RESPIROMETRIC TESTS ON YEAST CELLS LOCATED IN A SMALL SATELLITE SYSTEM

The primary aim of the research is to investigate about the respiratory activity (thermodynamics and kinetics) of eukaryotic cells in no gravity medium. This information can be precious both with reference to human activity in the same conditions and to possible applications to environmental sensing by respirometry [1-4]. One of the human main activities is surely respiration as strictly related to life condition: when breathing is not permitted, life expires. What happens to this function when excreted in a small satellite system ? How do the specific conditions there present affect the capacity of oxygen uptake and the shape of a respiration curve? In this presentation we face a research aiming to study the behaviour of a well common respirometric system, Saccharomyces Cerevisiae yeast cells when located within a closed system positioned inside a small satellite system. The experiments require particularly high attentions the respirometric models by themselves suffer a quite high variability (about 8%) due to the difficulty to rigorously control all the experimental conditions starting from the number of the tested cells. More the miniaturization of the Clark electrode to amperometrically determine oxygen brings to a further reason of uncertainness related to the high current density and consequent polarisation. On choosing with critical and analytical point of view the different aspects of the experiment we succeed in obtaining both a marked reproducibility (within 8%) and a stable signal, so the possibility to check any variation that would affect results, freeing us from misunderstanding these variations as due to the uncommon location of the experiment. Some problems were faced such as the aggregation of the cells able to close the circuit where solution is flowing in the experimental system, the formation of gaseous bubbles going to constitute cause of increasing electric resistance ,the rigorous stability of the applied tension, the miniaturization of reactor passed from a mean 20 mL model in normal lab to 1ml and less model when located in a small satellite system. In fig. 1,2,3,4 rhe components of trhe experimental circuit with electronics,cell,circuit and CAD project