Molecular Composition of Carbonaceous Globules in the Bells (CM2) Chondrite

Some meteorites and IDPs contain micron-size carbonaceous globules that are associated with significant H and/or N isotopic anomalies. This has been interpreted as indicating that such globules may contain at least partial preserved organic species formed in the outer reaches of the proto-solar disk or the presolar cold molecular cloud. Owing to their small sizes, relatively little is known about their chemical compositions. Here we present in situ measurements of aromatic molecular species in organic globules from the Bells (CM2) chondrite by microprobe two-step laser mass spectrometry. This meteorite was chosen for study because we have previously found this meteorite to contain high abundances of globules that often occur in clusters. The Bells (CM2) globules are also noteworthy for having particularly high enrichments in H-2. and N-15. In this study, we identified individual globules and clusters of globules using native UV fluorescence

Observation and analysis of in situ carbonaceous matter in Nakhla: Part I

New analyses of indigenous secondary material in the martian meteorite Nakhla reveal amorphous carbon-rich veins and dendrites. The texture and chemistry of this material resembles that of biogenically altered sub-ocean basaltic glasses

Observation and analysis of in situ carbonaceous matter in Nakhla: part II

Analysis of in situ carbonaceous matter in the Nakhla SNC meteorite has been carried out using a variety of techniques. Laser raman data shows the carbonaceous matter to be highly complex and static mass spectrometry has shown it to have an isotopic composition of '18 to '20' C

Coordinated Analyses of Diverse Components in Whole Stardust Cometary Tracks

Analyses of samples returned from Comet Wild-2 by the Stardust spacecraft have resulted in a number of surprising findings that show the origins of comets are more complex than previously suspected [1]. Stardust aerogel tracks show considerable compositional diversity and the degree of impact related thermal modification and destruction is also highly variable. We are performing systematic examinations of entire Stardust tracks to discern the representative mineralogy and origins of comet Wild 2 components and to search for well preserved fine grained materials. Previously, we used ultramicrotomy to prepare sequential thin sections of entire "carrot" and "bulbous" type tracks along their axis while preserving their original shapes [2]. This technique allows us to characterize the usually well-preserved terminal particle (TP), but also any associated, fine-grained fragments that were shed along the track pathway. This report focuses on coordinated analyses of surviving indigenous cometary materials (crystalline and amorphous) along the aerogel track walls, their interaction with aerogel during collection and comparisons with their TPs. We examined the distribution of fragments throughout the track from the entrance hole to the TP

Three-dimensional organotypic co-culture model of intestinal epithelial cells and macrophages to study Salmonella enterica colonization patterns

Three-dimensional models of human intestinal epithelium mimic the differentiated form and function of parental tissues often not exhibited by two-dimensional monolayers and respond to Salmonella in key ways that reflect in vivo infections. To further enhance the physiological relevance of three-dimensional models to more closely approximate in vivo intestinal microenvironments encountered by Salmonella, we developed and validated a novel three-dimensional co-culture infection model of colonic epithelial cells and macrophages using the NASA Rotating Wall Vessel bioreactor. First, U937 cells were activated upon collagen-coated scaffolds. HT-29 epithelial cells were then added and the three-dimensional model was cultured in the bioreactor until optimal differentiation was reached, as assessed by immunohistochemical profiling and bead uptake assays. The new co-culture model exhibited in vivo-like structural and phenotypic characteristics, including three-dimensional architecture, apical-basolateral polarity, well-formed tight/adherens junctions, mucin, multiple epithelial cell types, and functional macrophages. Phagocytic activity of macrophages was confirmed by uptake of inert, bacteria-sized beads. Contribution of macrophages to infection was assessed by colonization studies of Salmonella pathovars with different host adaptations and disease phenotypes (Typhimurium ST19 strain SL1344 and ST313 strain D23580; Typhi Ty2). In addition, Salmonella were cultured aerobically or microaerobically, recapitulating environments encountered prior to and during intestinal infection, respectively. All Salmonella strains exhibited decreased colonization in co-culture (HT-29-U937) relative to epithelial (HT-29) models, indicating antimicrobial function of macrophages. Interestingly, D23580 exhibited enhanced replication/survival in both models following invasion. Pathovar-specific differences in colonization and intracellular co-localization patterns were observed. These findings emphasize the power of incorporating a series of related three-dimensional models within a study to identify microenvironmental factors important for regulating infection

Truncated Hexa-Octahedral Magnetite Crystals in Martian Meteorite ALH84001: Evidence of Biogenic Activity on Early Mars

The landmark paper by McKay et al. [1] cited four lines of evidence associated with the Martian meteorite ALH84001 to support the hypothesis that life existed on Mars approximately 4 Ga ago. Now, more than five years later, attention has focused on the ALH84001 magnetite grains embedded within carbonate globules in the ALH84001 meteorite. We have suggested that up to approx.25% of the ALH84001 magnetite crystals are products of biological activity [e.g., 2]. The remaining magnetites lack sufficient characteristics to constrain their origin. The papers of Thomas Keprta et al. were criticized arguing that the three dimensional structure of ALH84001 magnetite crystals can only be unambiguously determined using electron tomographic techniques. Clemett et al. [3] confirmed that magnetites produced by magnetotactic bacteria strain MV-I display a truncated hexa-octahedral geometry using electron tomography and validated the use of the multi-tilt classical transmission microscopy technique used by [2]. Recently the geometry of the purported martian biogenic magnetites was shown be identical to that for MV-1 magnetites using electron tomography [6]

In Situ Coordinated Analysis of Carbonaceous Chondrite Organic Matter

Microanalytical studies of carbonaceous chondrites (CCs) have identified a vast array of isotopically, chemically and texturally distinct organic components. These components were synthesized and processed within a range of physical and chemical environments, including the interstellar medium, the solar nebula and within asteroids. The nature and abundance of these molecules can be used to unravel the geochemical and isotopic record of their origins as well as their subsequent evolutionary journey

Overview of the results of the organics PET Study of the cometary samples returned from comet Wild 2 by the Stardust mission

This presenation will provide an overview of the efforts and results produced by the Organics Preliminary Examination Team during their studies of the samples returned from comet Wild 2 by the Stardust spacecraft

The Caesar New Frontiers Mission: 2. Sample Science

No abstract availabl

Anatomy of a cluster IDP. Part 2: Noble gas abundances, trace element geochemistry, isotopic abundances, and trace organic chemistry of several fragments from L2008#5

The topics discussed include the following: noble gas content and release temperatures; trace element abundances; heating summary of cluster fragments; isotopic measurements; and trace organic chemistry