Structural identification of an anthrasteroid hydrocarbon from the sheep tick Ixodes ricinus

Teaching (and learning from) metabolomics: the 2006 PlantMetaNet ETNA Metabolomics Research School

Under the auspices of the European Training and Networking Activity programme of the European Union, a 'Metabolic Profiling and Data Analysis' Plant Genomics and Bioinformatics Summer School was hosted in Potsdam, Germany between 20 and 29 September 2006. Sixteen early career researchers were invited from the European Union partner nations and the so-called developing nations (Appendix). Lectures from invited leading European researchers provided an overview of the state of the art of these fields and seeded discussion regarding major challenges for their future advancement. Hands-on experience was provided by an example experiment - that of defining the metabolic response of Arabidopsis to treatment of a commercial herbicide of defined mode of action. This experiment was performed throughout the duration of the course in order to teach the concepts underlying extraction and machine handling as well as to provide a rich data set with which the required computation and statistical skills could be illustrated. Here we review the state of the field by describing both key lectures given at and practical aspects taught at the summer school. In addition, we disclose results that were obtained using the four distinct technical platforms at the different participating institutes. While the effects of the chosen herbicide are well documented, this study looks at a broader number of metabolites than in previous investigations. This allowed, on the one hand, not only to characterise further effects of the herbicide than previously observed but also to detect molecules other than the herbicide that were obviously present in the commercial formulation. These data and the workshop in general are all discussed in the context of the teaching of metabolomics.

Single insect NMR: A new tool to probe chemical biodiversity

Because of analytical limitations, multiple animals or plants are typically required to identify natural products. Using a unique 1-mm high-temperature superconducting NMR probe, we directly examined the chemical composition of defensive secretions from walking stick insects. Individual milkings were dissolved in D2O without purification and examined by NMR within 10 min of secretion. We found that Anisomorpha buprestoides secretes similar quantities of glucose and mixtures of monoterpene dialdehydes that are stereoisomers of dolichodial. Different individual animals produce different stereoisomeric mixtures, the ratio of which varies between individual animals raised in the same container and fed the same food. Another walking stick, Peruphasma schultei, also secretes glucose and a single, unique stereoisomer that we are naming "peruphasmal". These observations suggest a previously unrecognized significance of aqueous components in walking stick defensive sprays. Single-insect variability of venom demonstrates the potential importance of chemical biodiversity at the level of individual animals.