Key Cell-Physiological Parameters

SysMO is a European transnational funding and research initiative on "Systems Biology of Microorganisms".

The goal pursued by SysMO was to record and describe the dynamic molecular processes going on in unicellular microorganisms in a comprehensive way and to present these processes in the form of computerized mathematical models.

Systems biology will raise biomedical and biotechnological research to a new quality level and contribute markedly to progress in understanding. Pooling European research ...

Gene interaction networks and models of cation homeostasis in Saccharomyces cerevisiae

Experimental approaches to evaluate cellular response to Potassium limitation. For this purpose, a series of isogenic strains derived from BY4741 and lacking one (TRK1 or TRK2) or both TRK genes encoding specific potassium uptake systems was constructed using the homologous recombination and Cre-lox system.

Is cell volume affected by potassium starvation?

The volume reduction as a response to the shift of cells from a medium of high potassium to potassium free medium will be studied in mutants lacking certain membrane transporters like Trk1,2 Nha1, etc. The conditions for the experiments follow Navarrete et al. (2010). Additionally knockouts of related regulation proteins (SAP155, SAP185) will be tested. For each mutant several time points will be measured to generate time courses.

Time courses of the internal pH changes under the conditions of Navarrete et al. (2010) will be obtained. The usage of different mutants (transport systems and regulation factors) will reveal the influence and key systems of pH regulation.

To estimate the changes of internal pH, the pH-dependent variant of GFP pHluorin is expressed in cells from a multicopy plasmid, and the changes in cell fluorescence are monitored during 5 hours of incubation in YNB-F growth media without added potassium.

How does internal potassium changes (decreases) during several hours of potassium starvation. Is there a limit for internal potassium decrease? Sampling potassium content in cells during starvation The relative membrane potential will be measured according to the conditions of Navarrete et al. (2010). Various mutants will be tested for their effect. To estimate the relative changes of plasma-membrane potential, the diSC3(3) fluorescent probe was used and the changes in cell fluorescence monitored ...

Determination of protein content at several times.

The potassium content measurements of Navarrete et al. (2010) are the basis for potassium content analysis in various mutants (Nha1, Trk1, Trk2).

External concentration changes under the conditions of Navarrete et al. (2010) will be estimated from the internal concentration changes and the volume ratio of cell sample to medium.

External pH changes for the conditions of Navarrete et al. (2010) will be estimated from the internal pH changes and the volume ratio of cell sample to medium.

To estimate the relative level of plasma-membrane potential in the wild type, single trk1 and trk2 or double trk1 trk2 mutants, the diSC3(3) fluorescent probe was added to cells grown under various conditions and the levels of cell fluorescence were monitored.