Copper binding to chicken and human prion protein amylodogenic regions: Differences and similarities revealed by Ni as a diamagnetic probe

Both human (h) and chicken (Ch) prion proteins (PrP) bind copper ions within the so called “tandem repeat” N-terminal region. Outside this region, hPrP possesses two additional copper binding sites, localized at His-96 and His-111 in the so called “amylodogenic” or neurotoxic region (residues 91-126). Also ChPrP possesses a similar region (ChPrP_105−140) containing two His (His-110 and His-124) and an identical hydrophobic tail of 15 amino acids rich in Ala and Gly. The copper binding abilities within such region of ChPrP were investigated by NMR, CD and potentiometry using Ni²⁺ as diamagnetic probe. The formation of diamagnetic metal complexes allowed to monitor the chemical shift and signal intensity variations and to determine the structural and kinetic features of the His-110 and His-124 metal binding sites. Finally a comparison between the hPrP and ChPrP metal binding abilities was performed. We found that the two prion proteins exhibited different copper and nickel preferences with the favoured metal binding sites localized at opposite His: His-110 for ChPrP, and His-111 for hPrP.     

Assessing cytotoxicity of boron nitride nanotubes: Interference with the MTT assay

Thanks to a non-covalent wrapping with glycol-chitosan, highly biocompatible and highly concentrated dispersions of boron nitride nanotubes were obtained and tested on human neuroblastoma cells. A systematic investigation of the cytotoxicity of these nanovectors with several complementary qualitative and quantitative assays allowed a strong interference with the MTT metabolic assay to be highlighted, similar to a phenomenon already observed for carbon nanotubes, that would wrongly suggest toxicity of boron nitride nanotubes. These results confirm the high complexity of these new nanomaterials, and the needing of extensive investigations on their exciting potential applications in the biomedical field.     

Penicillium brasilianum as an enzyme factory; the essential role of feruloyl esterases for the hydrolysis of the plant cell wall

The production of arabinoxylan-degrading enzymes by the fungus Penicillium brasilianum, grown on different carbon and nitrogen sources as well as different environmental conditions was investigated. Highest feruloyl esterase (225 mU/ml) and alpha-L-arabinofuranosidase (211 mU/ml) activities were obtained when P. brasilianum was grown on sugar beet pulp, whereas maximum xylanase (17 U/ml) activity was found during growth on oat spelt xylan. Yeast extract was the preferable nitrogen source for the production of all the three enzymes. Further optimization of the production of the crude enzyme mixture was examined by experimental design using a D-optimal quadratic model. Investigation of the microbial regulation of enzyme production showed that the presence of free ferulic acid further stimulated the production and pointing to that the fungal regulatory mechanism involved a coordinated production and secretion of feruloyl esterase, xylanase and alpha-L-arabinofuranosidase. Since agroindustrial by-products are a potential source of phenolic acids, crude enzyme mixtures of P. brasilianum were tested for their hydrolysis abilities against eight complex or model substrates. While total release of phenolic acids and pentoses was not observed, the synergistic enhancement of hydrolysis in the presence of feruloyl esterase was clearly demonstrated.     

Stress-dependent relocalization of translationally primed mRNPs to cytoplasmic granules that are kinetically and spatially distinct from P-bodies

Cytoplasmic RNA granules serve key functions in the control of messenger RNA (mRNA) fate in eukaryotic cells. For instance, in yeast, severe stress induces mRNA relocalization to sites of degradation or storage called processing bodies (P-bodies). In this study, we show that the translation repression associated with glucose starvation causes the key translational mediators of mRNA recognition, eIF4E, eIF4G, and Pab1p, to resediment away from ribosomal fractions. These mediators then accumulate in P-bodies and in previously unrecognized cytoplasmic bodies, which we define as EGP-bodies. Our kinetic studies highlight the fundamental difference between EGP- and P-bodies and reflect the complex dynamics surrounding reconfiguration of the mRNA pool under stress conditions. An absence of key mRNA decay factors from EGP-bodies points toward an mRNA storage function for these bodies. Overall, this study highlights new potential control points in both the regulation of mRNA fate and the global control of translation initiation.     

Unique human tumor antigens: immunobiology and use in clinical trials

The individual, unique tumor Ags, which characterize each single tumor, were described 50 years ago in rodents but their molecular characterization was limited to few of them and obtained during the last 20 years. Here we summarize the evidence for the existence and the biological role of such Ags in human tumors, although such evidence was provided only during the last 10 years and by a limited number of studies, a fact leading to a misrepresentation of unique Ags in human tumor immunology. This was also due to the increasing knowledge on the shared, self-human tumor Ags, which have been extensively used as cancer vaccines. In this review, we highlight the biological and clinical importance of unique Ags and suggest how they could be used in clinical studies aimed at assessing their immunogenic and clinical potential both in active and adoptive immunotherapy of human tumors.     

Trifunctional norrisolide probes for the study of Golgi vesiculation

Inspired by the effect of norrisolide on the Golgi complex, we synthesized norrisolide probes that contain: the perhydroindane core of the parent natural product for Golgi localization, a crosslinking unit (aryl azide or epoxide) for covalent binding to the target, and a tag (biotin or iodine) for subsequent target purification. We found that biotin-containing probes 14, 20 and 24 induced inefficient Golgi vesiculation. However, the iodinated probe 25 induced extensive and irreversible Golgi fragmentation. This probe can be used for the isolation of the cellular target of norrisolide.     

Design, synthesis, and biological evaluation of new (2E,6E)-10-(dimethylamino)-3,7-dimethyl-2,6-decadien-1-ol ethers as inhibitors of human and Trypanosoma cruzi oxidosqualene cyclase

New dimethylamino truncated squalene ether derivatives containing a different aromatic moiety (phenyl, naphthyl, and biphenyl) or a simple alkyl (n-hexylic) group were synthesized as inhibitors of the oxidosqualene cyclase (OSC) and of the sterol biosynthetic pathway. The activity against human OSC was compared with the activity against the OSCs of pathogenic organisms such as Pneumocystis carinii and Trypanosoma cruzi. The phenyl derivative was the most potent inhibitor of T. cruzi OSC.     

Effect of a topical treatment in organotypic culture of human breast skin after exposure to gamma-rays

The early radiation of epidermal reactions can lead to healing of the lesion or radiation necrosis. There is no general agreement for either the prevention and/or treatment of radiation skin response, also as little is known about the immediate phases of this phenomenon. We investigated the early effects exerted by Healing and Wound Emulsion (HWE) on human skin response after ionizing radiation. Epidermal morphology, Heat Shock Protein (HSP) 70, and Transforming Growth Factor-beta1 (TGF-beta1) gene expression were investigated in organotypic human skin cultures undergoing a double dose of gamma-rays (2 Gy). HSP70 gene expression tended to be induced in the HWE group 6 hours after cream administration and was significantly up-regulated after 48 hours, when epidermal morphological alterations were evident. TGF-beta1 seems not affected in cream treated samples. HWE may stimulate skin to mount an early defensive response against damage induced by gamma rays.     

The minimum information required for reporting a molecular interaction experiment (MIMIx)

A wealth of molecular interaction data is available in the literature, ranging from large-scale datasets to a single interaction confirmed by several different techniques. These data are all too often reported either as free text or in tables of variable format, and are often missing key pieces of information essential for a full understanding of the experiment. Here we propose MIMIx, the minimum information required for reporting a molecular interaction experiment. Adherence to these reporting guidelines will result in publications of increased clarity and usefulness to the scientific community and will support the rapid, systematic capture of molecular interaction data in public databases, thereby improving access to valuable interaction data.     

Evaluating plant-soil feedback together with competition in a serpentine grassland

Plants can alter biotic and abiotic soil characteristics in ways that feedback to change the performance of that same plant species relative to co-occurring plants. Most evidence for this plant-soil feedback comes from greenhouse studies of potted plants, and consequently, little is known about the importance of feedback in relation to other biological processes known to structure plant communities, such as plant-plant competition. In a field experiment with three C4 grasses, negative feedback was expressed through reduced survival and shoot biomass when seedlings were planted within existing clumps of conspecifics compared with clumps of heterospecifics. However, the combined effects of feedback and competition were species-specific. Only Andropogon gerardii exhibited feedback when competition with the clumps was allowed. For Sorghastrum nutans, strong interspecific competition eliminated the feedback expressed in the absence of competition, and Schizachyrium scoparium showed no feedback at all. That arbuscular mycorrhizal (AM) fungi may play a role in the feedback was indicated by higher AM root colonization with conspecific plant neighbours. We suggest that feedback and competition should not be viewed as entirely separate processes and that their importance in structuring plant communities cannot be judged in isolation from each other.