A new role in hemostasis for the adhesion receptor P-selectin

The adhesion receptor P-selectin has long been known to support leukocyte rolling and emigration at sites of inflammation. Recently, P-selectin was also revealed to be a key molecule in hemostasis and thrombosis, mediating platelet rolling, generating procoagulant microparticles containing active tissue factor and enhancing fibrin deposition. Elevated levels of plasma P-selectin are indicative of thrombotic disorders and predictive of future cardiovascular events. Because the interaction between P-selectin and its receptor P-selectin glycoprotein ligand-1 (PSGL-1) represents an important mechanism by which P-selectin induces the formation of procoagulant microparticles and recruits the microparticles to thrombi, anti-thrombotic strategies are currently aimed at inhibiting this interaction. Recent developments also suggest that the procoagulant potential of P-selectin could be used to treat coagulation disorders such as hemophilia A.     

Fibronectin-coated beads are endocytosed by cells and align with microfilament bundles

Carboxylated latex beads coated with fibronectin bind to the surfaces of NIL8 hamster cells. Similar beads coated with bovine serum albumin, gelatin or normal rabbit immunoglobulin do not bind to the cells, whereas beads coated with polylysine or rabbit anti-hamster immunoglobulin bind, as do fibronectin-coated beads. Surface-bound beads are endocytosed by the cells. This endocytosis is inhibited by N-ethyl maleimide or low temperatures. The endocytosed beads form arrays aligned with the microfilament bundles inside the cells and after extended incubations (18–24 h) become concentrated in the perinuclear region. These results suggest that, after phagocytosis of large particles, the endocytic vesicles align with microfilament bundles, as previously reported for coated pits involved in receptor-mediated endocytosis. The system described here offers possibilities for the analysis of membrane and transmembrane interactions involved in cell-substratum binding and phagocytosis.     

Zu den phytozönologischen Problemen der AssoziationCaricetum gracilis Almquist 1929

Caricetum gracilis Almquist 1929 ist eine Assoziation mit ausgedehnter eurosibirischer Verbreitung, es bewahrt sich jedoch in seinem ganzen Areal eine mehr oder weniger konstante zönotische Zusammensetzung, die durch das Grundmerkmal—die Anwesenheit vonCarex gracilis als Dominante (Kondominante) und Ädifikator, bedingt ist. Als ausschlaggebonder Faktor für die Entstehung der Gesellschaft kommt der Wasserhaushalt mit charakteristischer Abwechslung der Überschwemmungen und Austrocknungen zur Geltung. Die geographischen, klimatischen und bodenökologischen Unterschiede der Standorte ermöglichen eine weitere Gliederung der Assoziation inCaricetum gracilis Subass.typicum mit grösstem Verbreitungsgebiet, die in drei Varianten zerfällt, weiter inCaricetum gracilis comaretosum, dessen Areal an nördliche Teile Mittel- und Osteuropas gebunden ist und das in zwei Varianten zerfällt, und schliesslich inCaricetum gracilis naumburgietosum, das vor allem an das Herzynische Gebiet und den Nordrand der Karpaten gebundon ist.     

Vegetation of vesicular lava cavities in Northern Iceland

Vesicular cavities in the lava fields of Northern Iceland communicate by small openings with the ground surface. Aeolian sediments, called the Icelandic Ioess, deposit over the bottom of these cavities, together with the reduced light intensity and equable microclimate, create specific biotopes occupied by sciophilous bryophytes andCystopteris fragilis. A new association within the allianceCtenidion Stefureac 1941—Cystopteri-Distichietum capillacei Bla?ková ass. nova— is described in the present paper.     

NPY in rat retina is present in neurons, in endothelial cells and also in microglial and Müller cells

NPY is present in the retina of different species but its role is not elucidated yet. In this work, using different rat retina in vitro models (whole retina, retinal cells in culture, microglial cell cultures, rat Müller cell line and retina endothelial cell line), we demonstrated that NPY staining is present in the retina in different cell types: neurons, macroglial, microglial and endothelial cells. Retinal cells in culture express NPY Y(1), Y(2), Y(4) and Y(5) receptors. Retina endothelial cells express all NPY receptors except NPY Y(5) receptor. Moreover, NPY is released from retinal cells in culture upon depolarization. In this study we showed for the first time that NPY is present in rat retina microglial cells and also in rat Müller cells. These in vitro models may open new perspectives to study the physiology and the potential pathophysiological role of NPY in the retina.