Senescence-associated mRNAs that may participate in signal transduction and protein trafficking

The differential display technique was used to generate cDNA probes in order to identify mRNAs that are up-regulated during senescence of Arabidopsis leaves. Three mRNAs were examined that had not previously been associated with senescence. The steady-state levels of these mRNAs are detectable in small amounts in mature green leaves, but increase considerably as chlorophyll levels begin to decline. This relationship to senescence occurs under natural circumstances as well as when senescence is accelerated by leaf detachment in the dark or by addition of 1-aminocyclopropane-1-carboxylic acid (ACC). Retardation of senescence by benzyladenine slows the increase of the mRNAs. One of these mRNAs appears to code for a protein (Sec 13) that may be involved in vesicle formation at the endoplasmic reticulum. Another mRNA codes for a protein with WD‐repeat motif whose function is as yet unidentified, and the third codes for a putative calcium-dependent protein kinase. A fourth cDNA has also been cloned by subtractive hybridization from senescing Arabidopsis leaves that encodes vacuolar-processing enzyme ( γ VPE). Incubation of detached leaves in darkness also caused an abrupt elevation in the steady-state levels of the γVPE , similar to that of the senescing attached leaves. The possible functions of the gene products and their involvement in cellular and biochemical processes during senescence are discussed.     

Rational Design of Hybrid Nanostructures for Advanced Photocatalysis

Nanocatalysis has been a growing field over the past few decades with significant developments in understanding the surface properties of nanocatalysts. With recent advances in synthetic methods, size, shape and composition of the nanoparticles can be controlled in a well defined manner which facilitates achieving selective reaction products in multipath reactions. Nanoparticles with specific exposed crystal facets can have different reactivity than other facets for reaction intermediates, which favours selective pathways during the course of reaction. Heterogeneous catalysts have been studied extensively; nano‐sized metal particles are absorbed on mesoporus supports, facilitating access to the large surface area of the nanoparticles and hence exposure of more catalytic sites. Photocatalysis is attractive area of catalysis, in which photoinduced charge carriers are used for a variety of catalytic applications. More interestingly, clean and renewable liquid fuels energy sources such as hydrogen and methyl alcohol can be generated using photocatalysts through water splitting and CO₂ reduction, respectively. Herein, we highlight the progress of nanocatalysis through metal, bimetallic nanoparticle, metal‐semiconductor hybrid nanostructures and oxide nanoparticles for various reactions.     

Graphene nanosheet reinforcement of polyurethane nanocomposite for green and sustainable photoluminescence,superhydrophobic, and anticorrosive paint

A simple and environmentally friendly method was developed for smart and efficient waterborne polyurethane (PUR) paint. Sugarcane bagasse was recycled into reduced graphene oxide nanosheets (rGONSs). Both lanthanide-doped aluminate nanoparticles (LAN; photoluminescent agent, 7–9 nm) and rGONSs (reinforcement agent) were integrated into a waterborne polyurethane to produce a novel photoluminescent, hydrophobic, and anticorrosive nanocomposite coating. Using ferrocene-based oxidation under masked circumstances, graphene oxide nanosheets were produced from sugarcane bagasse. The oxidized semicarbazide (SCB) nanostructures were integrated into polyurethane coatings as a drying, anticorrosion, and crosslinking agent. Polyurethane coatings with varying amounts of phosphor pigment were prepared and subsequently applied to mild steel. The produced paints (LAN/rGONSs@PUR) were tested for their hydrophobicity, hardness, and scratch resistance. Commission Internationale de l'éclairage (CIE) Laboratory parameters and photoluminescence analysis established the opacity and colourimetric properties of the nanocomposite coatings. When excited at 365 nm, the luminescent transparent paints emitted a strong greenish light at 517 nm. The anticorrosion characteristics of the coated steel were investigated. The phosphor-containing (11% w/w) polyurethane coatings displayed the most pronounced anticorrosion capability and long-persistent luminosity. The prepared waterborne polyurethane paints were very photostable and durable.     

Developing conservation strategies for endemic tree species when faced with time and data constraints: <Emphasis Type="Italic">Boswellia</Emphasis> spp. on Socotra (Yemen)

Many endemic tree species have important scientific, ecological and economic value but the scarcity of information about their biological and ecological features makes it difficult to develop conservation strategies for them. A four-step approach is presented to address this problem, based on the analysis of data collected in a limited-duration field study: (1) Data collected are used to analyse the ecological niche, population structure and regeneration status of the species in question. (2) Several IUCN Red List (RL) parameters, useful for assessing the species’ risk of extinction, are measured, including population counts, number of locations, extent and area of occurrence. (3) The IUCN RL parameters are used together with the other information gathered to set preliminary conservation priorities. (4) The analysis of utilization pattern is used to develop conservation actions specific to the environmental and socio-economic context. To test the applicability of this approach Boswellia spp. of Socotra island were analysed. Ground-rooted species (B. ameero, B. elongata and B. socotrana) were the most abundant and widespread and, according to the spatial analysis, were characterised by a geo-altitudinal zonation. However, the Weibull functions fitted on their stem diameters, and the absence or presence of only a small number of saplings highlighted a poor regeneration status. In the absence of conservation actions, these species will probably be subject to a progressive decline because of uncontrolled grazing. Of the four cliff-rooted species, which grow in sites that are less accessible to livestock, two (B. popoviana and B. dioscorides) were of lower conservation priority and may become the most numerically abundant. Conversely, the other two (B. nana and B. bullata), which may be threatened by stochastic events because of their reduced populations and small number of locations, were considered of very high priority. Different conservation actions were then identified for each species. In particular, for Boswellia species producing gum, the conservation-through-use action was discussed as a potential option.     

Adverse effects of tempol on hidrosaline balance in rats with acute sodium overload

We studied the effects of tempol, an oxygen radical scavenger, on hydrosaline balance in rats with acute sodium overload. Male rats with free access to water were injected with isotonic (control group) or hypertonic saline solution (0.80 mol/l NaCl) either alone (Na group) or with tempol (Na-T group). Hydrosaline balance was determined during a 90 min experimental period. Protein expressions of aquaporin 1 (AQP1), aquaporin 2 (AQP2), angiotensin II (Ang II) and endothelial nitric oxide synthase (eNOS) were measured in renal tissue. Water intake, creatinine clearance, diuresis and natriuresis increased in the Na group. Under conditions of sodium overload, tempol increased plasma sodium and protein levels and increased diuresis, natriuresis and sodium excretion. Tempol also decreased water intake without affecting creatinine clearance. AQP1 and eNOS were increased and Ang II decreased in the renal cortex of the Na group, whereas AQP2 was increased in the renal medulla. Nonglycosylated AQP1 and eNOS were increased further in the renal cortex of the Na-T group, whereas AQP2 was decreased in the renal medulla and was localized mainly in the cell membrane. Moreover, p47-phox immunostaining was increased in the hypothalamus of Na group, and this increase was prevented by tempol. Our findings suggest that tempol causes hypernatremia after acute sodium overload by inhibiting the thirst mechanism and facilitating diuresis, despite increasing renal eNOS expression and natriuresis.     

Binding of human serum albumin to silica particles by means of polymers: a liquid chromatographic study of the selectivity of resulting chiral stationary phases

Chiral stationary phases obtained by immobilization of human serum albumin (HSA) on various polymer-coated silicas were tested to resolve DL-tryptophan, DL-NBP, RS-oxazepam and RS-warfarin racemic mixtures. HSA immobilized on anion exchangers [quaternized poly(vinylimidazole)-coated silica] was highly selective. Stable and selective chiral stationary phases were also prepared by covalent binding of HSA to silica particles via reactive-polymers. Poly(acryloyl chloride), poly(methacryloyl chloride) and poly(vinyl chloroformate) derivatives were compared. Parameters that govern the selectivity of resulting chiral supports were evaluated, especially the orientation of HSA after immobilization, the mobility of polymer chains and the number of covalent linkages between the protein and the polymer.