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Insights from Human/Mouse genome comparisons

Description: Large-scale public genomic sequencing efforts have provided a wealth of vertebrate sequence data poised to provide insights into mammalian biology. These include deep genomic sequence coverage of human, mouse, rat, zebrafish, and two pufferfish (Fugu rubripes and Tetraodon nigroviridis) (Aparicio et al. 2002; Lander et al. 2001; Venter et al. 2001; Waterston et al. 2002). In addition, a high-priority has been placed on determining the genomic sequence of chimpanzee, dog, cow, frog, and chicken (Boguski 2002). While only recently available, whole genome sequence data have provided the unique opportunity to globally compare complete genome contents. Furthermore, the shared evolutionary ancestry of vertebrate species has allowed the development of comparative genomic approaches to identify ancient conserved sequences with functionality. Accordingly, this review focuses on the initial comparison of available mammalian genomes and describes various insights derived from such analysis.
Date: March 30, 2003
Creator: Pennacchio, Len A.
Partner: UNT Libraries Government Documents Department

Introduction to special section on Hydrologic Synthesis

Description: The Hydrological Synthesis special section presentssynthesis topics that have the potential to revolutionize hydrologicalsciences in a manner needed to meet critical water challenges that we nowface. The special section also highlights topics that are important andexciting enough to compel researchers to engage in collaborativesynthesis activities. This introductory paper provides a brief overviewof nine papers that are included in this special section, which discussthe synthesis of tools, data, concepts, theories, or approaches acrossdisciplines and scales. The wide range of topics that are exploredinclude groundwater quality, river restoration, water management,nitrogen cycling, and Earth surface dynamics. Collectively, the specialsection papers illustrate that the challenge to deal effectively withcomplex water problems is not purely a scientific, technological, orsocioeconomic one; it is instead a complex, 21st century problem thatrequires coordinated synthesis.
Date: January 23, 2006
Creator: Hubbard, Susan
Partner: UNT Libraries Government Documents Department

Fuzzy systems modeling of in situ bioremediation of chlorinatedsolve n ts

Description: A large-scale vadose zone-groundwater bioremediationdemonstration was conducted at the Savannah River Site (SRS) by injectingseveral types of gases (ambient air, methane, and nitrous oxide andtriethyl phosphate mixtures) through a horizontal well in the groundwaterat a 175 ft depth. Simultaneously, soil gas was extracted through aparallel horizontal well in the vadose zone at a 80 ft depth Monitoringrevealed a wide range of spatial and temporal variations ofconcentrations of VOCs, enzymes, and biomass in groundwater and vadosezone monitoring boreholes over the field site. One of the powerful modernapproaches to analyze uncertain and imprecise data chemical data is basedon the use of methods of fuzzy systems modeling. Using fuzzy modeling weanalyzed the spatio-temporal TCE and PCE concentrations and methanotrophdensities in groundwater to assess the effectiveness of differentcampaigns of air stripping and bioremediation, and to determine the fuzzyrelationship between these compounds. Our analysis revealed some detailsabout the processes involved in remediation, which were not identified inthe previous studies of the SRS demonstration. We also identified somefuture directions for using fuzzy systems modeling, such as theevaluation of the mass balance of the vadose zone - groundwater system,and the development of fuzzy-ruled methods for optimization of managingremediation activities, predictions, and risk assessment.
Date: September 5, 2001
Creator: Faybishenko, Boris & Hazen, Terry C.
Partner: UNT Libraries Government Documents Department

Galvanic interpretation of self-potential signals associated withmicrobial sulfate-reduction

Description: We have evaluated the usefulness of the self-potential (SP)geophysical method to track the onset and location of microbialsulfate-reduction in saturated sediments during organic carbon amendment.Following stimulation of sulfate-reducing bacteria (SRB) by addition oflactate, anomalous voltages exceeding 600 mV correlated in space and timewith the accumulation of dissolved sulfide. Abiotic experiments in whichthe sulfide concentration at the measurement electrode was systematicallyvaried showed a positive correlation between the magnitude of the SPanomaly and differences in the half-cell potential associated with themeasurement and reference electrodes. Thus, we infer that the SPanomaliesresulted from electrochemical differences that developedbetween sulfide-rich regions and areas having higher oxidation potential.In neither experiment did generation of an SP anomaly require thepresence of an in situ electronic conductor, as is required by othermodels. These findings emphasize the importance of incorporation ofelectrochemical effects at electrode surfaces in interpretation of SPdata from geophysical studies. We conclude that SP measurements provide aminimally invasive means for monitoring stimulated sulfate-reductionwithin saturated sediments.
Date: May 2, 2007
Creator: Williams, Kenneth H.; Hubbard, Susan S. & Banfield, Jillian F.
Partner: UNT Libraries Government Documents Department

The positive role of the ecological community in the genomicrevolution

Description: The exponential increase of genomic and metagenomic data,fueled in part by recent advancements in sequencing technology, aregreatly expanding our understanding of the phylogenetic diversity andmetabolic capacity present in the environment. Two of the centralchallenges that bioinformaticians and ecologists alike must face are thedesign of bioinformatic resources that facilitate the analysis of genomicand metagenomic data in a comparative context and the efficient captureand organization of the plethora of descriptive information required tousefully describe these data sets. In this commentary, we review threeinitiatives presented in the "new frontiers" session of the second SCOPEmeeting on Microbial Environmental Genomics (MicroEnGen-II, Shanghai,June 12-15, 2006). These are (1) the Integrated Microbial GenomesResources (IMG), (2) the Genomic Standards Consortium (GSC), and (3) theNatural Environment Research Council (NERC) Environmental BioinformaticsCentre (NEBC). These integrative bioinformatics and data managementinitiatives underscore the increasingly important role ecologists have toplay in the genomic (metagenomic) revolution.
Date: July 1, 2006
Creator: Field, Dawn; Methe, Barbara; Nelson, Karen & Kyrpides, Nikos
Partner: UNT Libraries Government Documents Department

The Life-cycle of Operons

Description: Operons are a major feature of all prokaryotic genomes, buthow and why operon structures vary is not well understood. To elucidatethe life-cycle of operons, we compared gene order between Escherichiacoli K12 and its relatives and identified the recently formed anddestroyed operons in E. coli. This allowed us to determine how operonsform, how they become closely spaced, and how they die. Our findingssuggest that operon evolution may be driven by selection on geneexpression patterns. First, both operon creation and operon destructionlead to large changes in gene expression patterns. For example, theremoval of lysA and ruvA from ancestral operons that contained essentialgenes allowed their expression to respond to lysine levels and DNAdamage, respectively. Second, some operons have undergone acceleratedevolution, with multiple new genes being added during a brief period.Third, although genes within operons are usually closely spaced becauseof a neutral bias toward deletion and because of selection against largeoverlaps, genes in highly expressed operons tend to be widely spacedbecause of regulatory fine-tuning by intervening sequences. Althoughoperon evolution may be adaptive, it need not be optimal: new operonsoften comprise functionally unrelated genes that were already inproximity before the operon formed.
Date: March 15, 2007
Creator: Price, Morgan N.; Arkin, Adam P. & Alm, Eric J.
Partner: UNT Libraries Government Documents Department

Selection against spurious promoter motifs correlates withtranslational efficiency across bacteria

Description: Because binding of RNAP to misplaced sites could compromise the efficiency of transcription, natural selection for the optimization of gene expression should regulate the distribution of DNA motifs capable of RNAP-binding across the genome. Here we analyze the distribution of the -10 promoter motifs that bind the {sigma}{sup 70} subunit of RNAP in 42 bacterial genomes. We show that selection on these motifs operates across the genome, maintaining an over-representation of -10 motifs in regulatory sequences while eliminating them from the nonfunctional and, in most cases, from the protein coding regions. In some genomes, however, -10 sites are over-represented in the coding sequences; these sites could induce pauses effecting regulatory roles throughout the length of a transcriptional unit. For nonfunctional sequences, the extent of motif under-representation varies across genomes in a manner that broadly correlates with the number of tRNA genes, a good indicator of translational speed and growth rate. This suggests that minimizing the time invested in gene transcription is an important selective pressure against spurious binding. However, selection against spurious binding is detectable in the reduced genomes of host-restricted bacteria that grow at slow rates, indicating that components of efficiency other than speed may also be important. Minimizing the number of RNAP molecules per cell required for transcription, and the corresponding energetic expense, may be most relevant in slow growers. These results indicate that genome-level properties affecting the efficiency of transcription and translation can respond in an integrated manner to optimize gene expression. The detection of selection against promoter motifs in nonfunctional regions also implies that no sequence may evolve free of selective constraints, at least in the relatively small and unstructured genomes of bacteria.
Date: May 1, 2007
Creator: Froula, Jeffrey L. & Francino, M. Pilar
Partner: UNT Libraries Government Documents Department

Sharing the burden of climate change stabilization: An energysector perspective

Description: In this paper we discuss long-term least cost CO2stabilization scenarios based on the SRES AIM A1B scenario in the contextof an international burden-sharing regime. Starting from a stabilizationtarget, regional emission caps are formulated dynamically on the basis ofpast emissions. With these regional caps, the cost-optimal supply fuelmix in the energy sector in the four SRES world regions is calculated,and lower bounds on the volume of traded carbon are estimated. Theallocation scheme provides incentives for early mitigation action. Weestimate additional regional costs incurred by the allocation scheme, andassess the sensitivity of results to changes in the concentrationceiling, discount rates, and start date for burden sharing.
Date: May 1, 2006
Creator: Wagner, Fabian & Sathaye, Jayant
Partner: UNT Libraries Government Documents Department

Identification and targeting of a TACE-dependent autocrine loopwhich predicts poor prognosis in breast cancer

Description: The ability to proliferate independently of signals from other cell types is a fundamental characteristic of tumor cells. Using a 3D culture model of human breast cancer progression, we have delineated a protease-dependent autocrine loop which provides an oncogenic stimulus in the absence of proto-oncogene mutation. Inhibition of this protease, TACE/ADAM17, reverts the malignant phenotype by preventing mobilization of two crucial growth factors, Amphiregulin and TGF{alpha}. We show further that the efficacy of EGFR inhibitors is overcome by physiological levels of growth factors and that successful EGFR inhibition is dependent on reducing ligand bioavailability. Using existing patient outcome data, we demonstrate a strong correlation between TACE and TGF{alpha} expression in human breast cancers that is predictive of poor prognosis.
Date: June 15, 2005
Creator: Kenny, Paraic A. & Bissell, Mina J.
Partner: UNT Libraries Government Documents Department

Process Control Minitoring by Stress Response

Description: Environmental contamination with a variety of pollutants hasprompted the development of effective bioremediation strategies. But howcan these processes be best monitored and controlled? One avenue underinvestigation is the development of stress response systems as tools foreffective and general process control. Although the microbial stressresponse has been the subject of intensive laboratory investigation, theenvironmental reflection of the laboratory response to specific stresseshas been little explored. However, it is only within an environmentalcontext, in which microorganisms are constantly exposed to multiplechanging environmental stresses, that there will be full understanding ofmicrobial adaptive resiliency. Knowledge of the stress response in theenvironment will facilitate the control of bioremediation and otherprocesses mediated by complex microbial communities.
Date: April 17, 2006
Creator: Hazen, Terry C. & Stahl, David A.
Partner: UNT Libraries Government Documents Department

Market failures, consumer preferences, and transaction costs inenergy efficiency purchase decisions

Description: Several factors limit the energy savings potential and increase the costs of energy-efficient technologies to consumers. These factors may usefully be placed into two categories; one category is what economists would define as market failures and the other is related to consumer preferences. This paper provides a conceptual framework for understanding the roles of these factors, and develops a methodology to quantify their effects on costs and potentials of two energy efficient end uses - residential lighting and clothes washers. It notes the significant roles played by the high implicit cost of obtaining information about the benefits of the two technologies and the apparent inability to process and utilize information. For compact fluorescent lamps, this report finds a conservative estimate of the cost of conserved energy of 3.1 cents per kWh. For clothes washers, including water savings reduces the cost of conserved energy from 13.6 cents to 4.3 cents per equivalent kWh. Despite these benefits, market share remains low. About 18 million tons of CO2 could be saved cost effectively from 2005 sales of these two technologies alone. The paper also notes that trading of carbon emissions will incur transaction costs that will range from less than 10 cents per metric ton of CO2 for larger size projects and programs to a few dollars per metric ton of carbon for the smaller ones.
Date: November 23, 2004
Creator: Sathaye, Jayant & Murtishaw, Scott
Partner: UNT Libraries Government Documents Department

Of extracellular matrix, scaffolds, and signaling: Tissuearchitectureregulates development, homeostasis, and cancer

Description: The microenvironment surrounding cells influences gene expression, such that a cell's behavior is largely determined by its interactions with the extracellular matrix, neighboring cells, and soluble cues released locally or by distant tissues. We describe the essential role of context and organ structure in directing mammary gland development and differentiated function, and in determining response to oncogenic insults including mutations. We expand on the concept of 'dynamic reciprocity' to present an integrated view of development, cancer, and aging, and posit that genes are like piano keys: while essential, it is the context that makes the music.
Date: March 9, 2006
Creator: Nelson, Celeste M. & Bissell, Mina J.
Partner: UNT Libraries Government Documents Department

On the transport of emulsions in porous media

Description: Emulsions appear in many subsurface applications includingbioremediation, surfactant-enhanced remediation, and enhancedoil-recovery. Modeling emulsion transport in porous media is particularlychallenging because the rheological and physical properties of emulsionsare different from averages of the components. Current modelingapproaches are based on filtration theories, which are not suited toadequately address the pore-scale permeability fluctuations and reductionof absolute permeability that are often encountered during emulsiontransport. In this communication, we introduce a continuous time randomwalk based alternative approach that captures these unique features ofemulsion transport. Calculations based on the proposed approach resultedin excellent match with experimental observations of emulsionbreakthrough from the literature. Specifically, the new approach explainsthe slow late-time tailing behavior that could not be fitted using thestandard approach. The theory presented in this paper also provides animportant stepping stone toward a generalizedself-consistent modeling ofmultiphase flow.
Date: June 27, 2007
Creator: Cortis, Andrea & Ghezzehei, Teamrat A.
Partner: UNT Libraries Government Documents Department

Targeting the tumor microenvironment

Description: Despite some notable successes cancer remains, for the most part, a seemingly intractable problem. There is, however, a growing appreciation that targeting the tumor epithelium in isolation is not sufficient as there is an intricate mutually sustaining synergy between the tumor epithelial cells and their surrounding stroma. As the details of this dialogue emerge, new therapeutic targets have been proposed. The FDA has already approved drugs targeting microenvironmental components such as VEGF and aromatase and many more agents are in the pipeline. In this article, we describe some of the 'druggable' targets and processes within the tumor microenvironment and review the approaches being taken to disrupt these interactions.
Date: November 7, 2006
Creator: Kenny, P.A.; Lee, G.Y. & Bissell, M.J.
Partner: UNT Libraries Government Documents Department

Proteomic Analysis of Calcium- and Phosphorylation-dependentCalmodulin Complexes in Mammalian Cells

Description: Protein conformational changes due to cofactor binding (e.g. metal ions, heme) and/or posttranslational modifications (e.g. phosphorylation) modulate dynamic protein complexes. Calmodulin (CaM) plays an essential role in regulating calcium (Ca{sup 2+}) signaling and homeostasis. No systematic approach on the identification of phosphorylation-dependent Ca{sup 2+}/CaM binding proteins has been published. Herein, we report a proteome-wide study of phosphorylation-dependent CaM binding proteins from mammalian cells. This method, termed 'Dynamic Phosphoprotein Complex Trapping', 'DPPC Trapping' for short, utilizes a combination of in vivo and in vitro assays. The basic strategy is to drastically shift the equilibrium towards endogenous phosphorylation of Ser, Thr, and Tyr at the global scale by inhibiting corresponding phosphatases in vivo. The phosphorylation-dependent calmodulin-binding proteins are then trapped in vitro in a Ca{sup 2+}-dependent manner by CaM-Sepharose chromatography. Finally, the isolated calmodulin-binding proteins are separated by SDS-PAGE and identified by LC/MS/MS. In parallel, the phosphorylation-dependent binding is visualized by silver staining and/or Western blotting. Using this method, we selectively identified over 120 CaM-associated proteins including many previously uncharacterized. We verified ubiquitin-protein ligase EDD1, inositol 1, 4, 5-triphosphate receptor type 1 (IP{sub 3}R1), and ATP-dependent RNA helicase DEAD box protein 3 (DDX3), as phosphorylation-dependent CaM binding proteins. To demonstrate the utilities of our method in understanding biological pathways, we showed that pSer/Thr of IP{sub 3}R1 in vivo by staurosporine-sensitive kinase(s), but not by PKA/PKG/PKC, significantly reduced the affinity of its Ca{sup 2+}-dependent CaM binding. However, pSer/Thr of IP{sub 3}R1 did not substantially affect its Ca{sup 2+}-independent CaM binding. We further showed that phosphatase PP1, but not PP2A or PP2B, plays a critical role in modulating the phosphorylation-dependent CaM binding for IP{sub 3}R1. If combined with other phosphoprotein and phosphopeptide enrichment techniques such as IMAC, our method may serve as a general strategy to identify and characterize phosphorylation-dependent and functionally important protein ...
Date: May 26, 2006
Creator: Jang, Deok-Jin & Wang, Daojing
Partner: UNT Libraries Government Documents Department

Nanometer-scale imaging and pore-scale fluid flow modeling inchalk

Description: For many rocks of high economic interest such as chalk,diatomite, tight gas sands or coal, nanometer scale resolution is neededto resolve the 3D-pore structure, which controls the flow and trapping offluids in the rocks. Such resolutions cannot be achieved with existingtomographic technologies. A new 3D imaging method, based on serialsectioning and using the Focused Ion Beam (FIB) technology has beendeveloped. FIB allows for the milling of layers as thin as 10 nanometersby using accelerated Ga+ ions to sputter atoms from the sample surface.After each milling step, as a new surface is exposed, a 2D image of thissurface is generated. Next, the 2D images are stacked to reconstruct the3D pore or grain structure. Resolutions as high as 10 nm are achievableusing this technique. A new image processing method uses directmorphological analysis of the pore space to characterize thepetrophysical properties of diverse formations. In addition to estimationof the petrophysical properties (porosity, permeability, relativepermeability and capillary pressures), the method is used for simulationof fluid displacement processes, such as those encountered in variousimproved oil recovery (IOR) approaches. Computed with the new methodcapillary pressure curves are in good agreement with laboratory data. Themethod has also been applied for visualization of the fluid distributionat various saturations from the new FIB data.
Date: August 23, 2005
Creator: Tomutsa, Liviu; Silin, Dmitriy & Radmilovich, Velimir
Partner: UNT Libraries Government Documents Department

Pore-scale spectral induced polarization (SIP) signaturesassociated with FeS biomineral transformations

Description: The authors measured Spectral Induced Polarization (SIP) signatures in sand columns during (1) FeS biomineralization produced by sulfate reducing bacteria (D. vulgaris) under anaerboci conditions, and (2) subsequent biomineral dissolution upon return to an aerobic state. The low-frequency (0.1-10 Hz peak) relaxations produced during biomineralization can be modeled with a Cole-Cole formulation, from which the evolution of the polarization magnitude and relaxation length scale can be estimated. They find that the modeled time constant is consistent with the polarizable elements being biomineral encrused pores. Evolution of the model parameters is consistent with FeS surface area increases and pore-size reduction during biomineral growth, and subsequent biomineral dissolution (FeS surface area decreases and pore expansion) upon return to the aerobic state. They conclude that SIP signatures are diagnostic of pore-scale geometrical changes associated with FeS biomineralization by sulfate reducing bacteria.
Date: October 1, 2007
Creator: Slater, Lee; Ntarlagiannis, Dimitrios; Personna, Yves R. & Hubbard, Susan
Partner: UNT Libraries Government Documents Department

Horizontal gene transfer and the evolution of transcriptionalregulation in Escherichia coli

Description: Background: Most bacterial genes were acquired by horizontalgene transfer from other bacteria instead of being inherited bycontinuous vertical descent from an ancient ancestor}. To understand howthe regulation of these {acquired} genes evolved, we examined theevolutionary histories of transcription factors and of regulatoryinteractions from the model bacterium Escherichia coli K12. Results:Although most transcription factors have paralogs, these usually arose byhorizontal gene transfer rather than by duplication within the E. colilineage, as previously believed. In general, most neighbor regulators --regulators that are adjacent to genes that they regulate -- were acquiredby horizontal gene transfer, while most global regulators evolvedvertically within the gamma-Proteobacteria. Neighbor regulators wereoften acquired together with the adjacent operon that they regulate, sothe proximity might be maintained by repeated transfers (like "selfishoperons"). Many of the as-yet-uncharacterized (putative) regulators havealso been acquired together with adjacent genes, so we predict that theseare neighbor regulators as well. When we analyzed the histories ofregulatory interactions, we found that the evolution of regulation byduplication was rare, and surprisingly, many of the regulatoryinteractions that are shared between paralogs result from convergentevolution. Another surprise was that horizontally transferred genes aremore likely than other genes to be regulated by multiple regulators, andmost of this complex regulation probably evolved after the transfer.Conclusions: Our results highlight the rapid evolution of niche-specificgene regulation in bacteria.
Date: December 20, 2007
Creator: Price, Morgan N.; Dehal, Paramvir S. & Arkin, Adam P.
Partner: UNT Libraries Government Documents Department

Transitive closure and metric inequality of weighted graphs:detecting protein interaction modules using cliques

Description: We study transitivity properties of edge weights in complex networks. We show that enforcing transitivity leads to a transitivity inequality which is equivalent to ultra-metric inequality. This can be used to define transitive closure on weighted undirected graphs, which can be computed using a modified Floyd-Warshall algorithm. We outline several applications and present results of detecting protein functional modules in a protein interaction network.
Date: June 2, 2006
Creator: Ding, Chris; He, Xiaofeng; Xiong, Hui; Peng, Hanchuan & Holbrook,Stephen R.
Partner: UNT Libraries Government Documents Department

The Shewanella oneidensis MR-1 Fluxome under Various OxygenConditions

Description: The central metabolic fluxes of Shewanella oneidensis MR-1were examined under carbon-limited (aerobic) and oxygen-limited(micro-aerobic) chemostat conditions using 13C labeled lactate as thesole carbon source. The carbon labeling patterns of key amino acids inbiomass were probed using both GC-MS and 13C-NMR. Based on the genomeannotation, a metabolic pathway model was constructed to quantify thecentral metabolic flux distributions. The model showed that thetricarboxylic acid (TCA) cycle is the major carbon metabolism route underboth conditions. The Entner-Doudoroff and pentose phosphate pathways weremainly utilized for biomass synthesis (flux below 5 percent of thelactate uptake rate). The anapleurotic reactions (pyruvate to malate andoxaloacetate to phosphoenolpyruvate) and the glyoxylate shunt wereactive. Under carbon-limited conditions, a substantial amount of carbonwas oxidized via the highly reversible serine metabolic pathway. Fluxesthrough the TCA cycle were less whereas acetate production was more underoxygen limitation than under carbon limitation. Although fluxdistributions under aerobic, micro-aerobic, and shake-flask cultureconditions were dramatically different, the relative flux ratios of thecentral metabolic reactions did not vary significantly. Hence, S.oneidensis metabolism appears to be quite robust to environmentalchanges. Our study also demonstrates the merit of coupling GC-MS with 13CNMR for metabolic flux analysis to reduce the use of 13C labeledsubstrates and to obtain more accurate flux values.
Date: March 17, 2006
Creator: Tang, Yinjie J.; Hwang, Judy S.; Wemmer, David E. & Keasling, Jay D.
Partner: UNT Libraries Government Documents Department

Rap1 integrates tissue polarity, lumen formation, and tumorigenicpotential in human breast epithelial cells

Description: Maintenance of apico-basal polarity in normal breast epithelial acini requires a balance between cell proliferation, cell death, and proper cell-cell and cell-extracellular matrix signaling. Aberrations in any of these processes can disrupt tissue architecture and initiate tumor formation. Here we show that the small GTPase Rap1 is a crucial element in organizing acinar structure and inducing lumen formation. Rap1 activity in malignant HMT-3522 T4-2 cells is appreciably higher than in S1 cells, their non-malignant counterparts. Expression of dominant-negative Rap1 resulted in phenotypic reversion of T4-2 cells, led to formation of acinar structures with correct apico-basal polarity, and dramatically reduced tumor incidence despite the persistence of genomic abnormalities. The resulting acini contained prominent central lumina not observed when other reverting agents were used. Conversely, expression of dominant-active Rap1 in T4-2 cells inhibited phenotypic reversion and led to increased invasiveness and tumorigenicity. Thus, Rap1 acts as a central regulator of breast architecture, with normal levels of activation instructing apical polarity during acinar morphogenesis, and increased activation inducing tumor formation and progression to malignancy.
Date: September 29, 2006
Creator: Itoh, Masahiko; Nelson, Celeste M.; Myers, Connie A. & Bissell,Mina J.
Partner: UNT Libraries Government Documents Department

Isotopic Studies of Contaminant Transport at the Hanford Site,WA

Description: Processes of fluid flow and chemical transport through thevadose zone can be characterized through the isotopic systematics ofnatural soils, minerals, pore fluids and groundwater. In thiscontribution, we first review our research using measured isotopicvariations, due both to natural and site related processes, of theelements H, O, N, Sr and U, to study the interconnection between vadosezone and groundwater contamination at the Hanford Site in south-centralWashington. We follow this brief review with a presentation of new datapertaining to vadose zone and groundwater contamination in the WMAT-TX-TY vicinity. Uranium (U) isotopic data for the C3832 core (WMA TX)indicates the involvement of processed natural U fuel, and links theobserved U contamination to the nearby single shelled tank TX-104. Thedata also precludes contamination from an early 1970 s TX-107 leak. Inthe case of the C4104 core (WMA T), the U isotopic data indicates amixture of processed natural and enriched U fuels consistent with themajor leak from T-106 in 1973. Uranium and Strontium isotopic data forthe cores also provides direct evidence for chemical interaction betweenhigh-pH waste fluid and sediment. Isotopic data for groundwater nitratecontamination in the vicinity of WMA-T strongly suggests high-level tankwaste (most likely from T-106) as the source of very high 99Tcconcentrations recently observed at the NE corner of WMAT.
Date: November 1, 2006
Creator: Christensen, J.N.; Conrad, M.E.; DePaolo, D.J. & Dresel, P.E.
Partner: UNT Libraries Government Documents Department