Using C enriched acetate in isotope labelling incubation experiments: a note of caution.

Vapour-phase fumigation with HCl is routinely used to remove inorganic carbon in preparation for the measurement of the concentration and C value of organic carbon in a sample using elemental analysis coupled to an isotope ratio mass spectrometer. Acidification of the sample to be analyzed can lead to the loss of low molecular weight conjugate bases as volatile organic acids during the acidification and/or the drying steps following fumigation, through protonation of the conjugate base and volatilization. Such loss could lead to a severe bias in incubation experiments where C-enriched compounds such as acetate are used to trace reaction pathways or metabolites in a cultivation medium or a mesocosm for example.

The Ubiquitous Soil Terpene Geosmin Acts as a Warning Chemical.

Known as the smell of earth after rain, geosmin is an odorous terpene detectable by humans at picomolar concentrations. Geosmin production is heavily conserved in actinobacteria, myxobacteria, cyanobacteria, and some fungi, but its biological activity is poorly understood. We theorized that geosmin was an aposematic signal used to indicate the unpalatability of toxin-producing microbes, discouraging predation by eukaryotes.

Influence of dose-death interval on colchicine and metabolite distribution in decomposed skeletal tissues.

The semi-quantitative analysis of decomposed bone of rats exposed to colchicine and euthanized following different time intervals postexposure (i.e., dose-death interval, DDI) is described.