A touching sight: SII/PV activation during the observation and experience of touch

Watching the movie scene in which a tarantula crawls on James Bond's chest can make us literally shiver--as if the spider crawled on our own chest. What neural mechanisms are responsible for this "tactile empathy"? The observation of the actions of others activates the premotor cortex normally involved in the execution of the same actions. If a similar mechanism applies to the sight of touch, movies depicting touch should automatically activate the somatosensory cortex of the observer. Here we found using fMRI that the secondary but not the primary somatosensory cortex is activated both when the participants were touched and when they observed someone or something else getting touched by objects. The neural mechanisms enabling our own sensation of touch may therefore be a window also to our understanding of touch.     

DNA modification by oxovanadium(IV) complexes of salen derivatives

Oxovanadium(IV) complexes of hydroxysalen derivatives have been prepared and tested as DNA reactive agents. The nuclease activity has been investigated under oxidative or reducing conditions, on the basis of the various oxidation states of vanadium: V^III, V^IV and V^V. In the absence of an activating agent, none of the compounds tested was able to induce cleavage of DNA, whereas in the presence of mercaptopropionic acid (MPA) or Oxone the four complexes induced DNA modifications. Under both conditions, the para-hydroxy complex was found to be the most active compound. Reaction of these salen complexes with DNA occurs essentially at guanine residues and is more efficient in the presence of Oxone than under reducing conditions. The extent of Oxone-mediated DNA oxidation by the four vanadyl complexes was clearly superior to VOSO₄ and was observed without piperidine treatment. EPR studies provided information on the reactive metal-oxo species involved under each conditions and a mechanism of reaction with DNA is discussed.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00775-004-0529-0Abbreviations BPE buffer bis-phosphate EDTA buffer - DMPO 5,5-dimethylpyrroline N-oxide - DMS dimethyl sulfate - HFS hyperfine structure - Lin linear - MPA 3-mercaptopropionic acid - Nck nicked - salen (salicylidene)ethylenediamine - Sc supercoiled - TBE buffer tris-borate EDTA buffer - Tris tris(hydroxymethyl)aminomethane     

ent-Labdane glycosides from the aquatic plant Potamogeton lucens and analytical evaluation of the lipophilic extract constituents of various Potamogeton species

Two new ent-labdane glycosides, one known furano-ent-labdane and a new hydroxylated fatty acid were isolated from the dichloromethane extract of the freshwater aquatic plant Potamogeton lucens. The new compounds were assigned the structures of beta-d-glucopyranosyl-8(17),13-ent-labdadien-16,15-olid-18-oate, 18-beta-d-glucopyranosyloxy-8(17),13-ent-labdadien-16,15-olide and 13(R)-hydroxy-octadeca-(9Z,11E,15Z)-trien-oic acid by spectroscopic means. The algicidal activity of these compounds was tested against Raphidocelis subcapitata. Based on our previous study of Potamogeton pectinatus, other constituents were identified in P. lucens by LC-UV-MS, LC-NMR and GC-MS. The lipophilic extract profiles of both species are presented. Two other species, Potamogeton perfoliatus and P. crispus, were also investigated by analytical comparison of their non-polar extracts. The distribution of ent-labdanes characterized in Potamogeton is summarized.     

Optimal sampling of a population to determine QTL location, variance, and allelic number

In a population intended for breeding and selection, questions of interest relative to a specific segregating QTL are the variance it generates in the population, and the number and effects of its alleles. One approach to address these questions is to extract several inbreds from the population and use them to generate multiple mapping families. Given random sampling of parents, sampling strategy may be an important factor determining the power of the analysis and its accuracy in estimating QTL variance and allelic number. We describe appropriate multiple-family QTL mapping methodology and apply it to simulated data sets to determine optimal sampling strategies in terms of family number versus family size. Genomes were simulated with seven chromosomes, on which 107 markers and six QTL were distributed. The total heritability was 0.60. Two to ten alleles were segregating at each QTL. Sampling strategies ranged from sampling two inbreds and generating a single family of 600 progeny to sampling 40 inbreds and generating 40 families of 15 progeny each. Strategies involving only one to five families were subject to variation due to the sampling of inbred parents. For QTL where more than two alleles were segregating, these strategies did not sample QTL alleles representative of the original population. Conversely, strategies involving 30 or more parents were subject to variation due to sampling of QTL genotypes within the small families obtained. Given these constraints, greatest QTL detection power was obtained for strategies involving five to ten mapping families. The most accurate estimation of the variance generated by the QTL, however, was obtained with strategies involving 20 or more families. Finally, strategies with an intermediate number of families best estimated the number of QTL alleles. We conclude that no overall optimal sampling strategy exists but that the strategy adopted must depend on the objective.Communicated by P. Langridge     

Peptidylpropyl isomerase B (PPIB): a suitable reference gene for mRNA quantification in peripheral whole blood

Quantitative real-time RT-PCR is a very powerful technique for measuring gene expression at the mRNA level. In order to compare mRNA expression in different experimental or clinical conditions, expression of a target gene has to be normalized to an appropriate internal standard, which is generally a housekeeping gene. In our study, we have tested several housekeeping genes in peripheral whole blood of healthy volunteers and patients suffering from inflammatory diseases. A first analysis of 91 samples illustrated that the mRNA expression of peptidylpropyl isomerase B (PPIB) encoding for cyclophilin B protein, is more stable than beta actin and glyceraldehyde-3-phosphate dehydrogenase, which are both commonly selected as internal standard. Among the three genes tested, beta actin displayed the highest inter-sample variation of expression. The constancy of PPIB mRNA expression was further confirmed by 214 additional samples. In conclusion, we showed that PPIB, in contrast to beta actin and glyceraldehyde-3-phosphate dehydrogenase, is a suitable housekeeping gene in human peripheral blood.     

Synthesis of N,N'-disubstituted 3-aminobenzo[c] and [d]azepin-2-ones as potent and specific farnesyl transferase inhibitors

A structure-activity study was performed by synthesis on N,N'-disubstitution of 3-aminobenzo[c] and [d]azepin-2-one 2 and 3 to afford potent and specific farnesyl transferase inhibitors with low nM enzymatic and cellular activities.     

3-D Structure of multilaminar lysosomes in antigen presenting cells reveals trapping of MHC II on the internal membranes

In late endosomes and lysosomes of antigen presenting cells major histocompatibility complex class II (MHC II) molecules bind peptides from degraded internalized pathogens. These compartments are called MHC class II compartments (MIICs), and from here peptide-loaded MHC II is transported to the cell surface for presentation to helper T-lymphocytes to generate an immune response. Recent studies from our group in mouse dendritic cells indicate that the MHC class II on internal vesicles of multivesicular late endosomes or multivesicular bodies is the main source of MHC II at the plasma membrane. We showed that dendritic cell activation triggers a back fusion mechanism whereby MHC II from the inner membranes is delivered to the multivesicular bodies' outer membrane. Another type of MIIC in B-lymphocytes and dendritic cells is more related to lysosomes and often appears as a multilaminar organelle with abundant MHC II-enriched internal membrane sheets. These multilaminar lysosomes have a functioning peptide-loading machinery, but to date it is not clear whether peptide-loaded MHC II molecules from the internal membranes can make their way to the cell surface and contribute to T cell activation. To obtain detailed information on the membrane organization of multilaminar lysosomes and investigate possible escape routes from the lumen of this organelle, we performed electron tomography on cryo-immobilized B-lymphocytes and dendritic cells. Our high-resolution 3-D reconstructions of multilaminar lysosomes indicate that their membranes are organized in such a way that MHC class II may be trapped on the inner membranes, without the possibility to escape to the cell surface.     

An in vitro dual model of mycobacterial granulomas to investigate the molecular interactions between mycobacteria and human host cells

In the majority of individuals infected with Mycobacterium tuberculosis, the bacilli cause a long-term asymptomatic infection called latent tuberculosis, a state during which the bacilli reside within granulomas. Latently infected individuals have around 10% risk of progression to clinical disease at a later stage. Determining the state of the mycobacteria and the host cells during this latent phase, i.e. within the granulomas, would greatly improve our understanding of the physiopathology of tuberculosis, and thus enable the development of new therapeutic means to treat the one-third of the world's population who are latently infected. We have developed an in vitro model of human mycobacterial granulomas, enabling the cellular and molecular analysis of the very first steps in the host granulomatous response to either mycobacterial compounds or live mycobacterial species. In vitro mycobacterial granulomas mimic natural granulomas very well, with the progressive recruitment of macrophages around live bacilli or mycobacterial antigen-coated beads, their differentiation into multinucleated giant cells and epithelioid cells, and the final recruitment of a ring of activated lymphocytes. Besides morphological similarities, in vitro granulomas also functionally resemble natural ones, with the development of intense cellular co-operation and intracellular mycobactericidal activities.     

Lead optimization of antifungal peptides with 3D NMR structures analysis

Antimicrobial peptides are key components of the innate immune response in most multicellular organisms. These molecules are considered as one of the most innovative class of anti-infective agents that have been discovered over the last two decades, and therefore, as a source of inspiration for novel drug design. Insect cystine-rich antimicrobial peptides with the CS alpha beta scaffold (an alpha-helix linked to a beta-sheet by two disulfide bridges) represent particularly attractive templates for the development of systemic agents owing to their remarkable resistance to protease degradation. We have selected heliomicin, a broad spectrum antifungal CS alpha beta peptide from Lepidoptera as the starting point of a lead optimization program based on phylogenic exploration and fine tuned mutagenesis. We report here the characterization, biological activity, and 3D structure of heliomicin improved analogs, namely the peptides ARD1, ETD-135, and ETD-151. The ARD1 peptide was initially purified from the immune hemolymph of the caterpillars of Archeoprepona demophoon. Although it differs from heliomicin by only two residues, it was found to be more active against the human pathogens Aspergillus fumigatus and Candida albicans. The peptides ETD-135 and ETD-151 were engineered by site-directed mutagenesis of ARD1 in either cationic or hydrophobic regions. ETD-135 and ETD-151 demonstrated an improved antifungal activity over the native peptides, heliomicin and ARD1. A comparative analysis of the 3D structure of the four molecules highlighted the direct impact of the modification of the amphipathic properties on the molecule potency. In addition, it allowed to characterize an optimal organization of cationic and hydrophobic regions to achieve best antifungal activity.