Deterministic progenitor behavior and unitary production of neurons in the neocortex

Radial glial progenitors (RGPs) are responsible for producing nearly all neocortical neurons. To gain insight into the patterns of RGP division and neuron production, we quantitatively analyzed excitatory neuron genesis in the mouse neocortex using Mosaic Analysis with Double Markers, which provides single-cell resolution of progenitor division patterns and potential in vivo. We found that RGPs progress through a coherent program in which their proliferative potential diminishes in a predictable manner. Upon entry into the neurogenic phase, individual RGPs produce ∼8–9 neurons distributed in both deep and superficial layers, indicating a unitary output in neuronal production. Removal of OTX1, a transcription factor transiently expressed in RGPs, results in both deep- and superficial-layer neuron loss and a reduction in neuronal unit size. Moreover, ∼1/6 of neurogenic RGPs proceed to produce glia. These results suggest that progenitor behavior and histogenesis in the mammalian neocortex conform to a remarkably orderly and deterministic program.

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Radial glial progenitors (RGPs) progress through a coherent proliferation program

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Individual RGPs produce a unitary output of neurons during the neurogenic phase

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OTX1 deletion in RGPs leads to a reduction in neuronal unit size

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A defined fraction of about one in six RGPs proceeds to gliogenesis after neurogenesis

Stellar dynamics. The fastest unbound star in our Galaxy ejected by a thermonuclear supernova

Hypervelocity stars (HVSs) travel with velocities so high that they exceed the escape velocity of the Galaxy. Several acceleration mechanisms have been discussed. Only one HVS (US 708, HVS 2) is a compact helium star. Here we present a spectroscopic and kinematic analysis of US 708. Traveling with a velocity of ~1200 kilometers per second, it is the fastest unbound star in our Galaxy. In reconstructing its trajectory, the Galactic center becomes very unlikely as an origin, which is hardly consistent with the most favored ejection mechanism for the other HVSs. Furthermore, we detected that US 708 is a fast rotator. According to our binary evolution model, it was spun-up by tidal interaction in a close binary and is likely to be the ejected donor remnant of a thermonuclear supernova.

Pixel-wise orthogonal decomposition for color illumination invariant and shadow-free image

In this paper, we propose a novel, effective and fast method to obtain a color illumination invariant and shadow-free image from a single outdoor image. Different from state-of-the-art methods for shadow-free image that either need shadow detection or statistical learning, we set up a linear equation set for each pixel value vector based on physically-based shadow invariants, deduce a pixel-wise orthogonal decomposition for its solutions, and then get an illumination invariant vector for each pixel value vector on an image. The illumination invariant vector is the unique particular solution of the linear equation set, which is orthogonal to its free solutions. With this illumination invariant vector and Lab color space, we propose an algorithm to generate a shadow-free image which well preserves the texture and color information of the original image. A series of experiments on a diverse set of outdoor images and the comparisons with the state-of-the-art methods validate our method.

Screening survey of co-production of fusaric acid, fusarin C, and fumonisins B₁, B₂ and B₃ by Fusarium strains grown in maize grains

Fusarium species isolated from Belgian maize were screened for their ability to produce fusarin C, fusaric acid, fumonisins B1 (FB1), FB2 and FB3 in maize grains. First, cultivation of Fusarium species in Myro liquid medium allowed overcoming the shortage of the standard of fusarin C on the market. All Fusarium verticillioides produced much higher contents of mycotoxins in Myro compared to Fusarium graminearum or Fusarium venenatum. The optimization of the LC-MS/MS method resulted in low limits of detection and quantification for fusarin C, fusaric acid, FB1, FB2 and FB3 determination in maize grains. Its application for screening the potential toxin production ability evidenced that the concentrations of the analytes were significantly increased at various levels when F. verticillioides strains were cultivated in maize grains and reached 441 mg kg(-1) for fusaric acid, 74 mg kg(-1) for fusarin C, 1,301 mg kg(-1) for FB1, 367 mg kg(-1) for FB2 and 753 mg kg(-1) for FB3.

Distinct lineage-dependent structural and functional organization of the hippocampus

The hippocampus, as part of the cerebral cortex, is essential for memory formation and spatial navigation. Although it has been extensively studied, especially as a model system for neurophysiology, the cellular processes involved in constructing and organizing the hippocampus remain largely unclear. Here, we show that clonally related excitatory neurons in the developing hippocampus are progressively organized into discrete horizontal, but not vertical, clusters in the stratum pyramidale, as revealed by both cell-type-specific retroviral labeling and mosaic analysis with double markers (MADM). Moreover, distinct from those in the neocortex, sister excitatory neurons in the cornu ammonis 1 region of the hippocampus rarely develop electrical or chemical synapses with each other. Instead, they preferentially receive common synaptic input from nearby fast-spiking (FS), but not non-FS, interneurons and exhibit synchronous synaptic activity. These results suggest that shared inhibitory input may specify horizontally clustered sister excitatory neurons as functional units in the hippocampus.

Graphene-protected copper and silver plasmonics

Plasmonics has established itself as a branch of physics which promises to revolutionize data processing, improve photovoltaics, and increase sensitivity of bio-detection. A widespread use of plasmonic devices is notably hindered by high losses and the absence of stable and inexpensive metal films suitable for plasmonic applications. To this end, there has been a continuous search for alternative plasmonic materials that are also compatible with complementary metal oxide semiconductor technology. Here we show that copper and silver protected by graphene are viable candidates. Copper films covered with one to a few graphene layers show excellent plasmonic characteristics. They can be used to fabricate plasmonic devices and survive for at least a year, even in wet and corroding conditions. As a proof of concept, we use the graphene-protected copper to demonstrate dielectric loaded plasmonic waveguides and test sensitivity of surface plasmon resonances. Our results are likely to initiate wide use of graphene-protected plasmonics.

Low-cost flexible thin-film detector for medical dosimetry applications

The purpose of this study is to characterize dosimetric properties of thin film photovoltaic sensors as a platform for development of prototype dose verification equipment in radiotherapy. Towards this goal, flexible thin‐film sensors of dose with embedded data acquisition electronics and wireless data transmission are prototyped and tested in kV and MV photon beams. Fundamental dosimetric properties are determined in view of a specific application to dose verification in multiple planes or curved surfaces inside a phantom. Uniqueness of the new thin‐film sensors consists in their mechanical properties, low‐power operation, and low‐cost. They are thinner and more flexible than dosimetric films. In principle, each thin‐film sensor can be fabricated in any size (mm² – cm² areas) and shape. Individual sensors can be put together in an array of sensors spreading over large areas and yet being light. Photovoltaic mode of charge collection (of electrons and holes) does not require external electric field applied to the sensor, and this implies simplicity of data acquisition electronics and low power operation. The prototype device use for testing consists of several thin film dose sensors, each of about 1.5 cm×5 cm area, connected to simple readout electronics. Sensitivity of the sensors is determined per unit area and compared to EPID sensitivity, as well as other standard photodiodes. Each sensor independently measures dose and is based on commercially available flexible thin‐film aSi photodiodes. Readout electronics consists of an ultra low‐power microcontroller, radio frequency transmitter, and a low‐noise amplification circuit implemented on a flexible printed circuit board. Detector output is digitized and transmitted wirelessly to an external host computer where it is integrated and processed. A megavoltage medical linear accelerator (Varian Tx) equipped with kilovoltage online imaging system and a Cobalt source are use to irradiate different thin‐film detector sensors in a Solid Water phantom under various irradiation conditions. Different factors are considered in characterization of the device attributes: energies (80 kVp, 130 kVp, 6 MV, 15 MV), dose rates (different ms × mA, 100–600 MU/min), total doses (0.1 cGy‐500 cGy), depths (0.5 cm–20 cm), irradiation angles with respect to the detector surface (0°‐180°), and IMRT tests (closed MLC, sweeping gap). The detector response to MV radiation is both linear with total dose (~1‐400 cGy) and independent of dose rate (100‐600 Mu/min). The sensitivity per unit area of thin‐film sensors is lower than for aSi flat‐panel detectors, but sufficient to acquire stable and accurate signals during irradiations. The proposed thin‐film photodiode system has properties which make it promising for clinical dosimetry. Due to the mechanical flexibility of each sensor and readout electronics, low‐cost, and wireless data acquisition, it could be considered for quality assurance (e.g., IMRT, mechanical linac QA), as well as real‐time dose monitoring in challenging setup configurations, including large area and 3D detection (multiple planes or curved surfaces).

PACS number: 87.56.Fc

Effective thermal resistance of a photonic crystal microcavity

We present a simple method to accurately measure the effective thermal resistance of a photonic crystal microcavity. The cavity is embedded between two Schottky contacts forming a metal-semiconductor-metal device. The photocarriers circulating in the device provide a local temperature rise that can be dominated by Joule effect under certain conditions. We show that the effective thermal resistance (R(th)) can be experimentally deduced from the spectral shift of the cavity resonance wavelength measured at different applied bias. We deduce a value of R(th)1.6×10(4) KW(-1) for a microcavity on silicon-on-insulator, which is in good agreement with 3D thermal modeling by finite elements.

Simultaneous determination of aflatoxin B1, aflatoxin B2, mycophenolic acid and sterigmatocystin in grape pomace by UHPLC-MS/MS

A reliable ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for the simultaneous determination of aflatoxin B1, aflatoxin B2, mycophenolic acid and sterigmatocystin in grape pomace. The samples were extracted by acetonitrile aqueous solution and further purified using a solid-phase extraction-based homemade clean-up cartridge. Next, the analytes were separated on a reversed-phase C18 column with a mobile phase consisting of water and acetonitrile. The separated compounds were detected with a tandem quadrupole mass spectrometer operating in positive electro-spray ionisation mode using multiple reaction monitoring. The established method was extensively validated by determining linearity (R2≯0.999), recovery (97.5-102.8%) and precision (relative standard deviation ≤7.0%). This method was then used for the simultaneous determination of the four mycotoxins in grape pomace samples.

Comparative Analysis of Immune Responses in Pigs to High and Low Pathogenic Porcine Reproductive and Respiratory Syndrome Viruses Isolated in China

The CH-1a and HuN4 strains of porcine reproductive and respiratory syndrome virus (PRRSV) show different pathogenicities in pigs. To understand host immune responses against these viruses, we investigated the dynamic changes in cytokine levels produced in peripheral blood of piglets infected with the highly pathogenic PRRSV HuN4 strain or the CH-1a strain. Clinical signs, virus loads and serum cytokine levels [interferon(IFN)-α, Interleukin (IL)-1, TNF-α, IL-6, IL-12, IFN-γ, IL-10 and TGF-β] were tested. The results showed that while piglets developed effective cellular immune responses against CH-1a infection, those infected with HuN4 displayed ineffective cellular immunity, organ lesions and persistent elevated levels of immunoregulatory cytokines (IL-10 and TGF-β), which delayed the development of PRRSV-specific immune responses. These results demonstrated that HuN4 infection induced higher cytokine levels than that of CH-1a infection induced. The changes in inflammatory cytokines intensified the inflammatory reaction and damaged the tissues and organs.

First Report of Pepper Fruit Rot Caused by Fusarium concentricum in China

Pepper (Capsicum annuum L.) is an important vegetable crop worldwide. Some Fusarium species can cause pepper fruit rot, leading to significant yield losses of pepper production and, for some Fusarium species, potential risk of mycotoxin contamination. A total of 106 diseased pepper fruit samples were collected from various pepper cultivars from seven provinces (Gansu, Hainan, Heilongjiang, Hunan, Shandong, Shanghai, and Zhejiang) in China during the 2012 growing season, where pepper production occurs on approximately 25,000 ha. Pepper fruit rot symptom incidence ranged from 5 to 20% in individual fields. Symptomatic fruit tissue was surface-sterilized in 0.1% HgCl₂ for 1 min, dipped in 70% ethanol for 30 s, then rinsed in sterilized distilled water three times, dried, and plated in 90 mm diameter petri dishes containing potato dextrose agar (PDA). After incubation for 5 days at 28°C in the dark, putative Fusarium colonies were purified by single-sporing. Forty-three Fusarium strains were isolated and identified to species as described previously (1,2). Morphological characteristics of one strain were identical to those of F. concentricum. Aerial mycelium was reddish-white with an average growth rate of 4.2 to 4.3 mm/day at 25°C in the dark on PDA. Pigments in the agar were formed in alternating red and orange concentric rings. Microconidia were 0- to 1-septate, mostly 0-septate, and oval, obovoid to allantoid. Macroconidia were relatively slender with no significant curvature, 3- to 5-septate, with a beaked apical cell and a foot-shaped basal cell. To confirm the species identity, the partial TEF gene sequence (646 bp) was amplified and sequenced (GenBank Accession No. KC816735). A BLASTn search with TEF gene sequences in NCBI and the Fusarium ID databases revealed 99.7 and 100% sequence identity, respectively, to known TEF sequences of F. concentricum. Thus, both morphological and molecular criteria supported identification of the strain as F. concentricum. This strain was deposited as Accession MUCL 54697 (http://bccm.belspo.be/about/mucl.php). Pathogenicity of the strain was confirmed by inoculating 10 wounded, mature pepper fruits that had been harvested 70 days after planting the cultivar Zhongjiao-5 with a conidial suspension (1 × 10⁶ spores/ml), as described previously (3). A control treatment consisted of inoculating 10 pepper fruits of the same cultivar with sterilized distilled water. The fruit were incubated at 25°C in a moist chamber, and the experiment was repeated independently in triplicate. Initially, green to dark brown lesions were observed on the outer surface of inoculated fruit. Typical soft-rot symptoms and lesions were observed on the inner wall when the fruit were cut open 10 days post-inoculation. Some infected seeds in the fruits were grayish-black and covered by mycelium, similar to the original fruit symptoms observed at the sampling sites. The control fruit remained healthy after 10 days of incubation. The same fungus was isolated from the inoculated infected fruit using the method described above, but no fungal growth was observed from the control fruit. To our knowledge, this is the first report of F. concentricum causing a pepper fruit rot. References: (1) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006. (2) K. O'Donnell et al. Proc. Nat. Acad. Sci. USA 95:2044, 1998. (3) Y. Yang et al. 2011. Int. J. Food Microbiol. 151:150, 2011.

Continuous critical current measurement of high-temperature superconductor tapes with magnetic substrates using magnetic-circuit method

The critical current (I(c)) of high-temperature superconductor (HTS) tapes has to be examined not only for short samples, but also for the entire tape, because local weak points can possibly lead to the quenching of the whole HTS device. Some methods were reported for continuous I(c) measurement along the length of a HTS tape, but few of them were applicable to tapes with magnetic substrates represented by YBa2Cu3O(7-δ)(YBCO)-coated conductors based on Ni5W alloy substrate by rolling assisted bi-axially textured substrate process. We previously presented a contact-free method using magnetic circuits to measure I(c) continuously of long HTS tapes, namely the magnetic-circuit (MC) method. This method has been previously applied with high speed and resolution to measure I(c) of HTS tapes with non-magnetic substrates, due to its resistance to noise aroused by mechanical vibration. In this work, its ability to measure HTS tapes with magnetic substrates is demonstrated both theoretically and experimentally. A 100 m long commercial YBCO tape based on Ni5W alloy substrate was measured and regular I(c) fluctuations were discovered. The MC method can be a powerful tool for quality control of HTS tapes, especially for tapes with magnetic substrates.

Tax-interacting protein 1 coordinates the spatiotemporal activation of Rho GTPases and regulates the infiltrative growth of human glioblastoma

PDZ domains represent one group of the major structural units that mediate protein interactions in intercellular contact, signal transduction and assembly of biological machineries. TIP-1 protein is composed of a single PDZ domain that distinguishes TIP-1 from other PDZ domain proteins that more often contain multiple protein domains and function as scaffolds for protein complex assembly. However, the biological functions of TIP-1, especially in cell transformation and tumor progression, are still controversial as observed in a variety of cell types. In this study, we have identified ARHGEF7, a guanine nucleotide exchange factor (GEF) for Rho GTPases, as one novel TIP-1 interacting protein in human glioblastoma cells. We found that the presence of TIP-1 protein is essential to the intracellular redistribution of ARHGEF7 and rhotekin, one Rho effector, and the spatiotemporally coordinated activation of Rho GTPases (RhoA, Cdc42 and Rac1) in migrating glioblastoma cells. TIP-1 knockdown resulted in both aberrant localization of ARHGEF7 and rhotekin, as well as abnormal activation of Rho GTPases that was accompanied with impaired motility of glioblastoma cells. Furthermore, TIP-1 knockdown suppressed tumor cell dispersal in orthotopic glioblastoma murine models. We also observed high levels of TIP-1 expression in human glioblastoma specimens, and the elevated TIP-1 levels are associated with advanced staging and poor prognosis in glioma patients. Although more studies are needed to further dissect the mechanism(s) by which TIP-1 modulates the intracellular redistribution and activation of Rho GTPases, this study suggests that TIP-1 holds potential as both a prognostic biomarker and a therapeutic target of malignant gliomas.

Forty-eight-week retrospective study of telbivudine and lamivudine treatment in patients with hepatitis B-related cirrhosis

The aim of this study was to evaluate the efficacy and safety of telbivudine 600 mg/day compared with lamivudine 100 mg/day for 48 weeks of treatment in patients with hepatitis B-related cirrhosis. Data were reviewed retrospectively from 165 hepatitis B-related cirrhotic patients (55 compensated patients and 110 decompensated) who received antiviral therapy with telbivudine or lamivudine. Serum alanine aminotransferase (ALT) and hepatitis B virus (HBV) DNA levels, hepatitis B e antigen (HBeAg) loss and seroconversion, histological improvement and various adverse events (AEs) were evaluated. Baseline characteristics were comparable. ALT levels declined but showed no significant difference in treatment with telbivudine or lamivudine (P > 0.05). Reduction in serum HBV DNA levels was evident by week 4 in compensated HBV-related cirrhosis patients (telbivudine, 2.34 log10 copies/mL; lamivudine, 2.07 log10 copies/mL; P = 0.02) and persisted by week 8. Patients administrated with telbivudine had slightly greater HBeAg loss and seroconversion than patients with lamivudine, but the difference was not statistically significant (P > 0.05). Accumulative HBeAg loss was seen at week 48 (25.0% vs 25.0% and 13.3% vs 10.0% for telbivudine vs lamivudine in compensated and decompensated cirrhotic groups, respectively), as well as HBeAg seroconversion (15.0% vs 8.3% and 8.9% vs 6.7%). Mean Knodell Histologic Activity Index scores decreased in both compensated and decompensated cirrhotic patients (3.92 vs 3.64, 3.85 vs 3.73, for telbivudine vs lamivudine). Telbivudine and lamivudine were both well tolerated with minor AEs. The results of this study support telbivudine as an effective therapy for patients with both compensated and decompensated HBV-related cirrhosis.