Melissa J. Towler

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The potent antimalarial sesquiterpene lactone, artemisinin, is produced in low quantities by the plant Artemisia annua L. The source and regulation of the isopentenyl diphosphate (IPP) used in the biosynthesis of artemisinin has not been completely characterized. Terpenoid biosynthesis occurs in plants via two IPP-generating pathways: the mevalonate pathway(More)
Transformed root cultures of Artemisia annua grown in autoclaved medium show large variations in biomass and artemisinin production regardless of the culture conditions or clonal type. However, using filter-sterilized sugars singly or in combination while holding the carbon level in the medium constant resulted in an unexpected variability in biomass(More)
The antimalarial sesquiterpene, artemisinin, is in short supply; demand is not being met, and the role of artemisinin in the plant is not well established. Prior work showed that addition of dimethyl sulfoxide (DMSO) to seedlings increased artemisinin in their shoots and this study further investigated that serendipitous observation. When in vitro-cultured(More)
Rooting of Artemisia annua increases trichome size on leaves and helps drive the final steps of the biosynthesis of the sesquiterpene antimalarial drug, artemisinin. Artemisia annua produces the antimalarial drug, artemisinin (AN), which is synthesized and stored in glandular trichomes (GLTs). In vitro-grown A. annua shoots produce more AN when they form(More)
We compared the growth and productivity of a tobacco line of hairy roots that produces murine interleukin 12 (mIL-12) grown in three different culture systems: shake flasks, an airlift reactor, and a scalable mist reactor. Of the total mIL-12 produced by cultures grown in shake flasks ( approximately 434.8 microg L(-1)), almost 21% was recovered from the(More)
Despite significant efforts over nearly 30 years, only a few products produced by in vitro plant cultures have been commercialized. Some new advances in culture methods and metabolic biochemistry have improved the useful potential of plant cell cultures. This review will provide references to recent relevant reviews along with a critical analysis of the(More)
Gas-phase reactors, including the mist reactor, have distinct advantages over liquid-phase reactors including the ability to manipulate the gas composition, to allow effective gas exchange in a densely growing biomass, and to affect secondary metabolite production. Mathematical modeling suggested that roots in a mist reactor are often too sparsely packed to(More)
A number of flavonoids including casticin and artemetin from Artemisia annua have shown synergism with artemisinin against Plasmodium falciparum, but it is unclear if the flavonoids are also extracted into a tea infusion of the plant. Using a tea infusion preparation protocol that was reported to be highly effective for artemisinin extraction, we measured(More)
The ability to immobilize plant tissue in a bioreactor is an important process tool. We have shown that roots of several species rapidly attach to poly-L-lysine coated polypropylene mesh in a liquid environment. Using transformed roots of Artemisia annua as a model, the attachment process was found to be enhanced by sheep serum, but not BSA and inhibited by(More)
Pharmaceutical monotherapies against human malaria have proven effective, although ephemeral, owing to the inevitable evolution of resistant parasites. Resistance to two or more drugs delivered in combination will evolve more slowly; hence combination therapies have become the preferred norm in the fight against malaria. At the forefront of these efforts(More)