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ABSTRACT: The Bronze2 (Bz2) gene in maize (Zea mays) encodes a glutathione S-transferase that performs the last genetically defined step in anthocyanin biosynthesis--tagging anthocyanin precursors with glutathione, allowing for recognition and entry of anthocyanins into the vacuole. Here we show that Bz2 gene expression is highly induced by heavy metals such as cadmium. Treatment of maize seedlings with cadmium results in a 20-fold increase in Bz2 message accumulation and a 50-fold increase in the presence of the unspliced, intron-containing transcript. The increase in message levels during cadmium stress appears to result, at least in part, from activation of an alternative mRNA start site approximately 200 nucleotides upstream of the normal start site; this site is not used in unstressed or heat-stressed tissues. The effect of cadmium on the RNA splicing of Bz2 seems to be specific: splicing of other intron-containing maize genes, including a maize actin gene under the control of the cadmium-inducible Bz2 promoter, is unaffected by cadmium stress. Conversely, Bz2 intron splicing is not affected by other stress conditions that induce Bz2 gene expression, such as abscisic acid, auxin, or cold stress. Surprisingly, the increase in Bz2 mRNA during cadmium stress does not result in an increase in Bz2 glutathione S-transferase activity. We propose that an alternative protein may be encoded by Bz2 that has a role during responses to heavy metals.
Plant physiology 02/1997; 113(1):93-102. · 6.53 Impact Factor
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ABSTRACT: Glutathione S-transferases (GSTs) are enzymes that detoxify heterocyclic compounds (xenobiotics) by covalently linking glutathione to the substrate, forming a glutathione S-conjugate. A glutathione pump in the vacuolar membrane of barley actively sequesters herbicide-glutathione S-conjugates; glutathionation allows recognition and entry of the conjugates into vacuoles. The protein encoded by the Bronze-2 gene in maize performs the last genetically defined step in anthocyanin biosynthesis, resulting in the deposition of red and purple pigments in the vacuoles of maize tissues. We show here that Bz2 encodes a GST with activity in maize, transformed Arabidopsis thaliana plants and Escherichia coli. We demonstrate that anthocyanins extracted from maize protoplasts expressing BZ2 are conjugated with glutathione, and that vanadate, a known inhibitor of the glutathione pump in plant vacuolar membranes, inhibits the accumulation of anthocyanins in the vacuole. These results provide a biochemical function for BZ2, and suggest a common mechanism for the ability of plants to sequester structurally similar but functionally diverse molecules in the vacuole.
Nature 07/1995; 375(6530):397-400. · 36.28 Impact Factor
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Methods in molecular biology (Clifton, N.J.) 02/1995; 55:121-31.
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Methods in molecular biology (Clifton, N.J.) 02/1995; 55:133-45.
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ABSTRACT: Whether caring for patients or conducting research, medical decision-makers need access to clinical data. To fulfill that need, commercial software developers have produced a wide range of database query tools that differ greatly in functionality and cost. Generally, tools that have a greater ability to conceal database complexity from the user also require more effort for administrative setup. We describe a cost-effective, commercially-available query tool that requires no special setup to perform most simple queries, yet can be customized to satisfy users' more complex querying requirements.
Proceedings / the ... Annual Symposium on Computer Application [sic] in Medical Care. Symposium on Computer Applications in Medical Care 02/1995;
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ABSTRACT: The time required to extract probabilities from medical literature is a primary reason decision analysis is not used more frequently for individual patient management decisions. Objective clinical trial information from the medical literature for one management decision was placed in a database which provided probabilities when queried. The database was tested with decision-analytic models of specific patient cases from the medical literature. Performance was assessed in terms of the ability to select trials which resembled the patients' individual characteristics, the number of trials providing probabilities for a given outcome, and the number of follow-up points available for that outcome. The timely assistance the database provides in expediting literature review and synthesis could enable the more common use of decision analysis in management decisions for individual patients.
Proceedings / the ... Annual Symposium on Computer Application [sic] in Medical Care. Symposium on Computer Applications in Medical Care 02/1995;
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ABSTRACT: With the consolidation of health care organizations and services, a clinical repository comprising data from a single site is no longer sufficient. Individual patient data are now spread across multiple sites comprising a single enterprise. Users require an integrated view, or at least a common view, of these clinical data across multiple sites. Many issues arise when one tries to merge data from multiple, distinct organizations into an existing schema. We have addressed these issues while extending our clinical repository for Barnes Hospital with data from Jewish Hospital, both of which are members of the recently formed BJC Health System. We describe the architecture of our existing repository, approaches and issues in extending this repository to include multiple sites, and the specific issues we addressed in our system.
Proceedings / the ... Annual Symposium on Computer Application [sic] in Medical Care. Symposium on Computer Applications in Medical Care 02/1995;
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ABSTRACT: Modern clinical information system developers recognize the need to associate temporal information with clinical data. However, specific clinical systems capture different temporal features using a variety of data modeling techniques. Two commonly used methods to represent temporal information are point-based events and interval-based durations. We recently implemented a rule-based expert system for drug dose monitoring on three clinical information systems. The expert system requires both static drug dosing information (drug name, amount, route, frequency) and temporal dosing information (duration of therapy, renewals, restarts). Our design goal was to use the same expert system code on all three information systems by defining a common database schema to hide differences in the original systems' data models. Although we have been successful in mapping clinical data from these three source systems into a unified temporal data representation, we describe how differences in handling time within the three clinical systems made this goal difficult to achieve.
Proceedings / the ... Annual Symposium on Computer Application [sic] in Medical Care. Symposium on Computer Applications in Medical Care 02/1995;
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ABSTRACT: We have isolated two genes from Zea mays encoding proteins of 82 and 81 kD that are highly homologous to the Drosophila 83-kD heat shock protein gene and have analyzed the structure and pattern of expression of these two genes during heat shock and development. Southern blot analysis and hybrid select translations indicate that the highly homologous hsp82 and hsp81 genes are members of a small multigene family composed of at least two and perhaps three or more gene family members. The deduced amino acid sequence of these proteins based on the nucleotide sequence of the coding regions shows 64-88% amino acid homology to other hsp90 family genes from human, yeast, Drosophila, and Arabidopsis. The promoter regions of both the hsp82 and hsp81 genes contain several heat shock elements (HSEs), which are putative binding sites for heat shock transcription factor (HSF) commonly found in the promoters of other heat shock genes. Gene-specific oligonucleotide probes were synthesized and used to examine the mRNA expression patterns of the hsp81 and hsp82 genes during heat shock, embryogenesis, and pollen development. The hsp81 gene is only mildly heat inducible in leaf tissue, but is strongly expressed in the absence of heat shock during the pre-meiotic and meiotic prophase stages of pollen development and in embryos, as well as in heat-shocked embryos and tassels. The hsp82 gene shows strong heat inducibility at heat-shock temperatures (37-42 degrees C) and in heat shocked embryos and tassels but is only weakly expressed in the absence of heat shock. Promoter-GUS reporter gene fusions made and analyzed by transient expression assays in Black Mexican Sweet (BMS) Maize protoplasts also indicate that the hsp82 and hsp81 are regulated differentially. The hsp82 promoter confers strong heat-inducible expression of the GUS reporter gene in heat-treated cells (60- to 80-fold over control levels), whereas the hsp81 promoter is only weakly heat inducible (5- to 10-fold over control levels).
Developmental Genetics 02/1993; 14(1):27-41.
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ABSTRACT: Access to clinical data which are distributed among multiple satellite information systems is crucial to delivering better care and reducing costs in many hospitals and medical centers. An integrated view of these data is needed to reduce the effort of users requiring data from multiple systems. We have addressed the issue of distributed data integration while developing both production and research decision-support applications. We describe an ideal integration solution, obstacles to realizing this solution, and our integration requirements and architecture. Our focus is a description of our specific schema and data integration techniques. We conclude with an analysis of our approach.
Proceedings / the ... Annual Symposium on Computer Application [sic] in Medical Care. Symposium on Computer Applications in Medical Care 02/1993;
