Extensional orogenic collapse captured by strike-slip tectonics:

The late Paleozoic collision between Gondwana and Laurussia resulted in the polyphase deformation and magmatism that characterizes the Iberian Massif of the Variscan orogen. In the Central Iberian Zone, initial con- tinental thickening (D1; folding and thrusting) was followed by extensional orogenic collapse (D2) responsible for the exhumation of high-grade rocks coeval to the emplacement of granitoids. This study presents a tectonometamorphic analysis of the Trancoso-Pinhel region (Central Iberian Zone) to ex- plain the processes in place during the transition froman extension-dominated state (D2) to a compression-dom- inated one (D3).Wereveal the existence of low-dipping D2 extensional structures later affected by several pulses of subhorizontal shortening, each of them typified by upright folds and strike-slip shearing (D3, D4 and D5, as identified by superimposition of structures). The D2 Pinhel extensional shear zone separates a low-grade domain from an underlying high-grade domain, and it contributed to the thermal reequilibration of the orogen by facil- itating heat advection from lower parts of the crust, crustal thinning, decompression melting, and magma intru- sion. Progressive lessening of the gravitational disequilibrium carried out by this D2 shear zone led to a switch from subhorizontal extension to compression and the eventual cessation and capture of the Pinhel shear zone by strike-slip tectonics during renewed crustal shortening. High-grade domains of the Pinhel shear zone were folded together with low-grade domains to define the current upright folded structure of the Trancoso-Pinhel re- gion, the D3 Tamames-Marofa-Sátão synform. Newdating of syn-orogenic granitoids (SHRIMP U\\Pb zircon dat- ing) intruding the Pinhel shear zone, together with the already published ages of early extensional fabrics constrain the functioning of this shear zone to ca. 331–311 Ma, with maximum tectonomagmatic activity at ca. 321–317 Ma. The capture and apparent cessation of movement of the Pinhel shear zone occurred at ca. 317– 311 Ma.

Enhanced sensitivity detection of protein immobilization by fluorescent interference on oxidized silicon.

We present a silicon chip-based approach for the enhanced sensitivity detection of surface-immobilized fluorescent molecules. Green fluorescent protein (GFP) is bound to the silicon substrate by a disuccinimidyl terephtalate-aminosilane immobilization procedure. The immobilized organic layers are characterized by surface analysis techniques, like ellipsometry, atomic force microscopy (AFM) and X-ray induced photoelectron spectroscopy. We obtain a 20-fold enhancement of the fluorescent signal, using constructive interference effects in a fused silica dielectric layer, deposited before immobilization onto the silicon. Our method opens perspectives to increase by an order of magnitude the fluorescent response of surface immobilized DNA- or protein-based layers for a variety of biosensor applications.

Caractérisation de l’ubiquitin-fold modifier (UFM1) dans un modèle C. elegans

L’ubiquitin-fold modifier (UFM1) fait partie de la classe 1 de la famille de protéine ubiquitin-like (Ubl). UFM1 et Ub ont très peu d’homologie de séquence, mais partagent des similarités remarquables au niveau de leur structure tertiaire. Tout comme l’Ub et la majorité des autres Ubls, UFM1 se lie de façon covalente à ses substrats par l’intermédiaire d’une cascade enzymatique. Il est de plus en plus fréquemment rapporté que les protéines Ubls sont impliquées dans des maladies humaines. Le gène Ufm1 est surexprimé chez des souris de type MCP développant une ischémie myocardique et dans les îlots de Langerhans de patients atteints du diabète de type 2. UFM1 et ses enzymes spécifiques, UBA5, UFL1 et UFC1, sont conservés chez les métazoaires et les plantes suggérant un rôle important pour les organismes multicellulaires. Le Caenorhabditis elegans est le modèle animal le plus simple utilisé en biologie. Sa morphologie, ses phénotypes visibles et ses lignées cellulaires ont été décrits de façon détaillée. De plus, son cycle de vie court permet de rapidement observer les effets de certains gènes sur la longévité. Ce modèle nous permet de facilement manipuler l’expression du gène Ufm1 et de mieux connaître ses fonctions. En diminuant l’expression du gène ufm-1 chez le C.elegans, par la technique de l’ARN interférence par alimentation, nous n’avons observé aucun problème morphologique grave. Les vers ressemblaient aux vers sauvages et possédaient un nombre de progéniture normal. Cependant, les vers sauvage exposés à l’ARNi d’ufm-1 vivent significativement moins longtemps que les contrôles et ce, de façon indépendante de la voie de signalisation de l’insuline/IGF. Chez le C. elegans la longévité et la résistance au stress cellulaire sont intimement liées. Nous n’avons remarqué aucun effet d’ufm-1 sur le stress thermal, osmotique ou oxydatif, mais il est requis pour la protection contre le stress protéotoxique. Il est également nécessaire au maintien de l’intégrité neuronale au cours du vieillissement des animaux. L’ensemble de nos données nous renseigne sur les fonctions putatives du gène Ufm1.

Inhibition of epidermal growth factor receptor expression by RNA interference in A549 cells

AIM: To investigate the biological features of A549 cells in which epidermal growth factor (EGF) receptors expression were suppressed by RNA interference (RNAi). METHODS: A549 cells were transfected using short small interfering RNAs (siRNAs) formulated with Lipofectamine 2000. The EGF receptor numbers were determined by Western blotting and flowcytometry. The antiproliferative effects of sequence specific double stranded RNA (dsRNA) were assessed using cell count, colony assay and scratch assay. The chemosensitivity of transfected cells to cisplatin was measured by MTT. RESULTS: Sequence specific dsRNA-EGFR down-regulated EGF receptor expression dramatically. Compared with the control group, dsRNA-EGFR reduced the cell number by 85.0 %, decreased the colonies by 63.3 %, inhibited the migration by 87.2 %, and increased the sensitivity of A549 to cisplatin by four-fold. CONCLUSION: Sequence specific dsRNA-EGFR were capable of suppressing EGF receptor expression, hence significantly inhibiting cellular proliferation and motility, and enhancing chemosensitivity of A549 cells to cisplatin. The successful application of dsRNA-EGFR for inhibition of proliferation in EGF receptor overexpressing cells can help extend the list of available therapeutic modalities in the treatment of non-small-cell lung carcinoma (NSCLC).

RNA interference against human papillomavirus oncogenes in cervical cancer cells results in increased sensitivity to cisplatin

Targeted inhibition of oncogenes in tumor cells is a rational approach toward the development of cancer therapies based on RNA interference (RNAi). Tumors caused by human papillomavirus (HPV) infection are an ideal model system for RNAi-based cancer therapies because the oncogenes that cause cervical cancer, E6 and E7, are expressed only in cancerous cells. We investigated whether targeting HPV E6 and E7 oncogenes yields cancer cells more sensitive to chemotherapy by cisplatin, the chemotherapeutic agent currently used for the treatment of advanced cervical cancer. We have designed siRNAs directed against the HPV E6 oncogene that simultaneously targets both E6 and E7, which results in an 80% reduction in E7 protein and reactivation of the p53 pathway. The loss of E6 and E7 resulted in a reduction in cellular viability concurrent with the induction of cellular senescence. Interference was specific in that no effect on HPV-negative cells was observed. We demonstrate that RNAi against E6 and E7 oncogenes enhances the chemotherapeutic effect of cisplatin in HeLa cells. The IC50 for HeLa cells treated with cisplatin was 9.4 mu M, but after the addition of a lentivirus-delivered shRNA against E6, the IC50 was reduced almost 4-fold to 2.4 mu M. We also observed a decrease in E7 expression with a concurrent increase in p53 protein levels upon cotreatment with shRNA and cisplatin over that seen with individual treatment alone. Our results provide strong evidence that loss of E6 and E7 results in increased sensitivity to cisplatin, probably because of increased p53 levels.

Biological activity of metal-edds (ethylenediaminedisuccinate) complexes in K562 and PBMC cells

The effect of S,S-ethylenediaminedisuccinic acid (edds) on the quenching of metal-catalyzed (metal = Mn, Fe, Co, Ni, Cu, Zn) oxidation of ascorbic acid was tested in vitro via oxidation of the fluorescent probe 1,2,3-dihydrorhodamine dihydrochloride. The pro-oxidant activity of iron was not fully suppressed, even at a four-fold molar excess of the ligand. The effect of serum on the toxicity to peripheral blood mononuclear cells (PBMC) and K562 cells was investigated. The cytotoxic effect of Fe-edds was abrogated in the presence of Trolox or serum proteins. The probable pathways of cell toxicity were investigated through blocking of the monocarboxylate transporters (MCT) in association with cell cycle studies by flow cytometry. Cells treated with metal complexes and alpha-cyano-4-hydroxycinnamic acid, a known MCT inhibitor, showed recovery of viability, suggesting that MCT proteins may be involved in the internalization of metal-edds complexes. The free acid induced cell cycle arrest in G0/G1 (PBMC) and S (K562) phases, suggesting direct DNA damage or interference in DNA replication.

On the interference of clinical outcome on rabies transmission an perpetuation

Rabies is a viral zoonotic infectious disease that affects mammals and is caused by genotypes/species of the Lyssavirus genus (Rhabdoviridae, Mononegavirales), with the genotype 1 (classic rabies virus - RABV) being the most prevalent. Despite continuous efforts, rabies is still an incurable disease that causes thousands of deaths amongst humans worldwide. Due to a wide range of hosts and the different evolutionary paths of RABV in each host, several host-specific variants have arisen in an ongoing process. The result of RABV replication in nervous tissues may lead to two opposite clinical outcomes, i.e., paralytic/dumb form and encephalitic/furious one. The paralytic form creates dead-end hosts mainly amongst herbivores, while the furious form of the disease allows for augmented transmission when manifested in gregarious carnivores, as their natural aggressive behavior is accentuated by the disease itself. The aim of this article is to propose a theoretical model intended to explore how the rabies virus intrinsically modulates the immune system of different host classes, the pathological changes that the virus causes in these animals and how these elements favor its own perpetuation in nature, thus providing a basis for better prediction of the patterns this disease may present.

Moxidectin interference on motor activity of rats

The present study investigated the effects of t moxidectin (MXD) in some parameters of rat motor function and neurochemical. The general activity in the open field and the motor coordination in the wooden beam were employed to evaluate the MXD effects. The results showed that, in the open field, even at high doses (2.0 and 20.0 mg/kg), the MXD did not alter the locomotion and the rearing frequencies. However, MXD was able to impair the motor coordination of the animals at wooden beam. Neurochemical studies of striatal GABA and dopamine neurotransmitters showed a reduced levels of dopamine and its metabolite, homovanillic acid, without interference on striatal GABA levels. Since GABAergic receptor stimulation had an inhibitory effect on dopaminergic striatal system, the decreased motor coordination could be attributed to an action of MXD on dopamine system via GABA activation.

RNA interference-mediated knockdown of CD49e (alpha 5 integrin chain) in human thymic epithelial cells modulates the expression of multiple genes and decreases thymocyte adhesion

Background: The thymus is a central lymphoid organ, in which bone marrow-derived T cell precursors undergo a complex process of maturation. Developing thymocytes interact with thymic microenvironment in a defined spatial order. A component of thymic microenvironment, the thymic epithelial cells, is crucial for the maturation of T-lymphocytes through cell-cell contact, cell matrix interactions and secretory of cytokines/chemokines. There is evidence that extracellular matrix molecules play a fundamental role in guiding differentiating thymocytes in both cortical and medullary regions of the thymic lobules. The interaction between the integrin alpha 5 beta 1 (CD49e/CD29; VLA-5) and fibronectin is relevant for thymocyte adhesion and migration within the thymic tissue. Our previous results have shown that adhesion of thymocytes to cultured TEC line is enhanced in the presence of fibronectin, and can be blocked with anti-VLA-5 antibody. Results: Herein, we studied the role of CD49e expressed by the human thymic epithelium. For this purpose we knocked down the CD49e by means of RNA interference. This procedure resulted in the modulation of more than 100 genes, some of them coding for other proteins also involved in adhesion of thymocytes; others related to signaling pathways triggered after integrin activation, or even involved in the control of F-actin stress fiber formation. Functionally, we demonstrated that disruption of VLA-5 in human TEC by CD49e-siRNA-induced gene knockdown decreased the ability of TEC to promote thymocyte adhesion. Such a decrease comprised all CD4/CD8-defined thymocyte subsets. Conclusion: Conceptually, our findings unravel the complexity of gene regulation, as regards key genes involved in the heterocellular cell adhesion between developing thymocytes and the major component of the thymic microenvironment, an interaction that is a mandatory event for proper intrathymic T cell differentiation.

Interlayer interference in double wells in a tilted magnetic field

Magnetotransport measurements on bilayer electron systems reveal repeated reentrance of the resistance minima at filling factors nu=4N+1 and nu=4N+3, where N is the Landau index number, in the tilted magnetic field. At high filling factors, the Shubnikov-de Haas oscillations exhibit beating effects at certain tilt angles. We attribute such behavior to oscillations of the tunneling gap due to Aharonov-Bohm interference effect between cyclotron orbits in different layers. The interplay between quantum and quasiclassical regimes is established.

Interference oscillations of microwave photoresistance in double quantum wells

We observe oscillatory magnetoresistance in double quantum wells under microwave irradiation. The results are explained in terms of the influence of subband coupling on the frequency dependent photoinduced part of the electron distribution function. As a consequence, the magnetoresistance demonstrates the interference of magnetointersubband oscillations and conventional microwave induced resistance oscillations.

Observation of Two-Source Interference in the Photoproduction Reaction AuAu -> AuAu rho(0)

In ultraperipheral relativistic heavy-ion collisions, a photon from the electromagnetic field of one nucleus can fluctuate to a quark-antiquark pair and scatter from the other nucleus, emerging as a rho(0). The rho(0) production occurs in two well-separated (median impact parameters of 20 and 40 F for the cases considered here) nuclei, so the system forms a two-source interferometer. At low transverse momenta, the two amplitudes interfere destructively, suppressing rho(0) production. Since the rho(0) decays before the production amplitudes from the two sources can overlap, the two-pion system can only be described with an entangled nonlocal wave function, and is thus an example of the Einstein-Podolsky-Rosen paradox. We observe this suppression in 200 GeV per nucleon-pair gold-gold collisions. The interference is 87%+/- 5%(stat.)+/- 8%(syst.) of the expected level. This translates into a limit on decoherence due to wave function collapse or other factors of 23% at the 90% confidence level.

Aharonov-Bohm Interference in Neutral Excitons: Effects of Built-In Electric Fields

We report a comprehensive discussion of quantum interference effects due to the finite structure of neutral excitons in quantum rings and their first experimental corroboration observed in the optical recombinations. The signatures of built-in electric fields and temperature on quantum interference are demonstrated by theoretical models that describe the modulation of the interference pattern and confirmed by complementary experimental procedures.

Quantitative determination of optical transmission through subwavelength slit arrays in Ag films: Role of surface wave interference and local coupling between adjacent slits

Measurement of the transmitted intensity from a coherent monomode light source through a series of subwavelength slit arrays in Ag films, with varying array pitch and number of slits, demonstrates enhancement (suppression) by factors of as much as 6 (9) when normalized to the transmission efficiency of an isolated slit. Pronounced minima in the transmitted intensity are observed at array pitches corresponding to lambda(SPP), 2 lambda(SPP), and 3 lambda(SPP), where lambda(SPP) is the wavelength of the surface plasmon polariton (SPP). The position of these minima arises from destructive interference between incident propagating waves and pi-phase-shifted SPP waves. Increasing the number of slits to four or more does not increase appreciably the per-slit transmission intensity. A simple interference model fits well the measured transmitted intensity profile.

Interference with Hemozoin Formation Represents an Important Mechanism of Schistosomicidal Action of Antimalarial Quinoline Methanols

Background: The parasitic trematode Schistosoma mansoni is one of the major causative agents of human schistosomiasis, which afflicts 200 million people worldwide. Praziquantel remains the main drug used for schistosomiasis treatment, and reliance on the single therapy has been prompting the search for new therapeutic compounds against this disease. Our group has demonstrated that heme crystallization into hemozoin (Hz) within the S. mansoni gut is a major heme detoxification route with lipid droplets involved in this process and acting as a potential chemotherapeutical target. In the present work, we investigated the effects of three antimalarial compounds, quinine (QN), quinidine (QND) and quinacrine (QCR) in a murine schistosomiasis model by using a combination of biochemical, cell biology and molecular biology approaches. Methodology/Principal Findings: Treatment of S. mansoni-infected female Swiss mice with daily intraperitoneal injections of QN, and QND (75 mg/kg/day) from the 11(th) to 17(th) day after infection caused significant decreases in worm burden (39%-61%) and egg production (42%-98%). Hz formation was significantly inhibited (40%-65%) in female worms recovered from QN- and QND-treated mice and correlated with reduction in the female worm burden. We also observed that QN treatment promoted remarkable ultrastructural changes in male and female worms, particularly in the gut epithelium and reduced the granulomatous reaction to parasite eggs trapped in the liver. Microarray gene expression analysis indicated that QN treatment increased the expression of transcripts related to musculature, protein synthesis and repair mechanisms. Conclusions: The overall significant reduction in several disease burden parameters by the antimalarial quinoline methanols indicates that interference with Hz formation in S. mansoni represents an important mechanism of schistosomicidal action of these compounds and points out the heme crystallization process as a valid chemotherapeutic target to treat schistosomiasis.