Damien L. Callahan

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BACKGROUND Rice is the primary source of food for billions of people in developing countries, yet the commonly consumed polished grain contains insufficient levels of the key micronutrients iron (Fe), zinc (Zn) and Vitamin A to meet daily dietary requirements. Experts estimate that a rice-based diet should contain 14.5 µg g(-1) Fe in endosperm, the main(More)
Metal-hyperaccumulating plants have the ability to take up extraordinary quantities of certain metal ions without succumbing to toxic effects. Most hyperaccumulators select for particular metals but the mechanisms of selection are not understood at the molecular level. While there are many metal-binding biomolecules, this review focuses only on ligands that(More)
Many species of microalgae produce greatly enhanced amounts of triacylglycerides (TAGs), the key product for biodiesel production, in response to specific environmental stresses. Improvement of TAG production by microalgae through optimization of growth regimes is of great interest. This relies on understanding microalgal lipid metabolism in relation to(More)
The lipid characteristics of microalgae are known to differ between species and change with growth conditions. This work provides a methodology for lipid characterization that enables selection of the optimal strain, cultivation conditions, and processing pathway for commercial biodiesel production from microalgae. Two different microalgal species,(More)
Walls from wheat (Triticum aestivum L.) endosperm are composed primarily of hetero-(arabino)xylans (AXs) (70%) and (1→3)(1→4)-β-D-glucans (20%) with minor amounts of cellulose and heteromannans (2% each). To understand the differential solubility properties of the AXs, as well as aspects of their biosynthesis, we are sequencing the xylan backbone and(More)
Targeted liquid chromatography-mass spectrometry (LC-MS) technology using size exclusion chromatography and metabolite profiling based on gas chromatography-mass spectrometry (GC-MS) were used to study the nickel-rich latex of the hyperaccumulating tree Sebertia acuminata. More than 120 compounds were detected, 57 of these were subsequently identified. A(More)
Experimental evidence suggests that nicotianamine (NA) is involved in the complexation of metal ions in some metal-hyperaccumulating plants. Closely-related nickel (Ni)- and zinc (Zn)-hyperaccumulating species were studied to determine whether a correlation exists between the Ni and Zn concentrations and NA in foliar tissues. A liquid chromatography-mass(More)
Metabolic engineering of omega-3 long-chain (≥C20) polyunsaturated fatty acids (ω3 LC-PUFA) in oilseeds has been one of the key targets in recent years. By expressing a transgenic pathway for enhancing the synthesis of the ω3 LC-PUFA docosahexaenoic acid (DHA) from endogenous α-linolenic acid (ALA), we obtained the production of fish oil-like proportions of(More)
Phomenoic acid, a long chain aliphatic carboxylic acid is a major metabolite produced by Leptosphaeria maculans, a fungal pathogen of Brassica napus (canola). This fungus has 15 predicted polyketide synthases (PKS) and seven of them have the appropriate domains for the biosynthesis of phomenoic acid. The most highly expressed PKS gene after 7 days growth in(More)
Primary and secondary amines, including amino acids, biogenic amines, hormones, neurotransmitters, and plant siderophores, are readily derivatized with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate using easily performed experimental methodology. Complex mixtures of these amine derivatives can be fractionated and quantified using liquid(More)