Fatty acid desaturation links germ cell loss to longevity through NHR-80/HNF4 in C. elegans.

Background: Preventing germline stem cell proliferation extends lifespan in nematodes and flies. So far, studies on germline-longevity signaling have focused on daf-16/FOXO and daf-12/VDR. Here, we report on NHR-80/HNF4, a nuclear receptor that specifically mediates longevity induced by depletion of the germ line through a mechanism that implicates fatty acid monodesaturation.

Architecture of the Helicobacter pylori Cag-type IV secretion system.

Type IV secretion systems (T4SS) are macromolecular assemblies used by bacteria to transport material across their membranes. T4SS are generally composed of a set of twelve proteins (VirB1-11 and VirD4). This represents a dynamic machine powered by three ATPases.

What's in a voice? Prosody as a test case for the Theory of Mind account of autism.

The human voice conveys a variety of information about people's feelings, emotions and mental states. Some of this information relies on sophisticated Theory of Mind (ToM) skills, whilst others are simpler and do not require ToM. This variety provides an interesting test case for the ToM account of autism, which would predict greater impairment as ToM requirements increase.

Carbonylated proteins are eliminated during reproduction in C. elegans.

Oxidatively damaged proteins accumulate with age in many species (Stadtman (1992) Science257, 1220-1224). This means that damage must be reset at the time of reproduction. To visualize this resetting in the roundworm Caenorhabditis elegans, a novel immunofluorescence technique that allows the detection of carbonylated proteins in situ was developed.

The extended conformation of the 2.9-Å crystal structure of the three-PASTA domain of a Ser/Thr kinase from the human pathogen Staphylococcus aureus.

PASTA (penicillin-binding protein and serine/threonine kinase associated) modules are found in penicillin-binding proteins and bacterial serine/threonine kinases mainly from Gram-positive Firmicutes and Actinobacteria. They may act as extracellular sensors by binding peptidoglycan fragments. We report here the first crystal structure of a multiple-PASTA domain from Ser/Thr kinase, that of the protein serine/threonine kinase 1 (Stk1) from the Firmicute Staphylococcus aureus.

Gyroscopic instability of a drop trapped inside an inclined circular hydraulic jump.

A drop of moderate size deposited inside a circular hydraulic jump remains trapped at the shock front and does not coalesce with the liquid flowing across the jump. For a small inclination of the plate on which the liquid is impacting, the drop does not always stay at the lowest position and oscillates around it with a sometimes large amplitude, and a frequency that slightly decreases with flow rate. We suggest that this striking behavior is linked to a gyroscopic instability in which the drop tries to keep constant its angular momentum while sliding along the jump.

Stability of buoyant convection in a layer submitted to acoustic streaming.

The linear stability of the flows induced in a fluid layer by buoyant convection (due to an applied horizontal temperature gradient) and by acoustic streaming (due to an applied horizontal ultrasound beam) is studied. The vertical profiles of the basic flows are determined analytically, and the eigenvalue problem resulting from the temporal stability analysis is solved by a spectral Tau Chebyshev method. Pure acoustic streaming flows are found to be sensitive to a shear instability developing in the plane of the flow (two-dimensional instability), and the thresholds for this oscillatory instability depend on the normalized width Hb of the ultrasound beam with a minimum for Hb=0.

The acid tolerant L-arabinose isomerase from the food grade Lactobacillus sakei 23K is an attractive D-tagatose producer.

The araA gene encoding an L-arabinose isomerase (L-AI) from the psychrotrophic and food grade Lactobacillus sakei 23K was cloned, sequenced and over-expressed in Escherichia coli. The recombinant enzyme has an apparent molecular weight of nearly 220 kDa, suggesting it is a tetramer of four 54 kDa monomers. The enzyme is distinguishable from previously reported L-AIs by its high activity and stability at temperatures from 4 to 40 degrees C, and pH from 3 to 8, and by its low metal requirement of only 0.

Processing of procollagen III by meprins: new players in extracellular matrix assembly?

Meprins α and β, a subgroup of zinc metalloproteinases belonging to the astacin family, are known to cleave components of the extracellular matrix, either during physiological remodeling or in pathological situations. In this study we present a new role for meprins in matrix assembly, namely the proteolytic processing of procollagens. Both meprins α and β release the N- and C-propeptides from procollagen III, with such processing events being critical steps in collagen fibril formation.

Wheat-germ cell-free production of prion proteins for solid-state NMR structural studies.

The expression of soluble, functional protein on a preparative scale poses a central challenge for structural studies. Cell-free protein expression has become a valuable alternative to cell-based methods, and allows today the expression of milligram quantities of protein. Its use is particularly attractive for NMR studies as it allows a multitude of isotopic labeling schemes.

Aerobic methylcyclohexane-promoted epoxidation of stilbene over gold nanoparticles supported on Gd-doped titania.

Aerobic partial oxidations of alkanes and alkenes are important processes of the petrochemical industry. The radical mechanisms involved can be catalyzed by soluble salts of transition metals (Co, Cu, Mn..

How do physical-chemical parameters influence the catalytic hydrogenation of 1,3-cyclohexadiene in ionic liquids?

The catalytic hydrogenation of 1,3-cyclohexadiene using [Rh(COD)(PPh(3))(2)]NTf(2) (COD = 1,5-cyclooctadiene) was performed in two ionic liquids: 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C(1)C(4)Im][NTf(2)], and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide, [C(1)C(1)C(4)Im][NTf(2)]. It is observed that the reaction is twice as fast in [C(1)C(4)Im][NTf(2)] than in [C(1)C(1)C(4)Im][NTf(2)]. To explain the difference in reactivity, molecular interactions and the microscopic structure of ionic liquid +1,3-cyclohexadiene mixtures were studied by NMR and titration calorimetry experiments, and by molecular simulation in the liquid phase.

Efficient bioconversion of lactose in milk and whey: immobilization and biochemical characterization of a beta-galactosidase from the dairy Streptococcus thermophilus LMD9 strain.

The gene encoding beta-galactosidase from dairy Streptococcus thermophilus strain LMD9 was cloned, sequenced and expressed in Escherichia coli. The recombinant enzyme was purified and showed high specific activity of 464 U/mg. This protein displays a homotetrameric arrangement composed of four 118 kDa monomers.

Prions: En route from structural models to structures.

The prion hypothesis states that the prion and non-prion form of a protein differ only in their 3D conformation and that different strains of a prion differ by their 3D structure. Recent technical developments have enabled solid-state NMR to address the atomic-resolution structures of full-length prions, and a first comparative study of two of them, HET-s and Ure2p, in fibrillar form, has recently appeared as a pair of companion papers. Interestingly, the two structures are rather different: HET-s features an exceedingly well-ordered prion domain and a partially disordered globular domain.

A novel stabilisation model for ruthenium nanoparticles in imidazolium ionic liquids: in situ spectroscopic and labelling evidence.

In situ labelling and spectroscopic experiments are used to explain the key points in the stabilisation of ruthenium nanoparticles (RuNPs) generated in imidazolium-based ionic liquids (ILs) by decomposition of (eta(4)-1,5-cyclooctadiene)(eta(6)-1,3,5-cyclooctatriene)ruthenium(0), Ru(COD)(COT), under dihydrogen. These are found to be: (1) the presence of hydrides at the RuNP surface and, (2) the confinement of RuNPs in the non-polar domains of the structured IL, induced by the rigid 3-D organisation. These results lead to a novel stabilisation model for NPs in ionic liquids.

Role of the netrin-like domain of procollagen C-proteinase enhancer-1 in the control of metalloproteinase activity.

The netrin-like (NTR) domain is a feature of several extracellular proteins, most notably the N-terminal domain of tissue inhibitors of metalloproteinases (TIMPs), where it functions as a strong inhibitor of matrix metalloproteinases and some other members of the metzincin superfamily. The presence of a C-terminal NTR domain in procollagen C-proteinase enhancers (PCPEs), proteins that stimulate the activity of astacin-like tolloid proteinases, raises the possibility that this might also have inhibitory activity. Here we show that both long and short forms of the PCPE-1 NTR domain, the latter beginning at the N-terminal cysteine known to be critical for TIMP activity, show no inhibition, at micromolar concentrations, of several members of the metzincin superfamily, including matrix metalloproteinase-2, bone morphogenetic protein-1 (a tolloid proteinase), and different ADAMTS (a disintegrin and a metalloproteinase with thrombospondin motifs) proteinases from the adamalysin family.

Scalar inferences in Autism Spectrum Disorders.

On being told "John or Mary will come", one might infer that not both of them will come. Yet the semantics of "or" is compatible with a situation where both John and Mary come. Inferences of this type, which enrich the semantics of "or" from an 'inclusive' to an 'exclusive' interpretation, have been extensively studied in linguistic pragmatics.

Synthesis and characterisation of ionic liquids based on 1-butyl-3-methylimidazolium chloride and MCl(4), M = Hf and Zr.

Dialkylimidazolium chlorometallate molten salts resulting from the combination of zirconium or hafnium tetrachloride and 1-butyl-3-methylimidazolium chloride, [C(1)C(4)Im][Cl], have been prepared with a molar fraction of MCl(4), R = n(MCl4)/n(MCl4) + n([C1C4IM][Cl]) equal to 0, 0.1, 0.2, 0.

UV and X-ray structural studies of a 101-residue long Tat protein from a HIV-1 primary isolate and of its mutated, detoxified, vaccine candidate.

The 101-residue long Tat protein of primary isolate 133 of the human immunodeficiency virus type 1 (HIV-1), wt-Tat(133) displays a high transactivation activity in vitro, whereas the mutant thereof, STLA-Tat(133), a vaccine candidate for HIV-1, has none. These two proteins were chemically synthesized and their biological activity was validated. Their structural properties were characterized using circular dichroism (CD), fluorescence emission, gel filtration, dynamic light scattering, and small angle X-ray scattering (SAXS) techniques.

Crystallization and initial X-ray diffraction study of the three PASTA domains of the Ser/Thr kinase Stk1 from the human pathogen Staphylococcus aureus.

PASTA subunits (approximately 70 amino acids) are specific to bacterial serine/threonine kinases and to penicillin-binding proteins (PBPs) and are involved in the synthesis of peptidoglycan. The human pathogen Staphylococcus aureus contains a serine/threonine kinase, Stk1, which plays a major role in virulence. A recombinant His-tagged portion of the extracellular domain of Stk1 containing three PASTA subunits has been crystallized using zinc sulfate as a crystallizing agent.

Strong cooperativity and loose geometry between CUB domains are the basis for procollagen c-proteinase enhancer activity.

Procollagen C-proteinase enhancers (PCPE-1 and -2) specifically activate bone morphogenetic protein-1 (BMP-1) and other members of the tolloid proteinase family during C-terminal processing of fibrillar collagen precursors. PCPEs consist of two CUB domains (CUB1 and CUB2) and one NTR domain separated by one short and one long linker. It was previously shown that PCPEs can strongly interact with procollagen molecules, but the exact mechanism by which they enhance BMP-1 activity remains largely unknown.

Prion fibrils of Ure2p assembled under physiological conditions contain highly ordered, natively folded modules.

The difference between the prion and the non-prion form of a protein is given solely by its three-dimensional structure, according to the prion hypothesis. It has been shown that solid-state NMR can unravel the atomic-resolution three-dimensional structure of prion fragments but, in the case of Ure2p, no highly resolved spectra are obtained from the isolated prion domain. Here, we demonstrate that the spectra of full-length fibrils of Ure2p interestingly lead to highly resolved solid-state NMR spectra.

Extracellular and cell surface proteases in wound healing: new players are still emerging.

Tissue remodelling results from the concerted action of numerous extracellular and cell surface proteases. These act to synchronize the synthesis and degradation of the extracellular matrix with the control of cytokine activity and cell signalling in order to create appropriate environments for cell proliferation, migration and differentiation. Wound healing is a complex example of tissue remodelling that includes several steps occurring either concomitantly or successively during the process of repair: haemostasis, inflammation, angiogenesis, re-epithelialisation, granulation tissue formation, wound contraction and matrix remodelling.

Structural determinants of product specificity of sucrose isomerases.

The healthy sweetener isomaltulose is industrially produced from the conversion of sucrose by the sucrose isomerase SmuA from Protaminobacter rubrum. Crystal structures of SmuA in native and deoxynojirimycin complexed forms completed with modeling studies unravel the characteristics of the isomaltulose synthases catalytic pocket and their substrate binding mode. Comparison with the trehalulose synthase MutB highlights the role of Arg(298) and Arg(306) active site residues and surface charges in controlling product specificity of sucrose isomerases (isomaltulose versus trehalulose).

Optimal sensorimotor control in eye movement sequences.

Fast and accurate motor behavior requires combining noisy and delayed sensory information with knowledge of self-generated body motion; much evidence indicates that humans do this in a near-optimal manner during arm movements. However, it is unclear whether this principle applies to eye movements. We measured the relative contributions of visual sensory feedback and the motor efference copy (and/or proprioceptive feedback) when humans perform two saccades in rapid succession, the first saccade to a visual target and the second to a memorized target.