Measurement of changes in CO2 generated from propionate in Caenorhabditis elegans using novel 13CO2 gas analysis

Caenorhabditis elegans contains two pathways for propionate metabolism, the vitamin B12-dependent and shunt pathways, which are similar to those in humans. In this study, we monitored the changes in propionate metabolism in the whole body of C. elegans using novel 13CO2 gas analysis. We measured the increase in 13CO2 excreted in the air after administering [1-13C]-labeled propionate ([13C]propionate) to the worms. The 13CO2 generated from [13C]propionate in C. elegans increased in a dose-dependent manner, reaching a maximum at 48 h. Enhanced expression of propionate metabolism-related genes was observed after administration of propionate. Knockdown of mmcm-1, which encodes the rate-limiting enzyme of the propionate metabolism, using RNAi reduced 13CO2 excretion. Thus, 13CO2 gas analysis could be confirmed 13CO2 excretion associated with changes in the metabolism of [13C]propionate in nematodes. This analysis can contribute to further understanding of the physiological effects of short-chain fatty acids.