all D-amino acids function just as well as those made up of only L-amino acids, but the two enzymes use the opposite stereoisomeric substrates. There are no biochemical reasons why L-amino acids would be favored over Damino acids. On Earth, the use of only L-amino acids in proteins by life is probably simply a matter of chance. We assume that if proteins and enzymes were a component of extinct or extant life on Mars, then amino acid homochirality would have been a requirement. However, the possibility that Martian life was (or is) based on D-amino acids would be equal to that based on L-amino acids. The detection of a nonracemic mixture of amino acids in a Martian sample would be strong evidence for the presence of an extinct or extant biota on Mars. The finding of an excess of D-amino acids would provide irrefutable evidence of unique Martian life that could not have been derived from seeding the planet with terrestrial life (or the seeding of the Earth with Martian life). In contrast, the presence of racemic amino acids, along with non-protein amino acids such as alpha-aminoisobutyric acid and isovaline, would be indicative of an abiotic origin, although we have to consider the possibility that the racemic amino acids were generated from the racemization of biotically produced amino acids.
ABSTRACT: In order to simulate prebiotic synthetic processes on Europa and other ice-covered planets and satellites, we have investigated the prebiotic synthesis of organic compounds from dilute solutions of NH4CN frozen for 25 years at -20 and -78 degrees C. In addition, the aqueous products of spark discharge reactions from a reducing atmosphere were frozen for 5 years at -20 degrees C. We find that both adenine and guanine, as well as a simple set of amino acids dominated by glycine, are produced in substantial yields under these conditions. These results indicate that some of the key components necessary for the origin of life may have been available on Europa throughout its history and suggest that the circumstellar zone where life might arise may be wider than previously thought.
Icarus 07/2000; 145(2):609-13. · 3.38 Impact Factor
ABSTRACT: Looking for organic compounds that are essential for biochemistry or indicative of extraterrestrial organic influx is the primary goal of MOD (Mars Organic Detector). MOD can also quantify adsorbed and chemisorbed water and evolved carbon dioxide.