Effects of microgravity and cosmic radiations on human T lymphocytes

In space living organisms, including cells, are affected by two new environmental conditions: microgravity and cosmic radiations. Several experiments in dedicated space missions and in simulated microgravity have shown that low gravity causes a dramatic depression of the mitogenic in vitro activation of T lymphocytes. The goal of this reserch was to determine in space (on board the International Space Station) the ability of adherent monocytes to migrate, as well as to interact with T-cells. A reduced motility of the J-111 cells and changes in the structures of actin, tubulin and vinculin were observed. Moreover, we demonstrated that LFA-I/ICAM-I interactions occur in space and are dependent on activation time but show differences in number, arrangement and fluorescence intensity, depending on time and experimental conditions. In order to evaluate the effects of cosmic radiations on the gene expression in human T lymphocytes we exposed these cells to high quote cosmic radiation during two stratospheric balloon trans-mediterranean flights (BIRBA missions). The gene expression was analized by cDNA microarray hybridization technology. Activated T cells react to the ionizing stress by activating genes involved in cell cycle check-point, oxidative stress response, heat shock proteins production or by repressing denes involved in antigen recognition

Paleogene palynostratigraphy of the eastern middle Magdalena Valley, Colombia

This work presents a detailed study of the pollen and spore distribution in the Paleocene-Eocene Lisama and La Paz Formations on the eastern border of the Middle Magdalena Valley, Colombia. One hundred and forty-seven samples obtained from cores and outcrops were prepared for palynological research, fifty-nine of which were rich in pollen and spores. Three hundred spore and pollen taxa were identified. The studied stratigraphic interval is a 2000 m thick coastal and fluvial deposit formed in a variable subsiding tectonic setting. The Lisama Formation is characterized by the dominance of the Proxapertites group. Some typical Paleocene forms start to disappear toward the upper part of the Lisama Formation (e.g.Bombacacidites annae, Ephedripites vanegensis, Retidiporites magdalenensis), and are followed by a barren interval probably linked to intense oxidation during paleosol development (the uppermost 266 m of the Lisama Formation). In the La Paz Formation there is a progressive appearance of early and middle Eocene species (e.g. Cyclusphaera scabrata, Foveotriporites hammenii, Monoporopollenites annulatus, Perfotricolpites digitatus, Spirosyncolpites spiralis, Striatopollis catatumbus, Bombacacidites gonzalezii). This biostratigraphic evidence indicates that an early-middle Eocene hiatus in the eastern area of the Middle Magdalena Valley basin is not present, as many authors have previously suggested. One new pollen genus, Foveomonoporites, and two new pollen species, Foveomonoporites variabilis and Psilamonocolpites operculatus are described and illustrated