Five novel antimicrobial peptides from skin secretions of the frog, Amolops loloensis

While investigating antimicrobial peptide diversity of Amolops loloensis, five novel antimicrobial peptides belonging to two families were identified from skin secretions of this frog. The first family including two members is esculentin-2-AL (esculentin-2-ALa and -ALb): the second family including three members is temporin-AL (temporin-ALd to -ALf). The family of esculentin-2-AL is composed of 37 amino acid residues (aa); the family of temporin-AL is composed of 16, 13 and 10 aa, respectively. All of these antimicrobial peptides showed antimicrobial activities against tested microorganisms. cDNAs encoding precursors of esculentin-2-ALs and temporin-ALs were cloned from the skin cDNA library of A. loloensis. All the precursors share similar overall structures. There is a typical prohormone processing signal (Lys-Arg) located between the acidic propiece and the mature peptide. The antimicrobial peptide family of esculentin-2 is firstly reported in the genus of Amolops. Combined with previous reports, a total of four antimicrobial peptide families have been identified from the genus of Amolops; three of them are also found in the genus of Rana. These results suggest the possible evolutionary connection between the genera Amolops and Rana. (C) 2009 Elsevier Inc. All rights reserved.

Hepatocyte growth factor enhances the generation of high-purity oligodendrocytes from human embryonic stem cells

Generation of homogeneous oligodendrocytes as donor cells is essential for human embryonic stem cell (hESC)-based cell therapy for demylinating diseases. Herein we present a novel method for efficiently obtaining mature oligodendrocytes from hESCs with high purity (79.7 +/- 6.9%), using hepatocyte growth factor (HGF) and G5 supplement(containing insulin, transferrin, selenite, biotin, hydrocortisone, basic fibroblast growth factor and epidermal growth factor) in a four-step method. We induced hESCs into neural progenitors (NP) with HGF (5 ng/ml) and G5 (1 x) supplemented medium in an adherent differentiation system. The purified NPs were amplified in suspension as neurospheres for 1 month, and terminal oligodendrocyte differentiation was then induced by G5 supplement withdrawal and HGF treatment (20 ng/ml). The cells generated displayed typical morphologies of mature oligodendrocytes and expressed oligodendrocyte markers O4 and myelin basic protein (MBP). Our result revealed that HGF significantly enhanced the proliferation of hESC-derived NPs and promoted the differentiation as well as the maturation of oligodendrocytes from NPs. Further studies suggest that HGF/c-Met signaling pathway might play an important role in oligodendrocyte differentiation in our system. Our studies provide a means for generating the clinically relevant cell type and a platform for deciphering the molecular mechanisms that control oligodendrocyte differentiation. (C) 2009 International Society of Differentiation. Published by Elsevier Ltd. All rights reserved.

Frontal and cingulate gray matter volume reduction in heroin dependence: Optimized voxel-based morphometry

Aims: Repeated exposure to heroin, a typical opiate, causes neuronal adaptation and may result in anatomical changes in specific brain regions, particularly the frontal and limbic cortices. The volume changes of gray matter (GM) of these brain regions, ho

Structure and magnetic property of (Ga,Cr)As films with different Cr contents

We report variations in structure and magnetic property of (Ga,Cr) As films with increasing Cr content x. Due to phase segregation, a tendency towards inhomogeneous distribution with increasing x is confirmed. Barkhausen-like magnetization and large remanent magnetic moment were also clearly observed in the samples with x<5.3%. However, spin-glass-like behaviors were observed in both dc and ac magnetic measurements, which might originate from the competition between magnetic nucleation and frustration of long ferromagnetic order in this inhomogeneous system. All the samples exhibit characteristics of variable-range hopping conductivity at temperature below 150 K. Typical magnetic circular dichroism structure was observed in the sample with x=7.9%.

Lineshape Analysis of the Beat Signal Between Optical Carrier and Delayed Sidebands

This paper presents the lineshape analysis of the beat signal between the optical carrier and the shifted and delayed side-bands produced by sinusoidal amplitude modulation. It is shown that the beat signal has a typical lineshape with a very narrow delta-peak superposed on a quasi-Lorentzian profile. Theoretical explanation for the appearance of this peak has been given based on optical spectral structure constructed by a large number of optical wave trains. It is predicted that the delta-peak is originated from the beat between the wave trains in the carrier and those in the delayed sidebands when their average coherence length is longer than the delay line. Experiments carried out using different delay lines clearly show that the delta-peak is always located at the modulation frequency and decreases with the increasing delay line. Our analysis explicitly indicates that the linewidth is related to the observation time. It is also suggested that the disappearance of the delta-peak can be used as the criterion of coherence elimination.

QtUCP-A program for determining unit-cell parameters in electron diffraction experiments using double-tilt and rotation-tilt holders

A computer program, QtUCP, has been developed based on several well-established algorithms using GCC 4.0 and Qt (R) 4.0 (Open Source Edition) under Debian GNU/Linux 4.0r0. it can determine the unit-cell parameters from an electron diffraction tilt series obtained from both double-tilt and rotation-tilt holders. In this approach, two or more primitive cells of the reciprocal lattice are determined from experimental data, in the meantime, the measurement errors of the tilt angles are checked and minimized. Subsequently, the derived primitive cells are converted into the reduced form and then transformed into the reduced direct primitive cell. Finally all the patterns are indexed and the least-squares refinement is employed to obtain the optimized results of the lattice parameters. Finally, two examples are given to show the application of the program, one is based on the experiment, the other is from the simulation. (C) 2008 Elsevier B.V. All rights reserved.

Multi-channel micro neural probe fabricated with SOI

Silicon-on-insulator (SOI) substrate is widely used in micro-electro-mechanical systems (MEMS). With the buried oxide layer of SOI acting as an etching stop, silicon based micro neural probe can be fabricated with improved uniformity and manufacturability. A seven-record-site neural probe was formed by inductive-coupled plasma (ICP) dry etching of an SOI substrate. The thickness of the probe is 15 mu m. The shaft of the probe has dimensions of 3 mmx100 mu mx15 mu m with typical area of the record site of 78.5 mu m(2). The impedance of the record site was measured in-vitro. The typical impedance characteristics of the record sites are around 2 M Omega at 1 kHz. The performance of the neural probe in-vivo was tested on anesthetic rat. The recorded neural spike was typically around 140 mu V. Spike from individual site could exceed 700 mu V. The average signal noise ratio was 7 or more.

Fabrication and performance of an index-coupled DFB laser with sampled grating

An index-coupled DFB laser with a sampled grating has been designed and fabricated. The key concept of the approaches is to utilize the +1st-order reflection of the sampled grating for laser operation, and use a conventional holographic exposure combined with the usual photolithography to form the sampled grating. The typical threshold current of the sampled grating DFB laser is 25 mA, and the optical output is about 10 mW at the injected current of 100 mA. The lasing wavelength of the device is 1.5314 mu m, which is the +1st-order peak of the sampled grating.

Control of the lasing wavelength by a sampled grating in a complex-coupled DFB laser

The lasing wavelength of a complex-coupled DFB laser is controlled by a sampled grating. The key concepts of the approach are to utilize the -1st order (negative first order) reflection of a sampled grating for laser single mode operation, and use conventional holographic exposure combined with the usual photolithography to fabricate the sampled grating. The typical threshold current of the sampled grating based DFB laser is 32 mA, and the optical output is about 10 mW at an injected current of 100 mA. The lasing wavelength of the device is 1.5356 mu m, which is the -1st order wavelength of the sampled grating.

Electron spin relaxation by nuclei and holes in single InAs quantum dots

Electron spin relaxation of charged excitons X+ and X2+ are investigated by time-resolved and polarization-resolved photoluminescence spectroscopy. For X+ configuration, the electron spin relaxation shows a typical decay curve induced by hyperfine interaction with nuclei, whereas for X2+ state the electron spin relaxation is affected not only by nuclei but also by electron-hole exchange interaction, leading to a power-law time dependence.