Physid Snails as Sentinels of Freshwater Nematomorphs

Freshwater nematomorphs, or gordiids, are parasitic as larvae, but free-living in aquatic environments as adults. Studies based on the collection of adults have reported gordiids to be widespread, but discontinuous in distribution. However, a relatively short adult life span and unknown life history make the detection of adults difficult. An alternative approach to investigate gordiid distribution is to use cysts. Of all paratenic hosts, snails were chosen because they lacked internal defense reactions to the cysts and become easily infected. Here, it is reported that the occurrence of gordiids on the basis of the cyst stage is much more common than previously reported, thus altering the perception of how common these worms are. Using this modified survey procedure, gordiid cysts were found at 70% of sites examined, in an area where extensive sampling over 3 yr yielded adults only at a single site. Of 1,000 snails dissected, 395 were infected with gordiids (intensity range: 1-465). Furthermore, different types of human-modified landscapes did not affect gordiid distribution, suggesting that as urban and suburban areas sprawl, human encounters or pseudoparasitism with nematomorphs may increase. The results of this study indicate that use of organismal-specific sampling techniques can be critical in studies of parasite distribution and biodiversity

Physid Snails as Sentinels of Freshwater Nematomorphs

Freshwater nematomorphs, or gordiids, are parasitic as larvae, but free-living in aquatic environments as adults. Studies based on the collection of adults have reported gordiids to be widespread, but discontinuous in distribution. However, a relatively short adult life span and unknown life history make the detection of adults difficult. An alternative approach to investigate gordiid distribution is to use cysts. Of all paratenic hosts, snails were chosen because they lacked internal defense reactions to the cysts and become easily infected. Here, it is reported that the occurrence of gordiids on the basis of the cyst stage is much more common than previously reported, thus altering the perception of how common these worms are. Using this modified survey procedure, gordiid cysts were found at 70% of sites examined, in an area where extensive sampling over 3 yr yielded adults only at a single site. Of 1,000 snails dissected, 395 were infected with gordiids (intensity range: 1-465). Furthermore, different types of human-modified landscapes did not affect gordiid distribution, suggesting that as urban and suburban areas sprawl, human encounters or pseudoparasitism with nematomorphs may increase. The results of this study indicate that use of organismal-specific sampling techniques can be critical in studies of parasite distribution and biodiversity

Self-assembling nanomaterial-based peptide surface for target cell adhesion

Non-covalent modification of electrode surfaces with nanoparticle-based peptides does not change the chemical properties of the electrode but allows electrochemical measurement of cell adhesion. This study examines the effect of self-modified nanomaterial/peptide surfaces on cell adhesion. This adhesion to the surface is caused by the negative Gibs free energy formed in the system because of the presence of -0H, sulfur, carbonyl, or reactive groups. A cheaper and more practical method for electrode surfaces targeting cell adhesion, which does not use heavy chemicals and EDC/NHS chemistry, is used in this work. Thanks to the bioactive materials immobilized on the screen-printed carbon electrode (SPCE) surface in a controlled manner and the surface chemistry offered by these materials, a biocompatible self-assembling nanomaterial-based peptide surface platform is created, and cell adhesion is measured by an electrochemical technique. After the characterization steps, electro­chemical techniques created a calibration curve of the current value as a function of concentration for each cell line. The adhesion of the generated bioactive electrode surfaces to the selected cell lines was examined comparatively

Polysaccharides on gelatin-based hydrogels differently affect chondrogenic differentiation of human mesenchymal stromal cells

Selection of feasible hybrid-hydrogels for best chondrogenic differentiation of human mesenchymal stromal cells (hMSCs) represents an important challenge in cartilage regeneration. In this study, three-dimensional hybrid hydrogels obtained by chemical crosslinking of poly (ethylene glycol) diglycidyl ether (PEGDGE), gelatin (G) without or with chitosan (Ch) or dextran (Dx) polysaccharides were developed. The hydrogels, namely G-PEG, G-PEG-Ch and G-PEG-Dx, were prepared with an innovative, versatile and cell-friendly technique that involves two preparation steps specifically chosen to increase the degree of crosslinking and the physical-mechanical stability of the product: a first homogeneous phase reaction followed by directional freezing, freeze-drying and post-curing. Chondrogenic differentiation of human bone marrow mesenchymal stromal cells (hBM-MSC) was tested on these hydrogels to ascertain whether the presence of different polysaccharides could favor the formation of the native cartilage structure. We demonstrated that the hydrogels exhibited an open pore porous morphology with high interconnectivity and the incorporation of Ch and Dx into the G-PEG common backbone determined a slightly reduced stiffness compared to that of G-PEG hydrogels. We demonstrated that G-PEG-Dx showed a significant increase of its anisotropic characteristic and G-PEG-Ch exhibited higher and faster stress relaxation behavior than the other hydrogels. These characteristics were associated to absence of chondrogenic differentiation on G-PEG-Dx scaffold and good chondrogenic differentiation on G-PEG and G-PEG-Ch. Furthermore, G-PEG-Ch induced the minor collagen proteins and the formation of collagen fibrils with a diameter like native cartilage. This study demonstrated that both anisotropic and stress relaxation characteristics of the hybrid hydrogels were important features directly influencing the chondrogenic differentiation potentiality of hBM-MSC

Chemical Characterization and Nematicidal Activity of the Essential Oil of Nepeta nuda L. ssp. pubescens and Nepeta curviflora Boiss. from Lebanon

The chemical characterization and the nematicidal activity of the essential oils from Nepeta nuda L. ssp. pubescens and Nepeta curviflora Boiss. growing wild in Lebanon are reported. A comparative study was carried out as, to the best of our knowledge, no information is available on Nepeta nuda L. ssp. pubescens. In addition, both Nepeta species were collected in the same geographical area in order to rule out the environmental factors influencing essential oil composition and bioactivity. The most abundant (> 5 %) components of N. nuda ssp. pubescens essential oil were pinene (12.89 %), 1-ethyl-1H-pyrrole (12.67 %), 1-cycloethyl- 1-(2-methylenecyclohexyl) ethanol (10.37 %), 3-methyl-2-cyclohexen-1-one (9.17 %) and 2,3-dimethyl-3- hexanol (5.88 %). Among oxygenated monoterpenes, two nepetalactones were identified, i.e. (E, Z)nepetalactone (2.24 %) and (Z, E)-nepetalactone (0.31 %). The major constituents (> 5 %) of N. curviflora essential oil were 2-isopropyl-5-methyl-3-cyclohexen-1-one (12.51%), (-)-spathulenol (11.73%), cis-Z-alpha-bisabolene epoxide (8.07 %), widdrol (7.0 %), (E, Z)-5,7-dodecadiene (6.93 %), dihydronepetalactone (5.57 %) and 4-propyl-cyclohexene (5.43 %). The essential oil of N. curviflora was more active than the N. nuda ssp. pubescens one against the nematode Panagrolaimus rigidus. According to the motility assay, LD50 was 0.5 mg/mL and 2.5 mg/mL 24 h after treatment with N. curviflora and N. nuda ssp. pubescens essential oil, respectively

Influence of stabilisers on the catalytic activity of supported Au colloidal nanoparticles for the liquid phase oxidation of glucose to glucaric acid: understanding the catalyst performance from NMR relaxation and computational studies

Supported Au colloidal nanoparticles have been prepared in the presence of stabilising polymers, such as, PVA, PVP and PEG (polyvinylalcohol, polyvinylpyrrolidone, polyethylene glycol). The effect of the polymer to Au weight ratio was investigated, for the synthesis of Au nanoparticles with varying particle size and particle size distribution. By varying the polymer/Au wt/wt ratio, Au nanoparticles with mean diameters from 3 to 8 nm were synthesised. The synthesised Au catalysts were studied in the liquid phase oxidation of glucose to glucaric acid under alkaline conditions. We demonstrated that the choice of polymer and polymer to Au weight ratio, have an important influence in terms of catalytic activity and yield to glucaric acid. The highest yield to glucaric acid (22%) was obtained using Au–PVA catalysts. A strong deactivation was observed using Au catalysts. Further evaluation of the possible reasons for deactivation were investigated using experimental, computational and NMR relaxation studies

On the Limited Role of Electronic Support Effects in Selective Alkyne Hydrogenation: A Kinetic Study of Au/MO\u3csub\u3ex\u3c/sub\u3e Catalysts Prepared from Oleylamine-Capped Colloidal Nanoparticles

We report a quantitative kinetic evaluation and study of support effects for partial alkyne hydrogenation using oleylaminecapped Au colloids as catalyst precursors. The amine capping agents can be removed under reducing conditions, generating supported Au nanoparticles of ~2.5 nm in diameter. The catalysts showed high alkene selectivity (\u3e90%) at all conversions during alkyne partial hydrogenation. Catalytic activity, observed rate constants, and apparent activation energies (25– 40 kJ/mol) were similar for all Au catalysts, indicating support effects are relatively small. Alkyne adsorption, probed with FTIR and DFT, showed adsorption on the support was associated with hydrogen-bonding interactions. DFT calculations indicate strong alkyne adsorption on Au sites, with the strongest adsorption sites at the metal-support interface (MSI). The catalysts had similar hydrogen reaction orders (0.7–0.9), and 1- octyne reaction orders (~ 0.2), suggesting a common mechanism. The reaction kinetics are most consistent with a mechanism involving the non-competitive activated adsorption of H2 on an alkyne-covered Au surface