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| Registros recuperados: 12.472 | |
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| Trujillo Toledo,Luis Enrique; Gómez Riera,Raúl; Banguela Castillo,Alexander; Soto Romero,Melvis; Arrieta Sosa,Juan Gabriel; Hernández García,Lázaro. |
| The influence of N-glycosylation on the kinetic and catalytical properties of a bacterial fructosyltransferase (LsdA) produced in Pichia pastoris was studied. The glycosylated enzyme behaved similarly to non-glycosylated LsdA when substrate specificity, fructo-oligosaccharide (FOS) production, sucrose hydrolysis or levan formation reactions were carried out under different experimental conditions. The kinetic parameters for native or yeast-expressed LsdA determined at 60ºC, condition for the highest hydrolytic activity, followed a conventional Michaelis-Menten kinetics. Synthase activity of this levansucrase increased in water-restricted environments by addition of salt or organic solvent to the reaction mixtures |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000200005 |
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| Vargas,Teresa E.; Mejías,Alexander; Oropeza,Maira; de García,Eva. |
| To establish an efficient regeneration system for Anthurium andreanum cv Rubrun, seeds from plant spadixes were germinated on a medium supplemented with 2.2 muM BA. After 2 weeks, 74% of the seeds germinated and four weeks later, micro-cuttings from these plantlets were subcultured on a medium containing 4.4 muM BA and 0.05 muM NAA. On average, 3.6 shoots per explant were obtained. Four weeks old in vitro plants from germinated seeds and the plantlets obtained from micro-cuttings, showed callus proliferation at the stem base. These tissues were subcultured on a medium supplemented with 8.9 muM BA and 2.7 muM NAA. After 6 weeks of culture, about 43.8 plantlets per square cm of callus were obtained. Anatomical studies showed the organogenic nature of these... |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000300010 |
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| Vijayaraghavan,Kuppusamy; Raj Jegan,Joseph; Palanivelu,Kandasamy; Velan,Manickam. |
| The batch removal of copper (II) ions from aqueous solution under different experimental conditions using Ulva reticulata was investigated in this study. The copper (II) uptake was dependent on initial pH and initial copper concentration, with pH 5.5 being the optimum value. The equilibrium data were fitted using Langmuir and Freundlich isotherm model, with the maximum copper (II) uptake of 74.63 mg/g determined at a pH of 5.5. The Freundlich model regression resulted in high correlation coefficients and the model parameters were largely dependent on initial solution pH. At various initial copper (II) concentrations (250 to 1000 mg/L), sorption equilibrium was attained between 30 and 120 min. The copper (II) uptake by U. reticulata was best described by... |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000100009 |
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| Ojalvo,Ariana G; Seralena,Alina; Vispo,Nelson S; Silva,Ricardo; Gonzalez,Noel; Guevara,Luis; Batista,Juan F; Montequin,Jose F.; Chaos,Nicolas; González,Rafael; Reima,Camilo; Peña,Yamile; Coca,Marcos; Perera,Alejandro; Vazquez,Raysa; Puchades,Yaquelin; Garcia-Osuna,Tamara; Dominguez,Heberto; Reyes,Jose L.; Ali,Alfonso; Herrera,Luis. |
| Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen that is angiogenic in vitro and in vivo. Several studies report on gene transfer of VEGF121 to promote angiogenesis in the ischemic myocardium of animals and patients. We hypothesized that intramyocardial administration of naked plasmid DNA encoding VEGF121 could improve myocardial perfusion and function in a porcine model of myocardial ischemia. Yorkshire swine underwent thoracotomy and placement of an ameroid constrictor on the circumflex coronary artery. Four weeks later, pVEGF121 plasmid was administered into the ischemic myocardium. Four weeks after gene transfer, SPECT imaging demonstrated significant reduction in the ischemic area in pVEGF121-treated animals compared... |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000300008 |
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| Wachiratianchai,Supawadee; Bhumiratana,Amaret; Udomsopagit,Suchat. |
| An extracellular L-glutamate oxidase (GLOD) was purified from soil-isolated Streptomyces sp 18G. The enzyme had a molecular weight of approximately 120,000 and consisted of two identical subunits, each with a molecular weight of 61,000. The isoelectric point was pH 8.5 and the enzyme had an optimal pH between 7.0-7.4. GLOD showed the maximum activity at 37ºC. The GLOD activity was stable at pH ranging from 6.5 to 7.0 for 1 hr. Among 21 amino acids tested for substrate specificity, L-glutamate was almost exclusively oxidized. D-glutamate and L-aspartate were oxidized but only to extents of 0.79% and 0.53%, respectively. |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000300009 |
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| Whitehead,Neil Evan; Tani,Atushi; Kazue,Tazaki; Motoji,Ikeya. |
| This preliminary work shows ESR (Electron Spin Resonance) can be used to detect biofilms, particularly from Fe-metabolising bacteria. A film was detected by ESR as early as 1 day, hence possibly more sensitively than by fluorescent methods. Films can probably be detected as early as one hour. Spectra contain a very broad peak at g=2.13, probably due to ferrihydrite. Results of field experiments from streams and ponds in New Zealand and Japan, particularly the Minoh River, showed a general increase of ferrihydrite with time. Loss by exfoliation was later than 20 days. The rate of accumulation was faster in a nutrient-rich stagnant pond. Hematite (g=4.3) was often observed, magnetite (g=9) once, and usually small amounts of a common bacterial decay product.... |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000300011 |
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| Verastegui,Javier; Martínez,Víctor; Roca,Willy; de Peña,Myriam; Gil,Lionel. |
| The Organization of American States is supporting the project "Biosafety Regulations in Latin America and The Caribbean within the framework of the International Biosafety Protocol". The general objective is to strengthen national skills for the assessment and management of risks of biotechnology food products, and to build up public awareness about their benefits and risks in the participant countries, with the ultimate goal to promote their safe and sustainable use within a protective and trusting environment for the public. The first phase has been focused on the evaluation of the political and regulatory systems in Chile, Peru and Colombia, identification of needs, and development of a series of biosafety seminar-workshops in the three countries, with... |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000100007 |
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| Baek,Kwang-Hyun; Skinner,Daniel Z. |
| Quantitative real-time PCR (qRT-PCR), used in conjunction with reverse transcriptase, has been applied to the determination of the number of copies of a transcript per unit mass of RNA, but did not indicate any change in the amount of total RNA per mass of tissue. In the present work, we described a simple method to use qRT-PCR to estimate the change in the amount of total RNA per unit mass of wheat (Triticum aestivum L.) tissue in response to cold temperature. Three qRT-PCR templates, i.e. control, cold-exposed, and one of RNA extracted from a sample consisting of equal masses of control and cold-exposed tissue, were analyzed. The number of copies of target transcript per unit mass of RNA was estimated from the three samples using standard qRT-PCR... |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000100008 |
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| Jain,Ashok K.. |
| A cDNA clone (peanut Gly-1) encoding for glycinin protein was isolated from the immature seeds (from yellow-1 maturity pods) and characterized. The clone spanning a total of 1836 bp, predicted protein of 529 amino acid residues with a calculated mass of 60,447.61 Da. Peanut Gly-1 sequence comparison shows high level of sequence homology with other two peanut glycinin (arachin) genes [Ara h3 (95%) and Ara h4 (94%)] and glycinin (legumin) genes of other legumes such as soybean, broad bean, French bean and pea etc., both at nucleotide (67 to 69%) and amino acid (60 to 63%) levels. The N- and C-terminals of peanut Gly-1 are highly conserved with other glycinin genes; central region of the gene possess three variable regions, which also show conservation with... |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000300003 |
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| Horsfall Jnr,Michael; Spiff,Ayebaemi I.. |
| Environmental protection requires the use of natural products instead of chemicals to minimize pollution. This investigation studies the use of a non-useful plant material as naturally occurring biosorbents for the removal of cationic pollutants in wastewater. The effect of pH on the sorption of Pb2+ and Cd2+ ion onto Caladium bicolor corm biomass was investigated. The experimental results have been analysed in terms of Langmuir, Freundlich and Flory-Huggins isotherms. The data showed that the maximum pH (pHmax) for efficient sorption of Pb2+ was 7.0 and for Cd2+ 5.0. Evaluation using Langmuir equation gave the monolayer sorption capacity as 88.50 mg/g and 65.50 mg/g at the respective pHmax for Pb2+ and Cd2+. Surface characterization of acid and base... |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000300014 |
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| Wakdikar,Sandhya. |
| Globally, there has been an unparalleled growth in the plant-derived medicinally useful formulations, drugs and health-care products, its market covering more than 60% products derived from plant origin. India exhibits remarkable outlook in modern medicines that are based on natural products besides traditional system of Indian medicines. Almost, 70% modern medicines in India are derived from natural products. Medicinal plants play a central role not only as traditional medicines but also as trade commodities, meeting the demand of distant markets. Ironically, India has a very small share (1.6%) of this ever-growing global market. To compete with the growing market, there is urgency to expeditiously utilize and scientifically validate more medicinally... |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000300002 |
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| Narayanan,Niju; Roychoudhury,Pradip K.; Srivastava,Aradhana. |
| Lactobacillus rhamnosus, a facultative anaerobe, which produces L (+) lactic acid and ethanol under anaerobic conditions, is used in the present study. An adh- mutant of Lactobacillus rhamnosus MTCC 1408, was developed by chemical mutagenesis, which could produce pure L(+) lactic acid as the only product. Batch fermentation kinetics of the wild type and the mutant strain were studied in glucose-yeast extract medium under conditions of temperature 40ºC and pH 6.2 anaerobically. The biomass yield was similar in both wild type and mutant strains, however lactic acid yield increased by 6.6%. A chemically defined media was optimized for supplementation of succinate, acetate and citrate for better biomass formation using single variable optimisation. It was... |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000100010 |
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| Vazquez,Raymond; Nelson,Marian R; Guzman,Juanita J; Corun,Charlene M; Steinberg,Mark. |
| Cytokines have been established as biomarkers to detect exposure of cells to chemical warfare agents such as sulfur mustard (2,2'-dichlorodiethyl sulfide, HD). In this study cultured normal and SV40 immortalized human epidermal keratinocyte (NHEK/IHEK) cells were compared as potential model systems to measure the efficacy of therapeutic drugs against HD. Immortalized human epidermal keratinocytes resemble their primary cell counterparts but have the advantage of being carried through long-term culture. Immortalized cells also provide consistency and durability and are less costly than primary keratinocytes. Immunoassay studies were performed to examine the response of these two cell lines to HD. We found that both normal and immortalized NHEKs secreted the... |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000200006 |
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| DaSilva,Edgar. |
| Biotechnology, in its voyage from ancient times into the expanding frontier areas of today's world of scientific research, has revealed itself as the gene of diplomacy and international cooperation in the relationships between nations (<a href="#16">DaSilva, 2002</a>). Economic and biotechnological considerations, strong elements in themselves, drive policy implementation that draws upon the support and sustenance of the public's logic and understanding of science obtained through the avenues of art and culture. More and more scientists are teaming up with artists to harness the world of microbes and biotechnology in the pursuit of one's natural well-being, of the conservation of environmental heritage, and of human comradeship and welfare. Art... |
| Tipo: Journal article |
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| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582004000200007 |
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| Registros recuperados: 12.472 | |
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