Characterization of the Channel Constriction Allowing the Access of the Substrate to the Active Site of Yeast Oxidosqualene Cyclase

In oxidosqualene cyclases (OSCs), an enzyme which has been extensively studied as a target for hypocholesterolemic or antifungal drugs, a lipophilic channel connects the surface of the protein with the active site cavity. Active site and channel are separated by a narrow constriction operating as a mobile gate for the substrate passage. In Saccharomyces cerevisiae OSC, two aminoacidic residues of the channel/constriction apparatus, Ala525 and Glu526, were previously showed as critical for maintaining the enzyme functionality. In this work sixteen novel mutants, each bearing a substitution at or around the channel constrictions, were tested for their enzymatic activity. Modelling studies showed that the most functionality-lowering substitutions deeply alter the H-bond network involving the channel/constriction apparatus. A rotation of Tyr239 is proposed as part of the mechanism permitting the access of the substrate to the active site. The inhibition of OSC by squalene was used as a tool for understanding whether the residues under study are involved in a pre-catalytic selection and docking of the substrate oxidosqualene

Serious damage by Diplodia africana on Pinus pinea in the Vesuvius National Park.

In some municipalities, located within the boundaries of the Vesuvius National Park, several area with forest cover of Pinus pinea showed severe withering of the crowns and damage to pine cones. In the present study, we have isolated in the period may 2013 ??? may 2014 from Ercolano, San Sebastiano, Terzigno, Torre del Greco and Trecase an anamorphic form of Botryosphaeriaceae. The latter cause dieback and serious canker on several woody plants, including species of Pinus. Morphological and cultural characteristics as well as DNA sequence data (5.8S rDNA, ITS-1 and ITS-4) were made on 30 isolates obtained from 5 municipalities. All strains belonged to only two species: Botryosphaeria dothidea and its anamorph, Diplodia africana. These two fungi were present on all pine cones collected and analyzed. Finally we carried out growth assays at different temperatures: 8 °C, 18 °C and 28 °C. All fungi found the optimum of growth at 28°C while at 8°C we noted the lowest growth. This seems to be the first report of D. africana on Pinus species in Campania Region

Harmonically mode-locked Ti:Er:LiNbO3 waveguide laser

Active mode locking of an Er-diffusion-doped Ti:LiNbO3 waveguide laser by intracavity phase modulation to as high as the fourth harmonic (5.12 GHz) of the axial-mode frequency spacing is reported. The diode-pumped, pigtailed, and fully packaged laser with a monolithically integrated intracavity phase modulator has a threshold of 9 mW (incident pump power Ep jj c) and emits transform-limited pulses of >3.8-ps width and <5.6-pJ pulse energy (gain-switched mode locking) at 1602-nm wavelength (Es jj c). The relative change of the mode-locking frequency with the temperature is 3.65 3 1025y±C. The mode-locking acceptance bandwidth is 675 kHz near the axial-mode frequency spacing at approximately five times the threshold pump power

Use of polyaspartates for the tartaric stabilisation of white and red wines and side effects on wine characteristics

Aim: The stabilising efficacy against tartaric precipitations of polyaspartates-based products (PAs), in particular potassium polyaspartate (KPA), was tested with six different wines (three white and three red). Some side effects on wine characteristics (white wine colour stability, wine turbidity and filterability) were also studied. Results and conclusions: All PAs showed good stabilising efficacy against tartaric precipitations according to the cold test. With the same test, the PAs were stable in wine for 1 year of storage, which was the total duration of the study. The dose of 100 mg/L was sufficient to stabilise the tested wines. No differences in filterability were observed in comparison with MTA (metatartaric acid). The hypothesised protective effect against colour browning in white wines was not observed. Significance and impact of the study: The international wine trade requires stable wines. This paper provides information to support wineries in managing the use of KPA, as little information is available to date in the literature on this stabilising additive

Assessment of in‐situ gelling microemulsion systems upon temperature and dilution condition for corneal delivery of bevacizumab

Bevacizumab (BVZ), a recombinant humanized monoclonal antibody, has recently been proposed as a topical application in the treatment of anterior segment neovascularization; however, as there are some disadvantages in the administration of common eye-drops, ophthalmic topical drug delivery systems are under study to improve the precorneal residence time, reducing the frequency of administration. In this work, oil-in-water and water-in-oil BVZ-loaded microemulsions are developed, able to increase their viscosity, either by the formation of a liquid-crystalline structure upon aqueous dilution, thanks to the presence of Epikuron® 200 and polysorbate 80, or by body-temperature-induced jellification for the presence of Pluronic® F127 aqueous solution as an external phase. In oil-in-water microemulsion, hydrophobic ion pairs of BVZ were also prepared, and their incorporation was determined by release studies. Microemulsions were characterized for rheological behavior, corneal opacity, in vitro corneal permeation, and adhesion properties. The studied microemulsions were able to incorporate BVZ (from 1.25 to 1.6 mg/mL), which maintained dose-dependent activity on retinal pigment epithelial ARPE-19 cell lines. BVZ loaded in microemulsions permeated the excised cornea easier (0.76–1.56% BVZ diffused, 4–20% BVZ accumulated) than BVZ commercial solution (0.4% BVZ diffused, 5% accumulated) and only a mild irritation effect on the excised cornea was observed. The good adhesion properties as well the increased viscosity after application, under conditions that mimic the corneal environment (from 1 × 103 to more than 100 × 103 mPa·s), might prolong precorneal residence time, proving these systems could be excellent topical BVZ release systems

Monolithically integrated DBR waveguidelaser and intensity modulator in erbiumdoped LiNbO3

For the first time, a DBR laser has been integrated with a Mach Zehnder intensity modulator in Er diffusion doped, Z cut LiNbO,, with Ti indiffused waveguides and dry etched Bragg gratings. The monolithically integrated device has a threshold of 54.8mW incident pump power (hp = 1480nm) and emits, in a single longitudinal mode, up to 0.65 mW CW output power at hs = 1561nm. The Mach-Zehnder type intensity modulator has an optical bandwidth > 3GHz

Er-Doped Integrated Optical Devices in LiNbO3

The state-of-the-art of Er-doped integrated optical devices in LiNbO3 is reviewed starting with a brief discussion of the technology of Er-indiffusion. This technique yields high-quality waveguides and allows a selective surface doping necessary to develop optical circuits of higher complexity. Doped waveguides have been used as single- and double-pass optical amplifiers for the wavelength range 1530 nm < < 1610 nm. If incorporated in conventional, lossy devices loss-compensating or even amplifying devices can be fabricated. Examples are an electrooptically scanned Ti:Er:LiNbO3 waveguide resonator used as an optical spectrum analyzer and an acoustooptically tunable filter used as a tunable narrowband amplifier. Different types of Ti:Er:LiNbO3 waveguide lasers are presented. Among them are free running Fabry–Perot lasers for six different wavelengths with a conitnuous-wave (CW)-output power up to 63 mW. Tunable lasers could be demonstrated by the intracavity integration of an acoustooptical amplifying wavelength filter yielding a tuning range up to 31 nm. With intracavity electrooptic phase modulation modelocked laser operation has been obtained with pulse repetition frequencies up to 10 GHz; pulses of only a few ps width could be generated.With intracavity amplitude modulation Q-switched laser operation has been achieved leading to the emission of pulses of up to 2.4 W peak power (0.18 J) at 2 kHz repetition frequency. Distributed Bragg reflector (DBR) lasers of emission linewidth 8 kHz have been developed using a dryetched surface grating as one of the mirrors of the laser resonator. Finally, as an example for a monolithic integration of lasers and extracavity devices on the same substrate, a DBR-laser/modulator combination is presented