Published online by Cambridge University Press: 15 January 1999
Results obtained using a new technique for studying cell metabolism arepresented. The technique, consisting in CO2 production monitoring, has been appliedto Saccharomyces cerevisiae yeast cells. Also the cells were irradiated using thesoft X-ray laser-plasma source at Rutherford Appleton Laboratory with the aim of producing a damage of metabolic processes at the wall level, responsible forfermentation, without great interference with respiration, taking place inmitochondria, and DNA activity. The source was calibrated with PIN diodes and X-rayspectrometers and used Teflon stripes as target, emitting X-rays at about 0.9 keV, witha very low penetration in biological material. X-ray doses delivered to the differentcell compartments were calculated following a Lambert-Bouguet-Beer law. Immediatelyafter irradiation, the damage to metabolic activity was measured again by monitoringCO2 production. Results showed a general reduction in gas production by irradiatedsamples, together with non-linear and non-monotone response to dose. There was alsoevidence of oscillations in cell metabolic activity and of X-ray induced changes inoscillation frequency.