Blanks, a nuclear siRNA/dsRNA-binding complex component, is required for Drosophila spermiogenesis

Small RNAs and a diverse array of protein partners control gene expression in eukaryotes through a variety of mechanisms. By combining siRNA affinity chromatography and mass spectrometry, we have identified the double-stranded RNA-binding domain protein Blanks to be an siRNA- and dsRNA-binding protein from Drosophila S2 cells. We find that Blanks is a nuclear factor that contributes to the efficiency of RNAi. Biochemical fractionation of a Blanks-containing complex shows that the Blanks complex is unlike previously described RNA-induced silencing complexes and associates with the DEAD-box helicase RM62, a protein previously implicated in RNA silencing. In flies, Blanks is highly expressed in testes tissues and is necessary for postmeiotic spermiogenesis, but loss of Blanks is not accompanied by detectable transposon derepression. Instead, genes related to innate immunity pathways are up-regulated in blanks mutant testes. These results reveal Blanks to be a unique component of a nuclear siRNA/dsRNA-binding complex that contributes to essential RNA silencing-related pathways in the male germ line

The Lyman Continuum escape fraction of galaxies at z=3.3 in the VUDS-LBC/COSMOS field

The Lyman continuum (LyC) flux escaping from high-z galaxies into the IGM is a fundamental quantity to understand the physical processes involved in the reionization epoch. We have investigated a sample of star-forming galaxies at z~3.3 in order to search for possible detections of LyC photons escaping from galaxy halos. UV deep imaging in the COSMOS field obtained with the prime focus camera LBC at the LBT telescope was used together with a catalog of spectroscopic redshifts obtained by the VIMOS Ultra Deep Survey (VUDS) to build a sample of 45 galaxies at z~3.3 with L>0.5L*. We obtained deep LBC images of galaxies with spectroscopic redshifts in the interval 3.27<z<3.40 both in the R and deep U bands. A sub-sample of 10 galaxies apparently shows escape fractions>28% but a detailed analysis of their properties reveals that, with the exception of two marginal detections (S/N~2) in the U band, all the other 8 galaxies are most likely contaminated by the UV flux of low-z interlopers located close to the high-z targets. The average escape fraction derived from the stacking of the cleaned sample was constrained to fesc_rel<2%. The implied HI photo-ionization rate is a factor two lower than that needed to keep the IGM ionized at z~3, as observed in the Lyman forest of high-z QSO spectra or by the proximity effect. These results support a scenario where high redshift, relatively bright (L>0.5L*) star-forming galaxies alone are unable to sustain the level of ionization observed in the cosmic IGM at z~3. Star-forming galaxies at higher redshift and at fainter luminosities (L<<L*) can be the major contributors to the reionization of the Universe only if their physical properties are subject to rapid changes from z~3 to z~6-10. Alternatively, ionizing sources could be discovered looking for fainter sources among the AGN population at high-z.Comment: 21 pages, 9 figures. Accepted for publication in A&

Rational Extension of the Ribosome Biogenesis Pathway Using Network-Guided Genetics

Gene networks are an efficient route for associating candidate genes with biological processes. Here, networks are used to discover more than 15 new genes for ribosomal subunit maturation, rRNA processing, and ribosomal export from the nucleus

How Organizational Network Analysis Facilitated Transition from a Regional to a Global IT Function

IT executives in most large enterprises must build organizations that can adapt and thrive in a global economy while operating with fewer resources. Yet despite implementing sophisticated organizational redesigns and collaboration technologies, improvements in performance are frequently disappointing. All too often, the problem can be traced to patterns of intra-firm collaboration that do not adapt to support strategic objectives and new organizational designs. This article describes one organization’s five-year journey in applying organizational network analysis (ONA) to help it transform from a regional to a global IT function by selectively investing in and tracking the improvement of its collaboration and social networks. It shows how performance transformation can be achieved through targeted efforts to align an organization’s informal collaboration networks with strategic objectives. Based on the experience of this organization, the article concludes with three lessons that can be applied by IT leaders as they seek to improve performance in a global environment

Nanocrystalline TiO2 on single walled carbon nanotube arrays: towards the assembly of organized C/TiO2 nanosystems

Arrays of single walled carbon nanotube bundles organized following different architectures have been coated by a homogeneous deposit of nanocrystalline titania. The nanotubes were grown treating nanosized C powders with atomic H in a purpose-designed chemical vapor deposition (CVD) reactor, the subsequent TiO2 deposition was performed at 400 C using the metal-organic CVD (MOCVD) technique and titanium tetraisopropoxide Ti(OiPr)4 as a precursor. X-ray diffraction and Raman spectroscopy evidence the anatase structure of the TiO2 coatings, formed by grains with an average size of about 55 nm. The structural and compositional characteristics of the TiO2 deposits are not sensitive to the organization of the nanotube arrays, which maintain their pristine architectures. The adopted synthetic procedure opens a new route for the immobilization of anatase-type TiO2 nanocrystallites onto geometrically varied structures and for the integration of composite nanotube/TiO2 systems in effective devices. 2006 Elsevier Ltd

Osteointegrative functionalization of titanium substrates for dental implant applications

Titanium and its alloys have been widely used for dental implants due to their non-toxicity, biocompatibility, corrosion resistance, and mechanical properties. In order to improve osseointegration, the Ti surface is generally functionalised. A typical methodology for surface modification is the coating of the Ti substrates with bioactive layers of calcium phosphate ceramics (CPCs). However, CPC coatings on metal implant usually suffer from poor adhesion. With the aim of improving the adhesion strength, the insertion of dense and compact ceramic interlayers is reported to be useful. Among various ceramics, crystalline titania (TiO2) has been extensively used as an interlayer thanks to its well-known biocompatibility and bioactivity. In this work, a new synergic deposition route for the osteointegrative functionalisation of Ti dental implants is proposed. Three types of Ti substrates (machined, sandblasted, and sandblasted/acid etched) were initially coated with a crystalline, dense and compact TiO2 interlayer via MOCVD. Then, a discontinuous and homogenously spread CPC top-layer was obtained by means of spray pyrolysis technique. Finally, a thermal treatment at high temperature was carried out in order to crystallize the final composite material. The influence of the pristine substrate morphology on the crystalline structures and morphology of the coatings is here presented. Moreover, surface wettability, ions release and in vitro acellular bioactivity have also been evaluated

Morphological, structural and tribocorrosion behaviour of TiO2 MOCVD coating on Ti substrates with different morphology

Titanium (cp-Ti) and its alloys have been widely used for dental implant applications due to their excellent combination of strength-to-weight ratio, excellent corrosion resistance and biocompatibility [1]. An essential surface feature of Ti is the capability to spontaneously form a thin (4-6 nm thick), stable amorphous TiO2 film under exposure to the atmosphere and/or physiological fluids. This passive film protects Ti from corrosion and promotes a favorable osseointegration [2]. During mastication in an oral environment, dental implants are exposed to mechanical (i.e. wear), chemical (i.e. corrosion), and adverse biological effects, leading to a complex process of degradation. In this way, a tribocorrosion phenomenon is characterized by the synergistic interaction of wear with corrosion, which may lead to implant failure and adverse biological reactions due to the release of wear particles and/or corrosion products into the body [3]. Various surface treatment techniques have been developed in order to grow up protective layers with improved surface characteristics, such as tribocorrosion resistance and, at the meantime, adequate biological responses [3]. Indeed, several in vitro and in vivo studies showed the positive effect of the functionalization of Ti surface: in this context deposited rutile and anatase layers compared to native TiO2 show enhanced bone-like precipitation at the surface in simulated body fluids. MOCVD technique has been applied to the growth of titanium dioxide coatings, which successfully underwent several biological tests both in vitro and in vivo [4 and ref. therein]. However, the MOCVD process has been weakly explored to improve the tribocorrosion resistance of the Ti substrates and no literature references were found on the evaluation of performance of the TiO2 MOCVD coating on substrates with specific morphology. In this regard, besides to the chemical surface composition, the roughness and the topography of the Ti surface are significant parameters that affect the rate and quality of osseointegration. In this work, three types of Ti substrates (i.e. Ti machined, sandblasted, and sandblasted/acid etched, all of commercial grade IV) with different morphology were coated with 200 nm titanium oxide films by using LP-MOCVD, operating at 350\ub0C and 100 Pa. The TiO2 source was titanium tetraispropoxide (TTIP). The titanium oxide thickness was chosen in order to have the best compromise between the increase of the Ti corrosion resistance and the optimal coating/substrate adhesion features. The influence of the pristine substrate morphology on TiO2 crystalline structure, and morphology, on surface wettability and on tribocorrosion performance is here presented. In particular, it is shown that the specific morphology of the pristine substrate influences both the crystalline phase of the TiO2 and the crystallite size. Scanning electron microscopy analysis shows an optimal conformal coverage of the MOCVD coating for all substrates, with specific grain size as a function of the substrate morphology (Figure 1). Even the wettability depends on the Ti substrate features, demonstrating a superhydrophilic behavior for the sandblasted/acid etched samples after MOCVD TiO2 deposition (Figure 2). Finally, tribocorrosion experiments were carried out in order to evaluate the coating stability under wear and corrosion in a special electrolyte, which mimics the oral cavity corrosive medium, namely, artificial saliva (AS)

A PE-MOCVD route to V2O5 nanostructured thin films

Vanadium pentoxide thin films are grown on glass and borosilicate substrates by PACVD using a vanadyl (IV) β-diketonate as precursor. The depositions are carried out in an RF-plasma reactor with Ar-O2 mixtures and soft process conditions, obtaining high-purity nanocrystalline layers with a strong preferential orientation. The microstructural and morphological characteristics of the films, analyzed respectively by XRD and AFM, show that the sample features can be accurately tailored by an adequate choice of the synthesis conditions. The composition and purity of the films are studied by XPS and SIMS analyses. Impedance Spectroscopy is used to study the conductivity of the layers and the dependence of electrical properties on microstructure