766 research outputs found
Osp/Claudin-11 Forms a Complex with a Novel Member of the Tetraspanin Super Family and β1 Integrin and Regulates Proliferation and Migration of Oligodendrocytes
Oligodendrocyte-specific protein (OSP)/claudin-11 is a major component of central nervous system myelin and forms tight junctions (TJs) within myelin sheaths. TJs are essential for forming a paracellular barrier and have been implicated in the regulation of growth and differentiation via signal transduction pathways. We have identified an OSP/claudin-11–associated protein (OAP)1, using a yeast two-hybrid screen. OAP-1 is a novel member of the tetraspanin superfamily, and it is widely expressed in several cell types, including oligodendrocytes. OAP-1, OSP/claudin-11, and β1 integrin form a complex as indicated by coimmunoprecipitation and confocal immunocytochemistry. Overexpression of OSP/claudin-11 or OAP-1 induced proliferation in an oligodendrocyte cell line. Anti–OAP-1, anti–OSP/claudin-11, and anti–β1 integrin antibodies inhibited migration of primary oligodendrocytes, and migration was impaired in OSP/claudin-11–deficient primary oligodendrocytes. These data suggest a role for OSP/claudin-11, OAP-1, and β1 integrin complex in regulating proliferation and migration of oligodendrocytes, a process essential for normal myelination and repair
Electrical Control of Plasmon Resonance with Graphene
Surface plasmon, with its unique capability to concentrate light into
sub-wavelength volume, has enabled great advances in photon science, ranging
from nano-antenna and single-molecule Raman scattering to plasmonic waveguide
and metamaterials. In many applications it is desirable to control the surface
plasmon resonance in situ with electric field. Graphene, with its unique
tunable optical properties, provides an ideal material to integrate with
nanometallic structures for realizing such control. Here we demonstrate
effective modulation of the plasmon resonance in a model system composed of
hybrid graphene-gold nanorod structure. Upon electrical gating the strong
optical transitions in graphene can be switched on and off, which leads to
significant modulation of both the resonance frequency and quality factor of
plasmon resonance in gold nanorods. Hybrid graphene-nanometallic structures, as
exemplified by this combination of graphene and gold nanorod, provide a general
and powerful way for electrical control of plasmon resonances. It holds promise
for novel active optical devices and plasmonic circuits at the deep
subwavelength scale
On Synchronization in a Lattice Model of Pulse-Coupled Oscillators
We analyze the collective behavior of a lattice model of pulse-coupled
oscillators. By means of computer simulations we find the relation between the
intrinsic dynamics of each member of the population and their mutual
interaction that ensures, in a general context, the existence of a fully
synchronized regime. This condition turns out to be the same than the obtained
for the globally coupled population. When the condition is not completely
satisfied we find different spatial structures. This also gives some hints
about self-organized criticality.Comment: 4 pages, RevTex, 1 PostScript available upon request, To appear in
Phys. Rev. Let
Terahertz All-Optical Modulation in a Silicon-Polymer Hybrid System
Although Gigahertz-scale free-carrier modulators have been previously
demonstrated in silicon, intensity modulators operating at Terahertz speeds
have not been reported because of silicon's weak ultrafast optical
nonlinearity. We have demonstrated intensity modulation of light with light in
a silicon-polymer integrated waveguide device, based on the all-optical Kerr
effect - the same ultrafast effect used in four-wave mixing. Direct
measurements of time-domain intensity modulation are made at speeds of 10 GHz.
We showed experimentally that the ultrafast mechanism of this modulation
functions at the optical frequency through spectral measurements, and that
intensity modulation at frequencies in excess of 1 THz can be obtained in this
device. By integrating optical polymers through evanescent coupling to
high-mode-confinement silicon waveguides, we greatly increase the effective
nonlinearity of the waveguide for cross-phase modulation. The combination of
high mode confinement, multiple integrated optical components, and high
nonlinearities produces all-optical ultrafast devices operating at
continuous-wave power levels compatible with telecommunication systems.
Although far from commercial radio frequency optical modulator standards in
terms of extinction, these devices are a first step in development of
large-scale integrated ultrafast optical logic in silicon, and are two orders
of magnitude faster than previously reported silicon devices.Comment: Under consideration at Nature Material
Phase 2 Study of the Safety and Tolerability of Maraviroc-Containing Regimens to Prevent HIV Infection in Men Who Have Sex With Men (HPTN 069/ACTG A5305)
Maraviroc (MVC) is a candidate for human immunodeficiency virus (HIV) pre-exposure prophylaxis
H4K20me1 Contributes to Downregulation of X-Linked Genes for C. elegans Dosage Compensation
The Caenorhabditis elegans dosage compensation complex (DCC) equalizes X-chromosome gene dosage between XO males and XX hermaphrodites by two-fold repression of X-linked gene expression in hermaphrodites. The DCC localizes to the X chromosomes in hermaphrodites but not in males, and some subunits form a complex homologous to condensin. The mechanism by which the DCC downregulates gene expression remains unclear. Here we show that the DCC controls the methylation state of lysine 20 of histone H4, leading to higher H4K20me1 and lower H4K20me3 levels on the X chromosomes of XX hermaphrodites relative to autosomes. We identify the PR-SET7 ortholog SET-1 and the Suv4-20 ortholog SET-4 as the major histone methyltransferases for monomethylation and di/trimethylation of H4K20, respectively, and provide evidence that X-chromosome enrichment of H4K20me1 involves inhibition of SET-4 activity on the X. RNAi knockdown of set-1 results in synthetic lethality with dosage compensation mutants and upregulation of X-linked gene expression, supporting a model whereby H4K20me1 functions with the condensin-like C. elegans DCC to repress transcription of X-linked genes. H4K20me1 is important for mitotic chromosome condensation in mammals, suggesting that increased H4K20me1 on the X may restrict access of the transcription machinery to X-linked genes via chromatin compaction
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