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1.
Dalton Trans ; 48(35): 13242-13247, 2019 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-31414094

RESUMO

Five examples of bis(pyrazolyl)borate Ni(ii) complexes 2-5, exhibiting C-HNi interactions, were readily prepared from the reactions of K[BBN(3-R1-4-R2-pz)2] with Ni(ii) precursors (Ni(acac)2 or NiCl2(PPh3)2) in dichloromethane or toluene. When R1 = R2 = H, complex 2a with square-planar geometry around the Ni centre and showing an unusual C-HNi anagostic interaction was obtained. In contrast, when R1 = Me, R2 = H or R1 = Me, R2 = Br, tetrahedral complexes 3 or 4 were formed preferentially with strong C-HNi agostic interactions, respectively. Additionally, some differences in the formation and transformation of 3 and 4 were also found including a 1,2-borotropic shift during the formation of 3 and a further geometrical transformation from tetrahedral 3 to square-planar 2b by the second 1,2-borotropic shift under continuous heating; in contrast, no ligand change and further conversion were found in 4. When the more hindered 3-iPr-substituted ligand 1d was introduced in the reaction, the hydrolysis and cleavage of one B-N bond in the ligand occurred, leading to the singly hydroxo-bridged complex 5. The experimental and theoretical results indicate that the preference to form a thermodynamically stable complex and then balancing with orbital energy should be the intrinsic reason for the reaction selectivity.

2.
Plant Cell Rep ; 36(4): 529-542, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28155114

RESUMO

KEY MESSAGE: Over-expression of SlJA2 decreased the accumulation of SA, which resulted in significant physiological and gene expression changes in transgenic tobacco plants, leading to the decreased heat tolerance of transgenic tobacco. NAC family, the largest transcription factors in plants, responses to different environmental stimuli. Here, we isolated a typical NAC transcription factor (SlJA2) from tomato and got transgenic tobacco with SlJA2 over-expression. Expression of SlJA2 was induced by heat stress (42 °C), chilling stress (4 °C), drought stress, osmotic stress, abscisic acid, and salicylic acid. Over-expression of SlJA2 decreased the accumulation of salicylic acid by regulating expression of salicylic acid degradation gene under heat stress. Compared to WT plants, stomatal apertures and water loss increased in transgenic plants, and the damage of photosynthetic apparatus and chlorophyll breakdown were more serious in transgenic plants under heat stress. Meanwhile, more H2O2 and O2·- were accumulated transgenic plants and proline synthesis was restricted, which resulted in more serious oxidative damage compared to WT. qRT-PCR analysis showed that over-expression of SlJA2 could down-regulate genes involved in reactive oxygen species scavenging, proline biosynthesis, and response to heat stress. All the above results indicated that SlJA2 may be a negative regulator responded to plant's heat tolerance. Thus, this study provides new insight into roles of NAC family member in plant response to abiotic stress.


Assuntos
Expressão Gênica , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Transdução de Sinais/genética , Estresse Fisiológico/genética , Termotolerância/genética , Tabaco/metabolismo , Secas , Expressão Gênica/efeitos dos fármacos , Expressão Gênica/genética , Peróxido de Hidrogênio/metabolismo , Lycopersicon esculentum/genética , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Ácido Salicílico/farmacologia , Transdução de Sinais/efeitos dos fármacos , Estresse Fisiológico/efeitos dos fármacos , Tabaco/efeitos dos fármacos , Tabaco/genética
3.
Plant Physiol Biochem ; 112: 218-226, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28092850

RESUMO

Plants are always exposed to abiotic and biotic stresses which can adversely affect their growth and development. As an important antioxidant, AsA plays a vital role in plant defence against damage caused by stresses. In this study, we cloned a tomato GDP-L-galactose phosphorylase-like (SlGGP-LIKE) gene and investigated its role in resistance to abiotic and biotic stresses by using antisense transgenic (AS) tomato lines. The AsA content in AS plants was lower than that in WT plants. Under chilling stress, the growth of AS plants was inhibited significantly, and they yielded higher levels of ROS, REC and MDA but demonstrated weaker APX activity than that shown by WT plants. Additionally, the declined values of Pn, Fv/Fm, oxidisable P700, and D1 protein content of PSII in AS lines were significant. Furthermore, the effect on xanthophyll cycle of AS plants was more severe than that on WT plants, and the ratio of zeaxanthin (Z)/(V + A + Z) and (Z + 0.5 A)/(V + A + Z) in AS lines was lower than that in WT plants. In spite of chilling stress, under Pseudomonas syringae pv.tomato (Pst) DC3000 strain infection, AS plants showed lesser bacterial cell growth and dead cells than those shown by WT plants. This finding indicated that AS plants demonstrated stronger resistance against pathogenic infection. Results suggest that SlGGP-LIKE gene played an important role in plant defence against chilling stress and pathogenic infection.


Assuntos
Temperatura Baixa , Genes de Plantas , Lycopersicon esculentum/microbiologia , Lycopersicon esculentum/fisiologia , Proteínas de Plantas/genética , Estresse Fisiológico/genética , Ascorbato Peroxidases/metabolismo , Ácido Ascórbico/metabolismo , Western Blotting , Membrana Celular/metabolismo , Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum/genética , Lycopersicon esculentum/crescimento & desenvolvimento , Fotossíntese , Pigmentos Biológicos/metabolismo , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Pseudomonas/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Reação em Cadeia da Polimerase em Tempo Real
4.
J Integr Plant Biol ; 59(2): 102-117, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27995772

RESUMO

SUMOylation is an important post-translational modification process that regulates different cellular functions in eukaryotes. SIZ/PIAS-type SAP and Miz1 (SIZ1) proteins exhibit SUMO E3 ligase activity, which modulates SUMOylation. However, SIZ1 in tomato has been rarely investigated. In this study, a tomato SIZ1 gene (SlSIZ1) was isolated and its molecular characteristics and role in tolerance to drought stress are described. SlSIZ1 was up-regulated by cold, sodium chloride (NaCl), polyethylene glycol (PEG), hydrogen peroxide (H2 O2 ) and abscisic acid (ABA), and the corresponding proteins were localized in the nucleus. The expression of SlSIZ1 in Arabidopsis thaliana (Arabidopsis) siz1-2 mutants partially complemented the phenotypes of dwarf, cold sensitivity and ABA hypersensitivity. SlSIZ1 also exhibited the activity of SUMO E3 ligase to promote the accumulation of SUMO conjugates. Under drought stress, the ectopic expression of SlSIZ1 in transgenic tobacco lines enhanced seed germination and reduced the accumulation of reactive oxygen species. SlSIZ1 overexpression conferred the plants with improved growth, high free proline content, minimal malondialdehyde accumulation and increased accumulation of SUMO conjugates. SlSIZ1 is a functional homolog of Arabidopsis SIZ1 with SUMO E3 ligase activity. Therefore, overexpression of SlSIZ1 enhanced the tolerance of transgenic tobacco to drought stress.


Assuntos
Adaptação Fisiológica , Secas , Lycopersicon esculentum/enzimologia , Proteínas de Plantas/metabolismo , Tabaco/genética , Tabaco/fisiologia , Ubiquitina-Proteína Ligases/metabolismo , Ácido Abscísico/farmacologia , Adaptação Fisiológica/efeitos dos fármacos , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Biologia Computacional , Teste de Complementação Genética , Germinação/efeitos dos fármacos , Resposta ao Choque Térmico/efeitos dos fármacos , Lycopersicon esculentum/efeitos dos fármacos , Mutação/genética , Fenótipo , Plantas Geneticamente Modificadas , Transporte Proteico/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Transdução de Sinais/efeitos dos fármacos , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo , Estresse Fisiológico/efeitos dos fármacos
5.
J Plant Physiol ; 209: 31-41, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28012364

RESUMO

Ascorbate (AsA) is very important in scavenging reactive oxygen species in plants. AsA can reduce photoinhibition by xanthophyll cycle to dissipate excess excitation energy. GGP is an important enzyme in AsA biosynthesis pathway in higher plants. In this study, we cloned a gene, SlGGP-LIKE, that has the same function but different sequence compared with SlGGP. The function of SlGGP-LIKE gene in response to oxidative stress was investigated using transgenic tobacco plants overexpressed SlGGP-LIKE under methyl viologen treatment. After oxidative stress treatment, transgenic tobacco lines exhibited higher levels of reduced AsA content and APX activity than WT plants. Under oxidative stress, transgenic tobacco plants accumulated less ROS and exhibited lower degrees of REC and MDA. Consequently, relatively higher levels of Pn, Fv/Fm, de-epoxidation status of xanthophyll cycle and D1 protein were maintained in transgenic tobacco plants. Hence, overexpression of SlGGP-LIKE gene enhances AsA biosynthesis and can alleviate the photoinhibition of PSII under oxidative stress.


Assuntos
Adaptação Fisiológica/genética , Genes de Plantas , Lycopersicon esculentum/genética , Estresse Oxidativo/efeitos dos fármacos , Paraquat/toxicidade , Tabaco/fisiologia , Sequência de Aminoácidos , Ascorbato Peroxidases/metabolismo , Ácido Ascórbico/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Luz , Malondialdeído/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Transporte Proteico/efeitos dos fármacos , Alinhamento de Sequência , Frações Subcelulares/metabolismo , Superóxidos/metabolismo , Tabaco/efeitos dos fármacos , Tabaco/genética , Tabaco/efeitos da radiação , Xantofilas/metabolismo , Zeaxantinas/metabolismo
6.
J Plant Physiol ; 204: 54-65, 2016 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-27518221

RESUMO

The NAC proteins are the largest transcription factors in plants. The functions of NACs are various and we focus on their roles in response to abiotic stress here. In our study, a typical NAC gene (SlNAM1) is isolated from tomato and its product is located in the nucleus. It also has a transcriptional activity region situated in C-terminal. The expression levels of SlNAM1 in tomato were induced by 4°C, PEG, NaCl, abscisic acid (ABA) and methyl jasmonate (MeJA) treatments. The function of SlNAM1 in response to chilling stress has been investigated. SlNAM1 overexpression in tobacco exhibited higher germination rates, minor wilting, and higher photosynthetic rates (Pn) under chilling stress. Meanwhile, overexpression of SlNAM1 improved the osmolytes contents and reduced the H2O2 and O2•- contents under low temperature, which contribute to alleviating the oxidative damage of cell membrane after chilling stress. Moreover, the transcripts of NtDREB1, NtP5CS, and NtERD10s were higher in transgenic tobacco, and those increased expressions may confer higher chilling tolerance of transgenic plants. These results indicated that overexpression of SlNAM1 could improve chilling stress tolerance of transgenic tobacco.


Assuntos
Adaptação Fisiológica , Temperatura Baixa , Lycopersicon esculentum/metabolismo , Proteínas de Plantas/metabolismo , Estresse Fisiológico , Tabaco/fisiologia , Fatores de Transcrição/metabolismo , Sequência de Aminoácidos , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Estresse Oxidativo , Proteínas de Plantas/química , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Alinhamento de Sequência , Frações Subcelulares/metabolismo , Superóxidos/metabolismo , Tabaco/genética , Tabaco/crescimento & desenvolvimento , Fatores de Transcrição/química , Ativação Transcricional/genética , Regulação para Cima/genética
7.
Zhongguo Zhong Yao Za Zhi ; 40(11): 2221-6, 2015 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-26552185

RESUMO

To study the toxicokinetics of bakuchiol, hepatic and renal toxicity in rats after single oral administration of Psoraleae Fructus and combined with Glycyrrhizae Radix et Rhizoma, in order to provide scientific evidences for clinical safe medication use. A total of 35 SD rats were randomly divided into seven groups: vehicle (distilled water) control group, Glycyrrhizae Radix et Rhizoma group, positive control (aristolochic acid A) group, Psoraleae Fructus (40 g x kg(-1)) group( both male and female rats), Psoraleae Fructus and Glycyrrhizae Radix et Rhizoma (40 +20) g x kg(-1) group (both male and female rats). HPLC-UV method was used to determine the concentration of bakuchiol in rat plasma at different time points after single oral administration. Plasma alanine transaminase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), plasma creatinine (Cr), N-acetyl-ß-D-glucosaminidase (NAG) and kidney injury molecule 1 (Kim-1) were measured after administration for 24 h. The main toxicokinetics parameters of bakuchiol in rats exert significantly gender difference. When Psoraleae Fructus combination with Glycyrrhizae Radix et Rhizoma, the total area under the plasma concentration-time curve( AUC), C(max), and plasma clearance (CL) of bakuchiol were increased, respectively; CL, half-life (t½) were decreased, and T(max) were prolonged. The biochemical indicators (including ALT, AST, BUN, Cr and KIM-1 level) in different dose of Psoraleae Fructus groups, were found no statistically significant difference when compared with vehicle control group. The level of NAG in both Psoraleae Fructus and compatibility with Glycyrrhizae Radix et Rhizoma groups were significant increased (P < 0.05). There are obvious effects on toxicokinetics of bakuchiol in rats when Psoraleae Fructus combined with Glycyrrhizae Radix et Rhizoma. Renal toxicity induced by Psoraleae Fructus at high dose was observed after single oral administration and no liver damage in rats was found.


Assuntos
Glycyrrhiza/toxicidade , Rim/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fenóis/toxicidade , Psoralea/toxicidade , Administração Oral , Animais , Feminino , Masculino , Fenóis/farmacocinética , Ratos , Ratos Sprague-Dawley , Rizoma/toxicidade , Toxicocinética
8.
Chem Commun (Camb) ; 51(83): 15253-6, 2015 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-26376755

RESUMO

A mono-adenine-functionalized pillar[5]arene and a guest including uracil were prepared. They formed a novel four-unit [c2]daisy chain both in the solid state and in a chloroform solution. As far as we know, this [c2]daisy chain is the first one without a covalently bound linear thread. This unique assembly behavior is mainly induced by hydrogen-bond interactions between A and U in the A-U base pairs.

9.
Dalton Trans ; 44(21): 10078-88, 2015 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-25948375

RESUMO

The electron donor-acceptor complexes, which undergo intramolecular charge transfer under external stimulus, are an emerging class of materials showing important application in nonlinear optics. Synthesizing ferrocene/fullerene complexes through face-to-face fusion would enjoy the merits of both ferrocene and fullerene due to their strong donor-acceptor interactions. Four ferrocene/fullerene hybrid complexes with the gradual extension of fullerene cage size, including CpFe(C60H5), CpFe(C66H5), CpFe(C70H5), and CpFe(C80H5) (Cp is cyclopentadienyl), have been investigated by density functional theory. These hybrid molecules give eclipsed and staggered isomers. The main reason that the eclipsed isomer is stable is that the eclipsed structure possesses large CpFefullerene bonding energy. The CpFefullerene interaction is smaller than that of CpFefullerene, which must come from two different interfaces. The presence of covalent bond character between CpFe and fullerene is supported by the localized orbital locator, deformation of electron density distribution and energy decomposition analysis. Significantly, the absorption bands and first hyperpolarizabilities of these hybrid complexes are strongly sensitive to the fullerene cage size, which is ascribed to a change in the charge transfer pattern, especially for CpFe(C80H5), which displays reverse π → π* charge transfer from bottom to top cage, leading to notable hyperpolarizability. Investigation of the structure-property relationship at the molecular level can benefit the design and preparation of such hybrid complexes in chemistry and materials science.


Assuntos
Compostos Ferrosos/química , Fulerenos/química , Metalocenos , Modelos Químicos , Rotação Ocular
10.
J Mol Graph Model ; 55: 33-40, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25424657

RESUMO

Hexathiophenalenylium (HTPLY) has gained increasing attention for its interesting and potentially useful optical properties as a result of the enhancement in spin delocalization and charge-transfer of phenalenyl radicals, occasioned by the attachment of successive three disulfide linkages. Herein, we performed density functional theory to calculate the binding interactions, electronic absorption spectra and the second hyperpolarizabilities of cation and radical dimers of HTPLY and its nitro derivatives. It is found that the equilibrium structures of the π dimers at fully staggered position are most stable. Among these π dimers, radical dimers exhibit stronger binding interactions with respect to cation dimers. In addition, obvious red shifts in electronic spectra of radical dimers are dependent on the large interlayer charge-transfers. More importantly, radical dimers [4]dim3 and [5]dim1 exhibit a significant increase in the second hyperpolarizabilities as compared to cation dimers, which is due to lower excitation energies and larger interlayer charge-transfers. We believe that the results presented in this article shall provide important evidence for the large interlayer charge-transfers in enhancing the NLO properties of the π dimers.


Assuntos
Dimerização , Dissulfetos/química , Elétrons , Fenalenos/química , Tiofenos/química , Cátions , Conformação Molecular , Termodinâmica
11.
Phys Chem Chem Phys ; 16(33): 18017-22, 2014 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-25050910

RESUMO

Density functional theory (DFT) calculations and natural bond orbital (NBO) analysis were carried out to investigate the electronic structures and bonding features between the ruthenium(ii) atom and the SO2 molecule in two ruthenium-sulfur dioxide (SO2) adducts, trans-Ru(NH3)4(SO2)Cl(+) and [{SiW11O39}Ru(II)(SO2)](6-). In addition, the bonding interactions between SO2 and the metal-ruthenium fragment were determined by binding energy (ΔEabs) calculation and electronic structures. The results indicate that the η(1)-S-planar model in both trans-Ru(NH3)4(SO2)Cl(+) and [{SiW11O39}Ru(II)(SO2)](6-) are more favorable. NBO analysis of the bonding interaction between ruthenium and sulfur centers in the [{SiW11O39}Ru(II)(SO2)](6-) complex shows that it possesses a σ and a π bond. It predicts that the polyoxometalate [SiW11O39Ru](6-) can serve as a potential adsorbent for the SO2 molecule because of the strong Ru-S bond relative to Ru(NH3)4Cl(+).

12.
Dalton Trans ; 43(13): 5069-75, 2014 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-24413566

RESUMO

The rotary motion based on metallacarboranes around a molecular axis can be controlled by simple electron transfer processes, which provides a basis for the structure-property relationship for the nonlinear optical (NLO) switching. However, this phenomenon has not been previously reported in the development of NLO properties of metallacarboranes. In this work, the metallacarboranes [Ni(III/IV)(C2B9H11)2](-/0) and their C-,B-functionalized derivatives are studied by the density functional theory (DFT) method. By calculating relative energies, we obtained the stable states before and after rotation controlled by simple electron transfer. Then, the static and frequency-dependent second-order NLO properties were calculated by several DFT functionals. According to the TDDFT results, the large NLO responses of the studied compounds are mainly caused by substituent group-to-carborane cage charge transfer (L'LCT) and substituent group-to-metal charge transfer (L'MCT) processes. The order of first hyperpolarizabilities (ß values) illustrates that the NLO response can be enhanced by introducing a strong electron-donating group. Significantly, the geometric interconversions resulting from the redox reaction of 1C/1T-6C/6T allow the NLO responses to be switched "ON" or "OFF". The B(9,9')-methoxyphenyl-functionalized derivative of nickelacarborane, having low energetic cost and large different NLO responses between two states (from 0 to 20 998 a.u.), can be an excellent switchable NLO material.

13.
Phys Chem Chem Phys ; 16(10): 4900-10, 2014 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-24472893

RESUMO

The studies of geometrical structures, thermal stabilities, redox properties, nonlinear responses and optoelectronic properties have been carried out on a series of novel ferrocenyl (Fc) chromophores with the view of assessing their switchable and tailorable second order nonlinear optics (NLO). The use of a constant Fc donor and a 4,4'-bipyridinium acceptor and varied conjugated bridges makes it possible to systematically determine the contribution of organic connectors to chromophore nonlinear optical activities. The structures reveal that both the reduction reactions and organic connectors have a significant influence on 4,4'-bipyridinium. The potential energy surface maps along with plots of reduced density gradient mirror the thermal stabilities of the Fc-based chromophores. The first and second reductions take place preferentially at the 4,4'-bipyridinium moieties. Significantly, the reduction processes result in the molecular switches with large NLO contrast varying from zero or very small to a large value. Moreover, time-dependent density functional theory results indicate that the absorption peaks are mainly attributed to Fc to 4,4'-bipyridinium charge transfer and the mixture of intramolecular charge transfer within the two respective 4,4'-bipyridinium moieties coupled with interlayer charge transfer between the two 4,4'-bipyridinium moieties. This provides us with comprehensive information on the effect of organic connectors on the NLO properties.

14.
J Mol Graph Model ; 48: 28-35, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24366003

RESUMO

The unusual properties of Li-doped boron nitride nanomaterials have been paid further attention due to their wide applications in many promising fields. Here, density functional theory (DFT) calculations have been carried out to investigate the second-order nonlinear optical (NLO) properties of boron nitride nanocone (BNNC) and its Li-doped BNNC derivatives. The natural bond orbital charge, electron location function, localized orbital locator and frontier molecular orbital analysis offer further insights into the electron density of the Li-doped BNNC derivatives. The electron density is effectively bounded by the Li atom and its neighboring B atoms. The Li-doped BNNC molecules exhibit large static first hyperpolarizabilities (ß(tot)) up to 1.19×10³ a.u. for Li@2N-BNNC, 5.05×10³ a.u. for Li@2B-BNNC, and 1.08×10³ a.u. for Li@BN-BNNC, which are significantly larger than that of the non-doped BNNC (1.07×10² a.u.). The further investigations show that there are clearly dependencies of the first hyperpolarizabilities on the transition energies and oscillator strengths. Moreover, time-dependent DFT results show that the charge transfer from BNNC to Li atom becomes more pronounced as doping the Li atom to BNNC. It is also found that the frequency-dependent effect on the first hyperpolarizabilities is weak, which may be beneficial to experimentalists for designing Li-doped BNNC molecules with large NLO responses.


Assuntos
Compostos de Boro/química , Lítio/química , Simulação por Computador , Complexos de Coordenação/química , Modelos Químicos , Modelos Moleculares , Conformação Molecular , Teoria Quântica , Termodinâmica
15.
Plant Cell Rep ; 33(1): 131-42, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24129846

RESUMO

KEY MESSAGE: Transgenic tomato plants overexpressing LeFAD3 sense and antisense sequences were generated. Salt stress suppressed the growth of WT and antisense plants to a higher extent than that in sense plants. In this study, we investigated the role of the LeFAD3-encoding ER-type omega-3 fatty acid desaturase in salt tolerance in tomato plants. We created transgenic tomato plants by overexpressing its sense and antisense sequences under the control of the cauliflower mosaic virus 35S promoter. Based on the results of northern and western blotting as well as quantitative reverse transcription-polymerase chain reaction, sense plants expressed more desaturase than wild-type (WT) plants, whereas antisense plants expressed less desaturase than WT. Salt stress suppressed the growth of both WT and antisense plants to a higher extent than that in sense plants, which can be attributed to the fact that sense plants performed better in maintaining the integrity of the membrane system, as revealed by electron microscopy. The concomitant increase in superoxide dismutase (EC 1.15.1.1) and ascorbate peroxidase (EC 1.11.1.7) may have alleviated the photoinhibition caused by the increased level of ROS in sense plants. Our results suggest that LeFAD3 overexpression can enhance the tolerance of early seedlings to salinity stress.


Assuntos
Retículo Endoplasmático/enzimologia , Ácidos Graxos Dessaturases/metabolismo , Lycopersicon esculentum/enzimologia , Lycopersicon esculentum/fisiologia , Salinidade , Tolerância ao Sal , Plântula/enzimologia , Ascorbato Peroxidases/metabolismo , Condutividade Elétrica , Retículo Endoplasmático/efeitos dos fármacos , Ácidos Graxos Dessaturases/genética , Ácidos Graxos/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Lycopersicon esculentum/efeitos dos fármacos , Lycopersicon esculentum/genética , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/genética , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/ultraestrutura , Plantas Geneticamente Modificadas , Tolerância ao Sal/efeitos dos fármacos , Tolerância ao Sal/genética , Plântula/efeitos dos fármacos , Plântula/fisiologia , Cloreto de Sódio/farmacologia , Estresse Fisiológico/efeitos dos fármacos , Estresse Fisiológico/genética , Superóxido Dismutase/metabolismo
16.
Plant Physiol Biochem ; 73: 309-20, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24184451

RESUMO

ICE1 (inducer of CBF expression 1), a MYC-type bHLH transcription factor, is an important activator of CBF3/DREB1A for regulating cold signaling and stress tolerance. In this study, we isolated the novel ICE1-like gene SlICE1a from tomato which contains the conserved bHLH domain, an S-rich motif, and ACT-domain. It is localized in the nucleus and harbors transcription-activating activity in the N-terminal. In addition, the SlICE1a transcript is slightly upregulated by cold stress, salt stress, and osmotic stress. SlICE1a overexpression in tobacco enhances the induction of CBF/DREB and their target genes, consequently increasing the levels of proline, soluble sugars, and late embryogenesis abundant (LEA) proteins, and enhancing tolerance to cold stress, osmotic stress, and salt stress. SlICE1a functions in abiotic stress responses by regulating the expression of stress-tolerant genes, and is thus beneficial for crop improvement.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Temperatura Baixa , Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum/genética , Pressão Osmótica , Tolerância ao Sal/genética , Tabaco/genética , Adaptação Fisiológica/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Metabolismo dos Carboidratos , Genes de Plantas , Lycopersicon esculentum/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Prolina/metabolismo , Estresse Fisiológico/genética , Tabaco/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
17.
J Phys Chem A ; 117(47): 12497-510, 2013 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-24180267

RESUMO

The second-order nonlinear optical (NLO) properties of a series of Pt(II) dithienylethene (DTE) complexes possessing the reversible photochromic behavior have been investigated by density functional theory (DFT) combined with the analytic derivatives method. The results show that the calculated static first hyperpolarizabilities (ßtot) of the open-ring and closed-ring systems significantly increase in the range of 2.1-4.5 times through strengthening of the electron-withdrawing ability of the substituent R (R = H, CF3, NO2) and an increase of the number of thiophene rings. Moreover, there is a large enhancement of the ßtot values from the open-ring systems to the corresponding closed-ring systems. This efficient enhancement is attributed to the better delocalization of the π-electron system, the more obvious degree of charge transfer, and the larger f(os)/E(gm)(3) (f(os) is the oscillator strength, and E(gm) is the transition energy between the ground and the excited states) values in the closed forms according to the bond length alternation (BLA) and time-dependent density functional theory (TDDFT) calculations. In addition, the dispersion has less influence on the frequency-dependent first hyperpolarizabilities (ßtot(ω)) of the studied systems at the low-frequency area ω (0.000-0.040 au). Our present work would be beneficial for further theoretical and experimental studies on large second-order NLO responses of metal complexes.


Assuntos
Compostos Organoplatínicos/química , Tiofenos/química , Estrutura Molecular , Fenômenos Ópticos , Processos Fotoquímicos , Teoria Quântica
18.
J Mol Model ; 19(12): 5479-87, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24241127

RESUMO

The polycyclic p-quinodimethanes are proposed to be the novel candidates of the high-performance nonlinear optical (NLO) materials because of their large third order polarizabilities (γ). We investigate the switchable NLO responses of a series of polycyclic p-quinodimethanes with redox properties by employing the density functional theory (DFT). The polycyclic p-quinodimethanes are forecasted to exhibit obvious pure diradical characters because of their large y 0 index (the y 0 index is a value between 0 [closed-shell state] and 1 [pure biradical state]). The γ values of these polycyclic p-quinodimethanes and their corresponding one-electron and two-electron reduced/oxidized species are calculated by the (U)BHandHLYP method. The γ values of polycyclic p-quinodimethanes and their corresponding one-electron reduced species are all positive and significantly different. The large differences of the γ values are due to a change in the transition energy and are related to the different delocalization of the spin density, which demonstrates that the NLO switching is more effective on one-electron reduction reactions. Therefore, the study on these polycyclic p-quinodimethanes provides a guideline for a molecular design of highly efficient NLO switching.

19.
J Phys Chem A ; 117(41): 10783-9, 2013 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-24099065

RESUMO

The switchable second-order nonlinear optical (NLO) properties on two-dimensional (2D) molecules based on Lindqvist-type [Mo6O19](2-) and dithienylperfluorocyclopentene (DTE) have been investigated at density functional theory (DFT) level. The CAM-B3LYP and M06-2X functionals were employed to study the switching behavior on NLO properties by photoisomerization reaction. The ßtot value of system 2c (closed-ring form) is 15920.5 au, which is 150.1 times larger than that of the corresponding open-ring form (system 2o). The time-dependent DFT calculations predict that the charge transfer from DTE to polyoxometalate, and DTE intramolecular charge transfer in closed-ring systems effectively improve the static first hyperpolarizability. Furthermore, the Λ-shaped systems possess a larger u value than those of W-shaped systems owing to different orientation for substituent groups.

20.
J Mol Graph Model ; 44: 26-32, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23732303

RESUMO

The ultraviolet-visible and electronic circular dichroism (UV-vis/ECD) spectra of diphosphonate-functionalized asymmetric cantilever-type chiral polyoxomolybdate (POM) enantiomer R-{Mo2O5[(Mo2O6)NH3CH2CH2CH2C(O)(PO3)2]2}(6-) (R) were systematically investigated using time-dependent density functional theory (TDDFT) method. From the view of molecular structure and relative energy, we inferred that there is likely a structural conversion from enantiomers R to S-{Mo2O5[(Mo2O6)NH3CH2CH2CH2C(O)(PO3)2]2}(6-) (S) via the intermediate configuration (IN). The ECD spectra of the enantiomer R were produced over the range of 3.0-6.3eV. The UV-vis and ECD spectra of enantiomer R in the gas phase and different solvents were calculated. The results reveal that the UV-vis and ECD spectra of the chiral POM in gas phase, polar solvent, or non-polar solvent are different. The calculated electron density difference maps (EDDMs) display that the POM cluster is a chiroptical chromophore in studied compound.


Assuntos
Dicroísmo Circular , Difosfonatos/química , Elétrons , Modelos Moleculares , Molibdênio/química , Polímeros/química , Solventes/química , Conformação Molecular
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