The proinflammatory effect of prostaglandin E2 in experimental inflammatory bowel disease is mediated through the IL-23-->IL-17 axis

Although Crohn's disease has been traditionally considered to be Th1-mediated, the newly identified Th17 cells emerged recently as crucial participants. Th1/Th17 differentiation is controlled primarily by the IL-12 family of cytokines secreted by activated dendritic cells (DCs) and macrophages. IL-23 and IL-12/IL-27 have opposite effects, supporting the Th17 and Th1 phenotypes, respectively. We found that PGE(2), a major lipid mediator released in inflammatory conditions, shifts the IL-12/IL-23 balance in DCs in favor of IL-23, and propose that high levels of PGE(2) exacerbate the inflammatory process in inflammatory bowel disease through the IL-23-->IL-17 axis. We assessed the effects of PGE(2) on IL-12, IL-27, and IL-23 and found that PGE(2) promotes IL-23, inhibits IL-12 and IL-27 expression and release from stimulated DCs, and subsequently induces IL-17 production in activated T cells. The effects of PGE(2) are mediated through the EP2/EP4 receptors on DCs. In vivo, we assessed the effects of PGE analogs in an experimental model for inflammatory bowel disease and found that the exacerbation of clinical symptoms and histopathology correlated with an increase in IL-23 and IL-17, a decrease in IL-12p35 expression in colon and mesenteric lymph nodes, and a substantial increase in the number of infiltrating neutrophils and of CD4(+)IL-17(+) T cells in the colonic tissue. These studies suggest that high levels of PGE(2) exacerbate the inflammatory process through the preferential expression and release of DC-derived IL-23 and the subsequent support of the autoreactive/inflammatory Th17 phenotype.     

Stimulation of gonadotropin release by arachidonic acid and its lipoxygenase metabolites in superfused pituitary cells

Luteinizing hormone and follicle stimulating hormone secretion was stimulated by 4 min pulses of arachidonic acid (3 X 10(-5) to 10(-4)M) in superfused rat pituitary cells. The effect of its lipoxygenase metabolites, 5-hydroxy-6,8,11,14-eicosatetranoic acid (5-HETE) and 15-hydroxy-5,8,10,14-eicosatetranoic acid (15-HETE) was more potent on hormone release when added in the same dose. Using 3 X 10(-5)M 5-HETE, its releasing activity on gonadotropins was comparable to that of GnRH (10(-9)M). 15-HETE (3 X 10(-5)M) was even more potent on LH and FSH secretion than 5-HETE. The secretory profile induced by 5-HETE and 15-HETE was also similar to that shown for GnRH, resulting in a rapid increase and a more prolonged decline of the hormone release. The addition of these fatty acids to superfused pituitary cells did not alter the response of the cells to their physiological ligand. These findings give further support to the proposal that metabolites of arachidonic acid may be involved in receptor-mediated mechanisms of gonadotropin release in pituitary cells.     

High frequency of drill holes in brachiopods from the Pliocene of Algeria and its ecological implications

The fossil record holds a wealth of ecological data, including data on biotic interactions. For example, holes in the skeletons of invertebrates produced by drilling activities of their enemies are widely used for exploring the intensity of such interactions through time because they are common and easily distinguished from non-biotic holes or holes produced by other types of interactions. Such drill holes have been described in numerous studies of Palaeozoic brachiopods but rarely in those focusing on brachiopods of the post-Palaeozoic, a striking pattern given that in the late Mesozoic and Cenozoic drilling gastropods diversified and frequencies of drilled molluscs increased dramatically. During the past several years, however, drilled brachiopods were reported in several studies of the Mesozoic and Cenozoic, suggesting that this phenomenon may be more common than has been previously assumed. Here we report on drilled brachiopods from a Pliocene locality in Algeria where 90 of 261 (34.5%) specimens of Megerlia truncata show evidence of predatory drilling. These data confirm that Cenozoic drilling frequencies of brachiopods may be locally high and, when taken together with other published data, that drilling frequencies are highly heterogeneous in space and time.     

Optimizing the search algorithm for protein engineering by directed evolution

An in silico protein model based on the Kauffman NK-landscape, where N is the number of variable positions in a protein and K is the degree of coupling between variable positions, was used to compare alternative search strategies for directed evolution. A simple genetic algorithm (GA) was used to model the performance of a standard DNA shuffling protocol. The search effectiveness of the GA was compared to that of a statistical approach called the protein sequence activity relationship (ProSAR) algorithm, which consists of two steps: model building and library design. A number of parameters were investigated and found to be important for the comparison, including the value of K, the screening size, the system noise and the number of replicates. The statistical model was found to accurately predict the measured activities for small values of the coupling between amino acids, K 相似文献   

Multiplex amplification of large sets of human exons

A new generation of technologies is poised to reduce DNA sequencing costs by several orders of magnitude. But our ability to fully leverage the power of these technologies is crippled by the absence of suitable 'front-end' methods for isolating complex subsets of a mammalian genome at a scale that matches the throughput at which these platforms will routinely operate. We show that targeting oligonucleotides released from programmable microarrays can be used to capture and amplify approximately 10,000 human exons in a single multiplex reaction. Additionally, we show integration of this protocol with ultra-high-throughput sequencing for targeted variation discovery. Although the multiplex capture reaction is highly specific, we found that nonuniform capture is a key issue that will need to be resolved by additional optimization. We anticipate that highly multiplexed methods for targeted amplification will enable the comprehensive resequencing of human exons at a fraction of the cost of whole-genome resequencing.     

The comparative biology of the closely related Senecio nebrodensis and S. viscosus, a narrow endemic and a widespread ruderal

The closely related Senecio nebrodensis , a perennial herb from four mountain ranges in Spain, and S. viscosus , an annual herb widespread in Europe, are being compared by the study of herbarium material and comparative cultivation. In cultivation, S. nebrodensis behaved as an annual, completing its life cycle within a shorter period of time than S. viscosus . The formation of basal leaf rosettes is much more pronounced in S. nebrodensis than in S. viscosus . The main difference between the two species, however, is their breeding system. While S. nebrodensis is self-incompatible, S. viscosus is self-compatible. Differences in reproductive morphology (mainly size and number of ray florets) are suggested to be related to this difference in breeding system. Despite differences in disc floret number and capitulum number observed in the cultivated material, the potential reproductive output of the two species is roughly comparable. Senecio viscosus is believed to be a descendant of S. nebrodensis . It is postulated that the former differentiated from thelatter at the latest in glacial or early postglacial times. Following postglacial climatic changes, S. nebrodensis retreated into high altitudes, while S. viscosus , adapting to these changes, expanded northwards. The strikingly different degree to which the two species exploit man-made disturbances is interpreted as being due to a difference in opportunity: In its climatically defined range S. nebrodensis experiences little disturbance. Senecio viscosus , on the other hand, inhabits areas strongly disturbed by human activity. It is concluded that S. viscosus shows no obvious adaptations to its habitat, but is well preadapted.     

Les processus de l'ontogenèse,comparés à ceux de la régénération des Phoronida

Résumé Une wise an point des connaissances actuelles sur l'ontogenèse des phoronidiens permet la comparaison avec les processus régénérateurs, décrits précédemment (Emig, 1972 a, b, 1973). Ceux-ci souvent le plus souvent le développement ontogénétique (embryogenèse ou métamorphose) de l'actinotroque. Pour certaines structures, la régénération met en jeu des processus qui se révèlent être distincts des schémas de l'ontogenèse et qui sont généralement plus rapides, plus simples et plus évolués. Certains points ont été particulièrement étudiés et discutés, notamment la division du ceelome (en proto-, méso-, méta-), l'évolution du système circulatoire dans le métasome.La régénération apparaît comme un élément important dans la définition de la position phylogénétique des phoronidiens. Ceux-ci sont considérés, d'après l'énsemble de nos résultats, comme des deutérostomes primitifs.

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Comparison of the processes of ontogenesis and regeneration in Phoronida

Summary A review of the present knowledge on the ontogenesis of Phoronida allows a comparison with the regeneration processes studied by Emig (1972a, b, 1973). On the whole, regeneration follows the ontogenesic development (embryo genesis or metamorphosis) of Actinotrocha larva. But the regeneration of some structures reveals processes distinct from those in ontogenesis, which are faster simpler and more highly developed. Some patterns are studied and discussed in particular detail, such as the division of coelom (proto-, meso-, meta-) and the evolution of the metasomic circulatory system.The regeneration appears to be important character for the determination of the phylogenetic position of the phylum Phoronida. According to the parameters of the present study, Phoronida must be classified as primitive deuterostomes.

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Abbréviations des figures a anus - b bouche - ba barre du T sanguin - bd branche droite du vaisseau latéral - bg branche gauche du vaisseau latéral - c capillaire sanguin (= bd en régéneration) - ca cavité coelomique anale - co cavité coelomique orale - coel coelome - cps cavité preséptale larvaire - d diaphragme - e épistome - en entonnoir néphridien - es expansions stomacales - est estomac - fg fibre nerveuse géante - gn ganglion nerveux - i intestin - lo lophophore - lp lobe préoral - ma mésentère anal - ml mésentère latéral - mld mésentère latéral droit - mlg mésentère latéral gauche - mm mésentère médian - mo mésentère oral - mp mésentère principal - mv mésentère ventral - n néphridie - ne nerf circulaire - né néphridiopore - o coesophage - p protocoelome ou protocoele - pa papille angle - pe préestomac - pu pore urinaire - s septum - sm sac métasomique - ta tentacule adulte - td tube digestif - tl tentacule larvaire - lpa lacune périanale - M métacoelome ou métacoele - m mésocoelome ou mésocoele - vl vaisseau sanguin latéral - vlo vaisseau sanguin lophophoral - vm vaisseau sanguin médian     

Comprehensive cluster analysis with Transitivity Clustering

Transitivity Clustering is a method for the partitioning of biological data into groups of similar objects, such as genes, for instance. It provides integrated access to various functions addressing each step of a typical cluster analysis. To facilitate this, Transitivity Clustering is accessible online and offers three user-friendly interfaces: a powerful stand-alone version, a web interface, and a collection of Cytoscape plug-ins. In this paper, we describe three major workflows: (i) protein (super)family detection with Cytoscape, (ii) protein homology detection with incomplete gold standards and (iii) clustering of gene expression data. This protocol guides the user through the most important features of Transitivity Clustering and takes ～1 h to complete.     

Probing erectile function: S-(2-boronoethyl)-L-cysteine binds to arginase as a transition state analogue and enhances smooth muscle relaxation in human penile corpus cavernosum

The boronic acid-based arginine analogue S-(2-boronoethyl)-L-cysteine (BEC) has been synthesized and assayed as a slow-binding competitive inhibitor of the binuclear manganese metalloenzyme arginase. Kinetic measurements indicate a K(I) value of 0.4-0.6 microM, which is in reasonable agreement with the dissociation constant of 2.22 microM measured by isothermal titration calorimetry. The X-ray crystal structure of the arginase-BEC complex has been determined at 2.3 A resolution from crystals perfectly twinned by hemihedry. The structure of the complex reveals that the boronic acid moiety undergoes nucleophilic attack by metal-bridging hydroxide ion to yield a tetrahedral boronate anion that bridges the binuclear manganese cluster, thereby mimicking the tetrahedral intermediate (and its flanking transition states) in the arginine hydrolysis reaction. Accordingly, the binding mode of BEC is consistent with the structure-based mechanism proposed for arginase as outlined in Cox et al. [Cox, J. D., Cama, E., Colleluori D. M., Pethe, S., Boucher, J. S., Mansuy, D., Ash, D. E., and Christianson, D. W. (2001) Biochemistry 40, 2689-2701.]. Since BEC does not inhibit nitric oxide synthase, BEC serves as a valuable reagent to probe the physiological relationship between arginase and nitric oxide (NO) synthase in regulating the NO-dependent smooth muscle relaxation in human penile corpus cavernosum tissue that is required for erection. Consequently, we demonstrate that arginase is present in human penile corpus cavernosum tissue, and that the arginase inhibitor BEC causes significant enhancement of NO-dependent smooth muscle relaxation in this tissue. Therefore, human penile arginase is a potential target for the treatment of sexual dysfunction in the male.