Evidence for capillarity contributions to gecko adhesion from single spatula nanomechanical measurements

The hairy attachment system on a gecko's toes, consisting of one billion spatulae in the case of Gekko gecko [Ruibal, R. & Ernst, V. (1965) J. Morphol. 117, 271–294], allows it to adhere to nearly all surface topographies. The mechanistic basis for gecko adhesion has been intensely investigated, but the lowest hierarchical level, that of the spatula, has become experimentally accessible only recently. This report details measurements of the adhesion force exerted by a single gecko spatula for various atmospheric conditions and surface chemistries. Through judicious choice and modification of substrates, the short- and long-range adhesive forces are separated. In contrast to previous work [Autumn, K., Sitti, M., Liang, Y. C. A., Peattie, A. M., Hansen, W. R., Sponberg, S., Kenny, T. W., Fearing, R., Israelachvili, J. N. & Full, R. J. (2002) Proc. Natl. Acad. Sci. USA 99, 12252–12256], our measurements clearly show that humidity contributes significantly to gecko adhesion on a nanoscopic level. These findings are crucial for the development of artificial biomimetic attachment systems

Dynamics and structure formation in thin polymer melt films

The stability of thin liquid coatings plays a fundamental role in everyday life. We studied the stability conditions of thin (3 to 300 nm) liquid polymer films on various substrates. The key role is played by the effective interface potential φ of the s

La Société de Biologie de Strasbourg : 100 ans au service de la science et de la société

Filiale de la Société de Biologie, la Société de Biologie de Strasbourg (SBS) est une société savante qui a pour objet la diffusion et la promotion du savoir scientifique en biologie et en médecine. Fondée en 1919, La SBS a célébré son Centenaire le mercredi 16 octobre 2019. Cette journée a permis de retracer les différents jalons de la SBS, à travers ses lignes de forces, ses difficultés et sa volonté permanente de mettre en exergue les défis scientifiques et sociétaux auxquels participent les recherches strasbourgeoises. Le fil rouge de cette journée a été la transmission d’un savoir en lien avec le passé, le présent, mais également le futur. En ce début du 21e siècle, la SBS se doit de continuer de se réinventer pour poursuivre son objectif de transmission des connaissances scientifiques en biologie et au-delà. L’ensemble des participants du Centenaire de la SBS a ainsi posé la première pierre du Bicentenaire de la SBS

Riluzole blocks persistent Na+ and Ca2+ currents and modulates release of glutamate via presynaptic NMDA receptors on neonatal rat hypoglossal motoneurons in vitro

The neuroprotective agent riluzole is used for the symptomatic treatment of motoneuron disease, which strongly affects the brainstem nucleus hypoglossus. The mechanism of action of riluzole was investigated using, as a model, patch-clamp recording from hypoglossal motoneurons of the neonatal rat brainstem slice preparation. In the presence of riluzole (10 mu M), theta-rhythm oscillations evoked by nicotine continued even though the persistent inward current (comprising sodium and calcium components) was halved, but they disappeared when the high frequency of spontaneous glutamatergic currents waned. Riluzole fully inhibited the persistent sodium current and partly depressed a tetrodotoxin (TTX)-insensitive slow current antagonized by Mn2+ or Cd2+. Repetitive firing was inhibited by riluzole without changing single action potentials. In the presence of TTX, riluzole depressed miniature glutamatergic currents occurring at high rate. Synaptic transmission with low release probability became sensitive to riluzole if release was stimulated by high potassium solution. Miniature current frequency was depressed by the N-methyl-D-aspartic acid (NMDA) receptor antagonist D-amino-phosphonovaleriate (50 mu M), which fully occluded the action of riluzole. As riluzole is a protein kinase C (PKC) inhibitor, the PKC antagonist chelerythrine (2.5 mu M) mimicked the effect of riluzole and prevented it. In summary, riluzole blocked the persistent sodium current fully, and the calcium one partly, plus it decreased glutamatergic transmission probably via inhibition of PKC that regulated presynaptic NMDA receptors having a facilitatory effect on glutamate release. Controlling NMDA receptor function and, thus, excitatory transmitter release via modulation of PKC suggests a novel potential target to contrast glutamate excitotoxicity in this motor nucleus