The Arabidopsis gene SIGMA FACTOR-BINDING PROTEIN 1 plays a role in the salicylate- and jasmonate-mediated defence responses

The chloroplast-localized SIB1 protein was previously identified by its interaction with SIGMA FACTOR 1 (SIG1), a component of the RNA polymerase machinery responsible for transcription of plastid genes. The physiological function of SIB1 is little known. We found that expression of SIB1 is induced by infection with Pseudomonas syringae, suggesting its possible involvement in the defence response. The sib1 loss-of-function mutation compromises induction of some defence-related genes triggered by pathogen infection and the treatments with salicylic acid (SA) and jasmonic acid (JA), two key signalling molecules in the defence response. Conversely, constitutive over-expression of SIB1 causes the plants to hyper-activate defence-related genes following pathogen infection or the SA and JA treatments, leading to enhanced resistance to infection by P. syringae. SIB1 is a member of the large plant-specific VQ motif-containing protein family, and might act as a link to connect defence signalling with chloroplast function.

Abdominal compartment syndrome associated with capillary leak syndrome after liver transplantation

Orthotopic liver transplantation was performed in a 49-year-old man with metastatic liver sarcoma. After surgery, both abdominal compartment syndrome (ACS) and capillary leak syndrome (CLS) developed. Exploratory laparotomy and colon exteriorization were performed. Five days later, a diagnosis of severe CLS was established, and hydroxyethyl starch was infused to prevent leakage of albumin. The patient gradually recovered over 3 weeks. Awareness of ACS and CLS is important to improve outcome because early diagnosis and immediate therapy are essential. Bladder pressure is a key factor in diagnosing ACS, and pressure of 35 mm Hg is an indication for decompressive laparotomy. During the early stage of CLS, hydroxyethyl starch but not albumin should be used to alleviate edema and hypoalbuminemia.

Mesenchymal stem cells inhibition of chronic ethanol-induced oxidative damage via upregulation of phosphatidylinositol-3-kinase/Akt and modulation of extracellular signal-regulated kinase 1/2 activation in PC12 cells and neurons

It is well known that chronic ethanol consumption damages CNS through oxidative stress which results in many dysfunctions. Recently, it has been demonstrated that as a promising strategy to treat several neurological diseases, transplanted bone marrow-derived mesenchymal stem cells (MSCs) can secrete lots of protective factors that in turn promote function recovery. In the present study, we assessed the potential effects of MSCs conditioned medium (MSC-CM) against chronic ethanol-associated damage on PC12 cells and primary cortical neurons. We found that pretreatment with MSC-CM notably improved cell survival, prevented chronic ethanol-associated apoptosis and abolished the robust deterioration in oxidative status. In addition, we also discovered that chronic ethanol exposure induced an inactivation of phosphatidylinositol-3-kinase (PI3K)/Akt and a lasting activation of extracellular signal-regulated kinase 1/2 (ERK1/2) in both PC12 cells and primary cortical neurons which were able to be reversed by MSC-CM. The PI3K inhibitor (LY294002) was able to reduce the antioxidative and cytoprotective effects conferred by MSC-CM, in part, and the ERK1/2 inhibitor (PD98059) was able to elicit significant protection from chronic ethanol cytotoxicity but not rescue the deterioration in oxidative status induced by chronic ethanol. Taken together, these findings provide the first evidence that MSCs might have potent antioxidant action to shield the apoptotic impairment from chronic ethanol exposure in PC12 cells and neurons, which is involved in upregulation of PI3K/Akt and modulation of ERK1/2 activation, at least partially.

Differential actions of urocortins on neurons of the myenteric division of the enteric nervous system in guinea pig distal colon

BACKGROUND AND PURPOSE

Urocortins (Ucns) 1, 2 and 3 are corticotropin-releasing factor (CRF)-related neuropeptides and may be involved in neural regulation of colonic motor functions. Nevertheless, details of the neural mechanism of action for Ucns have been unclear. We have, here, tested the hypothesis that Ucns act in the enteric nervous system (ENS) to influence colonic motor behaviour.

EXPERIMENTAL APPROACH

We used intracellular recording with 'sharp' microelectrodes, followed by intraneuronal injection of biocytin, and immunohistochemical localization of CRF(1) and CRF(2) receptors in guinea pig colonic tissue.

KEY RESULTS

Application of Ucn1 depolarized membrane potentials and elevated excitability in 58% of AH-type and 60% of S-type colonic myenteric neurons. In most of the neurons tested, depolarizing responses evoked by Ucn-1 were suppressed by the CRF(1) receptor antagonist NBI 27914, but were unaffected by the CRF(2) receptor antagonist antisauvagine-30. The selective CRF(2) receptor agonists, Ucn2 and Ucn3, evoked depolarizing responses in 12 and 8% of the AH-type myenteric neurons, respectively, and had no effect on S-type neurons. Antisauvagine-30, but not NBI 27914, suppressed these Ucn2- and Ucn3-evoked responses. Immunohistochemical staining identified CRF(1) as the predominant CRF receptor subtype expressed by ganglion cell somas, while CRF(2)-immunoreactive neuronal somas were sparse. Ucns did not affect excitatory synaptic transmission in the ENS.

CONCLUSIONS AND IMPLICATIONS

The results suggest that Ucns act as neuromodulators to influence myenteric neuronal excitability. The excitatory action of Ucn1 in myenteric neurons was primarily at CRF(1) receptors, and the excitatory action of Ucn2 and Ucn3 was at CRF(2) receptors.

Observation of time-reversal-protected single-dirac-cone topological-insulator states in Bi2Te3 and Sb2Te3

We show that the strongly spin-orbit coupled materials Bi2Te3 and Sb2Te3 and their derivatives belong to the Z2 topological-insulator class. Using a combination of first-principles theoretical calculations and photoemission spectroscopy, we directly show that Bi2Te3 is a large spin-orbit-induced indirect bulk band gap (delta approximately 150 meV) semiconductor whose surface is characterized by a single topological spin-Dirac cone. The electronic structure of self-doped Sb2Te3 exhibits similar Z2 topological properties. We demonstrate that the dynamics of spin-Dirac fermions can be controlled through systematic Mn doping, making these materials classes potentially suitable for topological device applications.

Differential role of N-methyl-D-aspartate receptor subunits 2A and 2B in mediating phencyclidine-induced perinatal neuronal apoptosis and behavioral deficits

The mechanism underlying phencyclidine (PCP)-induced apoptosis in perinatal rats and the development of schizophrenia-like behaviors is incompletely understood. We used antagonists for N-methyl-D-aspartate (NMDA) receptor subunit NR2A- and NR2B-containing NMDA receptor to test the hypothesis that the behavioral and apoptotic effects of PCP are mediated by blockade of NR1/NR2A-containing receptors, rather than NR1/NR2B-containing receptors. Sprague-Dawley rats were treated on PN7, PN9, and PN11 with PCP (10 mg/kg), PEAQX (NR2A-preferring antagonist; 10, 20, or 40 mg/kg), or ifenprodil (selective NR2B antagonist; 1, 5, or 10 mg/kg) and sacrificed for measurement of caspase-3 activity (an index of apoptosis) or allowed to age and tested for locomotor sensitization to PCP challenge on PN28-PN35. PCP or PEAQX on PN7, PN9, and PN11 markedly elevated caspase-3 activity in the cortex; ifenprodil showed no effect. Striatal apoptosis was evident only after subchronic treatment with a high dose of PEAQX (20 mg/kg). Animals treated with PCP or PEAQX on PN7, PN9, and PN11 showed a sensitized locomotor response to PCP challenge on PN28-PN35. Ifenprodil treatment had no effect on either measure. Therefore, PCP blockade of cortical NR1/NR2A, rather than NR1/NR2B, appears to be responsible for PCP-induced apoptosis and the development of long-lasting behavioral deficits.

A tunable topological insulator in the spin helical Dirac transport regime

Helical Dirac fermions-charge carriers that behave as massless relativistic particles with an intrinsic angular momentum (spin) locked to its translational momentum-are proposed to be the key to realizing fundamentally new phenomena in condensed matter physics. Prominent examples include the anomalous quantization of magneto-electric coupling, half-fermion states that are their own antiparticle, and charge fractionalization in a Bose-Einstein condensate, all of which are not possible with conventional Dirac fermions of the graphene variety. Helical Dirac fermions have so far remained elusive owing to the lack of necessary spin-sensitive measurements and because such fermions are forbidden to exist in conventional materials harbouring relativistic electrons, such as graphene or bismuth. It has recently been proposed that helical Dirac fermions may exist at the edges of certain types of topologically ordered insulators-materials with a bulk insulating gap of spin-orbit origin and surface states protected against scattering by time-reversal symmetry-and that their peculiar properties may be accessed provided the insulator is tuned into the so-called topological transport regime. However, helical Dirac fermions have not been observed in existing topological insulators. Here we report the realization and characterization of a tunable topological insulator in a bismuth-based class of material by combining spin-imaging and momentum-resolved spectroscopies, bulk charge compensation, Hall transport measurements and surface quantum control. Our results reveal a spin-momentum locked Dirac cone carrying a non-trivial Berry's phase that is nearly 100 per cent spin-polarized, which exhibits a tunable topological fermion density in the vicinity of the Kramers point and can be driven to the long-sought topological spin transport regime. The observed topological nodal state is shown to be protected even up to 300 K. Our demonstration of room-temperature topological order and non-trivial spin-texture in stoichiometric Bi(2)Se(3).M(x) (M(x) indicates surface doping or gating control) paves the way for future graphene-like studies of topological insulators, and applications of the observed spin-polarized edge channels in spintronic and computing technologies possibly at room temperature.

Fermi surface topology and low-lying quasiparticle dynamics of parent Fe1+xTe/Se superconductor

We report the first photoemission study of Fe1+xTe-the host compound of the newly discovered iron-chalcogenide superconductors (maximum Tc approximately 27 K). Our results reveal a pair of nearly electron-hole compensated Fermi pockets, strong Fermi velocity renormalization, and an absence of a spin-density-wave gap. A shadow hole pocket is observed at the "X" point of the Brillouin zone which is consistent with a long-range ordered magnetostructural ground state. No signature of Fermi surface nesting instability associated with Q=(pi/2,pi/2) is observed. Our results collectively reveal that the Fe1+xTe series is different from the undoped phases of the high Tc pnictides and likely harbor an unusual mechanism for superconductivity and magnetic order.

The effects of 41°C hyperthermia on the DNA repair protein, MRE11, correlate with radiosensitization in four human tumor cell lines

PURPOSE

The goal of this study was to determine if reduced availability of the DNA repair protein, MRE11, for the repair of damaged DNA is a basis for thermal radiosensitization induced by moderate hyperthermia. To test this hypothesis, we measured the total amount of MRE11 DNA repair protein and its heat-induced alterations in four human tumor cell lines requiring different heating times at 41 degrees C to induce measurable radiosensitization.

MATERIALS AND METHODS

Human colon adenocarcinoma cell lines (NSY42129, HT29 and HCT15) and HeLa cells were used as the test system. Cells were irradiated immediately after completion of hyperthermia. MRE11 levels in whole cell extract, nuclear extract and cytoplasmic extracts were measured by Western blotting. The nuclear and cytoplasmic extracts were separated by TX100 solubility. The subcellular localization of MRE11 was determined by immunofluorescence staining.

RESULTS

The results show that for the human tumor cell lines studied, the larger the endogenous amount of MRE11 protein per cell, the longer the heating time at 41 degrees C required for inducing measurable radiosensitization in that cell line. Further, the residual nuclear MRE11 protein level, measured in the nuclear extract and in the cytoplasmic extract as a function of heating time, both correlated with the thermal enhancement ratio (TER).

CONCLUSIONS

These observations are consistent with the possibility that delocalization of MRE11 from the nucleus is a critical step in the radiosensitization by moderate hyperthermia.

Neuroprotective effects of R,R-tetrahydrochrysene against glutamate-induced cell death through anti-excitotoxic and antioxidant actions involving estrogen receptor-dependent and -independent pathways

Glutamate-induced neural cell death is mediated by excitotoxicity and oxidative stress. Treatment of glutamate toxicity with estrogen and its related compounds for neuroprotection remains controversial. In this study, we examined the effects of selective estrogen receptor (ER) ligands on glutamate toxicity and found that R,R-tetrahydrochrysene (R,R-THC), an antagonist of ERbeta and agonist of ERalpha, has neuroprotective effects against glutamate-induced death in primary rat cortical cells and mouse N29/4 hypothalamic cells. The protective effect of R,R-THC was dose-dependent and was maintained even when added several hours after the initial glutamate exposure. R,R-THC blocked glutamate-induced depletion of intracellular glutathione, increased superoxide dismutase activity, and protected cells from hydrogen peroxide-induced death. R,R-THC also prevented glutamate-induced nuclear translocation of apoptotic inducing factor and release of mitochondrial cytochrome c. The protective effect of R,R-THC was blocked by methyl-piperidino-pyrazole (MPP; an ERalpha antagonist) in glutamate-treated cortical cells, and pretreatment with MK-801 (an NMDA receptor antagonist) but not CNQX (an AMPA/kainate receptor antagonist) increased cell survival. On the other hand, MPP did not block the protective effect of R,R-THC in glutamate-treated N29/4 cells, and neither MK-801 nor CNQX conferred protection. Activation of ERalpha and/or ERbeta with 17beta-estradiol (E2), propyl-pyrazole-triol or diarylpropionitrile did not provide effective neuroprotection, and pretreatment with ICI 182,780 did not inhibit the protective effect of R,R-THC in either type of cell. These results suggest that the use of ER agonists (including E2) has limited beneficial effects when both excitotoxicity and oxidative stress occur. In contrast to agonists of ERs, R,R-THC, which possesses anti-excitotoxic and antioxidant actions via ER-dependent and -independent pathways, provides significant neuroprotection.

Gene expression profiling of tolerant barley in response to Diuraphis noxia (Hemiptera: Aphididae) feeding

Aphids are, arguably, the single most damaging group of agricultural insect pests throughout the world. Plant tolerance, which is a plant response to an insect pest, is viewed as an excellent management strategy. Developing testable hypotheses based on genome-wide and more focused methods will help in understanding the molecular underpinnings of plant tolerance to aphid herbivory. As a first step in this process, we undertook transcript profiling with Affymetrix GeneChip Barley Genome arrays using RNA extracted from tissues of tolerant and susceptible genotypes collected at three hours, three days and six days after Diuraphis noxia introduction. Acquired data were compared to identify changes unique to the tolerant barley at each harvest date. Transcript abundance of 4086 genes was differentially changed over the three harvest dates in tolerant and susceptible barley in response to D. noxia feeding. Across the three harvest dates, the greatest number of genes was differentially expressed in both barleys at three days after aphid introduction. A total of 909 genes showed significant levels of change in the tolerant barley in response to D. noxia feeding as compared to susceptible plants infested with aphids. Many of these genes could be assigned to specific metabolic categories, including several associated with plant defense and scavenging of reactive oxygen species (ROS). Interestingly, two peroxidase genes, designated HvPRXA1 and HvPRXA2, were up-regulated to a greater degree in response to D. noxia feeding on tolerant barley plants, indicating that specific peroxidases could be important for the tolerance process. These findings suggest that the ability to elevate and sustain levels of ROS-scavenging enzymes could play an important role in the tolerant response.

Na+ mechanism of delta-opioid receptor induced protection from anoxic K+ leakage in the cortex

Activation of delta-opioid receptors (DOR) attenuates anoxic K(+) leakage and protects cortical neurons from anoxic insults by inhibiting Na(+) influx. It is unknown, however, which pathway(s) that mediates the Na(+) influx is the target of DOR signal. In the present work, we found that, in the cortex, (1) DOR protection was largely dependent on the inhibition of anoxic Na(+) influxes mediated by voltage-gated Na(+) channels; (2) DOR activation inhibited Na(+) influx mediated by ionotropic glutamate N-methyl-D-aspartate (NMDA) receptors, but not that by non-NMDA receptors, although both played a role in anoxic K(+) derangement; and (3) DOR activation had little effect on Na(+)/Ca(2+) exchanger-based response to anoxia. We conclude that DOR activation attenuates anoxic K(+) derangement by restricting Na(+) influx mediated by Na(+) channels and NMDA receptors, and that non-NMDA receptors and Na(+)/Ca(2+) exchangers, although involved in anoxic K(+) derangement in certain degrees, are less likely the targets of DOR signal.