Cytoskeleton changes and impaired motility of monocytes at modelled low gravity

Summary.: Investigations performed in space have shown that gravity changes affect important cellular mechanisms like proliferation, differentiation, genetic expression, cytoskeletal architecture, and motility in lymphocytes, monocytes, and other mammalian cells. In particular, a dramatic depression of the mitogenic in vitro activation of human peripheral blood lymphocytes was observed at low gravity. The hypothesis of the present work is that a reduced interaction between T lymphocytes and monocytes, essential for the second signalling pathway, might be one of the reasons for the observed depression of the in vitro activation of human lymphocytes. Cell motility and with it a continuous rearrangement of the cytoskeletal network within the cell is essential for cell-to-cell contacts. Whereas nonactivated lymphocytes in suspension are highly motile at low gravity, no data are available so far on the motility of adherent monocytes. It thus can be argued that impaired monocyte locomotion and cytoskeletal changes could be responsible for a reduced interaction of monocytes with T lymphocytes. In this study, the locomotion ability of J-111 cells, an adherent monocyte cell line, attached to colloidal gold particles on coverslips and exposed to modelled low gravity in the random positioning machine was found to be severely reduced compared with that of controls and the structures of actin, tubulin, and vinculin were affecte

"In vivo" physiological experiments in simulated microgravity conditions on rat bon marrow cells mineralization

The main goal of this research is to further contribute to the validation of the clinostat Random Positioning Machine (RPM) for "in vivo" experiments by studying bone marrow cells mineralization in the rat. These cells were obtained from the bone shafts of the femora and cultured for 13 days. The production of calcified matrix was analyzed by Alizarin Red staining demostrating that calcium deposition was significantly decreased in RPM samples. Moreover, we demostrated what Alkaline phosphatase (ALP) activity, a marker of osteoblastic phenotype, is down regulate by simulated microgravity. Also in vitro experiments in coltured osteoblasts (first subcolture) exposed to RPM for 9 days confirm a strongly decreased mineralization and differentiation

Effects of microgravity and hypergravity on early development stages of Xeonopus laevis.

The aim of this work is to evaluate the development of X.l. in modified gravity conditions. The simulation of hyper and microgravity was performed utilizing: an hyperfuge, a Clinostat and later on a Random Positioning Machine (RPM, 3d Clinostat). The effect of hypergravity on embryos is significantly higher than that of microgravity; the exposure of embryos to 3xg for 3 days before and after hatch causes an activation of HSP-60 and HSP-70. Embryos exposed to 3xg during the first 3 days of development are very sensitive and show a retard of development, with a lower content of DNA, neutral glycolipids and gangliosides compared to controls