Enhancement of Low pH Stress Tolerance in Anthocyanin-Enriched Transgenic Petunia Overexpressing RsMYB1 Gene.

We investigated whether the presence of anthocyanins in plants could contribute to low pH stress tolerance using anthocyanin-enriched transgenic petunia lines (PM2, PM6, and PM8) expressing RsMYB1 and wild-type (WT) plants. We examined several physiological and biochemical factors and the transcript levels of genes involved in abiotic stress tolerance. A reduction in plant growth, including plant height and fresh weight, was observed when plants (PM2, PM6, PM8, and WT) were exposed to low pH (pH 3.0) conditions compared to growth under normal (pH 5.8) conditions. A small reduction in the growth of PM6 was observed, followed by that in PM2, PM8, and WT, reflecting the anthocyanin levels in the plants (PM6 > PM2 and PM8 > WT). An analysis of physiological and biochemical factors also supports the degree of low pH tolerance in the plants (PM6 > PM2 and PM8 > WT). In addition, an enhanced expression of the genes [superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), osmotin, and vacuolar H+-ATPase (V-ATPase)] was observed in the transgenic lines (PM2, PM6, and PM8). The resultant of the enhanced transcript levels of the genes could promote antioxidant activities, proline content, and pH homeostasis involved in the mechanisms underlying abiotic stress tolerance in plants. These results suggest that anthocyanin-enriched plants overexpressing RsMYB1 enhances low pH stress tolerance by elevating the transcript levels of the relevant genes.

Overexpression of Rosea1 From Snapdragon Enhances Anthocyanin Accumulation and Abiotic Stress Tolerance in Transgenic Tobacco.

The co-expression of Rosea1 (Ros1) and Delila (Del) regulates anthocyanin levels in snapdragon flowers, as well as in tomato, petunia, and tobacco. However, there is little information on how Ros1 expression alone controls anthocyanin regulation and whether it is involved in the mechanism that leads to abiotic stress tolerance. In the present study, tobacco (Nicotiana tabacum 'Xanthi') transgenic plants overexpressing Ros1 (T2-Ros1-1, T2-Ros1-2, T2-Ros1-3, and T2-Ros1-4) promoted accumulation of anthocyanin in leaves and flowers by elevating the transcription of all key genes involved in the biosynthesis of this pigment. This promotion largely occurred through the upregulation of dihydroflavonol 4-reductase (DFR), and anthocyanidin synthase genes in leaves and upregulation of DFR in flowers. Under normal conditions, the transgenic lines and wild type (WT) plants showed well-developed broad leaves and regular roots, whereas a reduction in plant growth was observed under cold and drought stresses. However, the transgenic T2-Ros1 lines were able to tolerate the stresses better than the WT line by inducing reactive oxygen species scavenging activities, and the expression of antioxidant-related and stress-responsive genes. In addition, phylogenetic analysis clustered Ros1 with many transcription factors (TFs) that confer tolerance to different abiotic stresses. Overall, the results obtained here suggest that Ros1 overexpression upregulates anthocyanin biosynthetic, antioxidant-related, and stress-responsive genes thereby enhancing anthocyanin accumulation and abiotic stress tolerance.

Involvement of Sodium Nitroprusside (SNP) in the Mechanism That Delays Stem Bending of Different Gerbera Cultivars.

Longevity of cut flowers of many gerbera cultivars (Gerbera jamesonii) is typically short because of stem bending; hence, stem bending that occurs during the early vase life period is a major problem in gerbera. Here, we investigated the effects of sodium nitroprusside (SNP) on the delay of stem bending in the gerbera cultivars, Alliance, Rosalin, and Bintang, by examining relative fresh weight, bacterial density in the vase solution, transcriptional analysis of a lignin biosynthesis gene, antioxidant activity, and xylem blockage. All three gerbera cultivars responded to SNP by delaying stem bending, compared to the controls; however, the responses were dose- and cultivar-dependent. Among the treatments, SNP at 20 mg L-1 was the best to delay stem bending in Alliance, while dosages of 10 and 5 mg L-1 were the best for Rosalin and Bintang, respectively. However, stem bending in Alliance and Rosalin was faster than in Bintang, indicating a discrepancy influenced by genotype. According to our analysis of the role of SNP in the delay of stem bending, the results revealed that SNP treatment inhibited bacterial growth and xylem blockage, enhanced expression levels of a lignin biosynthesis gene, and maintained antioxidant activities. Therefore, it is suggested that the cause of stem bending is associated with the above-mentioned parameters and SNP is involved in the mechanism that delays stem bending in the different gerbera cultivars.

Synergistic Effect of Nano-Sliver with Sucrose on Extending Vase Life of the Carnation cv. Edun.

We investigated the effects of sucrose and nano-silver (NAg) on extending the vase life of cut carnation flowers "Edun". Sucrose (pulse treatment) suppressed ethylene production by downregulating the genes that code for its biosynthesis. Relative to the control, however, sucrose significantly promoted xylem blockage on cut stem surfaces and reduced relative fresh weight, antioxidant activity, and cysteine proteinase inhibitor gene (DcCPi) expression. Consequently, the sucrose-treated flowers had shorter vase lives than the control. In contrast, NAg suppressed ethylene production in the petal, prevented xylem blockage in the cut stem surface, and improved all the aforementioned parameters. Therefore, NAg increased flower longevity. The most effective treatment in terms of longevity extension and parameter improvement, however, was the combination of NAg and sucrose. These results suggest that sucrose can suppress ethylene production but does not necessarily extend the vase life of the flower cultivar. The role of NAg in increasing cut carnation longevity is mainly to inhibit xylem blockage rather than suppress ethylene production, and the combined effect of NAg and sucrose is most effective at prolonging cut carnation vase life, likely due to their synergetic effects on multiple modes of action.

Role of Nano-silver and the Bacterial Strain Enterobacter cloacae in Increasing Vase Life of Cut Carnation 'Omea'.

We investigated the role of nano-silver (NAg) and the bacterial strain Enterobacter cloacae in increasing the vase life of cut carnation flowers 'Omea.' NAg treatment extended vase life of the flowers by increasing relative fresh weight, antioxidant activities, and expression level of the cysteine proteinase inhibitor gene (DcCPi), and by suppressing bacterial blockage in stem segments, ethylene production and expression of ethylene biosynthesis genes and DcCP1 gene, compared with the control. Out of all the treatments, administration of 25 mg L-1 NAg gave the best results for all the analyzed parameters. Interestingly, application of E. cloacae also extended the vase life of cut flowers by 3 days in comparison with control flowers, and overall, showed better results than the control for all the analyzed parameters. Taken together, these results demonstrate the positive role of NAg and E. cloacae in increasing the longevity of cut carnation flowers, and indicate that this effect is brought about through multiple modes of action.

Methacholine and adenosine 5'-monophosphate (AMP) responsiveness, and the presence and degree of atopy in children with asthma.

The relationship between atopy and bronchial hyperresponsiveness (BHR), both key features of asthma, remains to be clarified. BHR is commonly evaluated by bronchial challenges using direct and indirect stimuli. The aim of this study was to investigate the degree of BHR to methacholine (direct stimulus) and adenosine 5'-monophosphate (AMP) (indirect stimulus) according to the presence and degree of atopy in children with asthma. We performed a retrospective analysis of data from 120 children presenting with a diagnosis of asthma. These children were characterized by skin-prick tests (SPTs), spirometry and bronchial challenges with methacholine and AMP. Atopy was defined by at least one positive reaction to SPTs, and its degree was measured using serum total IgE levels, number of positive SPTs and atopic scores (sum of graded wheal size). A provocative concentration causing a 20% decline in FEV(1) (PC(20) ) was determined for each challenge. Patients with atopy(n=94) had a significantly lower AMP PC(20) than non-atopic patients (n=26), whereas methacholine PC(20) was not different between the two groups. Among the patients with atopy, there was no association between methacholine PC(20) and any atopy parameter. In contrast, a significant association was found between AMP PC(20) and the degree of atopy reflected in serum total IgE, number of positive SPTs and atopic scores (anova trend test, p=0.002, 0.001, 0.003, respectively). AMP responsiveness was associated with the presence and degree of atopy, whereas such a relationship was not observed for methacholine responsiveness. These findings suggest that atopic status may be better reflected by bronchial responsiveness assessed by AMP than by methacholine.

The roles of a Th2 cytokine and CC chemokine in children with stable asthma: potential implication in eosinophil degranulation.

Th2 cytokine IL-5 and CC chemokine eotaxin are thought to be key regulators of eosinophils in bronchial asthma. However, their involvement in children with stable asthma (SA) has not been determined. We investigated the roles of IL-5 and eotaxin in eosinophil degranulation in children with SA. Induced sputum was obtained from 30 SA, 21 allergic rhinitis (AR), and 22 non-atopic healthy control (HC) children. We measured sputum levels of IL-5, eotaxin, and eosinophil indices [percentage eosinophils, eosinophil-derived neurotoxin (EDN), and eosinophil-cationic protein (ECP)]. We also examined correlations of IL-5 and eotaxin with eosinophil indices. Sputum percentage eosinophils and EDN and ECP levels were significantly higher in the SA group than in the HC group, while only the sputum EDN and ECP levels were significantly higher in the AR group than in the HC group. Unexpectedly, sputum levels of IL-5 were not significantly different among the three groups; however, the levels of eotaxin were higher in the SA group when compared to the HC group. No significant correlations were found between IL-5 and percentage eosinophils, EDN, or ECP levels; in contrast, eotaxin levels correlated significantly with percentage eosinophils (R(s) = 0.638; p = 0.0001), EDN (R(s) = 0.522; p = 0.003), and ECP levels (R(s) = 0.630 and p = 0.0002). The elevated levels and good correlations of eotaxin with sputum eosinophil indices, and no elevation or correlation of IL-5 with these indices, suggest that CC chemokine eotaxin may play a more important role in eosinophil degranulation in children with SA.

Effects of entropy on the gas-phase pyrolysis of ethyl N,N-dimethylcarbamate.

In this study, we examined the gas-phase pyrolysis of ethyl N,N-dimethylcarbamate theoretically at various theoretical levels. The reaction consists of a two-step mechanism, with N,N-dimethylcarbamic acid and ethylene as reaction intermediates. In the first step, the reaction proceeds via a six-membered cyclic transition state (TS), which is more favorable than that via a four-membered cyclic TS. Here, the contribution of entropy to the overall potential energy surface was found to play an important role in determining the rate-limiting step, which was found to be the second step when viewed in terms of the enthalpy of activation (DeltaH(not equal)), but the first step when entropy changes (-TDeltaS(not equal)) were considered. These results are consistent with experimental findings. Moreover, the experimental activation entropy can be reproduced by using the hindered rotor approximation, which converts some low vibration frequencies that correspond to internal rotational modes into hindered rotors.

Co-Pt alloy nanoparticles produced using a template of nanoparticle array.

A monolayer of Co-Pt alloy nanoparticles in the nanometer-size regime was fabricated using a nanotemplate approach. 1.7-nm-thick Co46Pt54 film was deposited onto a preexisting array of Ni seed particles embedded in a polyimide film. During subsequent annealing, the deposited Co46Pt54 film coalesced onto the seed particles to produce a monolayer of Co-Pt alloy particles. Deposition and annealing were repeated to increase both average particle size and volume fraction of the alloy particles. It was also shown that the annealing temperature was critical in controlling the particle size distribution and the final composition of the nanoparticles. This method of forming a single layer of vertically aligned nanoparticles can be easily extended to a large area as well as to produce a different combination of alloy particles on a polymer film.

Mono-layer of Ni(100-x)Fe(x) nanoparticles fabricated on a polyimide film under different curing atmospheres.

A mono-layer of nano-sized metal particles was prepared on the surface of a polyimide film by simply depositing a thin film of Ni80Fe20 on top of the polyamic acid that was spin coated onto a Si wafer. During thermal imidization of the polyamic acid film, Fe was selectively etched by reacting with the carbonyl group of the polyamic acid to leave behind uniformly distributed Ni-rich metallic particles. The average diameter of the particles was 4 nm and the particles were confined into a single layer on top of the polymer film. Moreover, it was also shown that the morphology of the nanoparticles can be substantially altered by curing the precursor film in a hydrogen atmosphere, without significantly damaging the polymer film. Thus produced nanoparticles lay exposed on top of the electrically insulating and chemically stable polymer film so that it is possible that the nanoparticles can be directly used for fabricating a nonvolatile flash memory device or as a template for building functional nano-structures.

Fabrication of Ni nanoparticles by selective oxidation of permalloy thin film during imidization of polyamic acid.

Ni nanoparticles embedded in a polyimide (PI) matrix were fabricated by selectively oxidizing a layer of Ni(80)Fe(20) metal film sandwiched between two PI precursor layers. Ni nanoparticles, formed in a monolayer between two PI layers, had an average particle size of approximately 5 nm. X-Ray photoelectron spectroscopy confirmed that Fe in the film was preferentially consumed, resulting in the formation of Ni nanoparticles.