Unwinding of a cholesteric liquid crystal and bidirectional surface anchoring

We examine the influence of bidirectional anchoring on the unwinding of a planar cholesteric liquid crystal induced by the application of a magnetic field. We consider a liquid crystal layer confined between two plates with the helical axis perpendicular to the substrates. We fixed the director twist on one boundary and allow for bidirectional anchoring on the other by introducing a high-order surface potential. By minimizing the total free energy for the system, we investigate the untwisting of the cholesteric helix as the liquid crystal attempts to align with the magnetic field. The transitions between metastable states occur as a series of pitchjumps as the helix expels quarter or half-turn twists, depending on the relative sizes of the strength of the surface potential and the bidirectional anchoring. We show that secondary easy axis directions can play a significant role in the unwinding of the cholesteric in its transition towards a nematic, especially when the surface anchoring strength is large

Neuronal Sirt3 Protects against Excitotoxic Injury in Mouse Cortical Neuron Culture

BACKGROUND: Sirtuins (Sirt), a family of nicotinamide adenine nucleotide (NAD) dependent deacetylases, are implicated in energy metabolism and life span. Among the known Sirt isoforms (Sirt1-7), Sirt3 was identified as a stress responsive deacetylase recently shown to play a role in protecting cells under stress conditions. Here, we demonstrated the presence of Sirt3 in neurons, and characterized the role of Sirt3 in neuron survival under NMDA-induced excitotoxicity. METHODOLOGY/PRINCIPAL FINDINGS: To induce excitotoxic injury, we exposed primary cultured mouse cortical neurons to NMDA (30 µM). NMDA induced a rapid decrease of cytoplasmic NAD (but not mitochondrial NAD) in neurons through poly (ADP-ribose) polymerase-1 (PARP-1) activation. Mitochondrial Sirt3 was increased following PARP-1 mediated NAD depletion, which was reversed by either inhibition of PARP-1 or exogenous NAD. We found that massive reactive oxygen species (ROS) produced under this NAD depleted condition mediated the increase in mitochondrial Sirt3. By transfecting primary neurons with a Sirt3 overexpressing plasmid or Sirt3 siRNA, we showed that Sirt3 is required for neuroprotection against excitotoxicity. CONCLUSIONS: This study demonstrated for the first time that mitochondrial Sirt3 acts as a prosurvival factor playing an essential role to protect neurons under excitotoxic injury

Genome sequence of mungbean and insights into evolution within Vigna species

Mungbean (Vigna radiata) is a fast-growing, warm-season legume crop that is primarily cultivated in developing countries of Asia. Here we construct a draft genome sequence of mungbean to facilitate genome research into the subgenus Ceratotropis, which includes several important dietary legumes in Asia, and to enable a better understanding of the evolution of leguminous species. Based on the de novo assembly of additional wild mungbean species, the divergence of what was eventually domesticated and the sampled wild mungbean species appears to have predated domestication. Moreover, the de novo assembly of a tetraploid Vigna species (V. reflexo-pilosa var. glabra) provides genomic evidence of a recent allopolyploid event. The species tree is constructed using de novo RNA-seq assemblies of 22 accessions of 18 Vigna species and protein sets of Glycine max. The present assembly of V. radiata var. radiata will facilitate genome research and accelerate molecular breeding of the subgenus Ceratotropis

Metamorphosis of Subarachnoid Hemorrhage Research: from Delayed Vasospasm to Early Brain Injury

Delayed vasospasm that develops 3–7 days after aneurysmal subarachnoid hemorrhage (SAH) has traditionally been considered the most important determinant of delayed ischemic injury and poor outcome. Consequently, most therapies against delayed ischemic injury are directed towards reducing the incidence of vasospasm. The clinical trials based on this strategy, however, have so far claimed limited success; the incidence of vasospasm is reduced without reduction in delayed ischemic injury or improvement in the long-term outcome. This fact has shifted research interest to the early brain injury (first 72 h) evoked by SAH. In recent years, several pathological mechanisms that activate within minutes after the initial bleed and lead to early brain injury are identified. In addition, it is found that many of these mechanisms evolve with time and participate in the pathogenesis of delayed ischemic injury and poor outcome. Therefore, a therapy or therapies focused on these early mechanisms may not only prevent the early brain injury but may also help reduce the intensity of later developing neurological complications. This manuscript reviews the pathological mechanisms of early brain injury after SAH and summarizes the status of current therapies

Development of alternative plant vitrification solutions in droplet-vitrification procedures

This study aimed at developing alternative vitrification solutions, modified either from the original PVS2 vitrification solution, by increasing glycerol and sucrose and/or decreasing dimethylsulfoxide and ethylene glycol concentration, or from the original PVS3 vitrification solution by decreasing glycerol and sucrose concentration. The application of these vitrification solutions to two model species, i.e. garlic and chrysanthemum in a droplet-vitrification procedure, revealed that PVS3 and variants were superior to PVS2 and variants and that most PVS2 variants were comparable to the original PVS2. Both species were sensitive to chemical toxicity of permeating cryoprotectants and chrysanthemum was also sensitive to osmotic stress. The lower recovery of cryopreserved garlic shoot apices dehydrated with PVS2 and variants compared with those dehydrated with PVS3 and variants seemed attributed to cytotoxicity of the vitrification solutions tested as well as to insufficient protection against freezing injury. Chrysanthemum shoot tips were very sensitive to both chemical toxicity and osmotic stress and therefore, induction of cytotoxity tolerance during preconditioning was required for successful cryopreservation. The present study revealed that some of the PVS2 variants tested which have increased glycerol and sucrose and/or decreased dimethylsulfoxide and ethylene glycol concentration can be applied when explants are of medium size, tolerant to chemical toxicity and moderately sensitive to osmotic stress. PVS3 and variants can be used widely when samples are heterogeneous, of large size and/or very sensitive to chemical toxicity and tolerant to osmotic stress

Control of liquid crystal pretilt angle by anchoring competition of the stacked alignment layers

We proposed a method to control the pretilt angle of liquid crystals by stacking of a vertical alignment layer on a planar alignment layer. The pretilt angle can be controlled over the full range (0 degrees-90 degrees) depending on the thickness of the vertical alignment layer. We also proposed a numerical model to describe the physical mechanism based on the anchoring competition between liquid crystal, planar, and vertical polyimide alignment layers.11Nsciescopu

Draft genome sequence of adzuki bean, Vigna angularis

Adzuki bean (Vigna angularis var. angularis) is a dietary legume crop in East Asia. The presumed progenitor (Vigna angularis var. nipponensis) is widely found in East Asia, suggesting speciation and domestication in these temperate climate regions. Here, we report a draft genome sequence of adzuki bean. The genome assembly covers 75% of the estimated genome and was mapped to 11 pseudo-chromosomes. Gene prediction revealed 26,857 high confidence protein-coding genes evidenced by RNAseq of different tissues. Comparative gene expression analysis with V. radiata showed that the tissue specificity of orthologous genes was highly conserved. Additional re-sequencing of wild adzuki bean, V. angularis var. nipponensis and V. nepalensis, was performed to analyze the variations between cultivated and wild adzuki bean. The determined divergence time of adzuki bean and the wild species predated archaeology-based domestication time. The present genome assembly will accelerate the genomics-assisted breeding of adzuki bean

Analysis of molecular genetic diversity and population structure in <i>Amaranthus</i> germplasm using SSR markers

<div><p>We assessed the molecular genetic diversity and population structure of <i>Amaranthus</i> species accessions using 11 simple sequence repeat markers. A total of 122 alleles were detected, and the number of alleles per marker (<i>N</i>_A) ranged from 6 to 21 with an average of 11.1 alleles. The frequency of major alleles per locus ranged from 0.148 to 0.695, with an average value of 0.496 per marker. The overall polymorphic information content values were 0.436–0.898, with an average value of 0.657. The observed heterozygosity (<i>H</i>_O) and expected heterozygosity (<i>H</i>_E) ranged from 0.056 to 0.876 and from 0.480 to 0.907, with average values of 0.287 and 0.698, respectively. The average <i>H</i>_O (0.240) was lower than the <i>H</i>_E and gene flow (<i>Nm</i>), and showed substantial genetic variability among all populations of amaranth accessions. The sample groupings did not strictly follow the geographic affiliations of the accessions. A similar pattern was obtained using model-based structure analysis without grouping by species type. Knowledge of the genetic diversity and population structure of amaranth can be used to select representative genotypes and manage <i>Amaranthus</i> germplasm breeding programs.</p></div