Histological approaches for high-quality imaging of zooplanktonic organisms

The investigation of the internal organization of zooplankton communities provides important information on the plankton biology with special interest for the study of ecological processes. Zooplanktoners can play a structural function as indicators for ecosystem health or stress, but their study using histological techniques is still limited. Here we report that the internal structure of zooplanktonic organisms can be facilely observed by a histological approach that combines optimal fixation and processing with a plastic resin (glycol methacrylate) embedding, resulting in increased tissue resolution. Using copepods, organisms that can dominate zooplankton assemblages, as models, collected from a tropical ecosystem (Paraibuna river, Brazil), we showed fine histological details of their muscular, nervous and digestive systems, structure of appendages and cell features. Critical advantages of this approach are that it permits optimal preservation and adequate handling of the organisms (embedded in agar after fixation) for further histological processing and investigation. This is important because it prevents both mechanically induced artifacts and loss of these diminutive organisms during the different steps of processing. Moreover, embedding in plastic resin showed a superior imaging of copepod internal structures compared to paraffin embedding. The use of glycol methacrylate is advantageous over paraffin/paraplast embedding by avoiding heat damage, tissue retraction and allowing faster embedding procedure and better tissue resolution. The value of histological approaches in enabling high-quality imaging of the internal structure of copepods is particularly important because these organisms can be used as indicators of environmental changes.     

Validation study of a rapid ELISA for detection of histamine in tuna

Neogen Corp. has developed an improved Veratox histamine test kit for the detection of histamine in tuna tissue. The purpose of this study was to validate the method under the requirements of AOAC Research Institute (RI) Performance Tested Methods. Three AOAC Official Methods for histamine (954.04, 957.07, and 977.13) and one ELISA method have been performance tested by the AOAC RI. The most popular is AOAC Official Method 977.13, the fluorometric method, which is considered the reference method, but is complicated and time-consuming. The need for a rapid ELISA test kit to be validated by the AOAC RI exists.     

Electrochemical and microsomal production of free radicals from 1,2,5-oxadiazole N-oxide as potential antiprotozoal drugs

The electron spin resonance (ESR) spectra of free radicals obtained by electrolytic or microsomal reduction of several potential antiprotozoal 1,2,5-oxadiazoles were characterized and analyzed. Ab initio molecular orbital calculations were performed to obtain the optimized geometries and the theoretical hyperfine constant was carried out using ZINDO semiempirical methodology. Density functional theory was used to rationalize the reduction potentials of these compounds.     

Polymer Optical Fibers and Nonlinear Optical Device Principles

Basic principles of the present optoelectronic research activities at Hoechst AG are presented in this contribution. Within the diversified broad band spectrum of optoelectronic materials and applications our interest is focused on new types of polymer optical fibers and nonlinear optical device principles using organic Langmuir–Blodgett films and electrically poled polymers. The basic principles and the limits of the present research and development activities which have a high market potential are outlined.     

Synthese et proprietes ionophores de macrocycles tetrapyrazoliques

The synthesis of a tetraaza-porphyrinogen tetra-substituted by dimelhylamino groups (electrodonor groups) has shown the influence of those substitutions above the ionophoretic properties of this macrocycle. The complexation of alkali, ammonium and calcium cations by these compounds has been studied by the extraction method. In all cases, the complexing ability of the substituted compound is higher than its unsubstituted homologue. This effect is less pronounced for the transport of the same cations across a liquid membrane.     

Highly chemoselective hydrogenation of 2-ethylanthraquinone to 2-ethylanthrahydroquinone catalyzed by palladium metal dispersed inside highly lipophilic functional resins

Most hydrogen peroxide is currently produced by the selective hydrogenation of 2-ethylanthraquinone (EAQ) to 2-ethylanthrahydroquinone (EAHQ), followed by treatment with dioxygen; this produces hydrogen peroxide and regenerates 2-ethylanthraquinone. We have developed novel catalysts for this process that are based on palladium supported on very lipophilic functional resins and that are able to promote a chemoselectivity for EAHQ slightly but definitely superior to that provided by an industrial catalyst under identical conditions. This finding demonstrates the potential of variations of the lipophilic/hydrophilic character of the support as a tool for the improvement of the chemoselectivity of resin-based metal catalysts.     

Solvent coordination in gas-phase [Mn.(H(2)O)(n)](2+) and [Mn.(ROH)(n)](2+) complexes: theory and experiment

An experimental gas-phase study of the intensities and fragmentation patterns of [Mn.(H(2)O)(n)](2+) and [Mn.(ROH)(n)](2+) complexes shows the combinations [Mn.(H(2)O)(4)](2+) and [Mn.(ROH)(4)](2+) to be stable. Evidence in complexes involving the alcohols methanol, ethanol, 1-propanol, and 2-propanol favors preferential fragmentation to [Mn.(ROH)(4)](2+), whereas the fragmentation data for water is less clear. Supporting density functional calculations show that both [Mn.(H(2)O)(4)](2+) and [Mn.(MeOH)(4)](2+) adopt stable tetrahedral configurations, similar to those proposed for biochemical systems where solvent availability and coordination is restricted. Calculated incremental binding energies show a gradual decline on going from one to six solvent molecules, with a step occurring between four and five molecules. The addition of further solvent molecules to the stable [Mn.(MeOH)(4)](2+) unit shows a preference for [Mn.(MeOH)(4)(MeOH)(1,2)](2+) structures, where the extra molecules occupy hydrogen-bonded sites in the form of a secondary solvation shell. Very similar behavior is seen on the part of water. As part of an analysis of the experimental data, the calculations have explored the influence different spins states of Mn(2+) have on solvent geometry. It is concluded that the experimental observations are best reproduced when the central Mn(2+) ion is in the high-spin (6)S ground state. The results are also considered in terms of the biochemical activity of Mn(2+) where the ion is capable of isomorphous substitution with Zn(2+), which itself exhibits a preference for tetrahedral coordination.     

Functional properties and fatty acids profile of different beans varieties

Dried seeds of four varieties of Phaseolus vulgaris, three of Vigna unguiculata ssp. unguiculata and two of Vigna angularis grown and marketed in Italy, Mexico, India, Japan, Ghana and Ivory Coast were analysed for fatty acids content. In oils from seeds of P. vulgaris, the main fatty acids were linolenic (34.7–41.5%) and linoleic (30.7–40.3%), followed by palmitic (10.7–16.8%). The first three aforementioned fatty acids in the lipid fraction of V. unguiculata varieties were 28.4, 28.7 and 26.2%, respectively; while in V. angularis varieties, main fatty acids were linoleic (36.4–39.1%) and palmitic (26.9–33.3%), followed by linolenic (17.9–22.2%). Statistical analyses indicate that botanical species play a rule in bean fatty acids distribution, while the same was not verified for geographical origin. Furthermore, the atherogenic index (AI) and the thrombogenic index (TI) were investigated for health and nutritional information. The results showed that these wide spread legumes have functional features to human health.     

Rational Enzyme Design without Structural Knowledge: A Sequence-Based Approach for Efficient Generation of Transglycosylases

Glycobiology is dogged by the relative scarcity of synthetic, defined oligosaccharides. Enzyme-catalysed glycosylation using glycoside hydrolases is feasible but is hampered by the innate hydrolytic activity of these enzymes. Protein engineering is useful to remedy this, but it usually requires prior structural knowledge of the target enzyme, and/or relies on extensive, time-consuming screening and analysis. Here, a straightforward strategy that involves rational rapid in silico analysis of protein sequences is described. The method pinpoints 6–12 single-mutant candidates to improve transglycosylation yields. Requiring very little prior knowledge of the target enzyme other than its sequence, the method is generic and procures catalysts for the formation of glycosidic bonds involving various d /l -, α/β-pyranosides or furanosides, and exo or endo action. Moreover, mutations validated in one enzyme can be transposed to others, even distantly related enzymes.     

Memory of Chirality in Flow Electrochemistry: Fast Optimisation with DoE and Online 2D-HPLC

Amino acid derivatives undergo non-Kolbe electrolysis to afford enantiomerically enriched α-alkoxyamino derivatives through intermediate chiral carbenium ions. The products contain N,O-acetals which are important structural motifs found in bioactive natural products. The reaction is performed in a continuous flow electrochemical reactor coupled to a 2D-HPLC for immediate online analysis. This allowed a fast screening of temperature, electrode material, current, flow-rate and concentration in a DoE approach. The combination with online HPLC demonstrates that also stereoselective reactions can benefit from a hugely accelerated optimisation by combining flow electrochemistry with multidimensional analysis.