The effects of external electric field: creating non-zero first hyperpolarizability for centrosymmetric benzene and strongly enhancing first hyperpolarizability for non-centrosymmetric edge-modified graphene ribbon H2N-(3,3)ZGNR-NO2

How to generate a non-zero first hyperpolarizability for a centrosymmetric molecule is a challenging question. In this paper, an external (pump) electric field is used to make a centrosymmetric benzene molecule generate a non-zero value of the electric field induced first hyperpolarizability (β ^F ). This comes from the centrosymmetry breaking of electron cloud. Two interesting rules are exhibited. (1) β ^F is anisotropic for different directional fields (F _i, i?=?X, Y, Z). (2) The field dependence of β ^F is a non-monotonic function, and an optimum external electric field causes the maximum value of β ^F . The largest first hyperpolarizability β ^F reaches the considerable level of 3.9?×?10⁵ a.u. under F _Y?=?330?×?10^?4 a.u. for benzene. The external electric field effects on non-centrosymmetric edge-modified graphene ribbon H₂N-(3,3)ZGNR-NO₂ was also studied in this work. The first hyperpolarizability reaches as much as 2.1?×?10⁷ a.u. under F _X?=?600?×?10^?4 a.u. for H₂N-(3,3)ZGNR-NO₂. We show that the external electric field can not only create a non-zero first hyperpolarizability for centrosymmetric molecule, but also remarkably enhance the first hyperpolarizability for a non-centrosymmetric molecule.     

金荞麦果实中有效成分的分析

采用HPLC法对金荞麦果实中的有效成分进行了分析,结果表明:金荞麦果实中含有芦丁、槲皮素和表儿茶素等有效成分,其中主要以芦丁为主,槲皮素、表儿茶素等含量甚微.金荞麦果实中的有效成分主要集中在种子部分,果皮中则不合或含量甚微.     

Characterization of two novel KRAB-domain-containing zinc finger genes, ZNF460 and ZNF461, on human chromosome 19q13.1-->q13.4

This study reports the cloning and characterization of two novel human zinc finger protein cDNAs (ZNF460 and ZNF461) from a fetal brain cDNA library. The ZNF460 cDNA is 3,135 bp in length encoding a 562-amino-acid polypeptide and the ZNF461 cDNA is 2,548 bp encoding a 563-amino-acid protein. Both of the proteins contain a KRAB A+B box and eleven C2H2 type zinc finger motifs. ZNF461 shows high similarity with the rat GIOT-1 gene (GIOT1). The ZNF460 gene mapped to 19q13.4 with 3 exons, and ZNF461 mapped to 19q13.1 with 6 exons. Both of the two genes are ubiquitously expressed in normal human tissues and the abundance of the ZNF460 mRNA is relatively low.     

Identifying MicroRNA and mRNA Expression Profiles in Embryonic Stem Cells Derived from Parthenogenetic, Androgenetic and Fertilized Blastocysts

MicroRNAs (miRNAs) are a class of highly conserved small non-coding RNA molecules that play a pivotal role in several cellular functions. In this study, miRNA and messenger RNA (mRNA) profiles were examined by Illumina microarray in mouse embryonic stem cells (ESCs) derived from parthenogenetic, androgenetic, and fertilized blastocysts. The global analysis of miRNA-mRNA target pairs provided insight into the role of miRNAs in gene expression. Results showed that a total of 125 miRNAs and 2394 mRNAs were differentially expressed between androgenetic ESCs (aESCs) and fertilized ESCs (fESCs), a total of 42 miRNAs and 87 mRNAs were differentially expressed between parthenogenetic ESCs (pESCs) and fESCs, and a total of 99 miRNAs and 1788 mRNAs were differentially expressed between aESCs and pESCs. In addition, a total of 575, 5 and 376 miRNA-mRNA target pairs were observed in aESCs vs. fESCs, pESCs vs. fESCs, and aESCs vs. pESCs, respectively. Furthermore, 15 known imprinted genes and 16 putative uniparentally expressed miRNAs with high expression levels were confirmed by both microarray and real-time RT-PCR. Finally, transfection of miRNA inhibitors was performed to validate the regulatory relationship between putative maternally expressed miRNAs and target mRNAs. Inhibition of miR-880 increased the expression of Peg3, Dyrk1b, and Prrg2 mRNA, inhibition of miR-363 increased the expression of Nfat5 and Soat1 mRNA, and inhibition of miR-883b-5p increased Nfat5, Tacstd2, and Ppapdc1 mRNA. These results warrant a functional study to fully understand the underlying regulation of genomic imprinting in early embryo development.     

Chromosome numbers of the Australian Cymodoceaceae

The somatic chromosome numbers of the eleven Australian seagrass species belonging to five genera in the Family Cymodoceaceae were determined. The chromosome numbers in Amphibolis and Thalassodendron are reported for the first time. Cymodocea and Halodule species have the following chromosome numbers: Cymodocea angustata Ostenf., 2n = 14, 28; C. rotundata Ehrenb. & Hempr. ex Asch., 2n = 14; C. serrulata (R. Br.) Asch. & Magnus, 2n = 14, 28; Halodule pinifolia (Miki) den Hartog, 2n = 32; H. uninervis (Forsk.) Asch., 2n = 32; H. tridentata (Steinh.) Endl. ex Unger, 2n = 14. Halodule has the highest chromosome numbers among the seagrasses and they are the largest in sizes with a distinct bimodal type in the family. Syringodium isoetifolium (Asch.) Dandy has 2n = 20. Both endemic Amphibolis antarctica (Labill.) Sonder ex Asch. and A. griffithii (J. Black) den Hartog have 2n = ca. 36 and have the smallest chromosomes in the family appearing as small dots. Thalassodendron pachyrhizum den Hartog has 2n = 28. Chromosome numbers appear to be identical or closely related among different species in the same genus but they vary in the five genera in the Cymodoceaceae suggesting that these five genera may have evolved independently in the past.     

Targeted delivery of a phosphopeptide prodrug inhibits the proliferation of a human glioma cell line

Peptides are ideal candidates for developing therapeutics. Polo-like kinase 1 is an important regulatory protein in the cell cycle and contains a C-terminal polo-box domain, which is the hallmark of this protein family. We developed a peptide inhibitor of polo-like kinase 1 that targets its polo-box domain. This new phosphopeptide, cRGDyK-S-S-CPLHSpT, preferentially penetrates the cancer cell membrane mediated by the integrin receptor, which is expressed at high levels by cancer cells. In the present study, using high performance liquid chromatography and mass spectroscopy, we determined the stability of cRGDyK-S-S-CPLHSpT and its cleavage by glutathione under typical conditions for cell culture. We further assessed the ability of the peptide to inhibit the proliferation of the U87MG glioma cell line. The phosphorylated peptide was stable, and the disulfide bond of cRGDyK-S-S-CPLHSpT was cleaved in 50 mM glutathione. This peptide inhibited the growth of cancer cells and changed their morphology. Therefore, we conclude that the phosphopeptide shows promise as a prodrug and has a high potential to act as an anticancer agent by inhibiting polo-like kinase 1 by binding its polo-box domain. These findings indicate the therapeutic potential of PLHSpT and peptides similarly targeted to surface receptors of cancer cells and to the functional domains of regulatory proteins.     

Affinity extraction of proteins with a reversed micellar system composed of Cibacron Blue-modified lecithin

Crude soybean lecithin was used as a novel surfactant to form reversed micelles in n-hexane. Cibacron Blue F-3GA (CB) was directly immobilized to the reversed micelles by a two-phase reaction. The reversed micellar system without CB showed low solubilizing capacity for low molecular weight proteins, lysozyme, and cytochrome c due to the weak electrostatic interactions. The introduction of CB significantly increased the solubilization of lysozyme because of its affinity binding to CB but showed no effect on the solubilization of cytochrome c since it did not bind to CB. Although bovine serum albumin had an affinity for CB, it was not extracted to the reversed micelles containing CB because its high molecular weight resulted in a significant steric hindrance effect. Thus the reversed micellar system had a high selectivity resulting from both biospecific and steric hindrance effects. The extraction yield of lysozyme decreased significantly with increasing ionic strength. Therefore, the back extraction of lysozyme was carried out using a stripping solution with an ionic strength of 0.865 mol/L. The overall recovery yield of lysozyme after back extraction could be increased to 87% by stripping for 2 h. The recovered lysozyme exhibited an activity equivalent to native lysozyme, and its secondary structure was also unchanged.     

Stimulation of Na+-K+-2Cl- cotransporter in neuronal cells by excitatory neurotransmitter glutamate

Na⁺-K⁺-2Clcotransporters are important in renal salt reabsorption and in saltsecretion by epithelia. They are also essential in maintenance andregulation of ion gradients and cell volume in both epithelial andnonepithelial cells. Expression ofNa⁺-K⁺-2Clcotransporters in brain tissues is high; however, little is known abouttheir function and regulation in neurons. In this study, we examinedregulation of theNa⁺-K⁺-2Clcotransporter by the excitatory neurotransmitter glutamate. The cotransporter activity in human neuroblastoma SH-SY5Y cells was assessed by bumetanide-sensitiveK⁺ influx, and protein expressionwas evaluated by Western blot analysis. Glutamate was found to induce adose- and time-dependent stimulation ofNa⁺-K⁺-2Clcotransporter activity in SH-SY5Y cells. Moreover, both the glutamate ionotropic receptor agonistN-methyl-D-asparticacid (NMDA) and the metabotropic receptor agonist(±)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD) significantlystimulated the cotransport activity in these cells.NMDA-mediated stimulation of theNa⁺-K⁺-2Clcotransporter was abolished by the selective NMDA-receptor antagonist (+)-MK-801 hydrogen maleate.trans-ACPD-mediated effect on the cotransporter was blocked by the metabotropic receptor antagonist (+)--methyl-(4-carboxyphenyl)glycine. The results demonstrate thatNa⁺-K⁺-2Clcotransporters in neurons are regulated by activation of both ionotropic and metabotropic glutamate receptors.

     

Production of L(+)-lactic acid with Rhizopus oryzae immobilized in polyurethane foam cubes

Summary Polyurethane foam cubes were employed as carriers to immobilize Rhizopus oryzae for L(+)-lactic acid production. The immobilizing capacity reached 450 g-fresh cell/l-cube. The production rate of L(+)-lactic acid could be threefold increased by using the immobilized R. oryzae. The immobilized cells could be steadily used in repetitive fermentations for more than 10 batches.     

Neuroprotective Effect of Oxysophocarpine by Modulation of MAPK Pathway in Rat Hippocampal Neurons Subject to Oxygen–Glucose Deprivation and Reperfusion

Oxysophocarpine (OSC), an alkaloid isolated from Sophora flavescens Ait, has been traditionally used as a medicinal agent based on the observed pharmacological effects. In this study, the direct effect of OSC against neuronal injuries induced by oxygen and glucose deprivation (OGD) in neonatal rat primary-cultured hippocampal neurons and its mechanisms were investigated. Cultured hippocampal neurons, which were exposed to OGD for 2 h followed by a 24 h reoxygenation, were used as an in vitro model of ischemia and reperfusion. 2-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and lactate dehydrogenase (LDH) assay were used to confirm neural damage and to further evaluate the protective effects of OSC. The concentration of intracellular-free calcium [Ca²⁺]_i and mitochondrial membrane potential (MMP) were measured to determine the intracellular mechanisms and to further estimate the degree of neuronal damage. Changes in expression of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, p-ERK1/2, p-JNK1/2, and p-p38 MAPK were also observed in the in vitro model. It was shown that OSC (0.8, 2, or 5 µmol/L) significantly attenuated the increased absorbance of MTT, and the release of LDH manifests the neuronal damage by the OGD/R. Meanwhile, the pretreatment of the neurons during the reoxygenation period with OSC significantly increased MMP; it also inhibited [Ca²⁺]_i the elevation in a dose-dependent manner. Furthermore, the pretreatment with OSC (0.8, 2, or 5 µmol/L) significantly down-regulated expressions of IL-1β, TNF-α, p-ERK1/2, p-JNK1/2, and p-p38 MAPK in neonatal rat primary-cultured hippocampal neurons induced by OGD/R injury. In conclusion, OSC displays a protective effect on OGD-injured hippocampal neurons by attenuating expression of inflammatory factors via down-regulated the MAPK signaling pathway.