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1.
J Mater Chem B ; 8(3): 568-577, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31854426

RESUMO

Rapid endothelialization and prevention of restenosis are two vital challenges for the preparation of a small-diameter vascular graft (SDVG), while postoperative infection after implantation is often neglected. In the present study, carboxymethyl chitosan (CMC) and chitosan (CS) were chosen as the anti-thrombotic and anti-bacterial components, respectively; and then an asymmetric vascular graft was fabricated by co-electrospinning of poly(ε-caprolactone) (PCL)/CMC and PCL/CS. The mechanical properties of the asymmetric vascular graft were much better than those of the native vessels. In vitro blood compatibility tests indicated that the inner layer of the graft could inhibit thrombosis effectively. The outer layer of the graft had a certain anti-bacterial effect owing to the addition of chitosan. Besides, the inner layer of the graft could greatly promote the growth of endothelial cells. It is believed that the asymmetric SDVG with anti-thrombotic and anti-bacterial functions could contribute to the future clinical implantation of tissue engineered vascular grafts.

2.
J Colloid Interface Sci ; 556: 492-502, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31473539

RESUMO

Given the complexity of pollutants in wastewater, development of facile and effective multifunctional materials, which can not only kill bacteria but also remove dyes from wastewater, is in high demand. Herein, a facile strategy for the preparation of positively-charged nanofibrous membranes (NFMs) is reported via the combination of electrospinning and in-situ cross-linked polymerization of poly ([2-(methacryloyloxy)-ethyl] trimethyl ammonium chloride) (PMETAC) in poly (ether sulfone) (PES) solution. The quaternary ammonium salt polymer of PMETAC enabled the NFMs with positive charge to kill bacteria and remove anionic dyes. The antibacterial tests including agar plate counting and live/dead staining indicate that the NFMs show strong antibacterial ability with bacterial killing ratios of nearly 99% for both Escherichia coli and Staphylococcus aureus, as well as remarkable recyclability towards killing bacteria. The dyes adsorption experiments show that the NFMs exhibit high adsorption capacity for anionic dyes up to 208 mg g-1 for Congo Red (CR) and good reusability toward CR. Impressively, the membrane adsorption column test indicates that the CR dye removal ratio is up to 100% for the first time, and that is still as high as 96.5% for the third time with a fresh dye solution. Given the above advantages, such fascinating NFMs may provide new perspectives in the exploitation of multifunctional membrane materials for complex water remediation.


Assuntos
Antibacterianos/química , Corantes/química , Escherichia coli/crescimento & desenvolvimento , Membranas Artificiais , Nanofibras/química , Polímeros/química , Staphylococcus aureus/crescimento & desenvolvimento , Sulfonas/química , Águas Residuárias , Adsorção , Águas Residuárias/química , Águas Residuárias/microbiologia
3.
Plant Physiol Biochem ; 139: 630-641, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31039504

RESUMO

Melatonin, an evolutionarily conserved molecule, is implicated in numerous physiological processes in plants. To explore the potential roles of melatonin in response to UV-B radiation, we examined the influence of exogenous melatonin on Malus hupehensis Rehd. seedlings under two levels of UV-B radiation. Under UV-B stress, seedlings showed significant reduction in plant growth, biomass production, and root system development. However, 1 µM melatonin solution markedly alleviated these effects, especially at the higher dosage of UV-B radiation. The inhibitory effects of UV-B radiation on photosynthetic parameters, chlorophyll fluorescence parameters, stomatal apertures, chlorophyll levels and leaf membrane damages were also markedly alleviated with melatonin application. Melatonin treatment was also associated with higher activity and expression of genes encoding antioxidant enzymes (ascorbate peroxidase, catalase and peroxidase) and greater decline of H2O2 content in leaves exposed to UV-B. Moreover, exogenous melatonin treatment and UV-B stress increased the concentration of endogenous melatonin. The content of several phenolic compounds, including chlorogenic acid, phloridzin and quercetin-3-galactoside, also increased under UV-B stress, and these were further elevated significantly with melatonin addition. This study provides insight into the role(s) of endogenous melatonin in response to UV-B stress, and will facilitate application of exogenous melatonin in agriculture.


Assuntos
Malus/efeitos dos fármacos , Malus/metabolismo , Melatonina/farmacologia , Raios Ultravioleta , Antioxidantes/metabolismo , Clorofila/metabolismo , Peróxido de Hidrogênio/metabolismo , Malus/efeitos da radiação , Fenóis/metabolismo , Espécies Reativas de Oxigênio/metabolismo
4.
Opt Lett ; 43(24): 5965-5968, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30547981

RESUMO

We reported, to the best of our knowledge, the first experimental evidence of the pulsating soliton with chaotic behavior in an ultrafast fiber laser. By virtue of a dispersive Fourier transformation method, the chaotic behavior of soliton pulsation is visualized by the fact that the mode-locked spectrum collapses abruptly in an unpredictable way during the pulsating process. The obtained results provide the experimental demonstration of the chaotic behavior in the pulsating soliton, which would also give some new insights into the soliton pulsation dynamics in dissipative systems.

5.
J Pineal Res ; 65(4): e12523, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30230015

RESUMO

Melatonin mediates many physiological processes in plants. The problem of apple replant disease is unsolved. Our study objectives were to evaluate the regulatory effect of melatonin on plant resistance to this challenge and investigate the preliminary mechanism by which melatonin helps alleviate the effects of this disease. Two-year-old trees of "Fuji" apple (Malus domestica), grafted onto rootstock M.26, were grown in "replant" soil for 6 months in the absence or presence of a 200 µmol/L melatonin supplement. The addition of melatonin to the soil significantly increased the rates of plant growth and net photosynthesis and chlorophyll concentrations under replant conditions. This molecule elevated the levels of K in leaves and roots and enhanced the activity of soil enzymes. Such supplementation also changed the composition of the bacterial and fungal communities in the soil. We concluded that the application of melatonin to a replant soil can protect their chloroplasts from oxidative damage and release the apple root from membrane damage, and also lead to increased soil enzyme activity and soil quality while altering the composition of bacterial and fungal communities. These changes can then promote seedling growth, stimulate photosynthesis, and elevate K levels, thereby alleviating the effects of apple replant disease.


Assuntos
Malus/efeitos dos fármacos , Malus/genética , Melatonina/farmacologia , Biologia Computacional , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/genética , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Caules de Planta/efeitos dos fármacos , Caules de Planta/genética , RNA Ribossômico 16S/genética
6.
Front Plant Sci ; 9: 755, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29922323

RESUMO

The frequency and intensity of water deficits is expected to increase because of global warming. Drought stress is often one of the most limiting factors for plant growth. We conducted greenhouse pot experiments to address how dopamine affects the drought-resistance traits of apple trees at the physiological and molecular levels. Our factorial design consisted of dopamine and no-dopamine applications combined with well-watered and moderate-drought conditions. Seedling biomass, photosynthesis rates, chlorophyll concentrations, and stomatal apertures were markedly reduced under stress but dopamine treatment mitigated the inhibiting effects of drought on plant growth and helped maintain strong photosynthesis, chlorophyll levels, and stomatal functioning. Concentrations of most macro-, micro-, and trace elements decreased in response to drought. This stress also diminished the uptake and transport of elements in the leaves and stems, but increased the partitioning of elements in the roots. Nutrient resorption proficiency decreased while nutrient resorption efficiency increased for most analyzed elements. Exogenous dopamine significantly increased the concentrations, uptake, and transport of nutrients under drought stress, and also altered their distribution within the whole plant. However, this molecule had a negative effect on nutrient resorption. Although transcript levels of a key chlorophyll degradation gene, pheide a oxygenase, and senescence-associate gene 12 were elevated upon drought treatment, dopamine significantly suppressed the upregulation of those genes under such stress conditions. These observations indicate that dopamine has an important anti-senescence effect that might be helpful for regulating nutrient uptake, transport, and resorption, and ultimately influencing overall plant growth. Thus, understanding the role of dopamine in drought tolerance introduces new possibilities to use this compound for agricultural purposes.

7.
BMC Plant Biol ; 18(1): 136, 2018 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-29940853

RESUMO

BACKGROUND: Improvement of water-use efficiency (WUE) can effectively reduce production losses caused by drought stress. A better understanding of the genetic determination of WUE in crops under drought stress has great potential value for developing cultivars adapted to arid regions. To identify the genetic loci associated with WUE and reveal genes responsible for the trait in apple, we aim to map the quantitative trait loci (QTLs) for carbon isotope composition, the proxy for WUE, applying two contrasting irrigating regimes over the two-year experiment and search for the candidate genes encompassed in the mapped QTLs. RESULTS: We constructed a high-density genetic linkage map with 10,172 markers of apple, using single nucleotide polymorphism (SNP) markers obtained through restriction site-associated DNA sequencing (RADseq) and a final segregating population of 350 seedlings from the cross of Honeycrisp and Qinguan. In total, 33 QTLs were identified for carbon isotope composition in apple under both well-watered and drought-stressed conditions. Three QTLs were stable over 2 years under drought stress on linkage groups LG8, LG15 and LG16, as validated by Kompetitive Allele-Specific PCR (KASP) assays. In those validated QTLs, 258 genes were screened according to their Gene Ontology functional annotations. Among them, 28 genes were identified, which exhibited significant responses to drought stress in 'Honeycrisp' and/or 'Qinguan'. These genes are involved in signaling, photosynthesis, response to stresses, carbohydrate metabolism, protein metabolism and modification, hormone metabolism and transport, transport, respiration, transcriptional regulation, and development regulation. They, especially those for photoprotection and relevant signal transduction, are potential candidate genes connected with WUE regulation in drought-stressed apple. CONCLUSIONS: We detected three stable QTLs for carbon isotope composition in apple under drought stress over 2 years, and validated them by KASP assay. Twenty-eight candidate genes encompassed in these QTLs were identified. These stable genetic loci and series of genes provided here serve as a foundation for further studies on marker-assisted selection of high WUE and regulatory mechanism of WUE in apple exposed to drought conditions, respectively.


Assuntos
Genes de Plantas/genética , Malus/genética , Locos de Características Quantitativas/genética , Característica Quantitativa Herdável , Arabidopsis , DNA de Plantas/genética , Desidratação , Genes de Plantas/fisiologia , Marcadores Genéticos/genética , Malus/fisiologia , Plantas Geneticamente Modificadas , Polimorfismo de Nucleotídeo Único/genética , Reação em Cadeia da Polimerase em Tempo Real , Água/metabolismo
8.
Int J Mol Sci ; 19(1)2018 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-29361738

RESUMO

Oxidative stress is a major source of damage of plants exposed to adverse environments. We examined the effect of exogenous melatonin (MT) in limiting of oxidative stress caused by methyl viologen (MV; paraquatin) in apple leaves (Malus domestica Borkh.). When detached leaves were pre-treated with melatonin, their level of stress tolerance increased. Under MV treatment, melatonin effectively alleviated the decrease in chlorophyll concentrations and maximum potential Photosystem II efficiency while also mitigating membrane damage and lipid peroxidation when compared with control leaves that were sprayed only with water prior to the stress experiment. The melatonin-treated leaves also showed higher activities and transcripts of antioxidant enzymes superoxide dismutase, peroxidase, and catalase. In addition, the expression of genes for those enzymes was upregulated. Melatonin-synthesis genes MdTDC1, MdT5H4, MdAANAT2, and MdASMT1 were also upregulated under oxidative stress in leaves but that expression was suppressed in response to 1 mM melatonin pretreatment during the MV treatments. Therefore, we conclude that exogenous melatonin mitigates the detrimental effects of oxidative stress, perhaps by slowing the decline in chlorophyll concentrations, moderating membrane damage and lipid peroxidation, increasing the activities of antioxidant enzymes, and changing the expression of genes for melatonin synthesis.


Assuntos
Malus/efeitos dos fármacos , Malus/metabolismo , Melatonina/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Paraquat/farmacologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Antioxidantes/metabolismo , Clorofila/metabolismo , Peroxidação de Lipídeos , Fenótipo , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico
9.
Plant Physiol Biochem ; 119: 346-359, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28945999

RESUMO

Dopamine mediates many physiological processes in plants. We investigated its role in regulating growth, root system architecture, nutrient uptake, and responses to nutrient deficiencies in Malus hupehensis Rehd. Under a nutrient deficiency, plants showed significant reductions in growth, chlorophyll concentrations, and net photosynthesis, along with disruptions in nutrient uptake, transport, and distribution. However, pretreatment with 100 µM dopamine markedly alleviated such inhibitions. Supplementation with that compound enabled plants to maintain their photosynthetic capacity and development of the root system while promoting the uptake of N, P, K, Ca, Mg, Fe, Mn, Cu, Zn, and B, altering the way in which those nutrients were partitioned throughout the plant. The addition of dopamine up-regulated genes for antioxidant enzymes involved in the ascorbate-glutathione cycle (MdcAPX, MdcGR, MdMDHAR, MdDHAR-1, and MdDHAR-2) but down-regulated genes for senescence (SAG12, PAO, and MdHXK). These results indicate that exogenous dopamine has an important antioxidant and anti-senescence effect that might be helpful for improving nutrient uptake. Our findings demonstrate that dopamine offers new opportunities for its use in agriculture, especially when addressing the problem of nutrient deficiencies.


Assuntos
Antioxidantes/metabolismo , Dopamina/farmacologia , Malus/metabolismo , Minerais , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , Estresse Fisiológico , Malus/genética
10.
J Pineal Res ; 61(2): 218-29, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27145234

RESUMO

Melatonin mediates many physiological processes in plants. We investigated its role in regulating growth, potassium uptake, and root system architecture under three types of stress: salinity or a deficiency of all nutrients in Malus hupehensis Rehd., as well as a K deficiency in Malus rockii Rehd. Each treatment caused a reduction in growth rates and disrupted the absorption of potassium. However, pretreatment with 0.1 mmol/L melatonin significantly alleviated such inhibitions. The addition of melatonin also upregulated genes for antioxidant enzymes involved in the ascorbate-glutathione cycle (MdcAPX, MdDHAR1, MdDHAR2, MdMDHAR, and MdcGR) and helped decrease the accumulation of H2 O2 while improving the expression of K transporters and genes for the CBL1-CIPK23 pathway. These results indicated that melatonin can regulate the ROS signal and activate the CBL1-CIPK23 pathway to regulate the expression of a potassium channel protein gene, thereby promoting the absorption of potassium ions. Our findings demonstrate that inducing melatonin production is an important mechanism for plant defenses that can serve as a platform for possible applications in agricultural or related fields of research.


Assuntos
Malus/metabolismo , Melatonina/farmacologia , Potássio/metabolismo , Estresse Fisiológico/efeitos dos fármacos , Antioxidantes/metabolismo , Ácido Ascórbico/metabolismo , Glutationa/metabolismo , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , Canais de Potássio/metabolismo
11.
Physiol Plant ; 153(4): 584-602, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25155951

RESUMO

Dopamine mediates many physiological processes in plants. We investigated its role in regulating growth, ion homeostasis and the response to salinity in Malus hupehensis Rehd. Both hydroponics and field-pot experiments were conducted under saline conditions. Salt-stressed plants had reduced growth and a marked decline in their net photosynthetic rates, values for Fv /Fm and chlorophyll contents. However, pretreatment with 100 or 200 µM dopamine significantly alleviated this inhibition and enabled plants to maintain their photosynthetic capacity. In addition to changing stomatal behavior, supplementation with dopamine positively influenced the uptake of K, N, P, S, Cu and Mn ions but had an inhibitory effect on Na and Cl uptake, the balance of which is responsible for managing the response to salinity by Malus plants. Dopamine pretreatment also controlled the burst of hydrogen peroxide, possibly through direct scavenging and by enhancing the activities of antioxidative enzymes and the capacity of the ascorbate-glutathione cycle. We also investigated whether dopamine might regulate salt overly sensitive pathway genes under salinity. Here, MdHKT1, MdNHX1 and MdSOS1 were greatly upregulated in roots and leaves, which possibly contributed to the maintenance of ion homeostasis and, thus, improved salinity resistance in plants exposed earlier to exogenous dopamine. These results support our conclusion that dopamine alleviates salt-induced stress not only at the level of antioxidant defense but also by regulating other mechanisms of ion homeostasis.


Assuntos
Dopamina/farmacologia , Malus/efeitos dos fármacos , Antioxidantes/metabolismo , Clorofila/metabolismo , Peróxido de Hidrogênio/metabolismo , Malus/fisiologia , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/fisiologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/fisiologia , Salinidade , Tolerância ao Sal/efeitos dos fármacos , Cloreto de Sódio/farmacologia , Estresse Fisiológico
12.
Plant Physiol Biochem ; 70: 164-73, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23774378

RESUMO

High salinity is a major abiotic factor that limits crop production. The dwarfing apple rootstock M.26 is sensitive to such stress. To obtain an apple that is adaptable to saline soils, we transformed this rootstock with a vacuolar Na(+)/H(+) antiporter, MdNHX1. Differences in salt tolerance between transgenic and wild-type (WT) rootstocks were examined under field conditions. We also compared differences when 'Naganofuji No. 2' apple was grafted onto these transgenic or WT rootstocks. Plants on the transgenic rootstocks grew well during 60 d of mild stress (100 mM NaCl) while the WT exhibited chlorosis, inhibited growth and even death. Compared with the untreated control, the stomatal density was greater in both non-grafted and grafted WT plants exposed to 200 mM NaCl. In contrast, that density was significantly decreased in leaves from grafted transgenic plants. At 200 mM NaCl, net photosynthesis, stomatal conductance, intercellular CO2 concentration, and chlorophyll contents were markedly reduced in the WT, whereas the declines in those values were only minor in similarly stressed transgenic plants. Therefore, we conclude that overexpressing plants utilize a better protective mechanism for retaining higher photosynthetic capacity. Furthermore, this contrast in tolerance and adaptability to stress is linked to differences in stomatal behavior and photosynthetic rates.


Assuntos
Genes de Plantas , Malus/genética , Fotossíntese/genética , Proteínas de Plantas/genética , Estômatos de Plantas , Tolerância ao Sal/genética , Trocadores de Sódio-Hidrogênio/genética , Dióxido de Carbono/metabolismo , Clorofila/metabolismo , Expressão Gênica , Malus/metabolismo , Malus/fisiologia , Folhas de Planta/anatomia & histologia , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Salinidade , Sais , Cloreto de Sódio/metabolismo , Trocadores de Sódio-Hidrogênio/metabolismo , Estresse Fisiológico/genética , Transformação Genética , Vacúolos/metabolismo
13.
J Pineal Res ; 54(3): 292-302, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23106234

RESUMO

To examine the potential roles of melatonin in drought tolerance, we tested the effects of its long-term exogenous application on 'Hanfu' apple (Malus domestica Borkh.). When 100 µm melatonin was added to soils under drought conditions, the resultant oxidative stress was eased and leaf senescence was delayed. This molecule significantly reduced chlorophyll degradation and suppressed the up-regulation of senescence-associated gene 12 (SAG12) and pheophorbide a oxygenase (PAO). Such treatment also alleviated the inhibition of photosynthesis brought on by drought stress. We also investigated quenching and the efficiency of Photosystem II (PSII) photochemistry under dark and light conditions and found that melatonin helped to maintain better function of PSII under drought. The addition of melatonin also controlled the burst of hydrogen peroxide, possibly through direct scavenging and by enhancing the activities of antioxidative enzymes and the capacity of the ascorbate-glutathione cycle. Thus, understanding this effect of melatonin on drought tolerance introduces new possibilities to use this compound for agricultural purposes.


Assuntos
Secas , Malus/efeitos dos fármacos , Melatonina/farmacologia , Estresse Fisiológico/efeitos dos fármacos , Envelhecimento/efeitos dos fármacos , Envelhecimento/fisiologia , Análise de Variância , Antioxidantes/análise , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Clorofila/genética , Clorofila/metabolismo , Malus/enzimologia , Malus/genética , Malus/metabolismo , Oxigenases/análise , Oxigenases/genética , Oxigenases/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Folhas de Planta/fisiologia , Proteínas de Plantas/análise , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
14.
Plant Physiol Biochem ; 58: 159-65, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22819861

RESUMO

Maintaining ion and water homeostasis in plants is an important defense strategy against salinity stress. Divergence in ion homeostasis between the salt-tolerant Malus hupehensis Rehd. and salt-sensitive Malus prunifolia 'yingyehaitang' was studied to understand their mechanisms for tolerance. Compared with the control on Day 15, plants of those two genotypes under high-salinity treatment had less K(+) in the leaves, stems, and roots. Contents were higher in the roots but lower in the leaves of M. hupehensis while levels in the stems were similar to those from M. prunifolia. For both genotypes, the sodium content increased after salinity treatment in all tissue types. However, the leaves from M. hupehensis had less Na(+) and maintained a lower Na(+)/K(+) ratio. To understand the basis for these differences, we studied the ion transporters and regulation of aquaporin transcripts in the leaves. Transcript levels for both MdHKT1 and MdSOS1 were higher in M. hupehensis, implying that this species had better capacity to exclude sodium so that less Na(+) occurred in the leaves but more in the stems. M. hupehensis also had a greater amount of MdNHX1 transcripts, which could have assisted in sequestering excess Na(+) into the vacuoles and sustaining a better cellular environment. A relatively higher level of aquaporin transcript was also found in M. hupehensis, suggesting that those plants were more capable of maintaining a better leaf water status and diluting excess ions effectively under high-salinity conditions. Therefore, these tested transporters may play important roles in determining how salinity tolerance is conferred in Malus species.


Assuntos
Aquaporinas/metabolismo , Bombas de Íon/metabolismo , Malus/metabolismo , Folhas de Planta/metabolismo , Tolerância ao Sal/genética , Sódio/farmacologia , Estresse Fisiológico/genética , Aquaporinas/genética , Proteínas de Transporte de Cátions/genética , Proteínas de Transporte de Cátions/metabolismo , Genes de Plantas , Genótipo , Bombas de Íon/genética , Íons/metabolismo , Malus/efeitos dos fármacos , Malus/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Caules de Planta/efeitos dos fármacos , Caules de Planta/metabolismo , Potássio/metabolismo , Sódio/metabolismo , Cloreto de Sódio/metabolismo , Cloreto de Sódio/farmacologia , Trocadores de Sódio-Hidrogênio/genética , Trocadores de Sódio-Hidrogênio/metabolismo , Simportadores/genética , Simportadores/metabolismo , Transcrição Genética/efeitos dos fármacos , Vacúolos/metabolismo , Água/fisiologia
15.
J Pineal Res ; 53(3): 298-306, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22507106

RESUMO

As an indoleamine molecule, melatonin mediates many physiological processes in plants. We investigated its role in regulating growth, ion homeostasis, and the response to oxidative stress in Malus hupehensis Rehd. under high-salinity conditions. Stressed plants had reduced growth and a marked decline in their net photosynthetic rates and chlorophyll contents. However, pretreatment with 0.1µm melatonin significantly alleviated this growth inhibition and enabled plants to maintain an improved photosynthetic capacity. The addition of melatonin also lessened the amount of oxidative damage brought on by salinity, perhaps by directly scavenging H(2) O(2) or enhancing the activities of antioxidative enzymes such as ascorbate peroxidase, catalase, and peroxidase. We also investigated whether melatonin might control the expression of ion-channel genes under salinity. Here, MdNHX1 and MdAKT1 were greatly up-regulated in the leaves, which possibly contributed to the maintenance of ion homeostasis and, thus, improved salinity resistance in plants exposed to exogenous melatonin.


Assuntos
Malus/metabolismo , Melatonina/farmacologia , Salinidade , Estresse Fisiológico/efeitos dos fármacos , Antioxidantes/metabolismo , Antiporters/metabolismo , Peróxido de Hidrogênio/farmacologia , Malus/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Raízes de Plantas/efeitos dos fármacos
16.
J Colloid Interface Sci ; 354(1): 76-81, 2011 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-21084095

RESUMO

A simple method was developed to prepare highly water-soluble nanocrystal powders of magnetic iron oxides with different oxidation degree from magnetite (Fe(3)O(4)) to maghemite (γ-Fe(2)O(3)) coated with gluconic acid (GLA). X-ray diffraction and transmission electron microscopy measurements show that the products have a narrow size distribution, and the cores are inverse spinel iron oxides and completely crystallized. Vibrating sample magnetometry measurements reveal that all the samples exhibit superparamagnetic behavior at room temperature. Fourier transform infrared (FTIR) and Raman spectra were used to identify the products. It is shown that GLA molecules are immobilized on the nanoparticle surface by chemical bonding and the carboxyl is asymmetrically bound to the surface iron atom, and the vacancies in the γ-Fe(2)O(3) cores are disordered. Compared with FTIR, Raman spectrum analysis is a rapid, simple, and accurate method for identifying inverse spinel iron oxides. The chemical stability and the high solubility of the products are explained in terms of the proposed coordination modes of the surface iron atom with GLA.

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