Alpha-tocopherol-mediated long-lasting protection against oxidative damage involves an attenuation of calcium entry through TRP-like channels in cultured hippocampal neurons

We have reported that a transient treatment of hippocampal neurons with alpha-tocopherol induced a long-lasting protection against oxidative damage mediated by Fe(2+) ions. This protection required protein synthesis. Here, we have studied whether this "hyposensitivity" to oxidative stress could be linked to an altered Ca(2+) homeostasis. Fe(2+) ions triggered a Ca(2+) entry which was required for Fe(2+) ion-induced toxicity. This influx was sensitive to blockers of TRP-like nonspecific Ca(2+) channels, including Ruthenium Red, La(3+), and Gd(3+) ions which also prevented the Fe(2+) ion-induced toxicity and oxidative stress as revealed by protein carbonylation status. The pretreatment with alpha-tocopherol resulted in a reduction of the Ca(2+) increase induced by Fe(2+) ions and masked the blocking effect of La(3+) ions. Moreover, such a pretreatment reduced the capacitive Ca(2+) entries (CCE) observed after metabotropic glutamate receptor stimulation, which are known to involve TRP-like channels. By contrast, in a model of "hypersensitivity" to oxidative stress obtained by chronic stimulation of glucocorticoid receptors, we observed an exacerbation of the various effects of Fe(2+) ions, i.e., cellular toxicity and Ca(2+) increase, and the glutamate-stimulated CCE. Therefore, we conclude that the long-lasting neuroprotection induced by alpha-tocopherol pretreatment likely results from an attenuation of Ca(2+) entries via TRP-like channels.     

Statistical strategies for relating metabolomics and proteomics data: a real case study in nutrition research area

The current investigations were carried out in the context of a nutritional case study aiming at assessing the postnatal impact of maternal dietary protein restriction during pregnancy and lactation on rat offspring plasma metabolome and hypothalamic proteome. Although data generated by different ??Omics?? technologies are usually considered and analyzed separately, their interrelation may offer a valuable opportunity for assessing the emerging ??integrated biology?? concept. The overall strategy of analysis first investigated data pretreatment and variable selection for each dataset. Then, three multivariate analyses were applied to investigate the links between the abundance of metabolites and the expression of proteins collected on the same samples. Unfold principal component analysis and regularized canonical correlation analysis did not take into account the presence of groups of individuals related to the intervention study. On the contrary, the predictive MultiBlock Partial Least Squares method used this information. Regularized canonical correlation analysis appeared as a relevant approach to investigate of the relationships between the two datasets. However, in order to highlight the molecular compounds, proteins and metabolites, associated in interacting or common metabolic pathways for the experimental groups, MultiBlock partial least squares was the most appropriate method in the present nutritional case study.     

1H-NMR-based metabolic profiling of maternal and umbilical cord blood indicates altered materno-foetal nutrient exchange in preterm infants

Background

Adequate foetal growth is primarily determined by nutrient availability, which is dependent on placental nutrient transport and foetal metabolism. We have used ¹H nuclear magnetic resonance (NMR) spectroscopy to probe the metabolic adaptations associated with premature birth.

Methodology

The metabolic profile in ¹H NMR spectra of plasma taken immediately after birth from umbilical vein, umbilical artery and maternal blood were recorded for mothers delivering very-low-birth-weight (VLBW) or normo-ponderal full-term (FT) neonates.

Principal Findings

Clear distinctions between maternal and cord plasma of all samples were observed by principal component analysis (PCA). Levels of amino acids, glucose, and albumin-lysyl in cord plasma exceeded those in maternal plasma, whereas lipoproteins (notably low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) and lipid levels were lower in cord plasma from both VLBW and FT neonates. The metabolic signature of mothers delivering VLBW infants included decreased levels of acetate and increased levels of lipids, pyruvate, glutamine, valine and threonine. Decreased levels of lipoproteins glucose, pyruvate and albumin-lysyl and increased levels of glutamine were characteristic of cord blood (both arterial and venous) from VLBW infants, along with a decrease in levels of several amino acids in arterial cord blood.

Conclusion

These results show that, because of its characteristics and simple non-invasive mode of collection, cord plasma is particularly suited for metabolomic analysis even in VLBW infants and provides new insights into the materno-foetal nutrient exchange in preterm infants.     

MAP65-3 microtubule-associated protein is essential for nematode-induced giant cell ontogenesis in Arabidopsis

The infection of plants by obligate parasitic nematodes constitutes an interesting model for investigating plant cytoskeleton functions. Root knot nematodes have evolved the ability to manipulate host functions to their own advantage by redifferentiating root cells into multinucleate and hypertrophied feeding cells. These giant cells result from repeated rounds of karyokinesis without cell division. Detailed functional analyses demonstrated that Arabidopsis thaliana Microtubule-Associated Protein65-3 (MAP65-3) was essential for giant cell ontogenesis and that cytokinesis was initiated but not completed in giant cells. In developing giant cells, MAP65-3 was associated with a novel kind of cell plate-the giant cell mini cell plate-that separates daughter nuclei. In the absence of functional MAP65-3, giant cells developed but failed to fully differentiate and were eventually destroyed. These defects in giant cells impaired the maturation of nematode larvae. Thus, MAP65-3 is essential for giant cell development during root knot nematode infection. Subcellular localization of MAP65-3 and analysis of microtubule organization in the dyc283 T-DNA map65-3 mutant demonstrated that MAP65-3 played a critical role in organizing the mitotic microtubule array during both early and late mitosis in all plant organs. Here, we propose a model for the role of MAP65-3 in giant cell ontogenesis.     

Genome sequence of the metazoan plant-parasitic nematode Meloidogyne incognita

Plant-parasitic nematodes are major agricultural pests worldwide and novel approaches to control them are sorely needed. We report the draft genome sequence of the root-knot nematode Meloidogyne incognita, a biotrophic parasite of many crops, including tomato, cotton and coffee. Most of the assembled sequence of this asexually reproducing nematode, totaling 86 Mb, exists in pairs of homologous but divergent segments. This suggests that ancient allelic regions in M. incognita are evolving toward effective haploidy, permitting new mechanisms of adaptation. The number and diversity of plant cell wall-degrading enzymes in M. incognita is unprecedented in any animal for which a genome sequence is available, and may derive from multiple horizontal gene transfers from bacterial sources. Our results provide insights into the adaptations required by metazoans to successfully parasitize immunocompetent plants, and open the way for discovering new antiparasitic strategies.     

Cholesterol is not crucial for the existence of microdomains in kidney brush-border membrane models.

The external membrane leaflet plays a key role in the organization of the cell plasma membrane as a mosaic of ordered microdomains enriched in sphingolipids and cholesterol and of fluid domains. In this study, the thermotropic behavior and the topology of bilayers made of a phosphatidylcholine/sphingomyelin mixture, which mimicks the lipid composition of the external leaflet of renal brush-border membranes, were examined by differential scanning calorimetry and atomic force microscopy. In the absence of cholesterol, a broad phase separation process occurred where ordered gel phase domains of size varying from the mesoscopic to the microscopic scale, enriched in sphingomyelin, occupied half of the bilayer surface at room temperature. Increasing amounts of cholesterol progressively decreased the enthalpy of the transition and modified the topology of membranes domains up to a concentration of 33 mol % for which no membrane domains were detected. These results strongly suggest that, in membranes highly enriched in sphingolipids like renal and intestinal brush borders, there is a threshold close to the physiological concentration above which cholesterol acts as a suppressor rather than as a promoter of membrane domains. They also suggest that cholesterol depletion does not abolish the lateral heterogenity in brush-border membranes.     

Infection dynamics of Marteilia refringens in flat oyster Ostrea edulis and copepod Paracartia grani in a claire pond of Marennes-Oléron Bay

The protozoan parasite Marteilia refringens has been partly responsible for the severe decrease in the production of the European flat oyster Ostrea edulis Linnaeus in France since the 1970s. The calanoid copepod Paracartia grani Sars was recently found to be a host for M. refringens in French shallow-water oyster ponds ('claires'). This study reconsidered M. refringens transmission dynamics in the light of this finding, taking into account not only oyster infection dynamics and environmental factors but also data concerning the copepod host. P. grani population dynamics in the claire under study revealed that this species is the dominant planktonic copepod in this confined ecosystem. During winter, M. refringens overwintered in O. edulis, with P. grani existing only as resting eggs in the sediment. The increase in temperature in spring controlled and synchronized both the release of M. refringens sporangia in the oyster feces, and the hatching of the benthic resting eggs of the copepod. Infection of oysters by M. refringens was limited to June, July and August, coinciding with (1) the highest temperature recorded in the claire, and (2) the highest abundance of P. grani. PCR detection of M. refringens in P. grani during the summer period was linked to the release of parasite sporangia by the oyster. Our results are supported by previous results on the effective transmission of this parasite from the oyster to the copepod.     

Benchmarking the DFT methodology for assessing antioxidant-related properties: quercetin and edaravone as case studies

The overall objective was to identify an accurate computational electronic method to virtually screen phenolic compounds through their antioxidant and free-radical scavenging activity. The impact of a key parameter of the density functional theory (DFT) approach was studied. Performances of the 21 most commonly used exchange-correlation functionals are thus detailed in the evaluation of the main energetic parameters related to the activities of two prototype antioxidants, namely quercetin and edaravone, is reported. These functionals have been chosen among those belonging to three different families of hybrid functionals, namely global, range separated, and double hybrids. Other computational parameters have also been considered, such as basis set and solvent effects. The selected parameters, namely bond dissociation enthalpy (BDE), ionization potential (IP), and proton dissociation enthalpy (PDE) allow a mechanistic evaluation of the antioxidant activities of free radical scavengers. Our results show that all the selected functionals provide a coherent picture of these properties, predicting the same order of BDEs and PDEs. However, with respect to the reference values, the errors found at CBS-Q3 level significantly vary with the functional. Although it is difficult to evidence a global trend from the reported data, it clearly appears that LC-ωPBE, M05-2X, and M06-2X are the most suitable approaches for the considered properties, giving the lowest cumulative mean absolute errors. These methods are therefore suggested for an accurate and fast evaluation of energetic parameters related to an antioxidant activity via free radical scavenging.     

HIV-1 efficient entry in inner foreskin is mediated by elevated CCL5/RANTES that recruits T cells and fuels conjugate formation with Langerhans cells

Male circumcision reduces acquisition of HIV-1 by 60%. Hence, the foreskin is an HIV-1 entry portal during sexual transmission. We recently reported that efficient HIV-1 transmission occurs following 1 h of polarized exposure of the inner, but not outer, foreskin to HIV-1-infected cells, but not to cell-free virus. At this early time point, Langerhans cells (LCs) and T-cells within the inner foreskin epidermis are the first cells targeted by the virus. To gain in-depth insight into the molecular mechanisms governing inner foreskin HIV-1 entry, foreskin explants were inoculated with HIV-1-infeceted cells for 4 h. The chemokine/cytokine milieu secreted by the foreskin tissue, and resulting modifications in density and spatial distribution of T-cells and LCs, were then investigated. Our studies show that in the inner foreskin, inoculation with HIV-1-infected cells induces increased CCL5/RANTES (1.63-fold) and decreased CCL20/MIP-3-alpha (0.62-fold) secretion. Elevated CCL5/RANTES mediates recruitment of T-cells from the dermis into the epidermis, which is blocked by a neutralizing CCL5/RANTES Ab. In parallel, HIV-1-infected cells mediate a bi-phasic modification in the spatial distribution of epidermal LCs: attraction to the apical surface at 1 h, followed by migration back towards the basement membrane later on at 4 h, in correlation with reduced CCL20/MIP-3-alpha at this time point. T-cell recruitment fuels the continuous formation of LC-T-cell conjugates, permitting the transfer of HIV-1 captured by LCs. Together, these results reveal that HIV-1 induces a dynamic process of immune cells relocation in the inner foreskin that is associated with specific chemokines secretion, which favors efficient HIV-1 entry at this site.