Enzymatic reduction of azo and indigoid compounds

A customer- and environment-friendly method for the decolorization azo dyes was developed. Azoreductases could be used both to bleach hair dyed with azo dyes and to reduce dyes in vat dyeing of textiles. A new reduced nicotinamide adenine dinucleotide-dependent azoreductase of Bacillus cereus, which showed high potential for reduction of these dyes, was purified using a combination of ammonium sulfate precipitation and chromatography and had a molecular mass of 21.5 kDa. The optimum pH of the azoreductase depended on the substrate and was within the range of pH 6 to 7, while the maximum temperature was reached at 40°C. Oxygen was shown to be an alternative electron acceptor to azo compounds and must therefore be excluded during enzymatic dye reduction. Biotransformation of the azo dyes Flame Orange and Ruby Red was studied in more detail using UV-visible spectroscopy, high-performance liquid chromatography, and mass spectrometry (MS). Reduction of the azo bonds leads to cleavage of the dyes resulting in the cleavage product 2-amino-1,3 dimethylimidazolium and N∼1∼,N∼1∼-dimethyl-1,4-benzenediamine for Ruby Red, while only the first was detected for Flame Orange because of MS instability of the expected 1,4-benzenediamine. The azoreductase was also found to reduce vat dyes like Indigo Carmine (C.I. Acid Blue 74). Hydrogen peroxide (H₂O₂) as an oxidizing agent was used to reoxidize the dye into the initial form. The reduction and oxidation mechanism of Indigo Carmine was studied using UV-visible spectroscopy.     

The case for a polyphyletic origin of mitochondria: Morphological and molecular comparisons

The comparative morphology and pigmentation of protists suggest that those with tubular mitochondrial cristae belong to a different lineage than those with lamellar cristae and that the evolutionary divergence might have been very early. We propose that the difference in cristal morphology is the result of separate origins of the mitochondria from endosymbionts related to the Rhodospirillaceae (purple nonsulfur bacteria) but differing in the morphology of their internal membranes. Comparisons of the cytochromes c of protists and the Rhodospirillaceae and of 16s rRNA T1 oligonucleotide catalogs in the Rhodospirillaceae do not contradict, and in fact provide support for, the idea. More extensive evidence may be lacking simply because cytochromes c have been studied in very few protists with tubular mitochondrial cristae.     

Oxidation and reduction of lignin-related aromatic compounds by Aureobasidium pullulans

Summary A yeast-like fungus, identified as Aureobasidium pullulans, was isolated from a kraft mill settling pond by enrichment culture on 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-propane-1,3-diol (I). The fungus was also able to use the following aromatic acids as sole carbon source: Benzoic, p-hydroxybenzoic, vanillic, syringic, ferulic and protocatechuic acids. Various aromatic alcohols were oxidised to their corresponding aldehydes and acids during aerobic culture, while aromatic aldehydes were both oxidised and reduced. However, the aromatic acids were not reduced, but were slowly metabolised. Dimer I was cleaved at the alkyl-phenyl linkage to give glycerol-2-guaiacyl ether in high yield. The identity of the latter was determined by mass spectrometry and proton nmr. The dimers 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-propane-1,3-diol (II), 3,4-dimethoxy--(2,6-dimethoxy-4-carboxyphenoxy)-acetophenone (III) and 5-carboxy-7-methoxy-2-(4-hydroxy-3-methoxyphenyl)-3-methyl-2,3-dihydrobenzo-[b]-furan (IV) were not metabolised. It is concluded that the fungus resembles Fusarium in many of its metabolic properties, and could be considered as a potential lignin degrader.     

Morphological integration and serial homology: A case study of the cranium and anterior vertebrae in salamanders

Serial homology or the repetition of equivalent developmental units and their derivatives is a phenomenon encountered in a variety of organisms, with the vertebrate axial skeleton as one of the most notable examples. Serially homologous structures can be viewed as an appropriate model system for studying morphological integration and modularity, due to the strong impact of development on their covariation. Here, we explored the pattern of morphological integration of the cranium and the first three serially homologous structures (atlas, first, and second trunk vertebrae) in salamandrid salamanders, using micro-CT scanning and three-dimensional geometric morphometrics. We explored the integration between structures at static and evolutionary levels. Effects of allometry on patterns of modularity were also taken into account. At the static level (within species), we analyzed inter-individual variation in shape to detect functional modules and intra-individual variation to detect developmental modules. Significant integration (based on inter-individual variation) among all structures was detected and allometry is shown to be an important integrating factor. The pattern of intra-individual, asymmetric variation indicates statistically significant developmental integration between the cranium and the atlas and between the first two trunk vertebrae. At the evolutionary level (among species), the cranium, atlas, and trunk vertebrae separate as different modules. Our results show that morphological integration at the evolutionary level coincides with morphological and functional differentiation of the axial skeleton, allowing the more or less independent evolutionary changes of the cranial skeleton and the vertebral column, regardless of the relatively strong integration at the static level. The observed patterns of morphological integration differ across levels, indicating different impacts of developmental and phylogenetic constraints and functional demands.     

Using liposomes as carriers for polyphenolic compounds: the case of trans-resveratrol

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a polyphenol found in various plants, especially in the skin of red grapes. The effect of resveratrol on human health is the topic of numerous studies. In fact this molecule has shown anti-cancer, anti-inflammatory, blood-sugar-lowering ability and beneficial cardiovascular effects. However, for many polyphenol compounds of natural origin bioavailability is limited by low solubility in biological fluids, as well as by rapid metabolization in vivo. Therefore, appropriate carriers are required to obtain efficient therapeutics along with low administration doses.Liposomes are excellent candidates for drug delivery purposes, due to their biocompatibility, wide choice of physico-chemical properties and easy preparation.In this paper liposome formulations made by a saturated phosphatidyl-choline (DPPC) and cholesterol (or its positively charged derivative DC-CHOL) were chosen to optimize the loading of a rigid hydrophobic molecule such as resveratrol.Plain and resveratrol loaded liposomes were characterized for size, surface charge and structural details by complementary techniques, i.e. Dynamic Light Scattering (DLS), Zeta potential and Small Angle X-ray Scattering (SAXS). Nuclear and Electron Spin magnetic resonances (NMR and ESR, respectively) were also used to gain information at the molecular scale.The obtained results allowed to give an account of loaded liposomes in which resveratrol interacted with the bilayer, being more deeply inserted in cationic liposomes than in zwitterionic liposomes. Relevant properties such as the mean size and the presence of oligolamellar structures were influenced by the loading of RESV guest molecules.The toxicity of all these systems was tested on stabilized cell lines (mouse fibroblast NIH-3T3 and human astrocytes U373-MG), showing that cell viability was not affected by the administration of liposomial resveratrol.     

Evaluation of electron-shuttling compounds in microbial ferric iron reduction

Iron-reducing bacteria can transfer electrons to ferric iron oxides which are barely soluble at neutral pH, and electron-shuttling compounds or chelators are discussed to be involved in this process. Experiments using semipermeable membranes for separation of ferric iron-reducing bacteria from ferric iron oxides do not provide conclusive results in this respect. Here, we used ferrihydrite embedded in 1% agar to check for electron-shuttling compounds in pure and in enrichment cultures. Geobacter sulfurreducens reduced spatially distant ferrihydrite only in the presence of anthraquinone-2,6-disulfonate, a small molecule known to shuttle electrons between the bacterial cell and ferrihydrite. However, indications for the production and excretion of electron-shuttling compounds or chelators were found in ferrihydrite-containing agar dilution cultures that were inoculated with ferric iron-reducing enrichment cultures.     

Stereoselective reduction of non-cyclic carbonyl compounds by some eumycetes

Summary Twelve strains of Eumycetes were able to perform the reduction of 2-pentanone, acetophenone and ethyl acetoacetate, sometimes in a yield suitable for preparative work. For each substrate, preferential reduction to the R-configurated alcohol was observed with one or more strains.     

Efficient nickel based catalyst for the homogeneous reduction of aromatic nitro compounds

The reduction of aromatic nitro compounds under CO under relatively mild conditions in the presence of NiX₂L₂ (XCl, Br, I; LPR₃, RMe, Et, Ph) and NiI₂(PhNH₂)₄ as catalyst precursors is described. The nitrobenzene is quantitatively converted into N,N′ diphenylurea in aniline solution and into alkylcarbanylate with a good yield, in aniline-alcohol mixtures. Nitrobenzene derivatives (p-RC₆H₄NO₂; RCH₃, Cl) and 2,4-dinitrotoluene, are also reduced in aniline solution; diphenylurea and amine, corresponding to the nitroderivatives, are the reaction products in these cases. This different behaviour is explained in terms of aminolysis of the expected N-aryl-N′-phenylurea. Sufficient data are produced to say that the observed increase of the catalytic activity, increasing in the sequence Cl, Br, I by changing the NiX₂L₂ complex, is due to an additional co-catalytic effect of the halide. On the basis of the chemical behaviour and IR evidence, the true catalytic species and some intermediates of reaction are suggested and a possible catalytic cycle is discussed.     

Morphological definition of a case of 'usual' interstitial pneumonia

A 61-year-old Caucasian female complained of shortness of breath, fever, and a period of rapid weight loss. After routine studies, the patient underwent an open lung biopsy in order to define the characteristics of the interstitial lung disease, and initiate appropriate therapeutic intervention. Typical fibrotic and cellular proliferation were evident in the parenchyma, as determined by standard light microscopy. However, in a correlated study using light microscopy of plastic embedded tissue, as well as scanning and transmission electron microscopy, a major proliferating cell type was identified as a type II pneumocyte. These cells were the predominant lining cells of the alveoli and clearly protruded into and limited available respiratory air spaces. The predominance of type II pneumocytes in the pathogenesis of certain respiratory diseases requires that a better explanation be sought for this phenomenon.     

Patterns of covert speech behavior and phonetic coding

In previous research a discriminative relationship has been established between patterns of covert speech behavior and the phonemic system when processing continuous linguistic material. The goal of the present research was to be more analytic and pinpoint covert neuromuscular speech patterns when one processes specific instances of phonemes. Electromyographic (EMG) recording indicated that the lips are significantly active when visually processing the letter "P"(an instance of bilabial material), but not when processing the letter "T" or a nonlinguistic control (C) stimulus. Similarly, the tongue is significantly active when processing the letter "T" (an instance of lingual-alveolar material), but not when processing the letters "P" or "C". It is concluded that the speech musculature covertly responds systematically as a function of class of phoneme being processed. These results accord with our model that semantic processing ("understanding") occurs when the speech (and other) musculature interacts with linguistic regions of the brain. In the interactions phonetic coding is generated and transmitted through neuromuscular circuits that have cybernetic characteristics.     

Effect of the concentration of nitrogen compounds on microbial reduction of sulphates.

A change of the N/S ratio in the reaction medium affects the degree of the microbial reduction of sulphates to sulphides (x'). The time interval between the initial and the log phase of the process (t0) also varies, depending on the N/S ratio. It was demonstrated that optimal reduction conditions by the studied strain of Desulfovibrio desulphuricans exist in media of N/S=0.33.