Competitive Adsorption of Lecithin and Saliva at the O/W Interface in Relation to the Oral Processing of Lipid Continuous Foods

This research is relevant to oral processing of lipid continuous foods. During this first step of food digestion, lipid continuous foods such as chocolate or margarine phase invert into oil-in-water emulsions stimulated through the mechanical action of tongue and teeth in combination with the change in temperature and the high surface activity of salivary proteins. These are hypothesised to stabilise the newly formed interface in competition with surfactants or surface active molecules released from the food if present. Here competitive adsorption between mechanically stimulated human whole saliva (HWS) and lecithin dissolved in sunflower oil freed of interfacially active contaminants was investigated in-vitro using a pendant drop tensiometer for dynamic interfacial tension and interfacial rheological measurements. Initially, it was validated that the interfacial properties of HWS samples remained unaffected by frozen storage at ?80 °C during 6 weeks. Protein concentration affected the absolute values of interfacial tension and in particular the dilatational elastic modulus. Competitive adsorption studies revealed a mixed interface and it follows that emulsion stabilisation during oral processing involves both salivary proteins and lecithin present in the oil phase.     

The CryoCapsule: Simplifying Correlative Light to Electron Microscopy

Correlating complementary multiple scale images of the same object is a straightforward means to decipher biological processes. Light microscopy and electron microscopy are the most commonly used imaging techniques, yet despite their complementarity, the experimental procedures available to correlate them are technically complex. We designed and manufactured a new device adapted to many biological specimens, the CryoCapsule, that simplifies the multiple sample preparation steps, which at present separate live cell fluorescence imaging from contextual high‐resolution electron microscopy, thus opening new strategies for full correlative light to electron microscopy. We tested the biological application of this highly optimized tool on three different specimens: the in vitro Xenopus laevis mitotic spindle, melanoma cells over‐expressing YFP‐langerin sequestered in organized membranous subcellular organelles and a pigmented melanocytic cell in which the endosomal system was labeled with internalized fluorescent transferrin.      

Genetically encoded impairment of neuronal KCC2 cotransporter function in human idiopathic generalized epilepsy

The KCC2 cotransporter establishes the low neuronal Cl⁻ levels required for GABA_A and glycine (Gly) receptor-mediated inhibition, and KCC2 deficiency in model organisms results in network hyperexcitability. However, no mutations in KCC2 have been documented in human disease. Here, we report two non-synonymous functional variants in human KCC2, R952H and R1049C, exhibiting clear statistical association with idiopathic generalized epilepsy (IGE). These variants reside in conserved residues in the KCC2 cytoplasmic C-terminus, exhibit significantly impaired Cl⁻-extrusion capacities resulting in less hyperpolarized Gly equilibrium potentials (E_Gly), and impair KCC2 stimulatory phosphorylation at serine 940, a key regulatory site. These data describe a novel KCC2 variant significantly associated with a human disease and suggest genetically encoded impairment of KCC2 functional regulation may be a risk factor for the development of human IGE.     

Loss of alpha2B-adrenoceptors increases magnitude of hypertension following nitric oxide synthase inhibition

Vascular alpha(2B)-adrenoceptors (alpha(2B)-AR) may mediate vasoconstriction and contribute to the development of hypertension. Therefore, we hypothesized that blood pressure would not increase as much in mice with mutated alpha(2B)-AR as in wild-type (WT) mice following nitric oxide (NO) synthase (NOS) inhibition with N(omega)-nitro-l-arginine (l-NNA, 250 mg/l in drinking water). Mean arterial pressure (MAP) was recorded in heterozygous (HET) alpha(2B)-AR knockout mice and WT littermates using telemetry devices for 7 control and 14 l-NNA treatment days. MAP in HET mice was increased significantly on treatment days 1 and 4 to 14, whereas MAP did not change in WT mice (days 0 and 14 = 113 +/- 3 and 114 +/- 4 mmHg in WT, 108 +/- 0.3 and 135 +/- 13 mmHg in HET, P < 0.05). MAP was significantly higher in HET than in WT mice days 10 through 14 (P < 0.05). Thus blood pressure increased more rather than less in mice with decreased alpha(2B)-AR expression. We therefore examined constrictor responses to phenylephrine (PE, 10(-9) to 10(-4) M) with and without NOS inhibition to determine basal NO contributions to arterial tone. In small pressurized mesenteric arteries (inner diameter = 177 +/- 5 microm), PE constriction was decreased in untreated HET arteries compared with WT (P < 0.05). l-NNA (100 microM) augmented PE constriction more in HET arteries than in WT arteries, and responses were not different between groups in the presence of l-NNA. Acetylcholine dilated preconstricted arteries from HET mice more than arteries from WT mice. Endothelial NOS expression was increased in HET compared with WT mesenteric arteries by Western analysis. Griess assay showed increased NO(x) concentrations in HET plasma compared with those in WT plasma. These data demonstrate that diminished alpha(2B)-AR expression increases the dependence of arterial pressure and vascular tone on NO production and that vascular alpha(2B)-AR either directly or indirectly regulates vascular endothelial NOS function.     

Molecular Analysis of a Large Subtelomeric Nucleotide-Binding-Site–Leucine-Rich-Repeat Family in Two Representative Genotypes of the Major Gene Pools of Phaseolus vulgaris

In common bean, the B4 disease resistance (R) gene cluster is a complex cluster localized at the end of linkage group (LG) B4, containing at least three R specificities to the fungus Colletotrichum lindemuthianum. To investigate the evolution of this R cluster since the divergence of Andean and Mesoamerican gene pools, DNA sequences were characterized from two representative genotypes of the two major gene pools of common bean (BAT93: Mesoamerican; JaloEEP558: Andean). Sequences encoding 29 B4-CC nucleotide-binding-site–leucine-rich-repeat (B4-CNL) genes were determined—12 from JaloEEP558 and 17 from BAT93. Although sequence exchange events were identified, phylogenetic analyses revealed that they were not frequent enough to lead to homogenization of B4-CNL sequences within a haplotype. Genetic mapping based on pulsed-field gel electrophoresis separation confirmed that the B4-CNL family is a large family specific to one end of LG B4 and is present at two distinct blocks separated by 26 cM. Fluorescent in situ hybridization on meiotic pachytene chromosomes revealed that two B4-CNL blocks are located in the subtelomeric region of the short arm of chromosome 4 on both sides of a heterochromatic block (knob), suggesting that this peculiar genomic environment may favor the proliferation of a large R gene cluster.     

The dynamics of energy allocation in adult arrhenotokous and thelytokous Venturia canescens

The ability to adjust resource allocation to the quality of the environment has broad implications for animal reproductive success. Organisms with complex life cycles that may experience various selection pressures during their lifetime are expected to evolve mechanisms to modulate the resource allocation strategies adopted during ontogeny to the conditions encountered by the adult. In the parasitoid Venturia canescens Gravenhorst (Hymenoptera: Ichneumonidae), thelytoky appears to have been selected for in anthropogenic habitats, where hosts are relatively numerous and food is absent, and arrhenotoky in natural habitats where hosts are more scarce and food is present. A previous study postulated that during their juvenile stage, females of both reproductive modes adopt strategies of energy allocation in accordance with these conditions, possibly providing a direct short‐term advantage to arrhenotokous forms, which partially co‐occur with thelytokous forms under natural conditions. To test this assumption, we provided daily adult thelytokous and arrhenotokous females with a small number of hosts together with food. To compare their lifetime resource allocation strategies, we recorded wasp longevities, egg loads, and carbohydrate reserves in wasps of different ages. Our analysis indicates that thelytokous females are able, to a certain extent, to cope with these conditions, because they reached the same longevity as arrhenotokous females. Nevertheless, thelytokous females suffered from a higher degree of time limitation compared with arrhenotokous ones, and arrhenotokous wasps appeared to maintain their energetic advantage over the adult stage. These results provide new insights, and point to the consideration of other activities, such as flight performance and/or ability to reach food and hosts, in the understanding of the role of resource allocation strategies in the maintenance of sex in this species.     

New selective carbonic anhydrase IX inhibitors: Synthesis and pharmacological evaluation of diarylpyrazole-benzenesulfonamides

Carbonic anhydrase (CA) IX expression is increased upon hypoxia and has been proposed as a therapeutic target since it has been associated with poor prognosis, tumor progression and pH regulation. We report the synthesis and the pharmacological evaluation of a new class of human carbonic anhydrase (hCA) inhibitors, 4-(5-aryl-2-hydroxymethyl-pyrazol-1-yl)-benzenesulfonamides. A molecular modeling study was conducted in order to simulate the binding mode of this new family of enzyme inhibitors within the active site of hCA IX. Pharmacological studies revealed high hCA IX inhibitory potency in the parameters nanomolar range. This study showed that the position of sulfonamide group in meta of the 1-phenylpyrazole increase a selectivity hCA IX versus hCA II of our compounds. An in vitro antiproliferative screening has been performed on the breast cancer MDA-MB-231 cell using doxorubicin as cytotoxic agent and in presence of selected CA IX inhibitor. The results shown that the cytotoxic efficiency of doxorubicin in an hypoxic environment, expressed in IC₅₀ value, is restored at 20% level with 1 μM CA IX inhibitor.     

Forest-cutting rapidly improves the demographic status of Paeonia officinalis, a species threatened by forest closure

In the Mediterranean region, the spread and densification of woodlands and shrublands subsequent to rural depopulation is a critical issue for the conservation of open-habitat plant species. Our objective was to assess the effectiveness of forest management to reduce the negative impact of forest closure on the persistence of a protected herbaceous perennial species Paeonia officinalis. Using demographic surveys from 2003 to 2008 in a woodland, open and managed habitat clear-cutted for the aim of our study, we assessed the effect of forest opening on plant performance and population dynamics. In addition, we performed a shading experiment on reproductive plants to mimic canopy closure and study its impact on plant growth and fecundity. Based on quadrat surveys and matrix models, we showed that forest cutting induced a rapid increase in plant performance and population asymptotic growth rate. Indeed, within 2 years, plant size, flower, seed and ovule numbers as well as the plant stage distribution, asymptotic growth rates and elasticity patterns shifted from values similar to those in the woodland habitat to values similar to those in the open habitat. Similarly, artificially shaded reproductive plants regressed within 2 years towards the vegetative stage. For perennial plants which have a stage in their life-cycle which allows for individual survival under unfavourable conditions such as the vegetative stage for P. officinalis, such demographic plasticity may be fundamental for their long-term persistence in temporally heterogeneous environments. Our study highlights the need to mix an experimental approach with a mid-term demographic survey in order to design efficient conservation management strategies for declining populations of rare species.