A single early activation of invariant NK T cells confers long-term protection against collagen-induced arthritis in a ligand-specific manner

The glycosphingolipid alpha-galactosylceramide (alpha-GalCer) has been shown to be a potent activator of invariant NKT (iNKT) cells, rapidly inducing large amounts of both Th1 and Th2 cytokines upon injection in mice. The C-glycoside analog of alpha-GalCer (alpha-C-GalCer), by contrast, results in an enhanced Th1-type response upon activation of iNKT cells. We administered a single dose of these Ags to DBA/1 mice during the early induction phase of collagen-induced arthritis and demonstrated therapeutic efficacy of alpha-GalCer when administered early rather than late during the disease. Surprisingly, the Th1-polarizing analog alpha-C-GalCer also conferred protection. Furthermore, a biphasic role of IFN-gamma in the effect of iNKT cell stimulation was observed. Whereas in vivo neutralization of IFN-gamma release induced by either alpha-GalCer or alpha-C-GalCer early during the course of disease resulted in partial improvement of clinical arthritis symptoms, blockade of IFN-gamma release later on resulted in a more rapid onset of arthritis. Although no phenotypic changes in conventional T cells, macrophages, or APCs could be detected, important functional differences in T cell cytokine production in serum were observed upon polyclonal T cell activation, 2 wk after onset of arthritis. Whereas alpha-GalCer-treated mice produced significantly higher amounts of IL-10 upon systemic anti-CD3 stimulation compared with PBS controls, T cells from alpha-C-GalCer-treated mice, by contrast, produced substantially lower levels of cytokines, suggesting the involvement of different protective mechanisms. In conclusion, these findings suggest long-term, ligand-specific, time-dependent, and partially IFN-gamma-dependent immunomodulatory effects of iNKT cells in collagen-induced arthritis.     

Molecular basis for chloronium-mediated meroterpene cyclization: cloning, sequencing, and heterologous expression of the napyradiomycin biosynthetic gene cluster

Structural inspection of the bacterial meroterpenoid antibiotics belonging to the napyradiomycin family of chlorinated dihydroquinones suggests that the biosynthetic cyclization of their terpenoid subunits is initiated via a chloronium ion. The vanadium-dependent haloperoxidases that catalyze such reactions are distributed in fungi and marine algae and have yet to be characterized from bacteria. The cloning and sequence analysis of the 43-kb napyradiomycin biosynthetic cluster (nap) from Streptomyces aculeolatus NRRL 18422 and from the undescribed marine sediment-derived Streptomyces sp. CNQ-525 revealed 33 open reading frames, three of which putatively encode vanadium-dependent chloroperoxidases. Heterologous expression of the CNQ-525-based nap biosynthetic cluster in Streptomyces albus produced at least seven napyradiomycins, including the new analog 2-deschloro-2-hydroxy-A80915C. These data not only revealed the molecular basis behind the biosynthesis of these novel meroterpenoid natural products but also resulted in the first in vivo verification of vanadium-dependent haloperoxidases.     

A search for phylogenetically informative wood characters within Lecythidaceae s.l

The wood structure of 71 species representing 24 genera of the pantropical Lecythidaceae s.l., including the edible Brazil nuts (Bertholletia excelsa) and the spectacular cannon-ball tree (Couroupita guianensis), was investigated using light and scanning electron microscopy. This study focused on finding phylogenetically informative characters to help elucidate any obscure evolutionary patterns within the family. The earliest diverging subfamily Napoleonaeoideae has mixed simple/scalariform vessel perforations, scalariform vessel-ray pitting, and high multiseriate rays, all features that are also present in Scytopetaloideae. The wood structure of Napoleonaea is distinct, but its supposed close relative Crateranthus strongly resembles Scytopetaloideae. The isolated position of Foetidia (Foetidioideae) can be supported by a unique type of vessel-ray pitting that is similar in shape and size to intervessel pitting (distinctly bordered, <5 μm). The more derived Planchonioideae and Lecythidoideae share exclusively simple perforations and two types of vessel-ray pitting, but they can easily be distinguished from each other by the size of intervessel pitting, shape of body ray cells in multiseriate rays, and the type of crystalliferous axial parenchyma cells. The anatomical diversity observed is clearly correlated with differences in plant size (shrubs vs. tall trees): the percentage of scalariform perforations, as well as vessel density, and the length of vessel elements, fibers, and multiseriate rays are negatively correlated with increasing plant size, while the reverse is true for vessel diameter.     

Myofilament calcium sensitivity does not affect cross-bridge activation-relaxation kinetics

We employed single myofibril techniques to test whether the presence of slow skeletal troponin-I (ssTnI) is sufficient to induce increased myofilament calcium sensitivity (EC(50)) and whether modulation of EC(50) affects the dynamics of force development. Studies were performed using rabbit psoas myofibrils activated by rapid solution switch and in which Tn was partially replaced for either recombinant cardiac Tn(cTn) or Tn composed of recombinant cTn-T (cTnT) and cTn-C (cTnC), and recombinant ssTnI (ssTnI-chimera Tn). Tn exchange was performed in rigor solution (0.5 mg/ml Tn; 20 degrees C; 2 h) and confirmed by SDS-PAGE. cTnI exchange induced a decrease in EC(50); ssTnI-chimera Tn exchange induced a further decrease in EC(50) (in microM: endogenous Tn, 1.35 +/- 0.08; cTnI, 1.04 +/- 0.13; ssTnI-chimera Tn, 0.47 +/- 0.03). EC(50) was also decreased by application of 100 microM bepridil (control: 2.04 +/- 0.03 microM; bepridil 1.35 +/- 0.03 microM). Maximum tension was not different between any groups. Despite marked alterations in EC(50), none of the dynamic activation-relaxation parameters were affected under any condition. Our results show that 1) incorporation of ssTnI into the fast skeletal sarcomere is sufficient to induce increased myofilament Ca(2+) sensitivity, and 2) the dynamics of actin-myosin interaction do not correlate with EC(50). This result suggests that intrinsic cross-bridge cycling rate is not altered by the dynamics of thin-filament activation.     

Cardiac effects of postconditioning depend critically on the duration of index ischemia

Postconditioning (POC) is known as the phenomenon whereby brief intermittent ischemia applied at the onset of reperfusion following index ischemia limits myocardial infarct size. Whereas there is evidence that the algorithm of the POC stimulus is an important determinant of the protective efficacy, the importance of the duration of index ischemia on the outcome of the effects of POC has received little attention. Pentobarbital sodium-anesthetized Wistar rats were therefore subjected to index ischemia produced by coronary artery occlusions (CAO) of varying duration (15-120 min) followed by reperfusion, without or with postconditioning produced by three cycles of 30-s reperfusion and reocclusion (3POC30). 3POC30 limited infarct size produced by 45-min CAO (CAO45) from 45 +/- 3% to 31 +/- 5%, and CAO60 from 60 +/- 3% to 47 +/- 6% (both P < or = 0.05). In contrast, 3POC30 increased infarct size produced by CAO15 from 3 +/- 1% to 19 +/- 6% and CAO30 from 36 +/- 6 to 48 +/- 4% (both P < or = 0.05). This deleterious effect of 3POC30 was not stimulus sensitive because postconditioning with 3POC5 and 3POC15 after CAO30 also increased infarct size. The cardioprotection by 3POC30 after CAO60 was accompanied by an increased stimulation of Akt phosphorylation at 7 min of reperfusion and a 36% lower superoxide production, measured by dihydroethidium fluorescence, after 2 h of reperfusion. Consistent with these results, cardioprotection by 3POC30 was abolished by phosphatidylinositol-3-OH-kinase inhibition, as well as nitric oxide (NO) synthase inhibition. The deleterious effect of 3POC30 after CAO15 was accompanied by an increased superoxide production with no change in Akt phosphorylation and was not affected by NO synthase inhibition. In conclusion, the effect of cardiac POC depends critically on the duration of the index ischemia and can be either beneficial or detrimental. These paradoxical effects of POC may be related to the divergent effects on Akt phosphorylation and superoxide production.     

Microtubule dynamics and Rac-1 signaling independently regulate barrier function in lung epithelial cells

Cadherin-mediated cell-cell adhesion controls the morphology and function of epithelial cells and is a critical component of the pathology of chronic inflammatory disorders. Dynamic interactions between cadherins and the actin cytoskeleton are required for stable cell-cell contact. Besides actin, microtubules also target intercellular, cadherin-based junctions and contribute to their formation and stability. Here, we studied the role of microtubules in conjunction with Rho-like GTPases in the regulation of lung epithelial barrier function using real-time monitoring of transepithelial electrical resistance. Unexpectedly, we found that disruption of microtubules promotes epithelial cell-cell adhesion. This increase in epithelial barrier function is accompanied by the accumulation of beta-catenin at cell-cell junctions, as detected by immunofluorescence. Moreover, we found that the increase in cell-cell contact, induced by microtubule depolymerization, requires signaling through a RhoA/Rho kinase pathway. The Rac-1 GTPase counteracts this pathway, because inhibition of Rac-1 signaling rapidly promotes epithelial barrier function, in a microtubule- and RhoA-independent fashion. Together, our data suggest that microtubule-RhoA-mediated signaling and Rac-1 control lung epithelial integrity through counteracting independent pathways.     

Zinc complexes of the biomimetic N,N,O ligand family of substituted 3,3-bis(1-alkylimidazol-2-yl)propionates: the formation of oxalate from pyruvate

The coordination chemistry of the 2-His-1-carboxylate facial triad mimics 3,3-bis(1-methylimidazol-2-yl)propionate (MIm(2)Pr) and 3,3-bis(1-ethyl-4-isopropylimidazol-2-yl) propionate (iPrEtIm(2)Pr) towards ZnCl(2) was studied both in solution and in the solid state. Different coordination modes were found depending both on the stoichiometry and on the ligand that was employed. In the 2:1 ligand-to-metal complex [Zn(MIm(2)Pr)(2)], the ligand coordinates in a tridentate, tripodal N,N,O fashion similar to the 2-His-1-carboxylate facial triad. However, the 1:1 ligand-to-metal complexes [Zn(MIm(2)Pr)Cl(H(2)O)] and [Zn(iPrEtIm(2)Pr)Cl] were crystallographically characterized and found to be polymeric in nature. A new, bridging coordination mode of the ligands was observed in both structures comprising N,N-bidentate coordination of the ligand to one zinc atom and O-monodentate coordination to a zinc second atom. A rather unique transformation of pyruvate into oxalate was found with [Zn(MIm(2)Pr)Cl], which resulted in the isolation of the new, oxalato bridged zinc coordination polymer [Zn(2)(MIm(2)Pr)(2)(ox)].6H(2)O, the structure of which was established by X-ray crystal structure determination.     

Characterization of a BAC Library from Channel Catfish <Emphasis Type="Italic">Ictalurus punctatus</Emphasis>: Indications of High Levels of Chromosomal Reshuffling Among Teleost Genomes

The CHORI-212 bacterial artificial chromosome (BAC) library was constructed by cloning EcoRI/EcoRI partially digested DNA into the pTARBAC2.1 vector. The library has an average insert size of 161 kb, and provides 10.6-fold coverage of the channel catfish haploid genome. Screening of 32 genes using overgo or cDNA probes indicated that this library had a good representation of the genome as all tested genes existed in the library. We previously reported sequencing of approximately 25,000 BAC ends that generated 20,366 high-quality BAC end sequences (BES) and identified a large number of sequences similar to known genes using BLASTX searches. In this work, particular attention was given to identification of BAC mate pairs with known genes from both ends. When identified, comparative genome analysis was conducted to determine syntenic regions of the catfish genome with the genomes of zebrafish and Tetraodon. Of the 141 mate pairs with known genes from channel catfish, conserved syntenies were identified in 34 (24.1%), with 30 conserved in the zebrafish genome and 14 conserved in the Tetraodon genome. Additional analysis of three of the 34 conserved syntenic groups by direct sequencing indicated conserved gene contents in all three species. This indicates that comparative genome analysis may provide shortcuts to genome analysis in catfish, especially for short genomic regions once the conserved syntenies are identified. Shaolin Wang and Peng Xu contributed equally to the article.     

Questions and answers about the effects of the depletion of the ozone layer on humans and the environment.

The ozone molecule contains three atoms of oxygen and is mainly formed by the action of the ultraviolet rays of the sun on the diatomic oxygen molecules in the upper part of the Earth's atmosphere (called the stratosphere). Atmospheric pollution near the Earth's surface can form localized areas of ozone. The stratospheric ozone layer protects life on Earth by absorbing most of the harmful ultraviolet radiation from the sun. In the mid 1970s it was discovered that some manmade products destroy ozone molecules in the stratosphere. This destruction can result in damage to ecosystems and to materials such as plastics. It may cause an increase in human diseases such as skin cancers and cataracts. The discovery of the role of the synthetic ozone-depleting chemicals such as chlorofluorocarbons (CFCs) stimulated increased research and monitoring in this field. Computer models predicted a disaster if no action was taken to protect the ozone layer. Based on this research and monitoring, the nations of the world took action in 1985 with the Vienna Convention for the Protection of the Ozone Layer followed by the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987. The Convention and Protocol were amended and adjusted several times as new knowledge was obtained. The Meetings of the Parties to the Montreal Protocol appointed three Assessment Panels to review the progress in scientific knowledge on their behalf. These panels are the Scientific Assessment Panel, the Technological and Economic Assessment Panel and the Environmental Effects Assessment Panel. Each panel covers a designated area and there is a natural level of overlap. The main reports of the Panels are published every four years as required by the Meeting of the Parties. All the reports have an executive summary that is distributed more widely than the main report itself. It became customary to add a set of questions and answers--mainly for non-expert readers--to the executive summaries. This document contains the questions and answers prepared by experts who comprise the Environmental Assessment Panel. It is based mainly on the 2006 report of the Panel but also contains information from previous assessments. Readers who need detailed information on any question should consult the full reports for a more complete scientific discussion. This set of questions refers mainly to the environmental effects of ozone depletion and climate change. The report of the Scientific Assessment Panel contains questions and answers related to the other scientific issues addressed by that Panel. All these reports can be found on the UNEP website (http://ozone.unep.org).