The Use of UV Radiation to Control the Architecture of Salvia splendens Plants. I. Effects on Plant Growth, Water Relations and Gas Exchange

In experiments with Salvia splendens plants grown in the greenhouse we evaluated the possible use of irradiation with unfiltered UV (UVA + UVB + UVC) lamps for the control of plant growth. The effect of UV Irradiation on the growth of S. splendens plants in the grcenhouse was closely dependent on the growing season and the level of available photosynthetically active radiation. In summer UV treatments were ineffective, but in the low light conditions of winter UV irradiation inhibited the growth via both photomorphogenic and photosynthetic effects. The reduction of stomatal conductance and expansion growth, which in turn depressed photosynthesis and dry matter accumulation, were not a consequence of an impairment of plant water status but appeared to be a direct UV effect on stomata and cell wall rheological propertles. Our findings suggest that the use of unfiltered UV irradiation could become an effective tool for the regulation of growth in greenhouse crops, particularly during the poor light conditions of the winter season.     

Kinetics of Stem Elongation in Light-Grown Tomato Plants. Responses to Different Photosynthetically Active Radiation Levels by Wild-Type and aurea Mutant Plants

Abstract— In this research, we measured the short- and long-term, stem elongation responses of wild-type and aurea(au) mutant tomato plants to different photosynthetically active radiation (PAR) levels by using linear voltage transducers. Stem elongation was continuously measured in green tomato plants over 2.75 days, under 12 h light/12 h dark photoperiods or in darkness after a 6 h irradiation period. There is no significant difference in stem elongation between wild-type plants pregrown at either LOO or 400 μmol m^?2 s^?1 and then exposed to 12 h photoperiods. However, in the au mutant there is a very large difference between plants pregrown under 100 or 400 umol m ^?2 s^?1 and then exposed either to 12 h photoperiods or to continuous darkness. Total stem elongation of the wild type appears to be maximal at 100 umol m^?2 s^?1, while that of the au mutant appears to be maximal with PAR 400 umol m^?2 s^?1. Wild-type plants displayed PAR-dependent (in the range 100-800 umol m^?2 s^?1) inhibition of growth both during the day and during the night. In contrast, the au mutant showed a fluence-rate-dependent promotion of growth during the dark periods in the range of 10-400 umol m^?2 s^?1. Large, fast and opposite changes in stem elongation rate at the light/dark and dark/light transitions were present in both genotypes. Internode elongation rate in the first half of the night was always modest in wild-type tomato, whereas it increased rapidly in the au mutant. Stem elongation rate of wild type starts to increase after about 6 h in darkness, showing the typical time course of escape from Pfr-mediated inhibition of elongation by an end-of-day response. The role of phytochrome level and type in sensing light quantity is discussed.     

ZnO荧光粉中的紫外发射和绿色发射之间的关系

通过在低氧分压和真空中热处理ZnO粉末, 获得了ZnO荧光粉. ZnO荧光粉有两个发射谱带, 分别位于380 nm(紫外)和510 nm(绿色). 紫外谱带对应于ZnO中的激子发射, 是一个单中心发光过程；绿色谱带是一个复合发光过程, 与ZnO中的本征缺陷相关, 如氧空位、锌空位等. 实验表明, 高密度的激发条件有利于紫外发射, 而低氧分压下的热处理有利于提高绿色发射谱带的强度. 研究结果还表明, 与紫外发射相联系的激子可向与本征缺陷相联系的绿色发光中心传递能量, 这种传递可能是通过激子扩散实现的.     

Effects of PAR and UV Radiation on the Structural and Functional Integrity of Phycocyanin,Phycoerythrin and Allophycocyanin Isolated from the Marine Cyanobacterium Lyngbya sp. A09DM

An in vitro analysis of the effects of photosynthetically active and ultraviolet radiations was executed to assess the photostability of biologically relevant pigments phycocyanin (PC), phycoerythrin (PE) and allophycocyanin (APC) isolated from Lyngbya sp. A09DM. Ultraviolet (UV) irradiances significantly affected the integrity of PC, PE and APC; however, PAR showed least effect. UV radiation affected the bilin chromophores covalently attached to phycobiliproteins (PBPs). Almost complete elimination of the chromophore bands associated with α‐ and β‐subunit of PE and APC occurred after 4 h of UV‐B exposure. After 5 h of UV‐B exposure, the content of PC, PE and APC decreased by 51.65%, 96.8% and 96.53%, respectively. Contrary to PAR and UV‐A radiation, a severe decrease in fluorescence of all PBPs was observed under UV‐B irradiation. The fluorescence activity of extracted PBP was gradually inhibited immediately after 15–30 min of UV‐B exposure. In comparison to the PC, the fluorescence properties of PE and APC were severely lost under UV‐B radiation. Moreover, the present study indicates that UV‐B radiation can damage the structural and functional integrity of phycobiliproteins leading to the loss of their ecological and biological functions.     

Solar PAR and UV radiation affects the physiology and morphology of the cyanobacterium Anabaena sp. PCC 7120

Solar UV radiation (280-400 nm) may affect morphology of cyanobacteria, however, little has been evidenced on this aspect while their physiological responses were examined. We investigated the impacts of solar PAR and UVR on the growth, photosynthetic performance and morphology of the cyanobacterium Anabaena sp. PCC7120 while it was grown under three different solar radiation treatments: exposures to (a) constant low PAR (photosynthetic active radiation, 400-700 nm), (b) natural levels of solar radiation with and (c) without UV radiation (290-400 nm). When the cells were exposed to solar PAR or PAR+UVR, the photochemical efficiency was reduced by about 40% and 90%, respectively, on day one and recovered faster under the treatment without UVR over the following days. Solar UVR inhibited the growth up to 40%, reduced trichome length by up to 49% and depressed the differentiation of heterocysts. Negligible concentrations of UV-absorbing compounds were found even in the presence of UVR. During the first 2 d of exposure to natural levels of PAR, carotenoid concentrations increased but no prolonged increase was evident. Heterocyst formation was enhanced under elevated PAR levels that stimulated quantum yield and growth after an initial inhibition. Higher concentrations of carotenoids and a twofold increase in the carotenoid to chlorophyll a ratio provided protection from the high levels of solar PAR. Under radiation treatments with UVR the relatively greater decrease in chlorophyll a concentrations compared with the increase in carotenoids was responsible for the higher carotenoid: chlorophyll a ratio. Heterocyst formation was disrupted in the presence of solar UVR. However, the longer term impact of heterocyst disruption to the survival of Anabaena sp. requires further study.     

Oxidative Modification in Human Hair: The Effect of the Levels of Cu (II) Ions,UV Exposure and Hair Pigmentation

Protein oxidative degradation is implicated in a wide range of deleterious effects. For human hair, this oxidative damage can lead to significant observable changes in fiber physical and visual properties. A redox proteomic approach was applied to map molecular modification in human hair proteins and correlate this modification with the abundance of copper (II) ions, the levels of UV exposure and the general level of hair pigmentation. An increase in oxidative modification was observed with increasing copper (II) ion levels, regardless of the pigmentation level. Significantly, increased protein oxidative modification was also observed to occur in both lightly and darkly pigmented hair tresses even in the absence of irradiation, albeit at lower relative levels. Modification levels increased with increased copper (II) ion concentration. This new finding indicates that the level of copper (II) ions in human hair plays a key role in mediating protein oxidation, with or without exposure to UV light. Overall, these results strongly suggest that minimization of the level of copper (II) ions in human hair will mitigate and/or slow protein oxidative modification and therefore lower overall hair damage.     

Determination of Myristicin and Linalool in Plants Exposed to Microwave Radiation by High-Performance Liquid Chromatography

The goal of this study was to develop and validate a high-performance liquid chromatography method for the quantification of two essential oil constituents (myristicin and linalool) from extracts of the three aromatic plants exposed to low-intensity microwave radiation. The analysis was performed by high-performance liquid chromatography using a mobile phase consisting of ultrapure water and acetonitrile. The separations were carried out in the following conditions: isocratic conditions for 30 minutes with 100% acetonitrile and then linear gradient conditions from 100% acetonitrile to 25% acetonitrile for 15 minutes. The developed method was validated in terms of linearity, limits of detection, limits of quantification, precision, accuracy, and robustness. The results show that plants react differently under microwave stress and change their essential oil content as a response.     

Comparison of Chemistry Induced by Direct and Indirect Plasma Treatment of Water to the Effect of UV Radiation

Plasma Chemistry and Plasma Processing - The yield of redox reactions (Fe2+ oxidation and Mn7+ reduction in aqueous solutions) under the action of hot plasma radiation in liquid and species formed...     

Control of dispersion in capillary electrochromatography coupled to UV and mass spectrometric detection

Capillary electrochromatography (CEC), along with other miniaturised chromatography techniques, such as capillary LC, offers the most benefit when efficiently coupled to mass spectrometric (MS) detectors. In conventional one-piece CEC columns, dispersion in the open connecting tube between the packed column and MS source reduces chromatographic performance to unacceptable levels. This paper examines the effect on dispersion of various column-tube arrangements and offers suggestions as to the most practical way of connecting CEC-UV-MS. Comparisons of theoretical and measured values for these different arrangements are shown.     

Investigation of Photosystem II Functional Size in Higher Plants under Physiological and Stress Conditions Using Radiation Target Analysis and Sucrose Gradient Ultracentrifugation

The photosystem II (PSII) reaction centre is the critical supramolecular pigment–protein complex in the chloroplast which catalyses the light-induced transfer of electrons from water to plastoquinone. Structural studies have demonstrated the existence of an oligomeric PSII. We carried out radiation inactivation target analysis (RTA), together with sucrose gradient ultracentrifugation (SGU) of PSII, to study the functional size of PSII in diverse plant species under physiological and stress conditions. Two PSII populations, made of dimeric and monomeric core particles, were revealed in Pisum sativum, Spinacea oleracea, Phaseulus vulgaris, Medicago sativa, Zea mais and Triticum durum. However, this core pattern was not ubiquitous in the higher plants since we found one monomeric core population in Vicia faba and a dimeric core in the Triticum durum yellow-green strain, respectively. The PSII functional sizes measured in the plant seedlings in vivo, as a decay of the maximum quantum yield of PSII for primary photochemistry, were in the range of 75–101 ± 18 kDa, 2 to 3 times lower than those determined in vitro. Two abiotic stresses, heat and drought, imposed individually on Pisum sativum, increased the content of the dimeric core in SGU and the minimum functional size determined by RTA in vivo. These data suggest that PSII can also function as a monomer in vivo, while under heat and drought stress conditions, the dimeric PSII structure is predominant.     

The Use of UV Spectroscopy and SIMCA for the Authentication of Indonesian Honeys According to Botanical,Entomological and Geographical Origins

As a functional food, honey is a food product that is exposed to the risk of food fraud. To mitigate this, the establishment of an authentication system for honey is very important in order to protect both producers and consumers from possible economic losses. This research presents a simple analytical method for the authentication and classification of Indonesian honeys according to their botanical, entomological, and geographical origins using ultraviolet (UV) spectroscopy and SIMCA (soft independent modeling of class analogy). The spectral data of a total of 1040 samples, representing six types of Indonesian honey of different botanical, entomological, and geographical origins, were acquired using a benchtop UV-visible spectrometer (190–400 nm). Three different pre-processing algorithms were simultaneously evaluated; namely an 11-point moving average smoothing, mean normalization, and Savitzky–Golay first derivative with 11 points and second-order polynomial fitting (ordo 2), in order to improve the original spectral data. Chemometrics methods, including exploratory analysis of PCA and SIMCA classification method, was used to classify the honey samples. A clear separation of the six different Indonesian honeys, based on botanical, entomological, and geographical origins, was obtained using PCA calculated from pre-processed spectra from 250–400 nm. The SIMCA classification method provided satisfactory results in classifying honey samples according to their botanical, entomological, and geographical origins and achieved 100% accuracy, sensitivity, and specificity. Several wavelengths were identified (266, 270, 280, 290, 300, 335, and 360 nm) as the most sensitive for discriminating between the different Indonesian honey samples.     

Use of capillary electrophoresis with UV detection as a screening method to determine histamine in fish samples.

Histamine levels in fish, extracted with methanol, were determined by capillary electrophoresis (CE) using phosphate buffer pH 2.5 and U.V. detection at 210 nm. Histamine was well separated from the other co-extracted components under the given CE condition without any cleanup of the methanol extract. The average recovery of spiked histamine in various types of fish samples was 96%. Using the same methanol extracts from various fish samples, we then compared histamine concentration obtained by CE and fluorometric methods.     

Oxidative Damage in Response to Natural Levels of UV-B Radiation in Larvae of the Tropical Sea Urchin Tripneustes gratilla

To assess the effects of UV radiation (280–400 nm) on development, oxidative damage and antioxidant defence in larvae of the tropical sea urchin Tripneustes gratilla, a field experiment was conducted at two depths in Aitutaki, Cook Islands (18.85°S, 159.75°E) in May 2008. Compared with field controls (larvae shielded from UV-R but exposed to VIS-radiation), UV-B exposure resulted in developmental abnormality and increases in oxidative damage to proteins (but not lipids) in embryos of T. gratilla held at 1 m depth. Results also indicated that larvae had the capacity to increase the activities of protective antioxidant enzymes when exposed to UV-B. The same trends in oxidative damage and antioxidant defence were observed for embryos held at 4 m, although the differences were smaller and more variable. In contrast to UV-B exposure, larvae exposed to UV-A only showed no significant increases in abnormality or oxidative damage to lipids and proteins compared with field controls. This was true at both experimental depths. Furthermore, exposure to UV-A did not cause a significant increase in the activities of antioxidants. This study indicates that oxidative stress is an important response of tropical sea urchin larvae to exposure to UV radiation.     

Relationships between unfolded configurations of proteins and dynamics of folding to the native state

We compare folding trajectories of chymotrypsin inhibitor (CI2) using a dynamic Monte Carlo scheme with Go-type potentials. The model considers the four backbone atoms of each residue and a sphere centered around C^β the diameter of which is chosen according to the type of the side group. Bond lengths and bond angles are kept fixed. Folding trajectories are obtained by giving random increments to the φ and ψ torsion angles with some bias toward the native state. Excluded volume effects are considered. Two sets of 20 trajectories are obtained, with different initial configurations. The first set is generated from random initial configurations. The initial configurations of the second set are generated according to knowledge-based neighbor dependent torsion probabilities derived from triplets in the Protein Data Bank. Compared to chains with randomly generated initial configurations, those generated with neighbor-dependent probabilities (i) fold faster, (ii) have better defined secondary structure elements, and (iii) have less number of non-native contacts during folding. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3667–3678, 2006     

The Calf Intestinal Alkaline Phosphatase. II. Reaction between the metal content and the enzyme activity

Pure alkaline phosphatase (EC 3.1.3.1; 1500 U/mg) was dialyzed at 4° during 168 h against water, 10^?4M EDTA or 10^?4M o-phenanthroline. During the dialysis, samples were periodically removed and analyzed for metal content and activity. The results indicate that 1 mol of native calf intestinal alkaline phosphatase contains 4 g-atom of zinc and 4 g-atom of magnesium tightly bound, and that both metal ions are necessary for full enzyme activity. The dialyzed, partially demetallized enzyme could be reactivated by the addition of zinc and/or magnesium salts.     

Polymer network structure and electro-optic performance of polymer stabilized cholesteric textures II. The effect of UV curing conditions

The effect of UV curing intensity and curing time on the electro-optic behaviour and network morphology of reverse mode polymer stabilized cholesteric textures (PSCTs) has been studied. Scanning electron micrographs indicate that increasing the curing intensity generally results in a more open polymer network characterized by a larger average void size, while the morphology of the individual strands remains largely unchanged. In addition, as the polymerization process proceeds, voids within the network are observed to decrease in size. PSCTs with sufficiently large network voids exhibit a two-stage switching behaviour consistent with a model in which the cholesteric liquid crystal is divided between two distinct environments one in which the liquid crystal is strongly dominated by the polymer network, the other in which a bulk-like behaviour, comparable to the unstabilized cholesteric material, is observed.     

Ionic interactions in solutions. II. The theoretical basis of the equilibrium between free and pairwise associated ions

It is shown from recent results based on the statistical mechanics treatment of ionic solutions that the notion of an equilibrium between free ions and paired ions which wasa priori introduced in the chemical model of Bjerrum is essentially correct. The mass-action law which is deduced from such a model is indeed derivable from the more exact treatments of Mayer, Rasaiah, and Friedman starting directly from Hamiltonian models and without any assumptions as to the chemical structure of the ionic solute in the solution. The transformation relation from a primitive-model result to any short-range Hamiltonian model equation is given. It allows a simple mathematical treatment of experimental data for dilute solutions, the derivation of useful information on the Gurney solvation effects, and an interpretation of the multistep association concept.