[Study of the intra- and extracellular electrolyte content in Paramecia cultures carried out during a space flight (author's transl)]. / Etude de la teneur intra et extracellulaire des electrolytes dans les cultures de Paramecies réalisées pendant un vol spatial.

In the results of previous investigations we have already reported that cultures of Paramecium tetraurelia submitted to a space flight present a stimulation of their proliferative ability, an increase in cell volume and a decrease in dry weight and in total protein content. These results suggest changes of cell metabolism induced by the space environment. In order to confirm this hypothesis we have studied the concentration of extracellular electrolytes in the control and the in-flight culture media with respect to the intracellular content of the same electrolytes. These measures concern Na, Cl, K, P, Mg, Ca. In this paper we report the results of these analyses and note that if no differences are noted for Na and Cl between control and in-flight cultures, modifications in P, K, Ca and Mg levels are observed. Generally there is a higher concentration of these elements in the in-flight medium but, in contrast, a lower intracellular content is noted for in-flight Paramecia. We have established a double comparison: on the one hand between control and in-flight media and between control and in flight cells, on the other hand between media and cells. All these data suggest possible changes in the membrane permeability, or of the binding proteins in Paramecia cultivated in hypogravity.

Space flight effects on Paramecium tetraurelia flown aboard Salyut 6 in the Cytos I and Cytos M experiments.

Results of the Cytos M experiment and complementary results of the Cytos I experiment flown aboard the Soviet orbital station Salyut 6 are shown. Space flight of Paramecia cultures resulted in a stimulating effect on cell proliferation, in a larger cell volume, in changes in cell dry weight, cell total protein and the electrolyte content of the culture media in which the organisms were grown. The assumption of a possible effect of weightlessness on membrane permeability is discussed.

Effects of very low doses of ionizing radiation on the clonal life-span in Paramecium tetraurelia.

Effects of very low doses of ionizing radiation were investigated on life-span in Paramecium tetraurelia. After autogamy single cell cultures were place (1) in a control chamber with radiopermeable walls; (2) in a shielded device with 10 cm thick lead walls; (3) in a similar shielding device including a 60Co source giving a dose of 760 mrad per year at the culture level. Life-spans, expressed in days and in mean total number of fissions measured from autogamy to the death of all sublines, were about 200 fissions and 55 days in controls. Life-spans of shielded sublines were increased and lower life-spans were observed in both shielded and irradiated sublines. These findings provide new evidence for a biological effect of very low doses of ionizing radiations and show that fission potential of Paramecium tetraurelia can be affected by variations in the background radiation level.

[Effect of the spatial environment on the mitotic activity, size and protein content of Paramecium tetraurelia]. / Influence de l'environnement spatial sur l'activité mitotique, la taille, et le contenu protéinique de Paramecium tetraurelia.

Cell proliferation, cell volume, protein components of paramecia and chemical analysis of culture medium were studied in Paramecium tetraurelia cultures placed in space environment. The space flight resulted in a marked stimulation of cell proliferation, an increase of cell volume, a decrease of mean protein components and changes of electrolytes in the culture medium.