Comparison of the effects of HGF,BDNF, CT‐1, CNTF,and the branchial arches on the growth of embryonic cranial motor neurons

In the developing embryo, axon growth and guidance depend on cues that include diffusible molecules. We have shown previously that the branchial arches and hepatocyte growth factor (HGF) are growth‐promoting and chemoattractant for young embryonic cranial motor axons. HGF is produced in the branchial arches of the embryo, but a number of lines of evidence suggest that HGF is unlikely to be the only factor involved in the growth and guidance of these axons. Here we investigate whether other neurotrophic factors could be involved in the growth of young cranial motor neurons in explant cultures. We find that brain‐derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF) and cardiotrophin‐1 (CT‐1) all promote the outgrowth of embryonic cranial motor neurons, while glial cell line‐derived neurotrophic factor (GDNF) and neurotrophin‐3 (NT‐3) fail to affect outgrowth. We next examined whether HGF and the branchial arches had similar effects on motor neuron subpopulations at different axial levels. Our results show that HGF acts as a generalized rather than a specific neurotrophic factor and guidance cue for cranial motor neurons. Although the branchial arches also had general growth‐promoting effects on all motor neuron subpopulations, they chemoattracted different axial levels differentially, with motor neurons from the caudal hindbrain showing the most striking response. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 101–114, 2002     

Novel benzimidazole derivatives as selective CB2 agonists

The preparation and evaluation of a novel class of CB2 agonists based on a benzimidazole moiety are reported. They showed binding affinities up to 1nM towards the CB2 receptor with partial to full agonist potencies. They also demonstrated good to excellent selectivity (>1000-fold) over the CB1 receptor.     

Dicer Is Required for Normal Cerebellar Development and to Restrain Medulloblastoma Formation

Dicer, a ribonuclease III enzyme, is required for the maturation of microRNAs. To assess its role in cerebellar and medulloblastoma development, we genetically deleted Dicer in Nestin-positive neural progenitors and in mice lacking one copy for the Sonic Hedgehog receptor, Patched 1. We found that conditional loss of Dicer in mouse neural progenitors induced massive Trp53-independent apoptosis in all proliferative zones of the brain and decreased proliferation of cerebellar granule progenitors at embryonic day 15.5 leading to abnormal cerebellar development and perinatal lethality. Loss of one copy of Dicer significantly accelerated the formation of mouse medulloblastoma of the Sonic Hedgehog subgroup in Patched1-heterozygous mice. We conclude that Dicer is required for proper cerebellar development, and to restrain medulloblastoma formation.     

Amphibious Shelter-Builder Oniscidea Species from the New World with Description of a New Subfamily,a New Genus and a New Species from Brazilian Cave (Isopoda,Synocheta, Styloniscidae)

The new subfamily Iuiuniscinae, Styloniscidae, is erected for the new genus Iuiuniscus and the new species I. iuiuensis, which is described from cave of the State of Bahia, Northeastern Brazil. A special ecological character is shown here for the first time for a New World Oniscidea: the construction of mud shelters. An introduction addressing the systematics of Synocheta with emphasis on Styloniscidae Vandel, 1952 is provided, as well as general comments about the dependence of water in some Oniscidea and ecological traits of amphibious Synocheta. The problems referring to nomenclature, taxonomy and the interrelationships in Styloniscidae are discussed.     

Camptosemin, a tetrameric lectin of Camptosema ellipticum: structural and functional analysis

Lectins have been classified into a structurally diverse group of proteins that bind carbohydrates and glycoconjugates with high specificity. They are extremely useful molecules in the characterization of saccharides, as drug delivery mediators, and even as cellular surface makers. In this study, we present camptosemin, a new lectin from Camptosema ellipticum. It was characterized as an N-acetyl-d-galactosamine-binding homo-tetrameric lectin, with a molecular weight around 26 kDa/monomers. The monomers were stable over a wide range of pH values and exhibited pH-dependent oligomerization. Camptosemin promoted adhesion of breast cancer cells and hemagglutination, and both activities were inhibited by its binding of sugar. The stability and unfolding/folding behavior of this lectin was characterized using fluorescence and far-UV circular dichroism spectroscopies. The results indicate that chemical unfolding of camptosemin proceeds as a two-state monomer-tetramer process. In addition, small-angle X-ray scattering shows that camptosemin behaves as a soluble and stable homo-tetramer molecule in solution.     

Partitioning of acidic, basic and neutral amino acids into imidazolium-based ionic liquids

In this paper, partitioning behaviors of typical neutral (Alanine), acidic (Glutamic acid) and basic (Lysine) amino acids into imidazolium-based ionic liquids [C₄mim][PF₆], [C₆mim][PF₆], [C₈mim][PF₆], [C₆mim][BF₄] and [C₈mim][BF₄] as extracting solvents were examined. [C₆mim][BF₄] showed the best efficiency for partitioning of amino acids. The partition coefficients of amino acids in ionic liquids were found to depend strongly on pH of the aqueous solution, amino acid and ionic liquid chemical structures. Different chemical forms of amino acids in aqueous solutions were pH dependent, so the pH value of the aqueous phase was a determining factor for extraction of amino acids into ionic liquid phase. Both water content of ionic liquids and charge densities of their anionic and cationic parts were important factors for partitioning of cationic and anionic forms of amino acids into ionic liquid phase. Extracted amino acids were back extracted into phosphate buffer solutions adjusted on appropriate pH values. The results showed that ionic liquids could be used as suitable modifiers on the stationary phase of an HPLC column for efficient separation of acidic, basic, and neutral amino acids.     

Antimutagenic and Antioxidant Potentials of Teucrium ramosissimum Essential Oil

The mutagenic and antimutagenic effects of the essential oil extracted from the aerial parts of Teucrium ramosissimum were evaluated by the bacterial reverse mutation assay in Salmonella typhimurium TA98, TA100, and TA1535, with and without exogenous metabolic activation (S9 fraction). The T. ramosissimum essential oil showed no mutagenic effect. In contrast, our results established that it possessed antimutagenic effects against sodium azide (SA), aflatoxin B1 (AFB1), benzo[a]pyrene (B[a]P), and 4‐nitro‐o‐phenylenediamine (NOPD). The antioxidant capacity of the tested essential oil was evaluated using enzymatic, i.e., the xanthine/xanthine oxidase (X/XOD) assay, and nonenzymatic systems, i.e., the nitro‐blue tetrazolium (NBT)/riboflavin and the DPPH assays. A moderate free radical‐scavenging activity was observed towards DPPH^. and O$\rm{{_{2}^{{^\cdot} -}}}$ . In contrast, T. ramosissimum essential oil showed no effect for all the tested concentrations in the X/XOD assay.     

Sequestration of the Aβ Peptide Prevents Toxicity and Promotes Degradation In Vivo

Protein aggregation, arising from the failure of the cell to regulate the synthesis or degradation of aggregation-prone proteins, underlies many neurodegenerative disorders. However, the balance between the synthesis, clearance, and assembly of misfolded proteins into neurotoxic aggregates remains poorly understood. Here we study the effects of modulating this balance for the amyloid-beta (Aβ) peptide by using a small engineered binding protein (Z_Aβ3) that binds with nanomolar affinity to Aβ, completely sequestering the aggregation-prone regions of the peptide and preventing its aggregation. Co-expression of Z_Aβ3 in the brains of Drosophila melanogaster expressing either Aβ₄₂ or the aggressive familial associated E22G variant of Aβ₄₂ abolishes their neurotoxic effects. Biochemical analysis indicates that monomer Aβ binding results in degradation of the peptide in vivo. Complementary biophysical studies emphasize the dynamic nature of Aβ aggregation and reveal that Z_Aβ3 not only inhibits the initial association of Aβ monomers into oligomers or fibrils, but also dissociates pre-formed oligomeric aggregates and, although very slowly, amyloid fibrils. Toxic effects of peptide aggregation in vivo can therefore be eliminated by sequestration of hydrophobic regions in monomeric peptides, even when these are extremely aggregation prone. Our studies also underline how a combination of in vivo and in vitro experiments provide mechanistic insight with regard to the relationship between protein aggregation and clearance and show that engineered binding proteins may provide powerful tools with which to address the physiological and pathological consequences of protein aggregation.     

Characterizing the interaction between pyrogallol and human serum albumin by spectroscopic and molecular docking methods

In the present study, the interaction of Pyrogallol (PG) with human serum albumin (HSA) was investigated by UV, fluorescence, Circular dichroism (CD), and molecular docking methods. The results of fluorescence experiments showed that the quenching of intrinsic fluorescence of HSA by PG was due to a static quenching. The calculated binding constants (K) for PG-HSA at different temperatures were in the order of 10⁴?M ^?1, and the corresponding numbers of binding sites, n were approximately equal to unity. The thermodynamic parameters, ΔH and ΔS were calculated to be negative, which indicated that the interaction of PG with HSA was driven mainly by van der Waals forces and hydrogen bonds. The negative value was obtained for ΔG showed that the reaction was spontaneous. In addition, the effect of PG on the secondary structure of HSA was analyzed by performing UV–vis, synchronous fluorescence, and CD experiments. The results indicated that PG induced conformational changes in the structure of HSA. According to Förster no-radiation energy transfer theory, the binding distance of HSA to PG was calculated to be 1.93?nm. The results of molecular docking calculations clarified the binding mode and the binding sites which were in good agreement with the results of experiments.

Communicated by Ramaswamy H. Sarma