Abstract: The invention provides methods of characterising the mode of action of a test compound by exposing populations of a living system to control and treatment conditions, using an unlabeled and labeled isotope source materials. The measurement of the isotopomer distribution of metabolites reveals the effect of the test compounds on the metabolism in that living systems. Further embodiments include where the living system is a plant, fungus, invertebrate, bacteria or virus, and where the test compound is a screening lead in a pesticide product development program.

Abstract: The present invention relates to an isotope labeling chamber for labeling metabolites in an organism, comprising a reactor chamber (1) and an air regulation chamber (2), wherein the reactor chamber (1) comprises the following components: optionally, a housing frame (3), housing walls (4), at least one injection valve (5), where at least one housing wall (4) can be opened fully and/or in part and where at least one housing wall has a lock (6), and furthermore wherein the air regulation chamber (2) comprises the following components: a temperature-regulating unit (7), an air humidification unit (8) and a gas absorption unit (9). Furthermore, the invention relates to a labeling method for plants in which the labeling chamber according to the invention is employed.

Abstract: The present invention provides a method for profiling phytohormone levels in plant tissue or tissue of other plastid containing organisms, i.e. a method for the simultaneous determination of a multitude of phytohormone levels in plant tissue or tissue of other plastid containing organisms.

Abstract: The present invention relates to an isotope labeling chamber for labeling metabolites in an organism, comprising a reactor chamber (1) and an air regulation chamber (2), wherein the reactor chamber (1) comprises the following components: optionally, a housing frame (3), housing walls (4), at least one injection valve (5), where at least one housing wall (4) can be opened fully and/or in part and where at least one housing wall has a lock (6), and furthermore wherein the air regulation chamber (2) comprises the following components: a temperature-regulating unit (7), an air humidification unit (8) and a gas absorption unit (9). Furthermore, the invention relates to a labeling method for plants in which the labeling chamber according to the invention is employed.

Abstract: The present invention provides a method for profiling phytohormone levels in plant tissue or tissue of other plastid containing organisms, i.e. a method for the simultaneous determination of a multitude of phytohormone levels in plant tissue or tissue of other plastid containing organisms, which method comprises the following steps: i. extraction of particulate tissue material of the plastid containing organism, in particulate tissue material of plants, with a liquid extractant, which is a mixture of at least one water miscible neutral organic solvent having from 1 to 3 carbon atoms and 1 heteroatom selected from O and N with water containing from 0.1 to 5% by weight, based on the extractant, of at least one acid, whereby a first liquid extract is obtained; ii. contacting the liquid extract obtained in step i. with a solid absorbent having a hydrophobically modified surface and removing the solid absorbent to obtain a second liquid extract; iii.