Noncollinear magnetic ordering in small Chromium Clusters

We investigate noncollinear effects in antiferromagnetically coupled clusters using the general, rotationally invariant form of local spin-density theory. The coupling to the electronic degrees of freedom is treated with relativistic non-local pseudopotentials and the ionic structure is optimized by Monte-Carlo techniques. We find that small chromium clusters (N \le 13) strongly favor noncollinear configurations of their local magnetic moments due to frustration. This effect is associated with a significantly lower total magnetization of the noncollinear ground states, ameliorating the disagreement between Stern-Gerlach measurements and previous collinear calculations for Cr_{12} and Cr_{13}. Our results further suggest that the trend to noncollinear configurations might be a feature common to most antiferromagnetic clusters.Comment: 9 pages, RevTeX plus .eps/.ps figure

Drinking water contamination, exposure, and associated health outcomes in rural Appalachia: a systematic review and meta-analysis

This record includes an extended abstract and MP4 presentation. Presented at the 42nd WEDC International Conferenc

HIV-1 TNPO3 dependence is the same in human and mouse cells.

<p><b>A</b>) Indicated cell lines were transfected with control siRNA or siRNA for TNP03. At 72 hours after transfection, cells were harvested and analyzed for TNPO3 protein levels. Tubulin loading control is shown also. <b>B</b>) MEFs treated with siRNAs (solid black bars: control siRNA; hatched gray bars: TNPO3 siRNA) were challenged with WT or N74D HIV-1 reporter virus. Intracellular luciferase activities were determined 72 hrs after infection. 17 and 18 refer to two independently derived MEF Nup358 knockout cell lines. P value, obtained using a two tailed T test, for the difference between control compared to TNPO3 siRNA is 0.005.</p

Verification of SupT1 knockdown in acutely and stably depleted cells and challenge with HIV-1, HIV-1 G89A, HIV-1 P90A, SIVmac, FIV, EIAV and MLV.

<p><b>A</b>) Extent, specificity and stability of shRNA knockdown. Cells frozen 1, 2, and 5 months after stable depletion by shRNA transduction were thawed, passaged for ten days and lysates were immunoblotted with mAb 414, which recognizes Nup358, Nup214, Nup153 and Nup62. Two different exposures of the left immunoblot are shown. A second immunoblot of the stable cell lines was also done (right blot). The mCherry marker co-encoded by the shRNA-transducing lentiviral vector was assessed by FACS to further verify stability of expression. These experiments were done simultaneously with the viral challenges shown in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003969#ppat-1003969-g009" target="_blank">Fig. 9B</a>. MW: molecular weight. C: control. A: acute. 1, 2, 5: cells assessed at 1, 2, and 5 months after stable cell line derivation. <b>B</b>) Control cells, acutely depleted cells and stably depleted cells that were assessed in panel A by immunoblotting (lanes C, A and 1 respectively) and FACS were challenged with HIV-1, HIV-1 G89A, HIV-1 P90A, SIVmac, FIV, EIAV and MLV vectors. G89V vector gave the same result as G89A vector (data not shown).</p

Generation of Nup358−/− cell lines.

<p><b>A</b>) Domain structures of wild type human Nup358 and deletion mutants expressed in Nup358 null (−/−) cells. The leucine rich region (LRR) and NPC (nuclear pore complex targeting) domain mediate nuclear pore localization. The Nup358 proteins were expressed prior to Cre-lox mediated murine Nup358 gene inactivation, with eGFP fused to their N-termini. The resulting cell lines were named Nup358^{−/−[GFP1-1340]}, Nup358^{−/−[GFP1-2561]}, etc. Pre-complementation with GFP-1-1340 prior to Cre-mediated knockout generates a situation analogous to removing the 1,884 C-terminal amino acids of Nup358. R1-4: Ran binding domains 1–4. IR: internal repeat region, which has SUMO E3 ligase activity. CHD: cyclophilin homology domain. Vertical lines: FG repeats. <b>B</b>) Knockout cell line generation. Crossing Nup358 hypomorph mice (Nup358^H/H) with FLPeR mice to excise an expression-attenuating <i>neoR</i> insertion yields floxed (Nup358^F/F) mice with loxP sites in introns flanking exon 2 <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003969#ppat.1003969-Hamada1" target="_blank">[58]</a>. Thus, F/F MEFs display Nup358 expression equivalent to wild type (+/+) MEFs <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003969#ppat.1003969-Hamada1" target="_blank">[58]</a>. Three separate Nup358^F/F lines, numbered 17, 18 and 19, were derived from 13.5 day old embryos. Transduction of these lines with a TSIN series lentiviral vector <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003969#ppat.1003969-Llano1" target="_blank">[80]</a> encoding Cre recombinase was used to excise exon 2, generating −/− 17, 18, and 19 cell lines that were or were not pre-complemented with the proteins shown in Figure 1A. <b>C</b>) PCR analysis of DNA isolated from parental Nup358^F/F, stable Nup358^{−/−[GFP1-1340]} MEFs, or Nup358^F/F parental MEFs 6 days post Cre-expression using primers spanning exon 2. The numbers below the lanes indicate individual F/F cell lines used. Expected bands are 650 bp for an Nup358F/F locus and 120 bp for a Nup358−/− locus. <b>D</b>) Immunoblot for Nup358 in the cell lines tested in panel C with Nup358 antibody. Nup358^{−/−[GFP1-3224]} is used as a size control; note that it is slightly larger than endogenous Nup358 as predicted. Tubulin is used as a loading control. <b>E</b>) Immunoblotting of cell lines using antibody to GFP. The predicted size for GFP1-1340 is 174 Kd. These lines, derived from F/F line 18, were used in the panel F-I experiments. The lower band detected in all lanes, including GFP-lacking F/F cells, is a non-specific band detected by this antibody. <b>F</b>) Wild type reporter virus HIV-1_luc<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003969#ppat.1003969-Llano1" target="_blank">[80]</a> and capsid mutant N74D HIV-1_luc were used to infect Nup358^F/F, Nup358^F/F+Cre and Nup358^{−/−[GFP1-1340]} cells. Luciferase activity was measured 24 hours later and normalized to trypan blue-excluding cells. Error bars denote the s. d. of duplicate luciferase activity measurements in each experiment. The experiment shown is representative of N = 3 for wild type capsid and N = 2 for N74D capsid. <b>G</b>) HIV-1_luc D64N was used to infect the indicated cell lines and 2-LTR circles were measured in triplicate 22 hours post-infection. Each error bar denotes s. d. of 3 measurements of each sample. <b>H</b>) Integration analysis on indicated cell lines. Integration was assayed on total DNA isolated from the indicated cell lines 10 days after challenge with HIV-1_luc with two inputs (10 and 50 µl). Each error bar denotes s. d. of 6 measurements of each sample. <b>I</b>) Infection with HIV-1, HIV-1 G89V and SIVmac, with and without Nup358 gene deletion, and with and without GFP1-1340 pre-expression. Experiments were performed as in Fig. 1F. The <i>x</i>-axis numbers 17 and 18 refer to two independently derived MEF Nup358 knockout cell lines. For line 18, we infected in parallel cells in which, prior to Cre-mediated gene expression, we had stably expressed a protein comprised of the N-terminal 1340 amino acid segment of Nup358 (black bars). Error bars denote the s. d. of duplicate luciferase activity measurements. Experiments are representative of N = 3 for wild type capsid HIV-1, N = 2 for G89V capsid HIV-1, and N = 2 for SIVmac.</p

Growth arrested cell experiments.

<p>MEFs were growth-arrested in aphidicolin 1 µg/ml for 24 hours prior to infection with HIV-1_luc. Aphidicolin was maintained throughout the experiment. Growth arrest was confirmed by FACS analysis (<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003969#ppat.1003969.s005" target="_blank">Figure S5</a>). Cells were harvested for luciferase activity measurement 48 hours after infection. Error bars indicate the standard deviation for duplicate luciferase activity measurements in each experiment.</p