Joel T Smith

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The stringent response to amino acid starvation, whereby stable RNA synthesis is curtailed in favour of transcription of amino acid biosynthetic genes, is controlled by the alarmone ppGpp. To elucidate the extent of gene expression effected by ppGpp, we designed an experimental system based on starvation for isoleucine, which could be applied to both(More)
GC-MS-based metabolite profiling was used to analyse the response of Medicago truncatula cell cultures to elicitation with methyl jasmonate (MeJa), yeast elicitor (YE), or ultraviolet light (UV). Marked changes in the levels of primary metabolites, including several amino acids, organic acids, and carbohydrates, were observed following elicitation with(More)
The carbon sources that support the growth of pathogenic Escherichia coli O157:H7 in the mammalian intestine have not previously been investigated. In vivo, the pathogenic E. coli EDL933 grows primarily as single cells dispersed within the mucus layer that overlies the mouse cecal epithelium. We therefore compared the pathogenic strain and the commensal E.(More)
A new approach involving the stepwise increase in electroosmotic flow during analysis in capillary zone electrophoresis is introduced and evaluated in the rapid separations of proteins and peptides. The stepwise increase in electroosmotic flow is based on the principle of coupled capillaries in series having different flow characteristics, a concept that(More)
Legumes such as alfalfa (Medicago sativa L.), barrel medic (Medicago truncatula), white sweet clover (Melilotus alba) and fenugreek (Trigonella graecum), normally accumulate (-)-medicarpin and its malonated glucose conjugate as natural inhibitors of fungal pathogens. These plants also accumulate the biosynthetic precursor formononetin as well as the(More)
This article represents an extension to a new approach introduced very recently by our laboratory for the control of the surface charge density as well as the hydrophobic character of micellar phases used in micellar electrokinetic capillary chromatography (MECC). The approach is based on the complexation of polyolic surfactants, e.g., alkylglucosides, with(More)
In this study, we investigated a novel series of micelle modifiers useful to alter selectivity in micellar electrokinetic capillary chromatography (MEKC). These modifiers were alkyl polyalcohols, including 1-octanol, 1,2-octanediol, 1,2,3-octanetriol, 1,2-hexanediol, and 1,2-butanediol, which act as class I organic modifiers in that their effects are on the(More)
A series of capillary surface modifications entailing multilayered coatings were introduced and evaluated in capillary zone electrophoresis of biological substances, e.g., proteins, peptides, oligosaccharides and nucleotides. In one set of surface modifications, large molecular weight hydroxypropyl cellulose afforded "zero" flow capillaries, which were used(More)
A CE-MS method for metabolic profiling of amino acids was developed and used in an integrated functional genomics project to study the response of Medicago truncatula liquid suspension cell cultures to stress. This project required the analysis of more than 500 root cell culture extracts. The CE-MS method profiled 20 biologically important amino acids. The(More)