Cgamma H2 of Met174 side chain is the site of covalent attachment of a substance P analog photoactivable in position 5

Analogs of substance P (H-RPKPQQFFGLM-NH(2)) incorporating a photoreactive para-benzoyl-l-phenylalanine (p-Bzl)Phe at position 4, 5, 6, 9, or 10 of the sequence have been synthesized and pharmacologically characterized previously as full NK-1 receptor agonists. In this study we show that all analogs, [BAPA(0), (p-Bzl)Phe(x), Met(O(2))(11)]SP also display high yields (40-70%) of NK-1 receptor photolabeling. To identify the site of photoinsertion in the receptor, covalent ligand/receptor complexes were digested with enzymes or chemically cleaved with cyanogen bromide and purified with streptavidin-coated magnetic beads before matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry analysis. Only the analog photoreactive at position 5 gave irreversible, reproducible, and unequivocal covalent linkage. Sequential digestions of the covalent complex, substance P analog photoreactive at position 5/NK-1 receptor, with trypsin, endo-GluC and carboxypeptidase Y, led to the identification of the tripeptide (173)TMP(175) in the second extracellular loop of the hNK-1 receptor as the site of photoinsertion. Reaction of cyanogen bromide on the pentapeptide TMPSR did not yield the expected cleavage on the carboxylic side of methionine. The high precision of mass spectrometry analysis on the mass measured led us to determine that C(gamma)H(2) of Met(174) was the site of covalent linkage of the photoreactive substance P analog. Such an insertion (photolinked ligand) on its C(gamma)H(2) renders methionine refractory to CNBr cleavage.     

Crumbs interacts with moesin and beta(Heavy)-spectrin in the apical membrane skeleton of Drosophila

The apical transmembrane protein Crumbs is necessary for both cell polarization and the assembly of the zonula adherens (ZA) in Drosophila epithelia. The apical spectrin-based membrane skeleton (SBMS) is a protein network that is essential for epithelial morphogenesis and ZA integrity, and exhibits close colocalization with Crumbs and the ZA in fly epithelia. These observations suggest that Crumbs may stabilize the ZA by recruiting the SBMS to the junctional region. Consistent with this hypothesis, we report that Crumbs is necessary for the organization of the apical SBMS in embryos and Schneider 2 cells, whereas the localization of Crumbs is not affected in karst mutants that eliminate the apical SBMS. Our data indicate that it is specifically the 4.1 protein/ezrin/radixin/moesin (FERM) domain binding consensus, and in particular, an arginine at position 7 in the cytoplasmic tail of Crumbs that is essential to efficiently recruit both the apical SBMS and the FERM domain protein, DMoesin. Crumbs, Discs lost, betaHeavy-spectrin, and DMoesin are all coimmunoprecipitated from embryos, confirming the existence of a multimolecular complex. We propose that Crumbs stabilizes the apical SBMS via DMoesin and actin, leading to reinforcement of the ZA and effectively coupling epithelial morphogenesis and cell polarity.     

Heavy metals in sewage sludges contribute to their adverse effects on the arbuscular mycorrhizal fungus<Emphasis Type="Italic">Glomus mosseae</Emphasis>

Applying sewage sludges to agricultural land is a widespread practice because of the sludges’ agronomic value as a source of plant nutrients and organic matter. Nevertheless, sludges often contain micropollutants that can constitute a menace for health and the environment. Arbuscular mycorrhizal fungi are sensitive to sewage sludges that have been spiked, or not, with metallic trace elements (MTE). Here we have investigated if MTE in sewage sludges could be responsible for effects on mycorrhizal development betweenGlomus mosseae andMedicago truncatula. The impact of a dehydrated or composted urban sewage sludge spiked or not with MTE, was tested on spore germination and root colonization byG. mosseae. The sewage sludges depressed both the presymbiotic andin planta stages of development of the mycorrhizal fungus. This negative effect was more related to the metallic pollutant contents of the sludges than to the presence of antagonistic microorganisms or phosphorus.     

Relationships between the brain and the immune system

The concept that the brain can modulate activity the immune system stems from the theory of stress. Recent advances in the study of the inter-relationships between the central nervous system and the immune system have demonstrated a vast network of communication pathways between the two systems. Lymphoid organs are innervated by branches of the autonomic nervous system. Accessory immune cells and lymphocytes have membrane receptors for most neurotransmitters and neuropeptides. These receptors are functional, and their activation leads to changes in immune functions, including cell proliferation, chimiotactism and specific immune responses. Brain lesions and stressors can induce a number of changes in the functioning of the immune system. All these changes are not necessarily mediated by the neuroendocrine system. They can also be dependent on autonomic nerve function. The communication pathways that link the brain to the immune system are normally activated by signals from the immune system, and they serve to regulate immune responses. These signals originate from accessory immune cells such as monocytes and macrophages and they are represented mainly by proinflammatory cytokines. Proinflammatory cytokines produced at the periphery act on the brain via two major pathways: (1) a humoral pathway allowing pathogen specific molecular patterns to act on Toll-like receptors in those brain areas that are devoid of a functional blood-brain barrier, the so-called circumventricular areas; (2) a neural pathway, represented by the afferent nerves that innervate the bodily site of infection and injury. In both cases, peripherally produced cytokines induce the expression of brain cytokines that are produced by resident macrophages and microglial cells. These locally produced cytokines diffuse throughout the brain parenchyma to act on target brain areas so as to organise the central components of the host response to infection (fever, neuroendocrine activation, and sickness behavior).     

Shorebird community variations indicative of a general perturbation in the Mont-Saint-Michel bay (France)

The Mont-Saint-Michel bay located on the East Atlantic Flyway is the first site in France for wintering shorebirds, with, on average, 53,000 individuals in January. Seven species represent 96% of that community: dunlin (Calidris alpina), knot (Calidris canutus), oystercatcher (Haematopus ostralegus), curlew (Numenius arquata), grey plover (Pluvialis squatarola), bar-tailed godwit (Limosa lapponica) and black-tailed godwit (Limosa limosa). The international bird census organised by Wetlands International in mid-January gave us the opportunity to study, for a 23 years period, population variations in the bay. Despite a quite good carrying capacity, we showed that the decreasing proportion of 4 species in the bay relative to the other French populations may indicate a general perturbation of the bay. We discuss the different hypotheses to explain that observation.     

The source of laterally transferred genes in bacterial genomes

Background  

Laterally transferred genes have often been identified on the basis of compositional features that distinguish them from ancestral genes in the genome. These genes are usually A+T-rich, arguing either that there is a bias towards acquiring genes from donor organisms having low G+C contents or that genes acquired from organisms of similar genomic base compositions go undetected in these analyses.     

Potential inhibitors of angiogenesis. Part I: 3-(imidazol-4(5)-ylmethylene)indolin-2-ones

The synthesis and pharmacological evaluation of new 3-(imidazol-4(5)-ylmethylene)indolin-2-ones, analogues of SU-5416, are reported. The final compounds 20-51 were obtained by Knoevenagel coupling between the substituted indolin-2-ones 1-15 and either the formylimidazole derivatives 16-18 or 2-formyl-3,5-dimethylpyrrole 19. Methylation at the nitrogen atom of the indolin-2-one and/or imidazole moities was carried out in the presence of the couple NaH/DMF. A Mannich reaction afforded the 1-dimethylaminomethyl derivatives 43 and 48. The antiangiogenic activity of these compounds was evaluated in a three dimensional in vitro rat aortic ring assay. In this test, compound 20 induced a decrease of angiogenesis comparable to that observed with SU-5416; the vascular density indexes at 1 microM were 30 +/- 18 and 22 +/- 4% of control, respectively. The compounds were also evaluated, in an independent manner, as inhibitors of the human EGF-receptor tyrosine kinase activity. As expected, only minor activities were observed with four compounds, out of thirty-one, exerting inhibitory effects in the range of 40-55% at 10 microM concentration.