Cadmium and arsenic-induced-stress differentially modulates Arabidopsis root architecture, peroxisome distribution, enzymatic activities and their nitric oxide content

In plant cells, cadmium (Cd) and arsenic (As) exert toxicity mainly by inducing oxidative stress through an imbalance between the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), and their detoxification. Nitric oxide (NO) is a RNS acting as signalling molecule coordinating plant development and stress responses, but also as oxidative stress inducer, depending on its cellular concentration. Peroxisomes are versatile organelles involved in plant metabolism and signalling, with a role in cellular redox balance thanks to their antioxidant enzymes, and their RNS (mainly NO) and ROS. This study analysed Cd or As effects on peroxisomes, and NO production and distribution in the root system, including primary root (PR) and lateral roots (LRs). Arabidopsis thaliana wild-type and transgenic plants enabling peroxisomes to be visualized in vivo, through the expression of the 35S-cyan fluorescent protein fused to the peroxisomal targeting signal1 (PTS1) were used. Peroxisomal enzymatic activities including the antioxidant catalase, the H2O2-generating glycolate oxidase, and the hydroxypyruvate reductase, and root system morphology were also evaluated under Cd/As exposure. Results showed that Cd and As differently modulate these activities, however, catalase activity was inhibited by both. Moreover, Arabidopsis root system was altered, with the pollutants differently affecting PR growth, but similarly enhancing LR formation. Only in the PR apex, and not in LR one, Cd more than As caused significant changes in peroxisome distribution, size, and in peroxisomal NO content. By contrast, neither pollutant caused significant changes in peroxisomes size and peroxisomal NO content in the LR apex

OECD reviews of higher education in regional and city development, State of Victoria, Australia

With more than 5.3 million inhabitants Victoria is the second most populous state in Australia. Once a manufacturing economy, Victoria is now transforming itself into a service and innovation-based economy. Currently, the largest sectors are education services and tourism. In terms of social structure, Victoria is characterised by a large migrant population, 24% of population were born overseas and 44% were either born overseas or have a parent who was born overseas. About 70% of the population resides in Melbourne. Victoria faces a number of challenges, ranging from an ageing population and skills shortages to drought and climate change and increased risk of natural disasters. Rapid population growth, 2% annually, has implications for service delivery and uneven development as well as regional disparities. There are barriers to connectivity in terms of transport and infrastructure, and a high degree of inter-institutional competition in tertiary education sector. The business structure in Victoria includes some highly innovative activities such as in biotechnology, but other sectors, especially those with high number of small and medium-sized enterprises, are lagging behind. Most of the larger manufacturing enterprises are externally controlled and there is uncertainty over the long term investments they will make in the state, as well as the place of Victoria in the global production networks

Nitric oxide alleviates cadmium- but not arsenic-induced damages in rice roots

Nitric oxide (NO) has signalling roles in plant stress responses. Cadmium (Cd) and arsenic (As) soil pollutants alter plant development, mainly the root-system, by increasing NO-content, triggering reactive oxygen species (ROS), and forming peroxynitrite by NO-reaction with the superoxide anion. Interactions of NO with ROS and peroxynitrite seem important for plant tolerance to heavy metal(oid)s, but the mechanisms underlying this process remain unclear. Our goal was to investigate NO-involvement in rice (Oryza sativa L.) root-system after exposure to Cd or As, to highlight possible differences in NO-behaviour between the two pollutants. To the aim, morpho-histological, chemical and epifluorescence analyses were carried out on roots of different origin in the root-system, under exposure to Cd or As, combined or not with sodium nitroprusside (SNP), a NO-donor compound. Results show that increased intracellular NO levels alleviate the root-system alterations induced by Cd, i.e., inhibition of adventitious root elongation and lateral root formation, increment in lignin deposition in the sclerenchyma/endodermis cell-walls, but, even if reducing As-induced endodermis lignification, do not recover the majority of the As-damages, i.e., enhancement of AR-elongation, reduction of LR-formation, anomalous tissue-proliferation. However, NO decreases both Cd and As uptake, without affecting the pollutants translocation-capability from roots to shoots. Moreover, NO reduces the Cd-induced, but not the As-induced, ROS levels by triggering peroxynitrite production. Altogether, results highlight a different behaviour of NO in modulating rice root-system response to the toxicity of the heavy metal Cd and the metalloid As, which depends by the NO-interaction with the specific pollutant

Role and distribution of different Ba-containing phases in supported Pt-Ba NSR catalysts

Pt-Ba/MeO (where MeO=Al2O3, CeO2, SiO2 and ZrO2) NO x storage-reduction catalysts with Ba-loading varying from 0wt.% to 28wt.% were investigated concerning stability of Ba phases and NO x storage-reduction efficiency. For Pt-Ba/Al2O3 three different Ba-containing phases with different thermal stability are distinguished based on their interaction with the support. The relative concentration of these phases varies with the Ba-loading and NO x storage tests indicated that the BaCO3 phase decomposing between 400°C and 800°C (LT-BaCO3) is the most efficient Ba containing phase for NO x storage. Similar investigations of Pt-Ba catalysts supported on CeO2, SiO2 and ZrO2 showed that the relative amount of LT-BaCO3 phase depends also on the support material. NO x storage measurements confirmed a correlation between the concentration of LT-BaCO3 and NO x storage efficiency. Basicity and textural properties of the support are identified as crucial parameters for efficient NO x storage catalyst

Cadmium and arsenic affect root development in Oryza sativa L. negatively interacting with auxin

Cadmium (Cd) and arsenic (As), non essential, but toxic, elements for animals and plants are frequently present in paddy fields. Oryza sativa L., a staple food for at least the half of world population, easily absorbs As and Cd by the root, and in this organ the pollutants evoke consistent damages, reducing/modifying the root system. Auxins are key hormones in regulating all developmental processes, including root organogenesis. Moreover, plants respond to environmental stresses, such as those caused by Cd and As, by changing levels and distribution of endogenous phytohormones. Even though the effects of Cd and As on the roots have been investigated in some species, it remains necessary to deepen the knowledge about the cross-talk between these toxic elements and auxin during root formation and development, in particular in agronomically important plants, such as rice. Hence, the research goal was to investigate the interactions between Cd and As, alone or combined, and auxin during the development of rice roots. To reach the aim, morphological, histological and histochemical analyses were carried out on seedlings, exposed or not to Cd and/or As, belonging to the wild type and transgenic lines useful for monitoring indole-3-acetic acid (IAA) localization, i.e., OsDR5:GUS, and IAA cellular influx and efflux, i.e., OsAUX1:GUS and OsPIN5b:GUS. Moreover, the transcript levels of the YUCCA2 and ASA2, IAA biosynthetic genes were also monitored in Cd and/or As exposed wild type seedlings. The results highlight that As and Cd affect cyto-histology and morphology of the roots. In particular, they alter the lateral root primordia organization and development with negative consequences on root system architecture. This is due to a disturbance of IAA biosynthesis and transport, as indicated by the altered expression of both ASA2 and YUCCA2 biosynthetic genes, and AUX1 and PIN5b transporter genes

Bibliografia

Abstract

On the reconstruction of diagonal elements of density matrix of quantum optical states by on/off detectors

We discuss a scheme for reconstructing experimentally the diagonal elements of the density matrix of quantum optical states. Applications to PDC heralded photons, multi-thermal and attenuated coherent states are illustrated and discussed in some details.Comment: 10 pages, presented at Palermo "TQMFA2005" Conference. To appear on "Open Systems & Information Dynamics" (2006

Quantum state reconstruction using binary data from on/off photodetection

The knowledge of the density matrix of a quantum state plays a fundamental role in several fields ranging from quantum information processing to experiments on foundations of quantum mechanics and quantum optics. Recently, a method has been suggested and implemented in order to obtain the reconstruction of the diagonal elements of the density matrix exploiting the information achievable with realistic on/off detectors, e.g. silicon avalanche photo-diodes, only able to discriminate the presence or the absence of light. The purpose of this paper is to provide an overview of the theoretical and experimental developments of the on/off method, including its extension to the reconstruction of the whole density matrix.Comment: revised version, 11 pages, 6 figures, to appear as a review paper on Adv. Science Let

Positive Operator-Valued Measure reconstruction of a beam-splitter tree based photon-number-resolving detector

Here we present a reconstruction of the Positive Operator-Value Measurement of a photon-number-resolving detector comprised of three 50:50 beamsplitters in a tree configuration, terminated with four single-photon avalanche detectors. The four detectors' outputs are processed by an electronic board that discriminates detected photon number states from 0 to 4 and implements a "smart counting" routine to compensate for dead time issues at high count rates

From asking to observing. Behavioural measures of socio-emotional and motivational skills in large-scale assessments

Socio-emotional and motivational skills are routinely measured using self-reports in large-scale educational assessments. Measures exploiting test-takers’ behaviour during the completion of questionnaires or cognitive tests are increasingly used as alternatives to self-reports in the economics of education literature. We compute behavioural measures of socio-emotional and motivational skills using data from the Programme for International Student Assessment (PISA). We find that these measures capture important aspects of students' academic profiles: some are importantly associated with contemporaneous performance and educational attainment and most measures have a high degree of stability over time. However, these measures are only limitedly correlated among themselves and have low correlations with self-report measures of the same constructs. This is likely a reflection of the fact that behavioural measures are representations of the test taker current ‘state’, rather than descriptions of the participant view of their own ‘trait’ like the self-report measures. Moreover, the low correlation across measures suggests that they capture different behavioural responses to the test-taking situation. These differences are still limitedly understood because the measures are constructed ex-post using collateral information collected during the administration of assessments rather than developed ex ante in line with theoretical models of human cognition and affect