Algal pigments in Lake Erie dreissenids,pseudofeces and sediments,as tracers of diet,selective feeding and bioaccumulation

Algal class biomarkers revealed the importance of diatoms and chlorophytes in the diet of dreissenids (n 18) collected from eastern Lake Erie (2–20 m depths; hard and soft substrate), during summer and fall, from 2003 to 2005. The most prominent biomarkers in dreissenids, typical of August, were fatty acid esters of carotenoids derived from diatoms (monoesters of fucoxanthinol, average 61%) and chlorophytes (diesters of mactraxanthin, average 30%), while non-esterified biomarkers from diatoms, chlorophytes, cryptophytes and cyanobacteria were below 4% of the total. At cool temperatures (June 2003, 13 °C), dreissenids had 84%:12% diatom:chlorophyte biomarkers, but with unseasonably warm temperatures (June 2004, 18 °C) and a nearshore chlorophyte bloom, dreissenids had a biomarker distribution similar to August. Bioconcentration factors in dreissenids relative to phytoplankton from Lake Erie were largest for the biomarkers from diatoms (21 L/g ww) and chlorophytes (29 L/g ww), compared to those from cryptophytes (2 L/g ww) and cyanobacteria (3 L/g ww). Unlike dreissenids (2003), matching pseudofeces (n 6) and sediments (n 16) contained a relatively large percentage of biomarkers for cryptophytes (20% June, 27% August) and cyanobacteria (31% August), suggesting that their low levels in dreissenids represent ingested feces, which are being rejected. Increased shell size (12–27 mm; surrogate for age; 3 sets) corresponded to an increase in diatom biomarkers (from 60 to 73%) but a decrease in chlorophyte biomarkers (from 31 to 17%); biomarker concentrations also decreased significantly (−3000 pmol/g ww/mm) in the most offshore collection, near Buffalo (Oct. 2005).     

Organic matter and modeling redox reactions during river bank filtration in an alluvial aquifer of the Lot River, France

A 3 year study of the infiltration of Lot River water into a well field located in an adjacent gravel and clay alluvial aquifer was conducted to assess the importance of organic matter regarding the redox processes which influence groundwater quality in a positive (denitrification) or negative (Mn dissolution) manner. Chloride was used to quantify the mixing of river water with groundwater. According to modeling with PHREEQC, the biodegradation of the infiltrated dissolved organic carbon (DOCi) is not sufficient to explain the observed consequences of the redox reactions (dissolved O2 depletion, denitrification, Mn dissolution). Another electron donor source must therefore be involved: we propose solid organic carbon (SOC) as a likely candidate, if made available for degradation by prior hydrolysis. Its contribution to redox reactions could be significant (30-80% of the total organic carbon consumed by redox reactions during river bank filtration). We show here also that even though the first few meters of infiltration are highly reactive, significant redox reactions can take place further in the aquifer, possibly affecting groundwater quality away from the river bank.     

Defensive Components in Insect Eggs: Are Anthraquinones Produced during Egg Development?

Eggs of several insect species are protected against natural enemies by noxious components. However, almost nothing is known about the fate of these defensive substances during egg development nor their site of biosynthesis. The eggs of several leaf beetle species of the taxon Galerucini contain components that are unusual in insects: 1,8-dihydroxylated anthraquinones and anthrones that deter predators such as ants and birds. These components, i.e., the anthrones dithranol and chrysarobin, and the anthraquinones chrysazin and chrysophanol, are not sequestered from host plants. We asked whether the amounts of these components in the overwintering eggs of Galeruca tanaceti change from deposition to larval hatching. Gas chromatography-mass spectroscopy (GC-MS) analyses of eggs revealed a significant decrease in total amounts of dithranol and chrysophanol from egg deposition in autumn to the next spring 5 months later. Thus, these results do not provide any hint of active anthraquinone biosynthesis within eggs. Instead, the anthrones and anthraquinones that must be incorporated by the female into the eggs seem to be degraded to some extent either by the embryo or endosymbionts. GC-MS analyses showed that parasitization of eggs had some effects on the quantities of anthrones and anthraquinones.     

Gene expression in synovial membrane cells after intraarticular delivery of plasmid-linked superparamagnetic iron oxide particles--a preliminary study in sheep

This study evaluated in vivo gene delivery and subsequent gene expression within cells of the synovium in the presence of static and pulsating magnetic field application following intraarticular injection of superparamagnetic iron oxide nanoparticles linked to plasmids containing reporter genes encoding for fluorescent proteins. Plasmids encoding genes for either green fluorescent protein or red fluorescent protein were bound to superparamagnetic nanoparticles coated with polyethyleneimine. Larger (200-250 nm) and smaller (50 nm) nanoparticles were compared to evaluate the effects of size on transfection efficiency as well as any associated intraarticular reaction. Comparisons between groups were evaluated at 24, 72, and 120 h time periods. Inflammatory response was mild to moderate for all injected particles, but was present in the majority of synovial membrane samples evaluated. Larger particles tended to be associated with more inflammation than smaller ones. Nevertheless, intraarticular application of both experimental and control nanoparticles were well tolerated clinically. Gene expression as determined by observation of either green or red intracellular fluorescence was difficult to assess by both epifluorescent light, and confocal microscopy. An insufficient concentration of nanoparticles in relation to joint volume likely resulted in a limited number of samples with positive evidence of iron staining and with suspected positive evidence of cells expressing fluorescent proteins. Our results indicate that intraarticular administration of functionalized superparamagnetic iron oxide nanoparticles resulted in a mild to moderate synovitis and there was in conclusive evidence of gene expression. Further research is warranted to determine the best and most effective reporter assay for assessment of the in vivo gene delivery into the joints. In addition, the best suited concentration and size of nanoparticles, which will optimize gene delivery and expression, while minimizing intraarticular inflammation, needs to be determined.     

Uptake and biocompatibility of functionalized poly(vinylalcohol) coated superparamagnetic maghemite nanoparticles by synoviocytes in vitro

Superparamagnetic iron oxide nanoparticles (SPION) were coated with either Polyvinyl alcohol (PVA) or Vinyl alcohol/vinyl amine copolymer and further functionalized with the fluorochromes Cy3.5 or Texas Red. A colloidally stable suspension of nanoparticles was incubated on sheep synovial cells in vitro for 3, 24, 72, and 120 hours. Nanoparticle internalization into synoviocytes as well as biocompatibility was visualized using light, fluorescence and confocal microscopy and fluorochrome labeled cells were quantified by flow cytometry. Data were analyzed by ANOVA factorial tests. Amino-PVA-SPION alone was detectable in cytoplasmic endosome-like structures after 3 hours of incubation but resulted in early cell death after 24 hours. Although amino-PVA-Cy3.5-SPION and PVA-TexasRed-SPION were taken up more slowly and less intensely, both labeled more than 80% of the cells in culture, but did not significantly change cell morphology or vitality at any time of evaluation in comparison to control cells. Results indicate that functionalized amino PVA-coated SPION are biocompatible, were successfully internalized by synoviocytes and hold promise for future biomedical applications utilizing magnetic drug targeting in joint disease.     

Molecular characterization of alkyd/acrylic latexes prepared by miniemulsion polymerization

The molecular characterization of alkyd/acrylic hybrid latexes produced by miniemulsion polymerization was characterized in terms of the resin degree of grafting, acrylic degree of grafting, reacted double bonds in the alkyd, gel content, and molecular weight distribution of the sol part. A simple method based on conventional size exclusion chromatography measurements was developed to estimate the fraction of alkyd resin grafted to the acrylic polymer. The method could be applied to completely soluble hybrids and to hybrids containing gel. Also, the limits of the extraction method used in the literature to estimate the fraction of acrylic polymer grafted to the alkyd was investigated; we found that this technique only provided accurate results at high values of the acrylic degree of grafting. The combination of this information with the reacted double bonds of the alkyd (determined by iodine titration) and the molecular weight distribution of the sol polymer provided a detailed characterization of the alkyd–acrylic hybrid polymer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Unconventional layer-by-layer assembly: surface molecular imprinting and its applications

Layer-by-layer assembly (LbL) is a rich, versatile, and powerful technique for fabricating multilayer thin films with controlled architecture and functions. Singly charged, uncharged, or water-repellent molecules cannot be used directly in conventional LbL assembly. This problem can be solved with unconventional LbL methods, by employing the preassembly of building blocks in solution and the use of these assemblies for LbL formation at the interface. This Concept summarizes different methods of unconventional LbL assembly, including electrostatic complex formation, hydrogen-bonded complexes, block-copolymer micelles, and π-π interaction complexes. These preassembly treatments endow the building blocks with enhanced abilities for advanced functionality, in particular, surface molecular imprinting, a new concept emerging from unconventional LbL. Molecular imprinting approaches are thus conceptually described based on different types of interactions and their great potential in applications is demonstrated by examples such as selective surface patterning and selective filtration.     

Impact of Gram-negative bacteria in interaction with a complex microbial consortium on biogenic amine content and sensory characteristics of an uncooked pressed cheese

The impact of Gram-negative bacteria on sensory characteristics and production of volatile compounds as well as biogenic amines (BA) in the core of an uncooked pressed type model cheese was investigated in the presence of a defined complex microbial consortium. Eleven strains of Gram-negative bacteria, selected on the basis of their biodiversity and in vitro BA-production ability, were individually tested in a model cheese. Four out of 6 strains of Enterobacteriaceae (Citrobacter freundii UCMA 4217, Klebsiella oxytoca 927, Hafnia alvei B16 and Proteus vulgaris UCMA 3780) reached counts close to 6 log CFU g⁻¹ in the model cheese. In core of cheeses inoculated with Gram-negative bacteria, only slight differences were observed for microbial counts (Enterococcus faecalis or Lactobacillus plantarum count differences below 1 log CFU g⁻¹), acetate concentration (differences below 200 mg kg⁻¹) and texture (greater firmness) in comparison to control cheeses. Cheese core colour, odour and volatile compound composition were not modified. Although ornithine, the precursor of putrescine, was present in all cheeses, putrescine was only detected in cheeses inoculated with H. alvei B16 and never exceeded 2.18 mmol kg⁻¹ cheese dry matter. Cadaverine was only detected in cheeses inoculated with H. alvei B16, K. oxytoca 927, Halomonas venusta 4C1A or Morganella morganii 3A2A but at lower concentrations (<1.05 mmol kg⁻¹ cheese dry matter), although lysine was available. Only insignificant amounts of the detrimental BA histamine and tyramine, as well as isopentylamine, tryptamine or phenylethylamine, were produced in the cheese model by any of the Gram-negative strains, including those which produced these BA at high levels in vitro.     

Mapping reactive flow patterns in monolithic nanoporous catalysts

The development of high-efficiency porous catalyst membranes critically depends on our understanding of where the majority of the chemical conversions occur within the porous structure. This requires mapping of chemical reactions and mass transport inside the complex nanoscale architecture of porous catalyst membranes which is a multiscale problem in both the temporal and spatial domains. To address this problem, we developed a multiscale mass transport computational framework based on the lattice Boltzmann method that allows us to account for catalytic reactions at the gas–solid interface by introducing a new boundary condition. In good agreement with experiments, the simulations reveal that most catalytic reactions occur near the gas-flow facing side of the catalyst membrane if chemical reactions are fast compared to mass transport within the porous catalyst membrane.