Optimisation and Assessment of Three Modern Touch Screen Tablet Computers for Clinical Vision Testing

Technological advances have led to the development of powerful yet portable tablet computers whose touch-screen resolutions now permit the presentation of targets small enough to test the limits of normal visual acuity. Such devices have become ubiquitous in daily life and are moving into the clinical space. However, in order to produce clinically valid tests, it is important to identify the limits imposed by the screen characteristics, such as resolution, brightness uniformity, contrast linearity and the effect of viewing angle. Previously we have conducted such tests on the iPad 3. Here we extend our investigations to 2 other devices and outline a protocol for calibrating such screens, using standardised methods to measure the gamma function, warm up time, screen uniformity and the effects of viewing angle and screen reflections. We demonstrate that all three devices manifest typical gamma functions for voltage and luminance with warm up times of approximately 15 minutes. However, there were differences in homogeneity and reflectance among the displays. We suggest practical means to optimise quality of display for vision testing including screen calibration.     

Mechanism of zinc uptake by microvilli isolated from human term placenta.

The mechanism of zinc (Zn) uptake by microvillous membrane vesicles prepared from human term placenta has been studied. The uptake was complex, with two processes being identified. In the first process, uptake was rapid, reaching equilibrium within 2 min, and was temperature dependent, with a Q10 of 1.5. Equilibrium Zn levels were sensitive to osmotic pressure, with Zn binding at infinite osmolarity being 69% iso-osmotic value. The uptake was saturable, with a Vmax of 58 +/- 2 nmol/mg protein/min and an apparent Kt of 128 +/- 13 microM. Uptake was inhibited by increasing extravesicular K+ concentration, dropping from 0.91 +/- 0.03 nmol/mg/min at 0 extravesicular K+ to 0.47 +/- 0.03 at an extravesicular K+ concentration of 150 mM ([Zn] = 1.0 microM). In the presence of both valinomycin, an electrogenic ionophore, and nigericin, an electroneutral exchanger, an outwardly directed K+ gradient stimulated Zn uptake. Similarly, preloading vesicles with Zn and imposing an inward gradient resulted in a temperature dependent efflux of Zn. The data suggest that there is a K+ dependent Zn transporter in vesicle membranes, and we suggest that the evidence is biased in favour of a Zn/K+ exchanger rather than Zn being dependent on the membrane potential.     

Dryland management regimes alter forest habitats and understory arthropod communities

Dryland forests, those characterised as having low precipitation and soil nutrients, account for over a quarter of forests globally. Increasing their productivity often relies on irrigation and fertilisation, but the impacts on the wider habitat are largely unknown. Understory invertebrates, in particular, play key roles in forest systems (e.g. nutrient cycling), but their responses to dryland forest management practices are untested. We investigated the impacts of irrigation, fertilisation and a combination of both on soil chemistry, understory vegetation, tree growth and understory arthropod communities in a Eucalyptus plantation to establish linkages between dryland management and ecosystem responses. Fertilisation increased all soil nutrients (N, NO₃N, P and K) with similar effects on the chemical composition of understory grasses. Fertilisation also caused declines in foliar silicon concentrations, an important herbivore defence in grasses. Irrigation increased growth of both understory plants (+90%) and trees (+68%). Irrigation increased the abundance of ground‐dwelling arthropods by over 480% relative to control plots, but depressed higher level taxon arthropod diversity by 15%, declining by a further 7% (?22%) in combined treatment plots. Irrigation also caused a surge in the abundance of Collembola (+1300%) and Isopoda (+323%). Fertilisation drove increases in the abundance of Isopoda (+196%) and Diptera (+63%), whereas fertilisation combined with irrigation increased populations of Thysanoptera (+166%) and Acarina (+328%). Airborne arthropods were less affected, but fertilisation increased the abundance of Apocrita (+95%) and depressed populations of Thysanoptera (?77%). Diptera abundance was positively related to understory vegetation growth, whereas the abundance of other groups (Collembola, Isopoda, Thysanoptera and Acarina) correlated positively with tree growth. We proposed that the large increases in populations of key detritivores, Collembola and Isopoda, were linked to increased leaf litter from enhanced tree growth in irrigated and combined treatment plots. Our findings suggest that dryland management can increase both plant productivity and abundance of arthropods, but cause arthropod diversity at the higher taxon level to decline overall.     

New series of 3,5-disubstituted tetrahydro-2H-1,3,5-thiadiazine thione (THTT) derivatives: Synthesis and potent antileishmanial activity

Four series of heterocyclic compounds, namely, tetrahydro-2H-1,3,5-thiadiazine thione derivatives were synthesized in good to excellent yields and were screened for their in vitro antileishmanial activities against Leishmania major (promastigotes). Most of the compounds showed significant antileishmanial activity within the range of IC₅₀?=?15.48–39.36?μM when compared with standard pentamidine (IC₅₀?=?14.95?μM). The structure-activity relationship showed that N-3 and N-5 substituents have a key role against leishmanicidal activity. The ester analogues (series B) were found to have a 1.5 to 5-fold reduced activity compared to their acidic counterparts. Cytotoxicity against mammalian mouse fibroblast 3?T3 cells was also evaluated and compared between the acid and its ester analogue. The reduction of antileishmanial activity and loss of toxicity in the newly developed THTT ester derivative indicates that these compounds can be used as a template study for the production of effective antileishmanial ester prodrugs.     

A virus-derived short hairpin RNA confers resistance against sugarcane mosaic virus in transgenic sugarcane

RNA interference (RNAi) is commonly used to produce virus tolerant transgenic plants. The objective of the current study was to generate transgenic sugarcane plants expressing a short hairpin RNAs (shRNA) targeting the coat protein (CP) gene of sugarcane mosaic virus (SCMV). Based on multiple sequence alignment, including genomic sequences of four SCMV strains, a conserved region of ~ 456 bp coat protein (CP) gene was selected as target gene and amplified through polymerase chain reaction (PCR). Subsequently, siRNAs2 and siRNA4 were engineered as stable short hairpin (shRNA) transgenes of 110 bp with stem and loop sequences derived from microRNA (sof-MIR168a; an active regulatory miRNA in sugarcane). These transgenes were cloned in independent RNAi constructs under the control of the polyubiquitin promoter. The RNAi constructs were delivered into two sugarcane cultivars ‘SPF-234 and NSG-311 in independent experiments using particle bombardment. Molecular identification through PCR and Southern blot revealed anti-SCMV positive transgenic lines. Upon mechanical inoculation of transgenic and non-transgenic sugarcane lines with SCMV, the degree of resistance was found variable among the two sugarcane cultivars. For sugarcane cultivar NSG-311, the mRNA expression of the CP–SCMV was reduced to 10% in shRNA2-transgenic lines and 80% in shRNA4-transgenic lines. In sugarcane cultivar SPF-234, the mRNA expression of the CP–SCMV was reduced to 20% in shRNA2-transgenic lines and 90% in shRNA4 transgenic lines, revealing that transgenic plants expressing shRNA4 were almost immune to SCMV infection.     

Evidence for Substrate Induction of a Nitrate Efflux System in Barley Roots

Induction of an NO3- efflux system in intact barley (Hordeum vulgare L.) roots was demonstrated. Since the measurement of NO3- efflux is dependent on its accumulation, experiments were devised to facilitate accumulation under noninducing conditions. This was accomplished by incubating seedlings in 10 mM NO3- in the presence of RNA and protein synthesis inhibitors. Under these conditions NO3- uptake is mediated by constitutive high- and low-affinity transport systems. Control roots were incubated with 1.0 mM NO3-. This resulted in the accumulation of similar levels of NO3- in both treated and control roots; however, cytoplasmic NO3- efflux from inhibitor-treated roots was much lower than from control roots. Following a brief lag period, efflux rates increased rapidly in the presence of NO3- for 8 to 12 h. The NO3- efflux system was also induced by ambient NO2-. After induction the efflux system was relatively stable in the presence of RNA and protein synthesis inhibitors as long as NO3- or NO2- was present. These results suggest that NO3- efflux may be an inducible system requiring both RNA and protein synthesis, as does induction of the uptake system. The efflux system, however, has a much slower turnover rate than the uptake system.     

Stress-inducible overexpression of <Emphasis Type="Italic">glyoxalase I</Emphasis> is preferable to its constitutive overexpression for abiotic stress tolerance in transgenic <Emphasis Type="Italic">Brassica juncea</Emphasis>

The glyoxalase system catalyzes the conversion of cytotoxic methylglyoxal to d-lactate via the intermediate S-d-lactoylglutathione. It comprises two enzymes, Glyoxalase I (Gly I) and Glyoxalase II (Gly II), and reduced glutathione which acts as a cofactor by anchoring the substrates in the active sites of the two enzymes. The overexpression of both Gly I and Gly II, either alone or in combination, has earlier been reported to confer tolerance to multiple abiotic stresses. In the present study, we sought to evaluate the consequences of constitutive and stress-induced overexpression of Gly I on the performance and productivity of plants. Towards this end, several Gly I transgenic Brassica juncea lines (designated as R and S lines) were generated in which the glyoxalase I (gly I) gene was expressed under the control of either a stress-inducible rd29A promoter or a constitutive CaMV 35S promoter. Both the R and S lines showed enhanced tolerance to salinity, heavy metal, and drought stress when compared to untransformed control plants. However, the S lines showed yield penalty under non-stress conditions while no such negative effect was observed in the R lines. Our results indicate that the overexpression of the gly I gene under the control of stress-inducible rd29A promoter is a better option for improving salt, drought and heavy metal stress tolerance in transgenic plants.     

Physiological and biochemical mechanisms of silicon-induced copper stress tolerance in cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L.)

Accumulation of excess copper (Cu) in agricultural soils can decrease growth and quality of crops grown on these soils and a little information is available on the role of silicon (Si) in reducing Cu toxicity in plants. A hydroponic study was conducted to investigate the effects of Si (1.0 mM) on growth and physiology of cotton seedlings grown on different Cu (0, 25, and 50 µM) concentrations. Elevated levels of Cu decreased growth, biomass, photosynthetic pigments, and gas exchange characteristics, and increased the electrolyte leakage (EL), hydrogen peroxide (H₂O₂), and thiobarbituric acid reactive substances (TBARS) contents in leaf, stem, and roots of cotton seedlings. Cu stress alone decreased the activities of key antioxidant enzymes in cotton seedlings. Exogenous application of Si alleviated the toxic effects of Cu on cotton seedlings by improving growth, photosynthetic pigments, and gas exchange characteristics under Cu stress. The Si application decreased Cu concentrations in leaves, stem, and roots as compared with the control plants. Furthermore, Si decreased oxidative stress as evidenced by decreased EL, H₂O₂, and TBARS contents, and increased the antioxidant enzyme activities in cotton seedlings. This study provides evidences of Si-mediated reduction of Cu toxicity in cotton seedlings at physiological and biochemical levels.     

Occurrence and Identification of Eggplant Mottled Crinkle Virus in India

A virus isolated in India from eggplant (Solanum melongena) showing chlorotic rings, line pattern and mosaic on leaves accompanied with stunted growth was identified as a strain of eggplant mottled crinkle virus on the basis of host range, in vitro properties, particle morphology, molecular weight of capsid protein and serological relationship. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis of virus coat protein revealed the presence of a single polypeptide with a molecular weight of 41,000. An antiserum to the virus produced in rabbit had a titre of 1: 2048 in double diffusion tests.     

Comparative Induction of Nitrate Reductase by Nitrate and Nitrite in Barley Leaves

The comparative induction of nitrate reductase (NR) by ambient NO₃⁻ and NO₂⁻ as a function of influx, reduction (as NR was induced) and accumulation in detached leaves of 8-day-old barley (Hordeum valgare L.) seedlings was determined. The dynamic interaction of NO₃⁻ influx, reduction and accumulation on NR induction was shown. The activity of NR, as it was induced, influenced its further induction by affecting the internal concentration of NO₃⁻. As the ambient concentration of NO₃⁻ increased, the relative influences imposed by influx and reduction on NO₃⁻ accumulation changed with influx becoming a more predominant regulant. Significant levels of NO₃⁻ accumulated in NO₂⁻-fed leaves. When the leaves were supplied cycloheximide or tungstate along with NO₂⁻, about 60% more NO₃⁻ accumulated in the leaves than in the absence of the inhibitors. In NO₃⁻-supplied leaves NR induction was observed at an ambient concentration of as low as 0.02 mm. No NR induction occurred in leaves supplied with NO₂⁻ until the ambient NO₂⁻ concentration was 0.5 mm. In fact, NR induction from NO₂⁻ solutions was not seen until NO₃⁻ was detected in the leaves. The amount of NO₃⁻ accumulating in NO₂⁻-fed leaves induced similar levels of NR as did equivalent amounts of NO₃⁻ accumulating from NO₃⁻-fed leaves. In all cases the internal concentration of NO₃⁻, but not NO₂⁻, was highly correlated with the amount of NR induced. The evidence indicated that NO₃⁻ was a more likely inducer of NR than was NO₂⁻.