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2.
In Silico Pharmacol ; 12(1): 35, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38680655

RESUMO

Dengue virus type 2 (DENV-2) is an arthropod-borne deadly RNA human pathogen transmitted through the mosquito Aedes. The DENV-2 roots viral infection by facilitating entry with its envelope glycoprotein to the receptor protein Dendritic-cell-specific ICAM3-grabbing non-integrin (DC-SIGN) through membrane fusion. Here, an organizational path is reported for inhibiting the transition due to fusion activation and by blocking the residues of the DC-SIGN-E-Glyco protein complex through citrus limonoids with its antiviral effect. Based on lower binding affinity obtained with E-glycoprotein, and based on ADMET and drug-likeness study, limonin was selected as having effective interaction with DC-SIGN-E-glycoprotein complex in comparison to other citrus limonoids. The FTIR spectra performed with the limonin-E-glycoprotein sample provide evidence of hydrogen bond formation that indicates the formation of a strong limonin-E-glycoprotein conjugate. Further, the strong physical interaction between DC-SIGN and small limonin molecules in comparison to that of E-glyco with DC-SIGN assures the development of immunity against DENV-2. Supplementary Information: The online version contains supplementary material available at 10.1007/s40203-024-00207-2.

3.
Immunity ; 57(5): 1124-1140.e9, 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38636522

RESUMO

Signaling through Notch receptors intrinsically regulates tumor cell development and growth. Here, we studied the role of the Notch ligand Jagged2 on immune evasion in non-small cell lung cancer (NSCLC). Higher expression of JAG2 in NSCLC negatively correlated with survival. In NSCLC pre-clinical models, deletion of Jag2, but not Jag1, in cancer cells attenuated tumor growth and activated protective anti-tumor T cell responses. Jag2-/- lung tumors exhibited higher frequencies of macrophages that expressed immunostimulatory mediators and triggered T cell-dependent anti-tumor immunity. Mechanistically, Jag2 ablation promoted Nr4a-mediated induction of Notch ligands DLL1/4 on cancer cells. DLL1/4-initiated Notch1/2 signaling in macrophages induced the expression of transcription factor IRF4 and macrophage immunostimulatory functionality. IRF4 expression was required for the anti-tumor effects of Jag2 deletion in lung tumors. Antibody targeting of Jagged2 inhibited tumor growth and activated IRF4-driven macrophage-mediated anti-tumor immunity. Thus, Jagged2 orchestrates immunosuppressive systems in NSCLC that can be overcome to incite macrophage-mediated anti-tumor immunity.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Fatores Reguladores de Interferon , Proteína Jagged-2 , Neoplasias Pulmonares , Camundongos Knockout , Macrófagos Associados a Tumor , Proteína Jagged-2/metabolismo , Proteína Jagged-2/genética , Proteína Jagged-2/imunologia , Animais , Neoplasias Pulmonares/imunologia , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/genética , Carcinoma Pulmonar de Células não Pequenas/imunologia , Carcinoma Pulmonar de Células não Pequenas/patologia , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Camundongos , Humanos , Fatores Reguladores de Interferon/metabolismo , Fatores Reguladores de Interferon/genética , Macrófagos Associados a Tumor/imunologia , Macrófagos Associados a Tumor/metabolismo , Transdução de Sinais , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas de Ligação ao Cálcio/genética , Linhagem Celular Tumoral , Camundongos Endogâmicos C57BL , Receptores Notch/metabolismo , Receptor Notch1/metabolismo , Receptor Notch1/genética , Macrófagos/imunologia , Macrófagos/metabolismo , Proteína Jagged-1/metabolismo , Proteína Jagged-1/genética , Evasão Tumoral/imunologia
4.
Anal Chim Acta ; 1273: 341500, 2023 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-37423659

RESUMO

Accurate and rapid detection and isolation become indispensable to restrict the spread of COVID-19. Since the start of COVID-19 pandemic in December 2019, many indisposal diagnostic tools are being developed incessantly. Out of all presently used tools, the gold standard rRT- PCR tool having very high sensitivity and specificity is a time consuming complicated molecular technique having requirements of special expensive equipment. Here, the main focus of this work is to develop rapid disposal paper capacitance sensor having simple and easy detection. We discovered a strong interaction between limonin and Spike-glycoprotein of SARS-COV-2 in comparison to its interaction with other similar viruses such as HCOV-OC43, HCOV-NL63, HCOV-HKU1, Influenza B and A viruses. The antibody free capacitive sensor having comb electrode structure was fabricated on whatman paper with drop coating of limonin (extracted using green method from pomelo seeds) and calibrated with known swab samples. The Blind test with unknown swab samples shows high sensitivity of 91.5% and high specificity of 88.37%. Requiring low sample volume and detection time and using biodegradable materials in the sensor fabrication assure the potential application as a point of care disposal diagnostic tool.


Assuntos
COVID-19 , Limoninas , Humanos , COVID-19/diagnóstico , SARS-CoV-2 , Pandemias , Teste para COVID-19
5.
Nat Chem ; 15(2): 160-162, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36702884
6.
Angew Chem Int Ed Engl ; 62(5): e202216540, 2023 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-36469042

RESUMO

Organic cages have gained increasing attention in recent years as molecular hosts and porous materials. Among these, barrel-shaped cages or molecular nanobarrels are promising systems to encapsulate large hosts as they possess windows of the same size as their internal cavity. However, these systems have received little attention and remain practically unexplored despite their potential. Herein, we report the design and synthesis of a new trigonal prismatic organic nanobarrel with two large triangular windows with a diameter of 12.7 Šoptimal for the encapsulation of C60 . Remarkably, this organic nanobarrel shows a high affinity for C60 in solvents in which C60 is virtually insoluble, providing stable solutions of C60 .

7.
Nat Chem Biol ; 19(1): 9-17, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36050494

RESUMO

The Notch pathway regulates cell fate decisions and is an emerging target for regenerative and cancer therapies. Recombinant Notch ligands are attractive candidates for modulating Notch signaling; however, their intrinsically low receptor-binding affinity restricts their utility in biomedical applications. To overcome this limitation, we evolved variants of the ligand Delta-like 4 with enhanced affinity and cross-reactivity. A consensus variant with maximized binding affinity, DeltaMAX, binds human and murine Notch receptors with 500- to 1,000-fold increased affinity compared with wild-type human Delta-like 4. DeltaMAX also potently activates Notch in plate-bound, bead-bound and cellular formats. When administered as a soluble decoy, DeltaMAX inhibits Notch in reporter and neuronal differentiation assays, highlighting its dual utility as an agonist or antagonist. Finally, we demonstrate that DeltaMAX stimulates increased proliferation and expression of effector mediators in T cells. Taken together, our data define DeltaMAX as a versatile tool for broad-spectrum activation or inhibition of Notch signaling.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Peptídeos e Proteínas de Sinalização Intercelular , Humanos , Animais , Camundongos , Ligantes , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Transdução de Sinais/fisiologia , Receptores Notch/metabolismo
8.
Cancer Cell ; 40(10): 1145-1160.e9, 2022 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-36150390

RESUMO

Activation of unfolded protein responses (UPRs) in cancer cells undergoing endoplasmic reticulum (ER) stress promotes survival. However, how UPR in tumor cells impacts anti-tumor immune responses remains poorly described. Here, we investigate the role of the UPR mediator pancreatic ER kinase (PKR)-like ER kinase (PERK) in cancer cells in the modulation of anti-tumor immunity. Deletion of PERK in cancer cells or pharmacological inhibition of PERK in melanoma-bearing mice incites robust activation of anti-tumor T cell immunity and attenuates tumor growth. PERK elimination in ER-stressed malignant cells triggers SEC61ß-induced paraptosis, thereby promoting immunogenic cell death (ICD) and systemic anti-tumor responses. ICD induction in PERK-ablated tumors stimulates type I interferon production in dendritic cells (DCs), which primes CCR2-dependent tumor trafficking of common-monocytic precursors and their intra-tumor commitment into monocytic-lineage inflammatory Ly6C+CD103+ DCs. These findings identify how tumor cell-derived PERK promotes immune evasion and highlight the potential of PERK-targeting therapies in cancer immunotherapy.


Assuntos
Interferon Tipo I , Neoplasias , Animais , Estresse do Retículo Endoplasmático , Interferon Tipo I/metabolismo , Camundongos , Transdução de Sinais , Linfócitos T/metabolismo , Resposta a Proteínas não Dobradas , eIF-2 Quinase/genética , eIF-2 Quinase/metabolismo
9.
Angew Chem Int Ed Engl ; 61(35): e202207641, 2022 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-35801523

RESUMO

Diels-Alder photocycloaddition, a well-known textbook reaction, has not been explored in materials chemistry. Herein we describe how this classical photochemistry can be used to modulate the lower critical solution temperature (LCST) of a molecular π-system, which can further be exploited for the controlled transmission of solar radiation for the management of indoor heat and light. An amphiphilic anthracene derivative 9-PA-1 exhibited LCST behavior at 27-32 °C with a reversible transition from a transparent to an opaque phase in water (1-5 mM). Irradiation of a toluene solution of 9-PA-1 with 365 nm light resulted in a [4+2] photocycloadduct 9-PA-2, which exhibited a modulated LCST behavior at 25-27 °C, at a concentration as low as 6 µM. The photocycloaddition of 9-PA-1 was significantly retarded in water, making it a stable candidate for the design of sustainable smart windows. We also demonstrated 100 cm2 smart window prototypes (ΔTlum 82 %, ΔTIR 68 %, ΔTsol 73 %) with more than 1000 cycles of stable operation.

10.
Chem Commun (Camb) ; 58(48): 6837-6840, 2022 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-35616190

RESUMO

High charge carrier mobility is a prerequisite for organic electronics for which molecular arrangement and morphology play a vital role. Herein, we report how the self-assembly of thienylenevinylenes T1 and T2 can achieve morphologically distinct nanostructures with improved charge carrier mobility. Morphological analysis revealed that T1 forms 2D nanosheets that further extend to an array of hierarchical pseudo-1D assemblies, whereas T2 results in 1D nanofibers. Flash photolysis - time resolved microwave conductivity and transient absorption spectroscopy (FP-TRMC and TAS) revealed that 1D fibers of T2 show 1.75 fold higher charge carrier mobility (9.2 × 10-2 cm2 V-1 s-1) when compared to the array of 2D sheets obtained from T1 (5.0 × 10-2 cm2 V-1 s-1). This simple approach can be extended to design self-assembled organic photoconducting materials for optoelectronic applications.

11.
Food Chem ; 381: 132248, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35123220

RESUMO

Limonin, a highly oxygenated triterpene biomolecule of citrus fruits is responsible for delayed bitterness of its juice lowering consumer's acceptability. Hence, limonin detection is essential for appropriate debittering intrusions. A novel interdigitated capacitive sensor using magnesium silicate-poly vinyl alcohol (MgSiO3.xH2O-PVA) composite has been introduced for quantification of limonin and debittering through selective adsorption of limonin from the citrus limetta juice. The sensor showed high sensitivity of 2.392 µF/ppm and fast response time of ∼6s. The sensor enables both quantification as well as measure debittering of citrus juice showing a reduction in limonin content from 5.77 ppm to 4.29 ppm with an exposure time of 60s to the sensing material making it distinctive in comparison to other methods. The sensor's results were validated with HPLC analysis. The device is simple, low-cost and reusable which promises easy, on-site and rapid quantification and reduction of limonin content in citrus juices without having toxicity.


Assuntos
Citrus , Limoninas , Triterpenos , Citrus/química , Eletrodos , Sucos de Frutas e Vegetais/análise , Limoninas/análise , Triterpenos/análise
12.
Food Chem ; 377: 131947, 2022 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-34998150

RESUMO

Maturity determination of pomelo fruits having health-benefiting attributes is an important issue to enhance the quality of harvesting. Here, an interdigitated electrode (IDE) based sensor is introduced to detect its maturity by determining the naringin content. The sensor was made by depositing amberlite IRA-400 as a sensing layer on IDE patterned PCB substrate at room temperature with hydrothermal and spin-coating techniques. The sensor exhibits excellent selectivity for naringin, high sensitivity of 0.008 µA for 10 ppb of naringin, and reusability up to 3-4 times for naringin quantification in maturity testing of fruits. The pomelo fruits start to mature when maximum values of current response and naringin content are found at 140 DAFS. The naringin content decreases as maturity progresses and maximum phytochemical attributes were obtained at 180-220 DAFS. The IDE sensor assures an appropriate period of plucking of pomelo fruits improving harvesting practices and trade of citrus fruits.


Assuntos
Citrus , Flavanonas , Eletrodos , Frutas
13.
RSC Adv ; 10(43): 25540-25546, 2020 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-35518573

RESUMO

We report the fabrication of a solution-processed n-type Thin Film Transistor (TFT) with current on/off ratios of 104, a turn-on voltage (V ON) of 1.2 V and a threshold voltage (V T) of 6.2 V. The TFT incorporates an insoluble and intractable dielectric layer (k = 7-9) prepared in situ from solution-processed and then photopolymerised ligand-stabilised, inorganic/organic TiO2 nanorods. A solution processed zinc oxide (ZnO) layer acts as the semiconductor. The new surface-modified TiO2 nanorods were synthesised using a ligand replacement process with a monolayer coating of photopolymerisable 10-undecynylphosphonic acid (10UCYPA) to render them both soluble in common organic solvents and be photopolymerisable using UV-illumination after having been deposited on substrate surfaces from solution and drying.

14.
Infect Disord Drug Targets ; 20(5): 651-658, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31258093

RESUMO

BACKGROUND: A high incidence of vitamin-D deficiency and abnormal bone mineral density (BMD) is reported among Human Immunodeficiency Virus (HIV) infected patients. The study highlighted the effect of oral low dose vitamin-D replacement in patients with a known vitamin- D deficiency on the levels of vitamin-D [25 (OH)D], parathyroid hormone (PTH) and Bone Mineral Density (BMD) of hip and spine. METHODS: Patients took a daily low dose of 800IU of vitamin-D. The following details were collected on all patients: demographics, CD-4 cell count, viral load, fracture risk factors, treatment history, corrected calcium, alkaline phosphatase (ALP), Parathyroid Hormone (PTH) (intact PTH), vitamin D 25(OH)D, inorganic phosphate and BMD of hip and spine at baseline, 12 and 36 months. RESULTS: Our Cohort consisted of 86 patients. Patient details included: mean age 42.8 (+/-7.7) years, 48 (55%) females 64, (74%) black African, CD-4 count 440.7 (+/-180.8) cells/dL, plasma VL 1.6 log (+/-2.3) copies/mL, duration of illness 80.9 (34.1) months, duration of exposure to antiretroviral 65.2 (+/-27.9) months. At baseline, no difference in BMD of hip or spine was observed, however, a higher PTH (0.001) in patients taking Tenofivir and a lower vitamin-D was noticed in patients taking Efavirenz. After 36 months, patients on vitamin D replacement (n=44) had a significant increase in vitamin- D level (15.4 +/-10.4 vs 104.1+/-29.1 p=0.0001), lower PTH (6.3 +/-3.4 vs 4.4 +/-1.4 p=0.0001) ALP (108.9+/-78.8 vs 90.6+/-45.8 p=0.05) but no change in corrected calcium (2.13 +/-0.1 vs 2.16 +/-0.34 p=0.5) and BMD of spine (1.039+/-0.226 vs.1.027+/-0.211, p=0.77), and BMD of hip (1.020 +/- 0.205 vs. 1.039, p=0.61). In a multivariate logistic regression analysis that included all significant variables, vitamin-D replacement independently was associated with increase in vitamin- D level (OR 2.08, CI 1.03, 4.12, p=0.005), decrease in PTH level (OR 0.53, CI 0.35, 0.82, p=0.04), but not with change in corrected calcium, alkaline phosphatase, BMD of hip or spine. CONCLUSION: After 36 months of follow up, the replacement of low dose once daily oral vitamin-D in the treatment experienced HIV infected patients with vitamin-D deficiency can increase vitamin- D level, reduce PTH level without any change in BMD of spine and hip.


Assuntos
Fármacos Anti-HIV/efeitos adversos , Densidade Óssea/efeitos dos fármacos , Infecções por HIV/complicações , Deficiência de Vitamina D/prevenção & controle , Vitamina D/administração & dosagem , Adulto , Alcinos/efeitos adversos , Alcinos/farmacologia , Fármacos Anti-HIV/farmacologia , Benzoxazinas/efeitos adversos , Benzoxazinas/farmacologia , Ciclopropanos/efeitos adversos , Ciclopropanos/farmacologia , Feminino , Seguimentos , Infecções por HIV/tratamento farmacológico , Infecções por HIV/etnologia , Humanos , Masculino , Pessoa de Meia-Idade , Hormônio Paratireóideo/metabolismo , Estudos Prospectivos , Tenofovir/efeitos adversos , Tenofovir/farmacologia , Vitamina D/farmacologia , Deficiência de Vitamina D/etnologia , Deficiência de Vitamina D/etiologia
15.
Infect Disord Drug Targets ; 20(2): 122-142, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-30574856

RESUMO

With the advent of combination antiretroviral therapy (cART), the survival of HIV patients has improved dramatically, but the complications of the disease and treatment have become an important issue in the management of HIV patients. Vitamin-D deficiency is common in HIV patients. Low vitamin-D is associated with different comorbidities in the HIV uninfected general population. In this review, we first briefly describe vitamin D synthesis and mechanism of action and we focus on the epidemiological and clinical data dealing with the relationship between vitamin D deficiency in HIV infection with several comorbidities which has been found to be increasingly common in patients living with HIV infection. We searched the PubMed database using the keywords "HIV," "vitamin D" and other common disorders or conditions that are relatively common in HIV infection. The other conditions included in the search were osteoporosis and fracture, cardiovascular disease, diabetes and insulin resistance, active tuberculosis, hepatitis-C co-infection, and HIV disease progression. Articles presenting original data as well as systematic reviews and met analysis related to HIV population were included in our analysis. Vitamin-D deficiency seems to be associated with several adverse outcomes in HIV patients but a definite cause and effect relationship with vitamin-D is yet to be confirmed in most of the cases. However, the literature supporting the efficacy of vitamin-D supplementation is lacking.


Assuntos
Síndrome da Imunodeficiência Adquirida/complicações , Síndrome da Imunodeficiência Adquirida/epidemiologia , Infecções por HIV/complicações , Infecções por HIV/epidemiologia , Deficiência de Vitamina D/complicações , Terapia Antirretroviral de Alta Atividade , Ensaios Clínicos como Assunto , Comorbidade , Suplementos Nutricionais , Humanos , Fatores de Risco , Vitamina D/sangue
17.
JMIR Form Res ; 3(2): e11242, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31042156

RESUMO

BACKGROUND: Young people aged 16-24 years are disproportionately affected by sexually transmitted infections (STIs). STIs can have serious health consequences for affected individuals and the estimated annual cost of treatment to the National Health Service is £620 million. Accordingly, the UK government has made reducing the rates of STIs among this group a priority. A missed opportunity to intervene to increase condom use is when young people obtain self-sampling kits for STIs via the internet. OBJECTIVE: Our aim was to develop a theory-based tailored intervention to increase condom use for 16-24-years-olds accessing chlamydia self-sampling websites. METHODS: The intervention, Wrapped, was developed using Intervention Mapping and was co-designed with young people. The following steps were performed: (1) identification of important determinants of condom use and evidence of their changeability using computer and digital interventions; (2) setting the intervention goal, performance objectives, and change objectives; (3) identification of Behavior Change Principles (BCPs) and practical strategies to target these determinants; and (4) development of intervention materials able to deliver the BCPs and practical strategies. RESULTS: Users of existing chlamydia self-sampling websites are signposted to Wrapped after placing an order for a sampling kit. Salient barriers to condom use are identified by each user and relevant intervention components are allocated to target these. The components include the following: (1) a sample box of condoms, (2) an online condom distribution service, (3) a product for carrying condoms, (4) a condom demonstration video, (5) a series of videos on communication about condom use, and (6) erotic films of real couples discussing and demonstrating condom use. CONCLUSIONS: This intervention will be directed at young people who may be particularly receptive to messages and support for behavior change due to their testing status.

18.
J Am Chem Soc ; 141(14): 5635-5639, 2019 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-30924646

RESUMO

Diels-Alder photocycloaddition of 9-phenylethynylanthracene results in multiple [4 + 2] and [4 + 4] cycloaddition products in solution, which can be controlled to form specific products under a restricted environment. We have exploited the gel phase of a 9-phenylethynylanthracence derivative as a confined medium to specifically yield the [4 + 2] cycloadduct in >90% yield. The photocycloadduct ( anti-form) exhibited a blue emission with CIE chromaticity of x = 0.16/ y = 0.16. Construction of an organic light emitting device with the photocycloadduct, using a carbazole-based hole transporting host, resulted in white light emission with a CIE chromaticity of x = 0.33/ y = 0.32. This observation not only highlights the use of gel chemistry to achieve the otherwise difficult to obtain photoproducts but also underlines their potential in optoelectronic device fabrication.

19.
Appl Psychol Health Well Being ; 10(3): 391-413, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30198101

RESUMO

BACKGROUND: Inconsistent use of the contraceptive pill and condoms contributes significantly to poor sexual health outcomes for young people. There is evidence that action planning interventions may improve pill and condom use, but this approach is not systematically used in sexual healthcare. This study is the first to assess acceptability and feasibility of evaluating a digital intervention to support action plan formation for three sexual health behaviours with clinic attendees. It also considered the role of trait self-control and whether the intervention supported production of quality plans. METHODS: Eighty-eight integrated sexual health clinic attendees aged 14-24 years (M = 20.27 years) were recruited to a pilot randomised controlled trial (RCT). Of these, 67 also completed three-month follow-up. Measures included self-reported contraceptive or condom "mishaps", theory of planned behaviour variables, and a measure of self-control. RESULTS: Descriptive analyses supported study acceptability and feasibility. The intervention supported pill and condom users to produce quality plans, though potential improvements were identified. Bivariate correlations suggested that high levels of trait self-control may negatively influence plan quality. Data suggest that the intervention may reduce pill or condom "mishaps". CONCLUSIONS: A future full RCT is likely feasible and brief digital action planning interventions may usefully be incorporated within sexual healthcare.


Assuntos
Terapia Comportamental/métodos , Preservativos , Anticoncepcionais Orais Hormonais , Comportamentos Relacionados com a Saúde , Autocontrole , Comportamento Sexual , Telemedicina/métodos , Adolescente , Adulto , Estudos de Viabilidade , Feminino , Seguimentos , Humanos , Masculino , Avaliação de Resultados em Cuidados de Saúde , Aceitação pelo Paciente de Cuidados de Saúde , Projetos Piloto , Adulto Jovem
20.
Plant Physiol Biochem ; 123: 213-221, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29248679

RESUMO

Water stress is a common problem in Indian agriculture and recent global climate change has aggravated this problem further. Plants have an adaptive response to water scarcity as reflected in differential root and shoot growth. In case of Vigna radiata seedlings we have observed earlier promotion of root growth while inhibition of shoot (hypocotyl) growth under mild water stress, which is probably mediated by ABA. However, the exact mechanism of ABA action is far from clear. The present study attempts to elucidate the action of ABA through apoplastic reactive oxygen species (ROS) and its impact upon antioxidant defence system during the growth of root and shoot under water stress. Thus promotion of root growth by application of exogenous ABA (10 µM) and mild water stress (ψ -0.5 MPa) may be correlated with enhanced apoplastic ROS production possibly by activating plasma membrane located NADPH oxidase (NOX) enzyme. On the contrary, in hypocotyls where growth was rather inhibited by application of water stress or ABA, neither NOX activity nor ROS accumulation was significantly detected upon these treatments. Overall activity of antioxidant enzymes [superoxide dismutase (SOD, EC 1.15.1.1), peroxidase (POX, EC 1.11.1.7), ascorbate peroxidase (APX, EC 1.11.1.1) and catalase (CAT, EC 1.11.1.6)] was high and somewhat promoted by ABA and water stress treatment in roots compared to hypocotyls. A possible ROS-mediated role of ABA in promoting growth and antioxidant activity in roots under water stress has been proposed.


Assuntos
Ácido Abscísico/metabolismo , Pressão Osmótica , Raízes de Plantas/crescimento & desenvolvimento , Brotos de Planta/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Vigna/crescimento & desenvolvimento
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