A novel coronavirus (CoV) has recently been identified as the aetiological agent of severe acute respiratory syndrome (SARS). Nucleocapsid (N) proteins of the Coronaviridae family have no discernable homology, but they share a common nucleolar-cytoplasmic distribution pattern. There are three putative nuclear localization signal (NLS) motifs present in the N. To determine the role of these putative NLSs in the intracellular localization of the SARS-CoV N, we performed a confocal microscopy analysis using rabbit anti-N antisera. In this report, we show that the wild type N was distributed mainly in the cytoplasm. The N-terminal of the N, which contains the NLS1 (aa38-44), was localized to the nucleus. The C-terminus of the N, which contains both NLS2 (aa257-265) and NLS3 (aa369-390) was localized to the cytoplasm and the nucleolus. Results derived from analysis of various deletion mutations show that the region containing amino acids 226-289 is able to mediate nucleolar localization. The deletion of two hydrophobic regions that flanked the NLS3 recovered its activity and localized to the nucleus. Furthermore, deletion of leucine rich region (220-LALLLLDRLNRL) resulted in the accumulation of N to the cytoplasm and nucleolus, and when fusing this peptide to EGFP localization was cytoplasmic, suggesting that the N may act as a shuttle protein. Differences in nuclear/nucleolar localization properties of N from other members of coronavirus family suggest a unique function for N, which may play an important role in the pathogenesis of SARS.

This paper presents an experimental and theoretical investigation of the Pd-catalyzed Negishi coupling reaction and reveals a novel second transmetalation reaction between an Ar(1)-Pd-Ar(2) species and the organozinc reagent Ar(2)-ZnX. Understanding of this second step reveals how homocoupling and dehalogenation products are formed. Thus, the second transmetalation generates Ar(2)PdAr(2) and Ar(1)ZnCl, which upon reductive elimination and hydrolysis, respectively, give the homocoupling product Ar(2)-Ar(2) and the dehalogenation product Ar(1)H. The ratio of the cross-coupling product Ar(1)-Ar(2) and the homocoupling product Ar(2)-Ar(2) is determined by competition between the second transmetalation and reductive elimination steps. This mechanism is further supported by density functional theoretical calculations. Calculations on a series of reactions suggest a strategy in controlling the selectivity of cross-coupling and homocoupling pathways, which we have experimentally verified.

The interaction between astral microtubules and the cell cortex is accompanied by constant cortical release and transport of LGN/dynein complex, which is modulated by cortical actin filaments. Regulated cortical release and transport of LGN/dynein complex along astral microtubules may contribute to spindle positioning in mammalian cells.

Organozinc halide reagents are not as simple as RZnCl. Differences in solution NMR spectra and kinetic behavior of phenyzinc halide reagents prepared from Grignard (1a system) and lithium reagents (1b system), respectively, were observed. In the 1a system, zero-order kinetic behavior indicates that transmetalation is not the rate-limiting step, while first-order kinetics were observed in the 1b system, and the transmetalation step proved to be rate-limiting. The structure of 1a was revealed by single-crystal X-ray diffraction analysis to contain (THF)(4)MgCl(2) complexed to PhZnX. DFT calculations suggest weaker Ph-Zn bonds in 1a than in 1b, consistent with the faster transmetalation process in catalytic reactions.

Two polarity proteins, partitioning defective 3 homologue (Par3) and mammalian homologues of Drosophila lethal(2)giant larvae (Lgl1/2), antagonize each other in modulating myosin II activation during cell–cell contact formation in Madin-Darby canine kidney cells. Altering the counteraction between Par3 and Lgl1/2 leads to entosis without matrix detachment.

properties because of their special struc ture. When the materials reach a nano meter size, the electrical, optical, magnetic, and other properties of the materials will be altered greatly because of the small size effect, quantum size effect, sur face and boundary effects, and Coulomb blockade effect. [1] Currently, nanomaterials have been widely applied in many fields, including computers, catalysis, sensors, energy, and environmental protection. [2][3][4][5][6][7][8][9][10][11] As the demand increases, people aspire to fabricate nanomaterials with greater prop erties. Many methods have been used to improve the properties of nanomaterials, including doping, surface reconstruc tion, semiconductor composite, and metal nanoparticle embedding. [12][13][14][15][16][17][18][19][20] These days, ion beam techniques, including ion implantation, irradiation, and focused ion beam (FIB), have been extensively used to modulate the properties of nanomaterials. Moreover, ion beam techniques are regarded as a promising technique for doping and surface modification. Compared with doping during growth and diffusion, ion implantation is more controllable and reproducible. In addition, ion implantation is also an effective method for embedding nanoclusters in body materials. Moreover, ion irradiation is an effective method to modulate the morphology and surface structure of the mate rials. Therefore, via using this technique, various properties of nanomaterials can be tailored. FIB is typically used for the in situ study of ionirradiated materials. Figure 1 shows the applications of ion beam techniques for nanomaterial surface modification.Ion implantation, as an ion beam technique, has been extensively applied to the modulation of nanomaterial sur faces. Moreover, the technique has also been extensively used in the field of microelectronics. Ion implantation has replaced diffusion as a doping method to introduce dopants into the semiconductors. As an industrial technique, it exhibits high controllability and accuracy. In contrast to other doping strat egies, almost all elements can be introduced into the target materials by ion implantation and it does not introduce other impurity elements. In addition, ion implantation is not restricted by the solid solubility of elements in the mate rials. Ion implantation can be described as a collision process Nanomaterials have gained plenty of research interest because of their excellent performance, which is derived from their small size and special structure. In practical applications, to acquire nanomaterials with high performance, many methods have been used to modulate the structure and components of materials. To date, ion beam techniques have extensively been applied for modulating the performance of various nanomaterials. Energetic ion beams can modulate the surface morphology and chemical components of nanomaterials. In addition, ion beam techniques have also been used to fabricate nanomaterials, including 2D materials, nanoparticles, and nanowires. Compared with conventional metho...

Objective The sphingolipid de novo synthesis pathway is considered a promising target for pharmacological intervention in atherosclerosis. However, its potential is hampered by the fact that the substance’s atherogenic mechanism is not completely understood. To unravel the complex mechanisms, we utilized the sphingomyelin synthase 2 (Sms2) gene knockout approach to test our hypothesis that selectively decreasing plasma lipoprotein SM, can play an important role in preventing atherosclerosis. Methods and Results We prepared Sms2 and Apoe double knockout (KO) mice. They showed a significant decrease in plasma lipoprotein SM levels (35%, P<0.01) and a significant increase in ceramide and dihydroceramide levels (87.5 and 27%, P<0.01, respectively), but no significant changes in other tested sphingolipids, cholesterol, and triglyceride. Non-HDL lipoproteins from the double KO mice showed a reduction of SM but not cholesterol and displayed a less tendency toward aortic sphingomyelinase-mediated lipoprotein aggregation in vitro and retention in aortas in vivo, compared to controls. More important, at age 19 weeks, Sms2 KO/Apoe KO mice showed a significant reduction in atherosclerotic lesions of the aortic arch and root (52%, P<0.01), compared to controls. We also found that the Sms2 KO/Apoe KO brachiocephalic artery (BCA) contained significantly less SM, ceramide, free cholesterol, and cholesteryl ester (35, 32, 58, and 60%, P<0.01, respectively), than that of Apoe KO BCA. Conclusions Decreasing plasma SM levels through decreasing SMS2 activity could become a promising treatment for atherosclerosis.

The induction period of Negishi coupling catalyzed by pincer thioamide-palladium complex 1 was investigated. A heterogeneous mechanism was excluded by kinetic studies and comparison with Negishi coupling reactions promoted by Pd(OAc)(2)/Bu(4)NBr (a palladium-nanoparticle system). Tetramer 2 was isolated from the reaction of 1 and organozinc reagents. Dissociation of complex 2 by PPh(3) was achieved, and the structure of resultant complex 8 was confirmed by X-ray diffraction analysis. A novel alkylated pincer thioimido-Pd(II) complex, 7, generated from catalyst precursor 1 and basic organometallic reagents (RM), was observed by in situ IR, (1)H NMR, and (13)C NMR spectroscopy for the first time. The reaction of 7 with methyl 2-iodobenzoate afforded 74% of the cross-coupled product, methyl 2-methylbenzoate, together with 60% of Pd(II) complex 2. Furthermore, the catalyst, as an electron-rich Pd(II) species, efficiently promoted the Negishi coupling of aryl iodides and alkylzinc reagents without an induction period, even at low temperatures (0 degrees C or -20 degrees C). To evaluate the influence of the catalyst structure upon the induction period, complex 9 was prepared, in which the nBu groups of 1 were displaced by more bulky 1,3,5-trimethylphenyl groups. Trimer 10 was isolated from the reaction of complex 9 and basic organometallic reagents such as CyZnCl or CyMgCl (Cy: cyclohexyl); this is consistent with the result obtained with complex 1. The rate in the induction period of the model reaction catalyzed by 9 was faster than that with 1. Plausible catalytic cycles for the reaction, based upon the experimental results, are discussed.