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Total phenol concentrations in coffee tree leaves during fruit development; Concentrações de fenóis totais nas folhas do cafeeiro durante desenvolvimento dos frutos

SALGADO, Paula Rodrigues; FAVARIN, José Laércio; LEANDRO, Roseli Aparecida; LIMA FILHO, Oscar Fontão de
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.24%
Vegetables have a natural defense against external factors synthesizing phenolic compounds, which depends on the maturity stage and on the climate. Total phenol grades were extracted from mature and young coffee leaves and were analyzed in relation to yield, phenology and climate. The climatic conditions were described by air temperature, global radiation and daily insolation. Evaluations were made on height, diameter and length of reproductive branches to determine the respective vegetative growth rates of the plants. The amounts of total phenols in the plants at the production stage was 174.0 mg g-1 and 138.9 mg g-1 for young and mature leaves, respectively, and for plants without fruit formation 186.5 mg g-1 and 127.6 mg g-1 for young and mature leaves, respectively. The total phenol concentrations in young leaves with and without fruit formation were 25% and 46% greater compared to mature leaves. The secondary phenol synthesis in seed (146.8 mg g-1) was 31% lower than during grain maturation (212.4 mg g-1). The total phenol metabolization depends indirectly on the temperature and on the global radiation, presenting an inverse trend in relation to these climatic variables. Crop protection management should take into consideration periods of endanger of this natural defense of the plant.; Os vegetais apresentam defesa natural contra fatores externos...

Exogenous ornithine is an effective precursor and the delta-ornithine amino transferase pathway contributes to proline accumulation under high N recycling in salt-stressed cashew leaves

Almeida da Rocha, Iza Marineves; Vitorello, Victor Alexandre; Silva, Jamille Santos; Ferreira-Silva, Sergio Luiz; Viegas, Ricardo Almeida; Silva, Evandro Nascimento; Gomes Silveira, Joaquim Albenisio
Fonte: ELSEVIER GMBH, URBAN & FISCHER VERLAG; JENA Publicador: ELSEVIER GMBH, URBAN & FISCHER VERLAG; JENA
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.2%
The role of the delta-ornithine amino transferase (OAT) pathway in proline synthesis is still controversial and was assessed in leaves of cashew plants subjected to salinity. The activities of enzymes and the concentrations of metabolites involved in proline synthesis were examined in parallel with the capacity of exogenous ornithine and glutamate to induce proline accumulation. Proline accumulation was best correlated with OAT activity, which increased 4-fold and was paralleled by NADH oxidation coupled to the activities of OAT and Delta(1)-pyrroline-5-carboxylate reductase (P5CR), demonstrating the potential of proline synthesis via OAT/P5C. Overall, the activities of GS. GOGAT and aminating GDH remained practically unchanged under salinity. The activity of P5CR did not respond to NaCl whereas Delta(1)-pyrroline-5-carboxylate dehydrogenase was sharply repressed by salinity. We suggest that if the export of P5C from the mitochondria to the cytosol is possible, its subsequent conversion to proline by P5CR may be important. In a time-course experiment, proline accumulation was associated with disturbances in amino acid metabolism as indicated by large increases in the concentrations of ammonia, free amino acids, glutamine, arginine and ornithine. Conversely...

Avaliação da dinâmica da população de microrganismos em plantas de cana-de-açúcar IAC (93-3046); Assessment of microorganisms dynamics in sugarcane IAC (93-3046) plants

Toledo Filho, Sérgio Gil de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 01/10/2010 PT
Relevância na Pesquisa
36.23%
O número das espécies microbianas presentes na forragem no ato da colheita é responsável pelo padrão de fermentação da silagem, sendo que o número de unidades formadoras de colônia (ufc) é alterado ao longo do ciclo da cultura e das condições ambientais, e esse fato, influencia fortemente a eficácia de aditivos utilizados no processo. Neste contexto, três experimentos foram conduzidos a fim de caracterizar a população microbiana em plantas de cana-de-açúcar. No primeiro experimento foi caracterizada a população microbiana em plantas de cana-de-açúcar por meio da técnica de plaqueamento. Os tratamentos impostos foram compostos por duas fontes de adubação (NPK e NPK associado a esteco bovino curtido 120kg de N/ha) da cana-de-açúcar colhidas manualmente com vista à quantificação do número de bactérias ácido láticas, leveduras e mofos, bem como relacionar suas freqüências de ocorrência com efeitos ambientais, fonte de fertilizante e estádio de maturação, com colheitas realizadas aos 10, 12, 14 e 18 meses, correspondendo aos meses de Março, Maio, Julho e Novembro de 2009, respectivamente. No segundo experimento foram avaliadas as variáveis biométricas, morfológicas, dinâmica de acúmulo de MS e dos nutrientes em cana-de-açúcar submetida às fontes de fertilização...

Caracterização do proteoma nuclear de folhas de cana-de-açúcar (Saccharum spp) de 1 e 4 meses de idade; Nuclear proteome characterization of one and four-month-old sugarcane (Saccharum spp) leaves

Silva, Danielle Izilda Rodrigues da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 26/10/2012 PT
Relevância na Pesquisa
46.09%
A cana-de-açúcar é uma cultura economicamente importante, cultivada especialmente pelo seu colmo, que constitui a matéria-prima para produtos como o açúcar e o bioetanol. Ademais, a compreensão do proteoma nuclear é essencial para decifrar os mecanismos que governam a regulação gênica. No presente estudo, é demonstrado o isolamento e a identificação através de 1D SDS-PAGE de proteínas nucleares originadas de folhas jovens de plantas de cana-de-açúcar. Os núcleos foram isolados de folhas F+1 frescas de cana-de-açúcar de 1 e 4 meses, usando o protocolo modificado de Folta e Kaufman (2000). O experimento consistiu em um delineamento inteiramente casualizado, com três repetições de 18 plantas cada. Após a purificação usando o gradiente de percoll, a integridade do núcleo foi avaliada por meio da coloração com orceína acetolática 1% e com DAPI. Os resultados obtidos revelam os núcleos como esferas uniformes com o diâmetro médio de 5 ?m. As proteínas nucleares foram isoladas usando o reagente TRI Reagent (Sigma) e quantificadas por meio do método de Bradford. As análises de Western blot foram usadas para demonstrar o enriquecimento de proteínas nucleares. As membranas foram incubadas com a RUBISCO, PEPCase...

Controle da atividade da nitrato redutase em plantas de abacaxizeiro submetidas a baixas temperaturas em diferentes fases do ciclo diurno; Nitrate reductase activity control in pineapple plants subject to low temperatures in different phases of diurnal cycle

Matsumura, Aline Tiemi
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 06/02/2013 PT
Relevância na Pesquisa
36.38%
O nitrato é uma das principais fontes de nitrogênio disponível para as plantas, sendo a nitrato redutase (NR) a enzima responsável pela sua redução a nitrito. O nitrito é considerado tóxico em altas concentrações e, por esse motivo, a atividade da NR possui uma regulação complexa, principalmente em nível transcricional e pós-traducional. Trabalhos anteriores do nosso grupo, utilizando plantas de abacaxizeiro cultivadas in vitro, demonstraram que, em condições de termoperíodo de 28ºC dia/15ºC noite, as raízes apresentaram um estímulo positivo de atividade da NR na ausência de luz quando comparado às plantas crescidas em temperatura constante de 28ºC, associado posteriormente à atividade da NR de membrana plasmática (NRPM). Baseado nesses resultados questionou-se qual seria a influência da aplicação do estímulo de frio associado ou não à presença de luz na atividade da NR em folhas e raízes de abacaxizeiro. Este trabalho teve como objetivos investigar os efeitos do frio na atividade da NR em folhas e raízes de abacaxizeiro em diferentes tempos de exposição, na presença ou ausência da luz e em diferentes fases do ciclo de 24 horas (claro/escuro). Buscou-se averiguar qual NR estaria envolvida nessas respostas: a NR citossólica (NRc) ou de membrana plasmática (NRPM)...

A simple and reliable method for the screening of transgenic tobacco plants

Freitas-Astua,Juliana; Astua-Monge,Gustavo; Polston,Jane Elisabeth; Hiebert,Ernest
Fonte: Embrapa Informação Tecnológica; Pesquisa Agropecuária Brasileira Publicador: Embrapa Informação Tecnológica; Pesquisa Agropecuária Brasileira
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2003 EN
Relevância na Pesquisa
36.22%
Even though much improvement has been made in plant transformation methods, the screening of transgenic plants is often a laborious work. Most approaches for detecting the transgene in transformed plants are still timeconsuming, and can be quite expensive. The objective of this study was to search for a simpler method to screen for transgenic plants. The infiltration of kanamycin (100 mg/mL) into tobacco leaves resulted in conspicuous chlorotic spots on the non-transgenic plant leaves, while no spots were seen on the leaves of transformed plants. This reaction occurred regardless of age of the tested plants, and the method has proven to be simple, fast, non-destructive, relatively cheap, and reliable. These results were comparable to those obtained by the polymerase chain reaction (PCR) amplification of the transgene using specific primers.

Influence of light regimes on respiration, activity of alternative respiratory pathway and carbohydrates content in mature leaves of Ajuga reptans L.

PYSTINA,NATALIA V.; DANILOV,ROMAN A.
Fonte: Sociedade Brasileira de Fisiologia Vegetal Publicador: Sociedade Brasileira de Fisiologia Vegetal
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2001 EN
Relevância na Pesquisa
36.44%
Influence of different light regimes (plants grown in shade and in the sun) on respiration, activity of alternative respiratory pathway and carbohydrates content in mature leaves of Ajuga reptans L. was investigated. All experiments were carried out under natural conditions. Sun plants had higher respiration, activity of the alternative pathway and carbohydrates content compared to the shade plants. Additional experiments were performed in order to study effects of darkening as well as evolution of respiration and carbohydrates concentrations in leaves of A. reptans during the day. Darkening led to a decline in total respiration in all types of plants investigated. Activity of the alternative pathway remained unchanged by 20 % in the leaves of the shade plants. On the other hand, darkness led to a twofold decrease in the activity of the alternative pathway in the leaves of the sun plants. Content of soluble carbohydrates in the darkness did not change in the leaves of the shade plants while significantly decreased in the leaves of the sun plants. Total respiration in the mature leaves of the shade plants studied did not change significantly during the day. However, a significant increase in the total respiration was detected in the mature leaves of the sun plants in the evening and in the night. Activity of the alternative respiratory pathway did not change significantly in the leaves of the shade plants during the day and corresponds to ca 20 % of the total respiration. The sun plants examined exhibited significantly higher activity of the alternative pathway during the period of active photosynthesis. In general...

Total phenol concentrations in coffee tree leaves during fruit development

Salgado,Paula Rodrigues; Favarin,José Laércio; Leandro,Roseli Aparecida; Lima Filho,Oscar Fontão de
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 EN
Relevância na Pesquisa
36.24%
Vegetables have a natural defense against external factors synthesizing phenolic compounds, which depends on the maturity stage and on the climate. Total phenol grades were extracted from mature and young coffee leaves and were analyzed in relation to yield, phenology and climate. The climatic conditions were described by air temperature, global radiation and daily insolation. Evaluations were made on height, diameter and length of reproductive branches to determine the respective vegetative growth rates of the plants. The amounts of total phenols in the plants at the production stage was 174.0 mg g-1 and 138.9 mg g-1 for young and mature leaves, respectively, and for plants without fruit formation 186.5 mg g-1 and 127.6 mg g-1 for young and mature leaves, respectively. The total phenol concentrations in young leaves with and without fruit formation were 25% and 46% greater compared to mature leaves. The secondary phenol synthesis in seed (146.8 mg g-1) was 31% lower than during grain maturation (212.4 mg g-1). The total phenol metabolization depends indirectly on the temperature and on the global radiation, presenting an inverse trend in relation to these climatic variables. Crop protection management should take into consideration periods of endanger of this natural defense of the plant.

Studies on mineral nutrition of the coffee plant (Coffea arabica L. cv. Catuaí Vermelho): LXIV. Remobilization and re-utilization of nitrogen and potassium by normal and deficient plants

Lima Filho,O. F. de; Malavolta,E.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2003 EN
Relevância na Pesquisa
36.38%
Remobilization and re-utilization of 15N and 85Rb labelled nitrogen and potassium reserves for new growth and fruit formation was studied under greenhouse conditions using both normal and deficient young coffee plants. It was found that K reserves are used in higher proportion than is stored N by fruits and other organs. The export of N by organs of residence in the normal plants obeyed the following proportions of the total: leaves 47%-58%, branches and flower buds 21%-27%, roots 21%-32%. The corresponding figures in the case of deficient plants were: leaves 49%-65%, branches and flower buds 21%-27%, roots 14%-25%. Re-utilization of K took place in the following proportions in the normal plants: leaves 54%-64%, branches and flower buds 20%-21%, roots 30%-41%. In K deficient plants the figures were: leaves 62%-79%, branches and flower buds 1.2%-4.4%, roots 20%-33%. In tissues formed after the initiation of flowering buds, the demand for N is met by reserves as follows: normal plants: fruits 20.6%-24.8%, leaves 15.6%-19.4%, twigs 19%-20.5%; deficient plants: fruits 43.5%-48.5%, leaves 48.1%-51.9%, twigs 46%-53%. The K needs for new tissues are met in the order: normal plants: fruits 40%-45.8%, leaves 27%-37.6%, twigs 26%-33.1%; deficient plants: fruits 65.7%-81.5%...

Evidence That Root Pressure Flow Is Required for Calcium Transport to Head Leaves of Cabbage 1

Palzkill, David A.; Tibbitts, Theodore W.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1977 EN
Relevância na Pesquisa
36.32%
Young cabbage plants (Brassica oleracea L. var. capitata) that were exposed to an atmosphere at 50% relative humidity transpired freely and accumulated significant quantities of 45Ca in the leaves. Plants that were enclosed by plastic bags to stop transpiration from all leaves exhibited guttation with the development of root pressure and also accumulated significant quantities of 45Ca in the leaves. 45Ca accumulation increased in the leaves and tended to decrease in roots and stems with increasing quantities of water transpired or guttated by the plant. When plants were only partially enclosed so that some leaves were covered and the remainder exposed, only the exposed leaves that were transpiring accumulated significant quantities of 45Ca. The covered leaves of partially enclosed plants exhibited no guttation and accumulated little 45Ca with no measurable 45Ca at the margins of the leaves. The results demonstrate that root pressure flow is required to transport adequate amounts of Ca to those tissues in plants that are not undergoing transpirational water loss.

NaJAZh Regulates a Subset of Defense Responses against Herbivores and Spontaneous Leaf Necrosis in Nicotiana attenuata Plants[C][W][OA]

Oh, Youngjoo; Baldwin, Ian T.; Gális, Ivan
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.26%
The JASMONATE ZIM DOMAIN (JAZ) proteins function as negative regulators of jasmonic acid signaling in plants. We cloned 12 JAZ genes from native tobacco (Nicotiana attenuata), including nine novel JAZs in tobacco, and examined their expression in plants that had leaves elicited by wounding or simulated herbivory. Most JAZ genes showed strong expression in the elicited leaves, but NaJAZg was mainly expressed in roots. Another novel herbivory-elicited gene, NaJAZh, was analyzed in detail. RNA interference suppression of this gene in inverted-repeat (ir)JAZh plants deregulated a specific branch of jasmonic acid-dependent direct and indirect defenses: irJAZh plants showed greater trypsin protease inhibitor activity, 17-hydroxygeranyllinalool diterpene glycosides accumulation, and emission of volatile organic compounds from leaves. Silencing of NaJAZh also revealed a novel cross talk in JAZ-regulated secondary metabolism, as irJAZh plants had significantly reduced nicotine levels. In addition, irJAZh spontaneously developed leaf necrosis during the transition to flowering. Because the lesions closely correlated with the elevated expression of programmed cell death genes and the accumulations of salicylic acid and hydrogen peroxide in the leaves...

A simple and reliable method for the screening of transgenic tobacco plants.

FREITAS-ASTUA, J.; ASTUA-MONGE, G.; POLSTON, J.E.; HIEBERT, E.
Fonte: Pesquisa Agropecuária Brasileira, Brasília, v.38, nº 7, p.893-896, jul. 2003. Publicador: Pesquisa Agropecuária Brasileira, Brasília, v.38, nº 7, p.893-896, jul. 2003.
Tipo: Artigo em periódico indexado (ALICE)
EN
Relevância na Pesquisa
36.22%
Even though much improvement has been made in plant transformation methods, the screening of transgenic plants is often a laborious work. Most approaches for detecting the transgene in transformed plants are still time-consuming, and can be quite expensive. The objective of this study was to search for a simpler method to screen for transgenic plants. The infiltration of kanamycin (100 mg/mL) into tobacco leaves resulted in conspicuous chlorotic spots on the non-transgenic plant leaves, while no spots were seen on the leaves of transformed plants. This reaction occurred regardless of age of the tested plants, and the method has proven to be simple, fast, non-destructive, relatively cheap, and reliable. These results were comparable to those obtained by the polymerase chain reaction (PCR) amplification of the transgene using specific primers.; 2003; NOTAS CIENTÍFICAS

Biotividade de extratos e frações das folhas da Eugenia uniflora L. e da Hyptidendron canum (Pohl ex Benth.) Harley em microrganismos (Bactérias e fungo) e em Oreochromis nilotius; Bioactivity of extracts and fractions from leaves of Eugenia L. uniflora and Hyptidendron canum (Pohl ex Benth.) Harley in microorganisms (bacteria and fungi) and Oreochromis nilotius

FIUZA, Tatiana de Sousa
Fonte: Universidade Federal de Goiás; BR; UFG; Doutorado em Biologia; Ciencias Biologicas Publicador: Universidade Federal de Goiás; BR; UFG; Doutorado em Biologia; Ciencias Biologicas
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
36.24%
The purpose of this work is to perform the pharmacognostic studies of the species Hyptidendron canum (Pohl ex Benth.) Harley (Lamiaceae) and Eugenia uniflora L. (Myrtaceae), investigate the population variability of the constituents of the essential oil from H. canum leaves and inflorescences, and assess the bioactivity of the crude ethanol extracts and fractions from leaves of this plants against microorganisms (bacteria and the fungus Candida albicans) and on Oreochromis niloticus Linnaeus. For the variability study of the H. canum essential oil, samples obtained from leaves and inflorescences from Hidrolândia, Silvânia, Bela Vista and Goiânia cities were analyzed by gas chromatography and gas chromatography with mass spectrometry. The anatomic analysis and the phytochemical screening of the leaves from the two species were performed using conventional techniques. The antimicrobial activity was assessed with Gram-positive and Gram-negative bacteria and with the Candida albicans fungus using the well diffusion test and the agar dilution method to determine the minimal inhibitory concentration (MIC). The biological activities of the crude ethanol extract and ethyl acetate, hexanic and chloroformic fractions of the leaves from the two species were tested in O. niloticus fish hepatopancreas and gill. The H. canum essential oils analysis indicated high chemovariability in the oils from different locations. The phytochemical screening and the thin layer chromatography (TLC) analysis of the H. canum leaves evidenced the presence of flavonoids...

Atividade antimicrobiana in vitro e antidiarr??ica em modelo experimental de extratos de folhas de plantas da fam??lia Myrtacea; In vitro antimicrobial activity and antidiarrhoeal in experimental leaf extracts of plants of the family Myrtaceae

PRESTES, Luciana de Souza
Fonte: Universidade Federal de Pelotas; Veterin??ria; Programa de P??s-Gradua????o em Veterin??ria; UFPel; BR Publicador: Universidade Federal de Pelotas; Veterin??ria; Programa de P??s-Gradua????o em Veterin??ria; UFPel; BR
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
36.31%
The use of medicinal plants in treatment of disease follows the history of mankind. In third world countries, including Brazil, where 70-80% of the population lacks health pharmaceutical, medicinal plants are used as alternative therapy. To evaluate the antimicrobial activity in vitro and in vivo, extracts of plants of the family Myrtaceae against microorganisms that cause diarrhea and its effect on intestinal motility through biological model in rats. We selected three plant family Myrtaceae popularly used in the treatment of diarrhea: guava (Psidium guajava L.), surinam cherry (Eugenia uniflora L.) and strawberry guava (Psidium cattleyanum Sabine) belonging to the COOPAVA (Cooperative Agricultural Production Vista Alegre). Hydroalcoholic extracts were prepared with essential oils and leaves of plants harvested at three phenological stages: fruit set, flowering, and rest. The extracts were tested for their antimicrobial activity against bacteria (Escherichia coli, Salmonella typhimurium and Staphylococcus aureus). Besides the hydroalcoholic extracts prepared essential oils from three plants and tested against the same microorganisms and some of its constituent were identified by gas chromatography coupled to the spectrometer massas-GC/MS. The hydroalcoholic extract of guava and infused with a better outcome in vitro test was chosen for the evaluation of antidiarrhoeal activity of the plant in vivo. In vitro tests were performed by broth microdilution technique for assessment of minimal bactericidal (MBC). The in vivo tests were performed by testing for induction of diarrhea with castor oil in rats. The constituents found in all plants by chromatographic analysis were α-and α-humulene copaene. The best result of the hydroalcoholic extract against S. aureus was prepared with fresh guava leaves harvested during the flowering season with geometric mean of quadruplicates of 3.25%...

Scaling photosynthesis and water use from leaves to paddocks

de Pury, David Guilloaume George
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Thesis (PhD)
Relevância na Pesquisa
36.26%
Plant breeders can select cultivars with physiological traits that confer a growth or yield advantage to individual plants. The extent to which single plant characters influence canopy performance depends on interactions between vegetation and the atmosphere and the non-linear response of physiological processes to the environment. Better understanding of the scaling of photosynthesis and water use will allow the assessment of changes to leaf scale physiological traits at the canopy scale and prediction of the response of vegetation to climate change. This thesis examines the relationship between reduced stomatal conductance and canopy scale water-use efficiency (ratio of instantaneous net canopy photosynthesis to total canopy evaporation). A multi-disciplinary research project was established with two large paddocks of wheat with cultivars of contrasting leaf-scale water-use efficiency, due to inherent differences in stomatal conductance. Intensive measurements were made of C02 and H20 fluxes at leaf and canopy scales. Different stomatal conductances at the leaf scale were reflected at the. canopy scale, although their effects on transpiration were reduced due to canopy boundary layers and soil evaporation. Comparison of scaling from leaf to canopy in the two crops was complicated by their different leaf area indices. To facilitate scaling from leaves to canopies...

Carbon acquisition in variable environments: aquatic plants of the River Murray, Australia.

Barrett, Melissa S.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2008
Relevância na Pesquisa
36.25%
This thesis considers the implications of changes in the supply of resources for photosynthesis, with regard for modes of carbon acquisition employed by aquatic plants of the River Murray. Carbon supplies are inherently more variable for aquatic plants than for those in terrestrial environments, and variations are intensified for plants in semi-arid regions, where water may be limiting. In changeable environments the most successful species are likely to be those with flexible carbon-uptake mechanisms, able to accommodate variations in the supply of resources. Studies were made of plants associated with wetland habitats of the Murray, including Crassula helmsii, Potamogeton tricarinatus, P. crispus and Vallisneria americana. The aim was to elucidate the mechanisms of carbon uptake and assimilation employed, and to determine how flexibility in carbon uptake and/or assimilation physiology affect survival and distribution. Stable carbon isotopes were used to explore the dynamics of carbon uptake and assimilation, and fluorescence was used to identify pathways and photosynthetic capacity. The studies suggest that physiological flexibility is adaptive survival in changeable environments, but probably does not enhance the spread or dominance of these species. V. americana is a known bicarbonate-user...

Functional Anatomy and Biophysical Mechanisms of Fluid Transport in Vascular Plants : Implications for Structural Optimisation in Fossil and Extant Plants; Gefässanatomie und Biophysik des Fluidtransportes in Gefässpflanzen : Konsequenzen für die strukturelle Optimierung fossiler und rezenter Pflanzen

Konrad, Wilfried
Fonte: Universität Tübingen Publicador: Universität Tübingen
Tipo: Dissertation; info:eu-repo/semantics/doctoralThesis
EN
Relevância na Pesquisa
36.38%
In plants, water and carbon dioxide molecules are transported either in liquid or gaseous state: From the roots to the leaves water flows as a liquid. Between leaves and atmosphere water and carbon dioxide are exchanged as gases. Accordingly, the driving forces and mechanisms of transport are also different. The driving force of the water transport between roots and leaves is transpiration which takes place in the gas-filled intercellulars of the leaves. Attached to this tissue is a network of water molecules which extends down to the ground water. This network is held together by short-ranged electro-magnetic forces (van der Waals forces'') between adjacent water molecules. Due to the weight of the molecular network the intermolecular forces are tensile which is --- macroscopically speaking --- equivalent to a negative water pressure. Such a system is thermodynamically metastable and has the tendency to collapse into a stable state, caused either by statistical fluctuations or by disturbances originating from the environment (e.g. by wind or animal action). In any case, gas bubbles containing water vapour and/or air develop within the water column and may lead to embolism, i.e. the breakdown of the water flow. Vascular plants have developed various strategies to cope with such incidents: they employ a multitude of parallel conduits which are segmented and (both laterally and longitudinally) connected by valve-like openings (pits''). Thus...

Acetylcholinesterase and butyrylcholinesterase inhibitory activity of some selected Nigerian medicinal plants

Elufioye,Taiwo O.; Obuotor,Efere M.; Sennuga,Afolake T.; Agbedahunsi,Joseph M.; Adesanya,Saburi A.
Fonte: Sociedade Brasileira de Farmacognosia Publicador: Sociedade Brasileira de Farmacognosia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2010 EN
Relevância na Pesquisa
36.36%
Plants have been found to be useful as memory enhansers as well as antiaging. Twenty two of such plants from sixteen families were investigated for their acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activities using the in vitro Ellman's spectrophotometric and in situ bioautographic methods with physostigmine as standard. At least three morphological parts were examined for each of the plants investigated and the test concentration was 42.5 µg/ mL. Some plants were active on both enzymes though with some morphological parts being more active than others. The root bark of Spondias mombin showed the highest activity to the two enzymes; 64.77% and 83.94% on AChE and BuChE respectively. Other plant parts of the selected plants exhibited some remarkable selectivity in their actions. Those selectively active against AChE were Alchornia laxiflora stem bark (41.12%) and root bark, Callophyllum inophyllurn root bark (56.52%). The leaves of C. jagus (74.25%), Morinda lucida leaves (40.15%), Peltophorum pterocarpum leaves and stem bark (49.5% and 68.85%, respectively), physiostigmine gave 90.31% inhibition. Generally higher activities were found against BuChE. Bombax bromoposenze leaves, root bark and stem bark were particularly active. The inhibition was over 80%. Other selective plant parts are the leaves Antiaris africana...

Altered epiphytic colonization of mannityl opine-producing transgenic tobacco plants by a mannityl opine-catabolizing strain of Pseudomonas syringae

Wilson, Mark; Savka, Michael; Hwang, I.; Farrand, Stephen; Lindow, S.
Fonte: American Society for Microbiology: Applied and Environmental Microbiology Publicador: American Society for Microbiology: Applied and Environmental Microbiology
Tipo: Artigo de Revista Científica Formato: 40553 bytes; application/pdf
EN_US
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The plasmid pYDH208, which confers the ability to catabolize the mannityl opines mannopine and agropine, was mobilized into the nonpathogenic Pseudomonas syringae strain Cit7. The growth of the mannityl opine-catabolizing strain Cit7(pYDH208) was compared with that of the near-isogenic non-opine-catabolizing strain Cit7xylE on leaves of wild-type tobacco (Nicotiana tabacum cv. Xanthi) and transgenic mannityl opine-producing tobacco plants (N. tabacum cv. Xanthi, line 2-26). The population size of Cit7(pYDH208) was significantly greater on the lower leaves of transgenic plants than on middle or upper leaves of those plants. The population size of Cit7(pYDH208) on lower leaves of transgenic plants was also significantly greater than the population size of Cit7xylE on similar leaves of wild-type plants. High-voltage paper electrophoresis demonstrated higher levels of mannityl opines in washings from lower- and mid-level leaves than in washings from upper-level leaves. The ability of Cit7(pYDH208) to catabolize mannityl opines in the carbon-limited phyllosphere increased the carrying capacity of the lower leaves of transgenic plants for Cit7(pYDH208). In coinoculations, the increase in the ratio of population sizes of Cit7(pYDH208) to Cit7xylE on transgenic plants was apparently due to a subtle difference in the growth rates of the two strains and to the difference in final population sizes. An ability to utilize additional carbon sources on the transgenic plants also enabled Cit7(pYDH208) to achieve a higher degree of coexistence with Cit7xylE on transgenic plants than on wild-type plants. This supports the hypothesis that the level of coexistence between epiphytic bacterial populations can be altered through nutritional resource partitioning.; Article may be found at: http://aem.asm.org/cgi/reprint/61/6/2151; This research was supported by a grant from the National Science Foundation (FD91-06782).

Concentrações de fenóis totais nas folhas do cafeeiro durante desenvolvimento dos frutos; Total phenol concentrations in coffee tree leaves during fruit development

Salgado, Paula Rodrigues; Favarin, José Laércio; Leandro, Roseli Aparecida; Lima Filho, Oscar Fontão de
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/01/2008 ENG
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Vegetables have a natural defense against external factors synthesizing phenolic compounds, which depends on the maturity stage and on the climate. Total phenol grades were extracted from mature and young coffee leaves and were analyzed in relation to yield, phenology and climate. The climatic conditions were described by air temperature, global radiation and daily insolation. Evaluations were made on height, diameter and length of reproductive branches to determine the respective vegetative growth rates of the plants. The amounts of total phenols in the plants at the production stage was 174.0 mg g-1 and 138.9 mg g-1 for young and mature leaves, respectively, and for plants without fruit formation 186.5 mg g-1 and 127.6 mg g-1 for young and mature leaves, respectively. The total phenol concentrations in young leaves with and without fruit formation were 25% and 46% greater compared to mature leaves. The secondary phenol synthesis in seed (146.8 mg g-1) was 31% lower than during grain maturation (212.4 mg g-1). The total phenol metabolization depends indirectly on the temperature and on the global radiation, presenting an inverse trend in relation to these climatic variables. Crop protection management should take into consideration periods of endanger of this natural defense of the plant.; Os vegetais apresentam defesa natural contra fatores externos...