Department Environmental Toxicology

Metabolomics in green algae


Aquatic organisms are exposed to an ever-increasing variety of chemicals. In the area of chemical risk assessment and molecular ecotoxicology it is therefore crucial to identify and understand the underlying molecular mechanisms of their stress response. Metabolites reflect the current biochemical state of an organism and hence can be used to capture the dynamics of the metabolic network in response to stress. Metabolic changes happen on a smaller timescale than the resulting physiological changes. In order to obtain insights into these metabolic adaptations we use a high throughput direct infusion method for the analysis of primary metabolites in algae and zebrafish at high temporal resolution and high number of experimental conditions.

Currently we are analyzing the metabolic response of model organisms to silver, zinc, copper and aluminum. A collaborative seed project with Anita Narwani (Eco) will investigate the impact of temperature and resource limitation on phytoplankton metabolism.

Publications

Multimode gradient high performance liquid chromatography mass spectrometry method applicable to metabolomics and environmental monitoring

Metabolomics or environmental investigations generate samples containing very large numbers of small molecular weight analytes. A single mode chromatographic separation excludes a substantial part of such complex analyte mixtures. For instance, a reversed-phase separation would not retain ionic species, resulting in a correspondingly huge front peak. To address this problem, we used two commercially available mixed-mode ion-exchange reversed-phase columns (WAX-1 and WCX-1) in sequence in a novel multimode separation method.
After trapping hydrophobics on a C18-trap in loop position, hydrophilics passing the trap are separated by a simultaneous gradient for HILIC, anion and cation exchange chromatography. This gradient ends in a washout phase with a high percentage of water, the correct starting conditions for a reversed-phase gradient eluting hydrophobics from the trap in a second step of the run. Amino acids (9), organic acids (2), sugars (8), fatty acid derived compounds (11), antioxidants (4), miscellanea (6) and xenobiotics (4) were analyzed. Compounds were separated after a single sample injection during a 50 min run. Lipids derived small fatty acids up to a chain length of 12 carbons were also accessible within this run time.
Ammann, A. A.; Suter, M. J. -F. (2016) Multimode gradient high performance liquid chromatography mass spectrometry method applicable to metabolomics and environmental monitoring, Journal of Chromatography A, 1456, 145-151, doi:10.1016/j.chroma.2016.06.001, Institutional Repository