Developmental emergence of two-stage nonlinear synaptic integration in cerebellar interneurons.

Synaptic transmission, connectivity, and dendritic morphology mature in parallel during brain development and are often disrupted in neurodevelopmental disorders. Yet how these changes influence the neuronal computations necessary for normal brain function are not well understood. To identify cellular mechanisms underlying the maturation of synaptic integration in interneurons, we combined patch-clamp recordings of excitatory inputs in mouse cerebellar stellate cells (SCs), three-dimensional reconstruction of SC morphology with excitatory synapse location, and biophysical modeling.

Charge transfer from and to manganese phthalocyanine: bulk materials and interfaces.

Manganese phthalocyanine (MnPc) is a member of the family of transition-metal phthalocyanines, which combines interesting electronic behavior in the fields of organic and molecular electronics with local magnetic moments. MnPc is characterized by hybrid states between the Mn 3d orbitals and the π orbitals of the ligand very close to the Fermi level. This causes particular physical properties, different from those of the other phthalocyanines, such as a rather small ionization potential, a small band gap and a large electron affinity.

Adaptive Response of Actin Bundles under Mechanical Stress.

Actin is one of the main components of the architecture of cells. Actin filaments form different polymer networks with versatile mechanical properties that depend on their spatial organization and the presence of cross-linkers. Here, we investigate the mechanical properties of actin bundles in the absence of cross-linkers.

Energy-level alignment at interfaces between manganese phthalocyanine and C.

We have used photoelectron spectroscopy to determine the energy-level alignment at organic heterojunctions made of manganese phthalocyanine (MnPc) and the fullerene C. We show that this energy-level alignment depends upon the preparation sequence, which is explained by different molecular orientations. Moreover, our results demonstrate that MnPc/C interfaces are hardly suited for application in organic photovoltaic devices, since the energy difference of the two lowest unoccupied molecular orbitals (LUMOs) is rather small.

STM Study of Au(111) Surface-Grafted Paramagnetic Macrocyclic Complexes [Ni2L(Hmba)](+) via Ambidentate Coligands.

Molecular anchoring and electronic properties of macrocyclic complexes fixed on gold surfaces have been investigated mainly by using scanning tunnelling microscopy (STM) and complemented with X-ray photoelectron spectroscopy (XPS). Exchange-coupled macrocyclic complexes [Ni2L(Hmba)](+) were deposited via 4-mercaptobenzoate ligands on the surface of a Au(111) single crystal from a mM solution of the perchlorate salt [Ni2L(Hmba)]ClO4 in dichloromethane. The combined results from STM and XPS show the formation of large monolayers anchored via Au-S bonds with a height of about 1.

In vitro characterization of Fluorescence by Unbound Excitation from Luminescence: broadening the scope of energy transfer.

Energy transfer mechanisms represent the basis for an array of valuable tools to infer interactions in vitro and in vivo, enhance detection or resolve interspecies distances such as with resonance. Based upon our own previously published studies and new results shown here we present a novel framework describing for the first time a model giving a view of the biophysical relationship between Fluorescence by Unbound Excitation from Luminescence (FUEL), a conventional radiative excitation-emission process, and bioluminescence resonance energy transfer. We show here that in homogeneous solutions and in fluorophore-targeted bacteria, FUEL is the dominant mechanism responsible for the production of red-shifted photons.

Attractive membrane domains control lateral diffusion.

Lipid membranes play a fundamental role in vital cellular functions such as signal transduction. Many of these processes rely on lateral diffusion within the membrane, generally a complex fluid containing ordered microdomains. However, little attention has been paid to the alterations in transport dynamics of a diffusing species caused by long-range interactions with membrane domains.

Diffusion of nanoparticles in monolayers is modulated by domain size.

Langmuir monolayers are often used as simple models for biological membranes. The possibility to change their composition and phase state in a very controlled manner as well as access to a large observation area makes them a versatile tool for the investigation of membrane-related interactions. Inspired by experiments in our group, we investigate the interaction of single, partially charged nanoparticles with lipid microdomains by Monte Carlo simulations.

Episomal vectors to monitor and induce somatic hypermutation in human Burkitt-Lymphoma cell lines.

Somatic hypermutation (SHM) occurs at a specific B-cell differentiation stage, during the germinal centre reaction, and provides a means to diversify and shape the antibody repertoire of the adaptive immune system. Burkitt-Lymphoma (BL) is a germinal centre derived B-cell malignancy. Presumably deregulation of the somatic hypermutation- and/or class switch recombination process causes a translocation between the myc-locus and one of the Ig-loci, which is characteristic for BL.

Proviral integration of an Abelson-murine leukemia virus deregulates BKLF-expression in the hypermutating pre-B cell line 18-81.

The transcription factor BKLF (basic Krüppel-like factor, KLF3) is a member of the Krüppel-like factors (KLF) family. KLF members harbor a characteristic C-terminal zinc-finger DNA-binding domain and bind preferentially to CACCC-motifs. BKLF is highly expressed in haematopoietic and erythoid cells and works either as repressor or activator of transcription in various genes.

Activation-induced cytidine deaminase fails to induce a mutator phenotype in the human pre-B cell line Nalm-6.

Activation-induced cytidine deaminase (AID) plays a key role in the induction of somatic hypermutation and class switching at the immunoglobulin loci of B lymphocytes. AID overexpression can induce a mutator phenotype in lymphoid and nonlymphoid cell lines, suggesting that AID by itself is sufficient to trigger hypermutation and class switching. AID expression in vivo is considered to be restricted to germinal center B lymphocytes, yet AID expression is also seen in many B cell lymphomas, hinting at a potential role for the development of these malignancies.

Dual reporter system to dissect cis- and trans-effects influencing the mutation rate in a hypermutating cell line.

Activation induced cytidine deaminase (AID) plays a key role in the induction of somatic hypermutation and class switching in the immunoglobulin genes of B-lymphocytes. AID expression by itself is sufficient to induce a GC-basepair biased mutator phenotype in lymphoid and non-lymphoid cell lines. Nevertheless a network of cis-regulatory elements and additional trans-factor proteins seems to govern the molecular mechanism of somatic hypermutation.