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| Registros recuperados: 10.260 | |
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| Federici,María Teresa; Shcherban,Andrei B.; Capdevielle,Fabián; Francis,Marta; Vaughan,Duncan. |
| The genetic relationships among 34 accessions of wild rice from Asia, Africa, America and Australia were analysed using RFLP technique. After southern blotting, DNA digestion pattern was hybridised with a highly repetitive DNA sequence of a retrotransposon from a gypsy family of mobile elements. A dendrogram was constructed from RFLP data in which the species clustered according to their genome designation (CC, BB, BBCC and CCDD genomes). Some species did not appear in the same group, for example, O. eichingeri from Africa and Sri Lanka clustered separately from each other. The same situation was observed for the accessions from China of O. officinalis, which cluster together showing a close relationship with O. rhizomatis, and O. eichingeri (both of CC... |
| Tipo: Journal article |
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| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582002000200012 |
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| Acevedo,Fernando. |
| Nowadays bioleaching occupies an increasingly important place among the available mining technologies. Today bioleaching is no longer a promising technology but an actual economical alternative for treating specific mineral ores. An important number of the current large-scale bioleaching operations are located in developing countries. This situation is determined by the fact that several developing countries have significant mineral reserves and by the characteristics of bioleaching that makes this technique especially suitable for these countries because of its simplicity and low capital cost requirement. The current situation of commercial-size bioleaching operations and ongoing projects in developing countries is presented and discussed with especial... |
| Tipo: Journal article |
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| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582002000200001 |
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| ul-Haq,Ikram; Ali,Sikander; Qadeer,M.A.; Iqbal,Javed. |
| Citric acid fermentation of cane-molasses by submerged fermentation in 15 L stirred fermentor (working volume 9 L) was carried out. A hyper mutant strain of Aspergillus niger GCMC-7 was used in the present study which was obtained from the culture collection of our own labs. Ferrocyanide treated molasses [K4Fe(CN)6 200 ppm] medium containing sugar 150 g/l was employed as the basal fermentation medium. Different cultural conditions such as incubation temperature (30ºC), initial pH (6.0), air supply (1.0 l-1l-1min), agitation intensity (200 rpm) and time profile (144 h after inoculation) were optimised for enhanced citric acid production. Maximum amount of anhydrous citric acid obtained during the course of study was 106.65 g/l, with a sugar consumption of... |
| Tipo: Journal article |
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| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582002000200007 |
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| Ali,Sikander; Haq,Ikram-ul-; Qadeer,M.A.; Iqbal,Javed. |
| The present investigation deals with the kinetics of submerged citric acid fermentation by Aspergillus niger using blackstrap molasses as the basal fermentation media. A laboratory scale stirred fermentor of 15-L capacity having working volume of 9-L was used for cultivation process and nutritional analysis. Among the 10 stock cultures of Aspergillus niger, the strain GCBT7 was found to enhance citric acid production. This strain was subjected to parametric studies. Major effects were caused due to oxygen tension (1.0 l/l/min), pH value (6.0) and incubation temperature (30ºC). All fermentations were carried out following the growth on 150 g/l raw molasses sugars for 144 hours. Ferrocyanide (200 ppm) was used to control the trace metals present in the... |
| Tipo: Journal article |
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| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582002000300010 |
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| León Fiszman,Gabriel; Karara,Armando Luis; Finocchiaro,Liliana María Elena; Glikin,Gerardo Claudio. |
| The microencapsulation of recombinant cells, widely used for in vitro high-density cell culture, is a novel and potentially cost-effective method of in vivo heterologous protein delivery, where the protein producing cells are immunologically protected from tissue rejection. We report here a simple, reliable and inexpensive laboratory method to generate calcium alginate microcapsules containing genetically engineered, interleukin-2 expressing, Chinese hamster ovary (CHO) cells. |
| Tipo: Journal article |
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| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582002000300012 |
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| Petrova,Ventsislava Yankova; Rasheva,Tanya Vassileva; Kujumdzieva,Anna V.. |
| Catalase and superoxide dismutase activities have been explored in the yeast Saccharomyces cerevisiae during batchwise growth experiment. During the diauxic growth in YPD medium high Ys values were obtained (0.415 - 0.423) and correlation between the total activities of both enzymes has been found. A mitochondrial fraction from three type strains of Saccharomyces cerevisiae has been isolated. The purity of this fraction was proved through different enzyme assays: hexokinase, glucose-6-phosphate dehydrogenase, D-amino acid oxidase, isocitric lyase, succinate dehydrogenase. Then the catalase, peroxidase, Mn and Cu/Zn superoxide dismutase activities were evaluated in the mitochondrial fraction. Polyacrylamide gel electrophoresis separations allowed to... |
| Tipo: Journal article |
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| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582002000100010 |
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| DaSilva,Edgar J.; Baydoun,Elias; Badran,Adnan. |
| The life sciences offer opportunities for revolutionizing human welfare activities. Enriched by inputs from genomic research, biotechnology is a major force for development in all countries. Entwined with culture and socio-ethical values, biotechnology contributes to solving problems like food and water insecurity that impede national development and threaten peace in the developing world. The lack of facilities and professional skills in biotechnology limits R & D initiatives in the developing and the least developed countries (LDCs); and, restricts their full participation in take-off activities in national and self-reliant regional ventures in sustainable development. The practice of biotechnology different in many developing countries is... |
| Tipo: Journal article |
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| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582002000100013 |
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| Kopytko,Maria; Chalela,Graciela; Zauscher,Fernando. |
| The purpose of this project was to evaluate the biodegradation of two commercial herbicides (Gramoxone and Matancha) by the bacteria Pseudomonas putida. Gramoxones active ingredient is Paraquat (1,1-dimethyl-4,4-bipyridylium) and Matanchas is 2,4-D (2,4-dichlorophenoxiacetic acid). To carry out the biodegradation experiments, a factorial design 2³ was executed, where the independent variables were: herbicide concentration, nutrient concentration and the use or no use of activated charcoal (AC) in the same experiment with bacteria. Duplicate experiments were performed for a period of three days using 500 ml bioreactors. The best results obtained when no AC was used were: 47,29% degradation for Gramoxone (by UV/VIS) and 68.72% for Matancha (by HPLC). The... |
| Tipo: Journal article |
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| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582002000200013 |
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| Pelizer,Lúcia Helena; Carvalho,J.C.M.; Sato,Sunao; de Oliveira Moraes,Iracema. |
| Spirulina platensis is a cyanobacterium that has a high protein content and therefore, a high nutritional value. It can be cultivated either in a liquid or in a solid culture. When cultivated in aqueous culture the cell growth can be determined by following the optical density. On the other hand, when produced by solid cultivation the growth can be determined only indirectly, such as, through determination of the protein content of the fermenting solids. In this work the possibility of estimating cell growth by pH determination was verified. From the results it was concluded that pH and protein production (solid or surface culture) or cell content (liquid culture) correlate well, therefore pH determination seems to be a good method to determine cell growth. |
| Tipo: Journal article |
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| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582002000300009 |
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| Wang-Pruski,Gefu; Szalay,Aladar A.. |
| Engineering of higher plants for increased cold tolerance requires a chemical modification of membrane fluidity in both organelles and cytoplasm of plant cells. A small number of microorganisms use branched chain fatty acids as their membrane constituents to maintain membrane fluidity, instead of unsaturated fatty acids. One of the key enzymes facilitating synthesis of branched chain fatty acids in Bacillus subtilis 168s is the branched chain alpha-oxo acid decarboxylase. To examine the role of branched chain fatty acids in plants and the potential for low temperature tolerance, the A and B genes encoding the alpha and beta polypeptides, respectively, of the branched chain alpha-oxo acid decarboxylase were introduced into the genome of tomato plants. The... |
| Tipo: Journal article |
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| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582002000200009 |
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| Ali,Sikander; ul-Haq,Ikram; Qadeer,M.A.. |
| L-DOPA is a useful drug for Parkinsons disease. This investigation deals with the biosynthesis of L-DOPA by parental (GCB-6) and mutant (UV-7) strains of Aspergillus oryzae. There was a marked difference between the mycelial morphology and pellet type of the parental and UV-irradiated mutant cultures. The mutant strain of Aspergillus oryzae UV-6 showed pellet-like mycelial morphology and improved tyrosinase activity. Mould mycelium was used for biochemical conversion of L-tyrosine to L-DOPA since tyrosinase is an intracellular enzyme. The mutant was found to give 3.72 folds higher production of L-DOPA than the parental strain. The comparison of kinetic parameters was also done which showed greater ability of the mutant to yield L-DOPA (i.e. Yp/x 32.73... |
| Tipo: Journal article |
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| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582002000200006 |
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| Ramin,Hosseini; Mulligan,Bernard J.. |
| Changes in the DNA content and organisation of senescing rice cell cultures (Taipei 309) were studied, using PCR and Southern blot analyses. A mitochondrial gene (coxII), a plastid gene (psaA) and a nuclear DNA maker (RG64) were analysed. The amplification of mitochondrial (mt), plastid and nuclear DNA produced the expected fragments, indicating that there were still some intact organelles and nuclei in the senescing rice cells. However, in plastid and nuclear DNA, changes in the number and size of the PCR products were observed. Southern blot analysis revealed that mt and nuclear DNA contents declined, but plastid DNA content remained relatively the same throughout the senescence. |
| Tipo: Journal article |
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| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582002000100012 |
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| Hosseini,Ramin; Mulligan,Bernard J.. |
| Single Strand-Preferring Nucleases (SSPNs) have been implicated in the triggering and progress of cell death pathways, including senescence in higher plants, though the biological roles of such enzymes are still obscure. In the present study, heterotrophic cell suspension cultures of Oryza sativa L. (rice) cv Taipei 309 were used to investigate changes in Single Strand-Preferring Nuclease activity associated with cell death in vitro. An acid nuclease activity (pH 5.5) was found which was strongly stimulated in the presence of 10 mM Zn2+ and inhibited by 10 mM EDTA and EGTA. An increase in SSPN activity was concomitant with a loss of cell viability, total protein and the onset of stationary phase of growth in the cell cultures. Using DNA-SDS-PAGE two major... |
| Tipo: Journal article |
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| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582002000100011 |
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| Registros recuperados: 10.260 | |
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