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Your search keyword '"Huston, Ted J."' showing total 17 results
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17 results on '"Huston, Ted J."'

3. tRNA-guanine transglycosylase from Escherichia coli is a zinc metalloprotein. Site-directed mutagenesis studies to identify the zinc ligands

Author

Chong, Shaorong, Curnow, Alan W., Huston, Ted J., and Garcia, George A.

Subjects
Escherichia coli -- Research, Metalloproteins -- Genetic aspects, Zinc -- Analysis, Biological sciences, Chemistry
Abstract

Atomic emission spectrometry and site-directed mutagenesis studies of tRNA-guanine transglycosylase (TGT) from Escherichia coli suggest that wild-type TGT possesses 0.8 mol of zinc per molecule of subunit. Cysteines 302, 304 and 307 and histidine 317 are the ligands to the zinc, as suggested by structural probes, enzyme activity and tRNA-binding assays. TGT homodimer formation and tRNA binding require the zinc site.

Published
1995

4. Fluoride content of foraminiferal calcite: relations to life habitat, oxygen isotope composition, and minor element chemistry

Author

Opdyke, Bradley N., Walter, Lynn M., and Huston, Ted J.

Subjects
Calcite -- Composition, Foraminifera, Fossil -- Composition, Fluorides -- Analysis, Oxygen -- Isotopes, Isotope geology -- Research, Earth sciences
Abstract

Fluoride contents of planktonic foraminiferal calcite show a strong relation to the depth habitat of a given species. Shallow-water species such as Globigerinoides ruber and Globigerinoides sacculifer have fluoride contents more than three times those of deeper dwelling species such as Globorotalia truncatulinoides and Globorotalia menardii. This correspondence between chemistry and life habitat is consistent from glacial to interglacial samples and from tropical to mid-latitude samples. Oxygen isotopic composition and minor element contents (Sr, Mg) all have a positive covariance with F content, suggesting that F content is controlled by temperature and/or growth rate. Species-specific vital effects may also have an influence on F content. These initial data suggest that habitat differences among species and possibly temperature variations within species may be determined by the F content of foraminiferal calcite in well-preserved materials. Fluoride contents of older Cenozoic planktonic foraminiferal species may provide a useful test of assumed life habitats.

Published
1993

6. Formation waters from Mississippian-Pennsylvanian reservoirs, Illinois basin, USA: Chemical and isotopic constraints on evolution and migration

Author

Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109, USA, Department of Geography and Earth Science, Southern Illinois University, Edwardsville, IL 62026, USA, Department of Geological Sciences, Wright State University, Dayton, OH 45435, USA, Stueber, Alan M., Walter, Lynn M., Huston, Ted J., Pushkar, Paul, Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109, USA, Department of Geography and Earth Science, Southern Illinois University, Edwardsville, IL 62026, USA, Department of Geological Sciences, Wright State University, Dayton, OH 45435, USA, Stueber, Alan M., Walter, Lynn M., Huston, Ted J., and Pushkar, Paul

Abstract

We have analyzed a suite of seventy-four formation-water samples from Mississippian and Pennsylvanian carbonate and siliciclastic strata in the Illinois basin for major, minor, and trace element concentrations and for strontium isotopic composition. A subset of these samples was also analyzed for boron isotopic composition. Data are used to interpret origin of salinity and chemical and Sr isotopic evolution of the brines and in comparison with a similar data set from an earlier study of basin formation waters from Silurian-Devonian reservoirs. Systematics of Cl-Br-Na show that present Mississippian-Pennsylvanian brine salinity can be explained by a combination of subaerial seawater evaporation short of halite saturation and subsurface dissolution of halite from an evaporite zone in the middle Mississippian St. Louis Limestone, along with extensive dilution by mixing with meteoric waters. Additional diagenetic modifications in the subsurface interpreted from cation/Br ratios include K depletion through interaction with clay minerals, Ca enrichment, and Mg depletion by dolomitization, and Sr enrichment through CaCO3 recrystallization and dolomitization. Ste. Genevieve Limestone (middle Mississippian) formation waters show 87Sr/86Sr ratios in the range 0.70782-0.70900, whereas waters from the siliciclastic reservoirs are in the range 0.70900-0.71052. Inverse correlations between 87Sr/86Sr and B, Li, and Mg concentrations suggest that the brines acquired radiogenic 87Sr through interaction with siliciclastic minerals. Completely unsystematic relations between 87Sr/86Sr and 1/Sr are observed; Sr concentrations in Ste. Genevieve and Aux Vases (middle Mississippian) waters appear to be buffered by equilibrium with respect to SrSO4. Although there are many similarities in their origin and evolution, these formation waters are distinguished from Silurian-Devonian brines in the basin by elevated Cl/Br and Na/Br ratios and by unsystematic Sr isotope relationships. Thus waters

Published
2006

7. Chemical studies of H chondrites. I - Mobile trace elements and gas retention ages

Author

Lingner, David W, Huston, Ted J, Hutson, Melinda, and Lipschutz, Michael E

Subjects
Lunar And Planetary Exploration
Abstract

Trends for 16 trace elements (Ag, As, Au, Bi, Cd, Co, Cs, Ga, In, K, Rb, Sb, Se, Te, Tl, and Zn), chosen to span a broad geochemical and thermal response range, in 44 H4-6 chondrites, differ widely from those in L4-6 chondrites. In particular, H chondrites classified as heavily shocked petrologically do not necessarily exhibit Ar-40 loss and vice versa. The clear-cut causal relationship between siderophile and mobile element loss with increasing late shock seen in L chondrites is not generally evident in the H group. H chondrite parent material experienced an early high temperature genetic episode that mobilized a substantial proportion of these trace elements so that later thermal episodes resulted in more subtle, collateral fractionations. Mildly shocked L chondrites escaped this early high temperature event, indicating that the two most numerous meteorite groups differ fundamentally in genetic history.

Published
1987
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