Mono- and tetra-nuclear copper complexes bearing bis(imino)phenoxide derived ligands: catalytic evaluation for benzene oxidation and ROP of epsilon-caprolactone

Complexes of the type [Cu(L)2] (1) and [Cu4L2(μ4−O)(OAc)4] (2) have been obtained from the reaction of the phenoxydiimine 1,3-(2,6-R22C6H3N=CH)2-5-R1C6H2OH-2 (LH) (where R1 = Me, tBu, Cl; R2 = Me, iPr) with copper(II) acetate [Cu(OAc)2]; changing the molar ratio of the reactants affords 10 differing amounts of 1 or 2. Reaction of the parent dialdehyde [1,3-(CHO)2-5-MeC6H2OH-2] with [Cu(OAc)2] in the presence of Et3N afforded, following work-up, a polymeric chain (3) comprising {[Cu2(OAc)4]OAc}n, HNEt3 and MeCN. The crystal structures of 1 (R1 = Me, R2 = iPr 1a; R1 = Cl, R2 = iPr 1b), 2 (R1 = Me, R2 = Me 2a; R1 = Me, R2 = iPr 2b; R1 = tBu, R2 = Me 2c; R1 = Cl, R2 = Me 2d; R1 = Cl, R2 = iPr 2e; R1 = tBu, R2 =iPr 2f) and 3 are reported (synchrotron radiation was necessary for 3). The 15 magnetic properties of the cluster 2b are presented. Complexes of type 2 and 3 were screened for the ring opening polymerization (ROP) of ε-caprolactone, with or without benzyl alcohol present, under a variety of conditions, however only trace polymer was isolated. The electrochemistry of all complexes was also investigated, together with their ability to catalyze benzene oxidation (using hydrogen peroxide); although low conversions were observed, the tetra-nuclear complexes exhibited excellent selectivity

Photoregulating RNA Digestion Using Azobenzene Linked Dumbbell Antisense Oligodeoxynucleotides

Introduction of 4,4′-bis­(hydroxymethyl)-azobenzene (azo) to dumbbell hairpin oligonucleotides at the loop position was able to reversibly control the stability of the whole hairpin structure via UV or visible light irradiation. Here, we designed and synthesized a series of azobenzene linked dumbbell antisense oligodeoxynucleotides (asODNs) containing two terminal hairpins that are composed of an asODN and a short inhibitory sense strand. Thermal melting studies of these azobenzene linked dumbbell asODNs indicated that efficient <i>trans</i> to <i>cis</i> photoisomerization of azobenzene moieties induced large difference in thermal stability (Δ<i>T</i>_m = 12.1–21.3 °C). In addition, photomodulation of their RNA binding abilities and RNA digestion by RNase H was investigated. The <i>trans</i>-azobenzene linked asODNs with the optimized base pairs between asODN strands and inhibitory sense strands could only bind few percentage of the target RNA, while it was able to recover their binding to the target RNA and degrade it by RNase H after light irradiation. Upon optimization, it is promising to use these azobenzene linked asODNs for reversible spatial and temporal regulation of antisense activities based on both steric binding and RNA digestion by RNase H

Vpr complementation does not affect Vpr-defective single-cycle HIV-1 infection of MDDCs.

<p>(A) Vpr incorporation in VSV-G-pseudotyped, single-cycle HIV-Vpr+ and Vpr-complemented HIV-Vpr-. Virion pellets were analyzed by immunoblotting with anti-Vpr and anti-p24, respectively. (B) Vpr complementation does not affect single-cycle HIV-Vpr- infection of MDDCs. Infected cells were lysed at indicated times post infection for the detection of HIV-1 infection by measuring luciferase activity and normalized to protein content (20 µg/sample). cps, counts per second. The data shown represents one of three independent experiments carried out with three individual donors.</p

Vpr-mediated enhancement of single-cycle HIV-1 infection is independent of VSV-G and Ampho envelopes used for virus pseudotyping.

<p>(A) HuT/CCR5 cells were infected at an MOI of 1.0 with single-cycle HIV-1 Vpr⁺/VSV-G and HIV-1 Vpr⁻/VSV-G. Luciferase expression from the integrated provirus in the infected cells was assessed at the indicated time and normalized to protein content (10 µg/sample). The data shown represents one of three independent experiments, and error bars represent standard deviation of the mean of triplicate samples. (B) The MLV amphotrophic (Ampho) envelope pseudotyped, HIV-1 Vpr⁺ and HIV-1 Vpr⁻ stocks generated from pNL-Luc-E⁻R⁺ and pNL-Luc-E⁻R⁻ proviral constructs were analyzed by immunoblotting for the presence of Vpr. (C) HuT/CCR5 cells were infected at an MOI of 1.0 with HIV-1 Vpr⁺/Ampho and HIV-1 Vpr⁻/Ampho. Luciferase expression from the integrated provirus in the infected cells was assessed 3 days post infection and normalized to protein content. Error bars represent standard deviation of the mean of triplicate samples. Statistically significant differences are indicated by the asterisks (<i>P<</i>0.05) and the <i>P</i> value.</p

Characterization of Vpr⁺ and Vpr⁻ single-cycle, VSV-G-pseudotyped HIV-1 stocks produced from HEK293T cells.

<p>(A) Quantification of luciferase (Luc) expression from the pNL-Luc-E⁻R⁺ (HIV-1 Vpr⁺) and pNL-Luc-E⁻R⁻ (HIV-1 Vpr⁻) proviral DNA constructs in HEK293T cells. Luciferase activity was determined 48 h following plasmid transfection and normalized to protein content. Error bars represent the standard deviation of the mean of three independent experiments. (B) The VSV-G pseudotyped, HIV-1 Vpr⁺ and HIV-1 Vpr⁻ stocks generated from pNL-Luc-E⁻R⁺ and pNL-Luc-E⁻R⁻ were analyzed by immunoblotting for the incorporation of Vpr into virion particles.</p

Comparison of the viral DNA profiles in HIV-1_NLAD8 and HIV-1_NLAD8ΔVpr infected cells.

<p>Quantitative PCR analysis was performed to determine levels of late reverse transcription (Late-RT) products, 2-LTR circles, and integrated proviral copies over a period of 7 days following infection of activated PBMCs (A-C) and MDDCs (D-F) following infection with HIV-1_NLAD8 and HIV-1_NLAD8ΔVpr. Real-time PCR amplification of the <i>glyceraldehyde-3-phosphate dehydrogenase</i> gene was performed for each sample to normalize for the amount of input DNA in each of the amplification reactions. Error bars represent standard error of the mean of duplicate samples. Statistically significant differences are indicated by the asterisks (<i>P<</i>0.05) and <i>P</i> values. The data shown represents one of three independent experiments carried out for each cell type from three different donors.</p

Titration of infectivity of single-cycle and replication-competent HIV-1 stocks.

a<p>Single-cycle, VSV-G-pseudotyped luciferase reporter HIV-1 Vpr⁺, HIV-1 Vpr⁻, and Vpr complemented HIV-1 Vpr⁻ stocks. The data represent average results of duplicated samples from two independent experiments.</p>b<p>Single-cycle, MLV amphotrophic (Ampho) envelope-pseudotyped luciferase reporter HIV-1 Vpr⁺ and HIV-1 Vpr⁻ virus stocks.</p>c<p>Replication-competent HIV-1_NLAD8(WT) and HIV-1_NLAD8(ΔVpr) stocks. All viral stocks were prepared from HEK293T cells and analyzed for p24 concentration by ELISA. The infectivity of each virus stock was evaluated on HIV-1 indicator GHOST/R5 cells by a limiting dilution assay <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035385#pone.0035385-Janas1" target="_blank">[35]</a>. The relative infectivity of each virus stock is presented as the number of infectious units (IU) per 1 ng of p24.</p

Vpr significantly enhances replication-competent HIV-1_NLAD8 infection in MDDCs.

<p>(A) The HIV-1_NLAD8 and HIV-1_NLAD8ΔVpr virus stocks produced from HEK293T cells were analyzed by immunoblotting for the presence of Vpr. (B) PHA-activated PBMCs and (C) MDDCs were infected with 5 ng and 20 ng of p24, respectively, from HIV-1_NLAD8 and HIV-1_NLAD8ΔVpr virus and levels of p24 capsid released into the media during virus replication were assayed over a period of 10 days and 7 days post infection for PBMCs and MDDCs, respectively. The data shown represents one of three independent experiments carried out with three individual donors, and error bars represent standard deviation of triplicate infections. Statistically significant differences are indicated by the asterisks (<i>P<</i>0.05).</p

Vpr enhances single-cycle HIV-1 infection of activated PBMCs, primary CD4⁺ T cells, and MDDCs.

<p>(A) PHA-activated peripheral blood mononucleocytes (PBMCs), (B) PHA-activated CD4⁺ T cells, and (C) Monocyte-derived dendritic cells (MDDCs) were infected at an MOI of 1.0 with single-cycle HIV-1 Vpr⁺/VSV-G and HIV-1 Vpr⁻/VSV-G to test the role of Vpr in HIV-1 infection. Luciferase expression from the integrated provirus in the infected cells was assessed at the indicated time and normalized to protein content (10 µg/sample). The data shown represents one of three independent experiments carried out for each cell type from three different donors. Error bars represent the standard deviation of the mean of triplicate samples. Statistically significant differences are indicated by the asterisks (<i>P</i><0.05).</p

Photosynthetic recovery and acclimation to excess light intensity in the rehydrated lichen soil crusts

<div><p>As an important successional stage and main type of biological soil crusts (BSCs) in Shapotou region of China (southeastern edge of Tengger Desert), lichen soil crusts (LSCs) often suffer from many stresses, such as desiccation and excess light intensity. In this study, the chlorophyll fluorescence and CO₂ exchange in the rehydrated LSCs were detected under a series of photosynthetically active radiation (PAR) gradients to study the photosynthetic acclimation of LSCs. The results showed that although desiccation leaded to the loss of photosynthetic activity in LSCs, the fluorescence parameters including Fo, Fv and Fv/Fm of LSCs could be well recovered after rehydration. After the recovery of photosynthetic activity, the effective photosynthetic efficiency Φ_PSII detected by Imaging PAM had declined to nearly 0 within both the lichen thallus upper and lower layers when the PAR increased to 200 μE m^-2 s^-1, however the net photosynthesis detected by the CO₂ gas analyzer in the LSCs still appeared when the PAR increased to 1000 μE m^-2 s^-1. Our results indicate that LSCs acclimating to high PAR, on the one hand is ascribed to the special structure in crust lichens, making the incident light into the lichen thallus be weakened; on the other hand the massive accumulation of photosynthetic pigments in LSCs also provides a protective barrier for the photosynthetic organisms against radiation damage. Furthermore, the excessive light energy absorbed by crust lichens is also possibly dissipated by the increasing non-photochemical quenching, therefore to some extent providing some protection for LSCs.</p></div