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1.
J Synchrotron Radiat ; 24(Pt 1): 232-239, 2017 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-28009562

RESUMO

Experiments were conducted to study the effects of static magnetic fields (SMFs) on the venation network of soybean leaves using the synchrotron-based X-ray micro-imaging technique. The seeds of soybean (Glycine max, variety JS-335) were pretreated with different SMFs from 50 to 300 mT in steps of 50 mT for 1 h. The phase-contrast images obtained showed that, as the strength of the SMF increased, the area, width of the midrib, area of the midrib and minor vein of the middle leaflets of third trifoliate leaves also increased up to the SMF strength of 200 mT (1 h) and decreased thereafter. Quantification of the major conducting vein also showed the differences in the major and minor vein structures of the soybean leaves as compared with control leaves. Further, the phase-retrieval technique has been applied to make the segmentation process easy and to quantify the major and minor veins in the venation network. The width and area of midrib enhancement by pre-treatment with SMF implies an enhancement in the uptake of water, which in turn causes an increased rate of photosynthesis and stomatal conductance.


Assuntos
Folhas de Planta/química , Síncrotrons , Fotossíntese , Folhas de Planta/fisiologia , Sementes , Glycine max
2.
J Synchrotron Radiat ; 23(Pt 3): 795-801, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27140160

RESUMO

The hydraulic efficiency of a leaf depends on its vascular structure as this is responsible for transport activities. To investigate the effect of exclusion of UVAB and UVB radiation from the solar spectrum on the micro-structure of leaves of soybean (Glycine max, variety JS-335), a field experiment was conducted using synchrotron-based phase contrast imaging (PCI). Plants were grown in specially designed UV exclusion chambers, and wrapped with filters that excluded UVB (280-315 nm) or UVAB (280-400 nm), or transmitted all the ambient solar UV (280-400 nm) radiation (filter control). Qualitative observation of high-resolution X-ray PCI images obtained at 10 keV has shown the differences in major and minor vein structures of the leaves. The mid-rib width of the middle leaflet of third trifoliate leaves, for all treatments, were obtained using quantitative image analysis. The width of the mid-rib of the middle leaflet of third trifoliate leaves of UVB excluded plants was found to be more compared to leaves of filter control plants, which are exposed to ambient UV. The mid-rib or the main conducting vein transports water and sugars to the whole plant; therefore, mid-rib enhancement by the exclusion of solar UV radiation possibly implies enhancement in the leaf area which in turn causes an increased rate of photosynthesis.


Assuntos
Glycine max , Folhas de Planta , Luz Solar , Síncrotrons , Raios Ultravioleta , Raios X
3.
Pestic Biochem Physiol ; 114: 61-6, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25175651

RESUMO

A field study was conducted to investigate the impact of the fungicide pyraclostrobin (F500 - Headline®; a.i. 20%) on the activity of nitrogenase in soybean (var. JS-335). Pyraclostrobin (F500) was applied on the leaves of soybean plants at 10 and 20 days after emergence (DAE) of seedlings at concentrations ranging from 0.05% to 1%. Leghemoglobin (Lb) content and nitrogenase activity in root nodules were analyzed at 45(th)day after emergence of seedlings indicated a remarkable increase in Lb content and enhanced activity of nitrogenase in the root nodules of pyraclostrobin treated plants. The fungicide also enhanced the number of nodules along with weight of nodules, root biomass and growth of shoot and leaves. Enhanced nitrogen fixation in the root nodules by pyraclostrobin improves the growth of the plant in soybean before flowering and pod formation which ultimately resulted in yield and yield attributes. These results suggest that pyraclostrobin (F500) can be successfully employed as a foliar spray under field conditions to enhance the growth, nitrogen assimilation and hence yield of soybean.


Assuntos
Carbamatos/farmacologia , Fungicidas Industriais/farmacologia , Glycine max/efeitos dos fármacos , Nitrogenase/metabolismo , Proteínas de Plantas/metabolismo , Pirazóis/farmacologia , Nódulos Radiculares de Plantas/efeitos dos fármacos , Biomassa , Fixação de Nitrogênio/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/fisiologia , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/fisiologia , Nódulos Radiculares de Plantas/fisiologia , Glycine max/fisiologia , Estrobilurinas
4.
J Assoc Physicians India ; 62(12): 60-4, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26259427

RESUMO

Tuberous sclerosis complex [TSC] is a genetic multisystem disorder characterised by the growth of numerous hamartomas in several organs including the brain, heart, skin, eyes, kidney, lung and liver. The affected genes are TSC1 and TSC2 encoding hamartin and tuberin respectively. TSC has a wide range of severity and some people with this condition will only be mildly affected. At present it is impossible to accurately predict who will remain only mildly affected and who will be more severely affected by TSC. Even members of the same family can be affected differently. Many family members show signs of being carriers of the genes for the disease when carefully examined. This article reports a family with documented Tuberous sclerosis in two generations involving three members which is a rare entity.


Assuntos
Esclerose Tuberosa/genética , Adulto , Humanos , Masculino , Linhagem , Esclerose Tuberosa/diagnóstico
5.
Indian J Exp Biol ; 52(1): 80-8, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24617019

RESUMO

Brinjal (Solanum melongena L.) var. Mattu Gulla (MG) and var. Perampalli Gulla (PG) are unique varieties with distinct flavour cultivated in Udupi, Karnataka State, and are exposed to several biotic and abiotic stresses. An efficient and reproducible in vitro regeneration method is required to expedite the manipulation of these brinjal varieties to cope up with stress by tissue culture and gene transfer methods. The present study, reports a rapid and efficient in vitro regeneration protocol for these two varieties. The in vitro growth response was studied on Murashige and Skoog (MS) medium supplemented with 2, 4-D, BAP and IAA, and the plantlets were regenerated efficiently from callus cultures of leaf, cotyledon and hypocotyl explants. Among the three explants, the hypocotyl explants were found to have better callus induction and multiple shoot regeneration. High frequency of shoot initiation was achieved from hypocotyl derived calluses in MS media with 2.0 mg/L BAP and 0.5 mg/L IAA in MG and PG. Efficient and rapid shoot proliferation, and elongation were noted in MS medium with 1.0 mg/L BAP and 0.3 mg/L GA3. The in vitro regenerated shoots produced healthy roots when they were cultured on MS medium supplemented with 0.5 mg/L IBA. A significant difference was observed in percentage of callus induction, number of shoots per callus, shoot elongation and number of hardened plantlets of MG and PG. MG showed maximum response in all stages of culture than PG. Hardening of plantlets in tissue culture was achieved in three weeks. The hardened plantlets were grown in pots for further acclimatization in green house and finally transplanted to experimental garden where they developed into flowering plants and produced mature fruits with viable seeds.


Assuntos
Reguladores de Crescimento de Plantas/farmacologia , Brotos de Planta/crescimento & desenvolvimento , Regeneração/fisiologia , Sementes/crescimento & desenvolvimento , Solanum melongena/crescimento & desenvolvimento , Técnicas de Cultura de Células , Cotilédone/citologia , Cotilédone/crescimento & desenvolvimento , Meios de Cultura , Índia , Folhas de Planta/citologia , Folhas de Planta/crescimento & desenvolvimento , Raízes de Plantas/citologia , Raízes de Plantas/crescimento & desenvolvimento , Brotos de Planta/citologia , Sementes/citologia
6.
Front Pharmacol ; 14: 1096614, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37025487

RESUMO

Glioma is the most devastating high-grade tumor of the central nervous system, with dismal prognosis. Existing treatment modality does not provide substantial benefit to patients and demands novel strategies. One of the first-line treatments for glioma, temozolomide, provides marginal benefit to glioma patients. Repurposing of existing non-cancer drugs to treat oncology patients is gaining momentum in recent years. In this study, we investigated the therapeutic benefits of combining three repurposed drugs, namely, metformin (anti-diabetic) and epigallocatechin gallate (green tea-derived antioxidant) together with temozolomide in a glioma-induced xenograft rat model. Our triple-drug combination therapy significantly inhibited tumor growth in vivo and increased the survival rate (50%) of rats when compared with individual or dual treatments. Molecular and cellular analyses revealed that our triple-drug cocktail treatment inhibited glioma tumor growth in rat model through ROS-mediated inactivation of PI3K/AKT/mTOR pathway, arrest of the cell cycle at G1 phase and induction of molecular mechanisms of caspases-dependent apoptosis.In addition, the docking analysis and quantum mechanics studies performed here hypothesize that the effect of triple-drug combination could have been attributed by their difference in molecular interactions, that maybe due to varying electrostatic potential. Thus, repurposing metformin and epigallocatechin gallate and concurrent administration with temozolomide would serve as a prospective therapy in glioma patients.

8.
Bioelectromagnetics ; 33(5): 428-37, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22253132

RESUMO

Our previous investigation reported the beneficial effect of pre-sowing magnetic treatment for improving germination parameters and biomass accumulation in soybean. In this study, soybean seeds treated with static magnetic fields of 150 and 200 mT for 1 h were evaluated for reactive oxygen species (ROS) and activity of antioxidant enzymes. Superoxide and hydroxyl radicals were measured in embryos and hypocotyls of germinating seeds by electron paramagnetic resonance spectroscopy and kinetics of superoxide production; hydrogen peroxide and antioxidant activities were estimated spectrophotometrically. Magnetic field treatment resulted in enhanced production of ROS mediated by cell wall peroxidase while ascorbic acid content, superoxide dismutase and ascorbate peroxidase activity decreased in the hypocotyl of germinating seeds. An increase in the cytosolic peroxidase activity indicated that this antioxidant enzyme had a vital role in scavenging the increased H(2)O(2) produced in seedlings from the magnetically treated seeds. Hence, these studies contribute to our first report on the biochemical basis of enhanced germination and seedling growth in magnetically treated seeds of soybean in relation to increased production of ROS.


Assuntos
Glycine max/metabolismo , Campos Magnéticos/efeitos adversos , Espécies Reativas de Oxigênio/metabolismo , Antioxidantes/metabolismo , Ácido Ascórbico/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica , Germinação , Tamanho do Órgão , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Sementes/crescimento & desenvolvimento , Sementes/metabolismo , Glycine max/enzimologia , Glycine max/crescimento & desenvolvimento , Fatores de Tempo
9.
Biomed Chromatogr ; 26(2): 142-6, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21538417

RESUMO

High-performance liquid chromatographic methods were developed for separation of the enantiomers of mirtazapine and its four process-related substances. The direct separations were achieved on chiral stationary phases containing amylose tris(3,5-dimethylphenylcarbamate) (Chiralpak AD-H), cellulose tris(3,5-dimethylphenylcarbamate) (Chiralcel OD-H) and cellulose tris(4-methylbenzoate) (Chiralcel OJ-H ). The experimental data were utilized to discuss the effects of the mobile phase composition, the nature of the alcoholic modifier and the specific structural features of the analytes on retention and separation. The elution sequence was determined under the optimized separation conditions.


Assuntos
Amilose/análogos & derivados , Celulose/análogos & derivados , Cromatografia Líquida de Alta Pressão/instrumentação , Mianserina/análogos & derivados , Fenilcarbamatos/química , Amilose/química , Celulose/química , Cromatografia Líquida de Alta Pressão/métodos , Mianserina/química , Mianserina/normas , Mirtazapina , Estereoisomerismo
10.
Bioelectromagnetics ; 32(6): 474-84, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21381047

RESUMO

Experiments were conducted to study the effect of static magnetic fields on the seeds of soybean (Glycine max (L.) Merr. var: JS-335) by exposing the seeds to different magnetic field strengths from 0 to 300 mT in steps of 50 mT for 30, 60, and 90 min. Treatment with magnetic fields improved germination-related parameters like water uptake, speed of germination, seedling length, fresh weight, dry weight and vigor indices of soybean seeds under laboratory conditions. Improvement over untreated control was 5-42% for speed of germination, 4-73% for seedling length, 9-53% for fresh weight, 5-16% for dry weight, and 3-88% and 4-27% for vigor indices I and II, respectively. Treatment of 200 mT (60 min) and 150 mT (60 min), which were more effective than others in increasing most of the seedling parameters, were further explored for their effect on plant growth, leaf photosynthetic efficiency, and leaf protein content under field conditions. Among different growth parameters, leaf area, and leaf fresh weight showed maximum enhancement (more than twofold) in 1-month-old plants. Polyphasic chlorophyll a fluorescence (OJIP) transients from magnetically treated plants gave a higher fluorescence yield at the J-I-P phase. The total soluble protein map (SDS-polyacrylamide gel) of leaves showed increased intensities of the bands corresponding to a larger subunit (53 KDa) and smaller subunit (14 KDa) of Rubisco in the treated plants. We report here the beneficial effect of pre-sowing magnetic treatment for improving germination parameters and biomass accumulation in soybean.


Assuntos
Germinação/fisiologia , Glycine max/fisiologia , Campos Magnéticos , Fotossíntese , Sementes/crescimento & desenvolvimento , Clorofila/metabolismo , Clorofila A , Eletroforese em Gel de Poliacrilamida , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Ribulose-Bifosfato Carboxilase/metabolismo , Plântula/crescimento & desenvolvimento , Glycine max/crescimento & desenvolvimento , Água/metabolismo
11.
Physiol Mol Biol Plants ; 17(3): 223-9, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23573013

RESUMO

A field experiment was conducted to study the impact of solar UV-B (280-315 nm) and UV-A (315-400 nm) components on the growth and antioxidant enzyme activity in cotton plant (Gossypium hirsutum var. Vikram). Solar UV components were excluded by filtering the sunlight through selective UV-B (<315 nm) and UV-B/A (<400 nm) absorbing polyester films. Plants grown under filters that transmitted solar UV served as controls. Exclusion of UV-B and UV-B/A enhanced plant height, leaf area and total biomass of plants. The activity of antioxidant enzymes superoxide dismutase (SOD), ascorbic acid peroxidase (APX), glutathione reductase (GR) and guaiacol peroxidase (GPx) assayed in the leaves were lesser in the UV excluded plants. The level of ascorbic acid and UV absorbing substances were also decreased by the exclusion of UV. Solar UV components exerted a limitation on the potential growth of cotton plants. Reduction in the antioxidant enzyme activity and ascorbic acid after UV exclusion indicated that ambient UV components exert a significant stress on cotton plants. Reduction in the production of UAS indicated a changed pattern of metabolism leading to improved primary metabolism. Exclusion of UV components is advantageous from the agricultural point to enhance the growth of cotton plants.

12.
Saudi J Biol Sci ; 28(5): 2626-2633, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-34025146

RESUMO

The modulatory effect of opera was investigated on the physiological and morphological aspects in soybean thriving in water stress environment. The data procured from current investigation indicated that water stress significantly declined the plant growth, leaf area in addition to photosynthetic efficiency, nitrate reductase activity and crop yield at various stages of growth such as vegetative (VS), flowering (FS) and pod filling stage (PFS). However, foliar application of opera (0.15%) was effective to enhance the the leaf area (42%), rate of photosynthesis (194%), and nitrate reductase activity (68%) at FS stage while the maximum enhancement in biomass accumulation (92%) and yield (119%) was observed at PFS stage as compared to their control plants. The opera is applied as foliar spray in field experiments to augment the assimilation of nitrogen and carbon in soybean which contributes to increased crop development and productivity under water stress conditions.

13.
Free Radic Biol Med ; 152: 715-727, 2020 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-31968231

RESUMO

The present study illustrates mitochondria-mediated impact of ionizing radiation which is paralleled by activation of several pro-adaptive responses in normal human dermal fibroblast cells. Irradiation of cells with X-rays (5 Gy) led to an increase in fragmentation and mitochondrial mass. Distinct temporal changes in cytosolic and mitochondrial reactive oxygen species (ROS) were noted in response to radiation, which was associated with depletion in mitochondrial membrane potential followed by decrease in ATP levels. Long Amplicon-Polymerase Chain Reaction (LA-PCR) analysis showed time-dependent increase in mitochondrial DNA damage that preceded mitochondrial ROS generation. Irradiation of cells led to an initial G2/M arrest at 8 h that persisted till 16 h, with subsequent block at G0/G1 measured at 48 and 72 h time points. Interestingly, cells activated autophagy as a countermeasure against radiation-mediated cellular insults and aided in removal of damaged mitochondria. Blocking autophagy using 3-methyladenine led to cell death via activation of enhanced ROS, PARP-1 and caspase 3 cleavage. Upregulation of mitochondrial biogenesis factors Nrf1/PGC-1α, following irradiation was observed. Irradiated cells exhibited an increase in the phosphorylation of GCN2, PERK and eIF2α that might be responsible for the up-regulation of ATF4 and CHOP thereby regulating autophagy and components of integrated stress response. Apart from this, we measured accumulation of mitochondrial chaperones (HSP60/HSP10) and ATF5 which is a major molecule involved in mitochondrial stress. Taken together, mitochondria are one of the major cytoplasmic targets for ionizing radiation and possibly act as an early indicator of cellular insult. The findings also show that stressed mitochondria might influence endoplasmic reticulum (ER)-related signalling leading to the activation of adaptive mechanisms like cytoprotective autophagy, and molecules responsible for mitochondrial biogenesis and protein quality control in order to replenish mitochondrial pool and maintain cellular homeostasis.


Assuntos
Biogênese de Organelas , Proteostase , Apoptose , Autofagia , Estresse do Retículo Endoplasmático , Humanos , Radiação Ionizante , Espécies Reativas de Oxigênio
14.
Physiol Mol Biol Plants ; 15(4): 367-70, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23572947

RESUMO

Seedlings of Amaranthus caudatus grown under UV exclusion filters (-UV -B <320nm; -UV -B/A <400nm) in the ambient solar radiation showed an enhancement in growth. This was accompanied by reduction in the synthesis of betacyanin but enhancement in the level of amino acids and proteins. The growth promotion and the accompanying biochemical changes were similar to the external application of GA3 to the seedlings under ambient solar radiation. The results are discussed in the light of similarities between UV exclusion and GA3 application in terms of diversion of amino acid precursors towards enhanced primary metabolism.

15.
Physiol Mol Biol Plants ; 14(4): 369-75, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23572904

RESUMO

Most of the Indian soybean varieties were found to be highly sensitive to photoperiod, which limits their cultivation in only localized area. Identification of genetically diverse source of photoperiod insensitive would help to broaden the genetic base for this trait. Present study was undertaken with RAPD markers for genetic diversity estimation in 44 accessions of soybean differing in response to photoperiod sensitivity. The selected twenty-five RAPD primers produced a total of 199 amplicons, which generated 89.9 % polymorphism. The number of amplification products ranged from 2 to 13 for different primers. The polymorphism information content ranged from 0.0 for monomorphic loci to 0.5 with an average of 0.289. Genetic diversity between pairs of genotypes was 37.7% with a range of 3.9 to 71.6%. UPGMA cluster analysis placed all the accessions of soybean into four major clusters. No discernable geographical patterns were observed in clustering however; the smaller groups corresponded well with pedigree. Mantel's test (r = 0.915) indicates very good fit for clustering pattern. Two genotypes, MACS 330 and 111/2/1939 made a very divergent group from other accessions of soybean and highly photoperiod insensitive that may be potential source for broadening the genetic base of soybean for this trait.

16.
Indian J Biochem Biophys ; 44(1): 31-7, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17385338

RESUMO

To assess the role of antioxidant defense system on exposure to ultra-violet-B (UV-B) radiation, the activities of antioxidant enzymes superoxide dismutase (SOD), ascorbic acid peroxidase (APX), glutathione reductase (GR) and guaiacol peroxidase (GPX), as well as the level of antioxidants ascorbic acid (AA) and alpha-tocopherol were monitored in cucumber (Cucumis sativus L. var long green) cotyledons. UV-B enhanced the activity of antioxidant enzymes as well as AA content, but decreased the level of alpha-tocopherol. Significant increase was observed in the activities of SOD and GPX. Analysis of isoforms of antioxidant enzymes by native-PAGE and activity staining revealed three isoforms of GPX in unexposed dark-grown cotyledons (control), and their intensity was enhanced by UV-B exposure. In addition, four new isoforms of GPX were observed in cotyledons after UV-B exposure. Although no new isoforms were observed for the other antioxidant enzymes, the activities of their existing isoforms were enhanced by UV-B.


Assuntos
Antioxidantes/metabolismo , Cucumis sativus/enzimologia , Cucumis sativus/efeitos da radiação , Ascorbato Peroxidases , Cotilédone/enzimologia , Cotilédone/efeitos da radiação , Glutationa Redutase/metabolismo , Glutationa Redutase/efeitos da radiação , Isoenzimas/metabolismo , Isoenzimas/efeitos da radiação , Peroxidase/metabolismo , Peroxidase/efeitos da radiação , Peroxidases/metabolismo , Peroxidases/efeitos da radiação , Superóxido Dismutase/metabolismo , Superóxido Dismutase/efeitos da radiação , Raios Ultravioleta
17.
Indian J Biochem Biophys ; 43(1): 41-7, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16955751

RESUMO

The effect of field weathering on oxyradical accumulation and subsequent changes were studied in the seeds of soybean [Glycine max (L.) Merr.] cv. JS 71-05. Electron spin resonance (ESR) quantification of oxyradical revealed that field weathering plays an important role in acceleration of their accumulation. One week of weathering increased the accumulation of oxyradicals to almost 2-fold and triggered the deteriorative cascade, by enhancing the lipid peroxidation and membrane perturbation, leading to cell death in seed tissues and poor germinability and vigour of soybean seeds. Thus, the weather conditions at the time of physiological maturity to harvesting of crop are very crucial and the field weathering plays a critical role for the maintenance of seed quality.


Assuntos
Glycine max/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Sementes/metabolismo , Tempo (Meteorologia) , Espectroscopia de Ressonância de Spin Eletrônica , Sementes/química , Glycine max/crescimento & desenvolvimento
18.
Indian J Exp Biol ; 43(10): 910-5, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16235726

RESUMO

Cytokinin-induced expansion growth of cucumber cotyledons and its interaction with UV-B (280-320 nm) was studied with reference to oxyradicals. UV-B radiation enhanced the level of oxyradicals in the cotyledons measured by EPR spectroscopy. Cytokinin promoted expansion growth was inhibited by UV-B radiation. Cytokinins reduced the level of oxyradicals in dark grown cotyledons, while promoting growth. Overproduction of oxyradicals by UV-B could not be fully accounted for the inhibition of growth of cotyledons, since quenching of radicals by cytokinins did not fully restore inhibition of growth.


Assuntos
Cucumis sativus/metabolismo , Citocininas/química , Radicais Livres , Oxigênio/química , Relação Dose-Resposta a Droga , Espectroscopia de Ressonância de Spin Eletrônica , Sementes/metabolismo , Fatores de Tempo , Raios Ultravioleta
19.
Plant Physiol Biochem ; 97: 400-11, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26555898

RESUMO

Field studies were conducted to determine the potential for alterations in photosynthetic performance and grain yield of four wheat (Triticum aestivum) varieties of India- Vidisha, Purna, Swarna and Naveen Chandausi by ambient ultraviolet radiation (UV). The plants were grown in specially designed UV exclusion chambers, wrapped with filters that excluded UV-B (<315 nm), UV-A/B (<400 nm) or transmitted ambient UV or lacked filters. The results indicated that solar UV exclusion increased the leaf mass per area ratio, leaf weight ratio and chlorophylls per unit area of flag leaves in all the four varieties of wheat. Polyphasic chlorophyll a fluorescence transients from the flag leaves of UV excluded wheat plants gave a higher fluorescence yield. Exclusion of solar UV significantly enhanced photosynthetic performance as a consequence of increased efficiency of PS II, performance index (PIABS) and rate of photosynthesis in the flag leaves of wheat varieties along with a remarkable increase in carbonic anhydrase, Rubisco and nitrate reductase activities. This additional fixation of carbon and nitrogen by exclusion of UV was channelized towards the improvement in grain yield of wheat varieties as there was a decrease in the UV-B absorbing substances and an increase in soluble protein content in flag leaves of all the four varieties of wheat. The magnitude of response for UV exclusion for all the measured parameters was higher in two varieties of wheat Vidisha and Purna as compared to Swarna and Naveen Chandausi. Cumulative stress response index (CSRI) for each variety was developed from the cumulative sum of physiological and yield parameters such as leaf mass area ratio of flag leaf, total chlorophyll content, performance index at absorption basis, rate of photosynthesis and grain yield. All the varieties had a negative CSRI, demonstrating a negative impact of ambient UV radiation. Naveen Chandausi and Swarna are less sensitive to ambient UV radiation; Vidisha is more sensitive to both UV-A and UV-B and Purna is more sensitive to ambient UV-B radiation.


Assuntos
Fotossíntese/efeitos da radiação , Triticum/crescimento & desenvolvimento , Triticum/efeitos da radiação , Raios Ultravioleta , Biomassa , Anidrases Carbônicas/metabolismo , Clorofila/metabolismo , Gases/metabolismo , Modelos Biológicos , Nitrato Redutase/metabolismo , Folhas de Planta/efeitos da radiação , Proteínas de Plantas/metabolismo , Ribulose-Bifosfato Carboxilase/metabolismo , Solubilidade , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Estresse Fisiológico
20.
Protein Sci ; 2(2): 264-76, 1993 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8443603

RESUMO

The family of aspartic proteinases includes several human enzymes that may play roles in both physiological and pathophysiological processes. The human lysosomal aspartic proteinase cathepsin D is thought to function in the normal degradation of intracellular and endocytosed proteins but has also emerged as a prognostic indicator of breast tumor invasiveness. Presented here are results from a continuing effort to elucidate the factors that contribute to specificity of ligand binding at individual subsites within the cathepsin D active site. The synthetic peptide Lys-Pro-Ile-Glu-Phe*Nph-Arg-Leu has proven to be an excellent chromogenic substrate for cathepsin D yielding a value of kcat/Km = 0.92 x 10(-6) s-1 M-1 for enzyme isolated from human placenta. In contrast, the peptide Lys-Pro-Ala-Lys-Phe*Nph-Arg-Leu and all derivatives with Ala-Lys in the P3-P2 positions are either not cleaved at all or cleaved with extremely poor efficiency. To explore the binding requirements of the S3 and S2 subsites of cathepsin D, a series of synthetic peptides was prepared with systematic replacements at the P2 position fixing either Ile or Ala in P3. Kinetic parameters were determined using both human placenta cathepsin D and recombinant human fibroblast cathepsin D expressed in Escherichia coli. A rule-based structural model of human cathepsin D, constructed on the basis of known three-dimensional structures of other aspartic proteinases, was utilized in an effort to rationalize the observed substrate selectivity.


Assuntos
Catepsina D/metabolismo , Compostos Cromogênicos/metabolismo , Oligopeptídeos/metabolismo , Sequência de Aminoácidos , Ácido Aspártico Endopeptidases/metabolismo , Catepsina D/química , Catepsina D/genética , Compostos Cromogênicos/química , Simulação por Computador , Escherichia coli/genética , Fibroblastos/enzimologia , Humanos , Cinética , Modelos Moleculares , Dados de Sequência Molecular , Oligopeptídeos/química , Placenta/enzimologia , Inibidores de Proteases/metabolismo , Proteínas Recombinantes/metabolismo , Relação Estrutura-Atividade , Especificidade por Substrato
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