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| Registros recuperados: 8.909 | |
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| da Costa,Antonio Carlos Augusto; Mora Tavares,Ana Paula; Pessôa de França,Francisca. |
| The biosorption of zinc and calcium was investigated with a biomass of Sargassum sp., a brown seaweed, in a continuous system consisting of three serial tubular fixed-bed laboratory reactors. Results indicated that zinc was efficiently recovered by the biomass. After treatment of 9.0 liters of a mixed solution containing 130.0 mg/l zinc and 260.0 mg/l calcium, the first column of the system saturated with zinc; the remaining columns did not saturate with zinc as a result of the pre treatment performed by the first reactor. Calcium was also efficiently biosorbed by the biomass, saturating the system much faster than zinc. X-ray fluorescence spectrum indicated the presence of various elements in the structure of the Sargassum sp. biomass, especially alkaline... |
| Tipo: Journal article |
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| Ano: 2001 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000300007 |
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| Fontana Capalbo,Deise Maria; Valicente,Fernando Hercule; Oliveira Moraes,Iracema de; Pelizer,Lúcia Helena. |
| The well-known entomopathogenic bacterium Bacillus thuringiensis (Bt) produces a spore-crystal complex which is responsible for its biocide characteristic, and the bacterium can be obtained by fermentation, either in liquid or semi-solid substrates. This paper presents a successful way to achieve solid-state fermentation of active Bt var. tolworthi (Btt) against Spodoptera frugiperda (fall armyworm) in corn. More than 10(9) CFU/g were obtained using humidified rice as substrate maintained in polypropylene bags. This active complex (substrate plus spore-crystal of Bt) was prepared in order to obtain 2 x 10(6) spores/mL; the final suspension then sprayed via tractor on corn fields. On the treated plants, mortality of neonate larvae was 100% within two days... |
| Tipo: Journal article |
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| Ano: 2001 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000200009 |
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| Guebel,Daniel V.; Torres Darias,Néstor V.. |
| Idiophase, the citric acid producing stage of Aspergillus niger was mathematically modeled to identify required genetic manipulations to optimize citric acid production rate. For this reason, a consistent picture of cell functioning had to be achieved. The transient idiophase nature was established by stoichiometric analysis. The main intracellular fluxes were computed by application of material and physiological constraints (ATP, reduction equivalents, proton motive force) at culture time 120 hours. The HMP pathway accounts for 16% of the glucose input (carbon basis), the Krebs cycle for 13% and the citric acid synthesis for the remaining 71%. This profile implies an operative glycerol-P shuttle. It recycles 93% of the cytosolic glycerol-P to cytosolic... |
| Tipo: Journal article |
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| Ano: 2001 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000100001 |
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| Falk,Torsten; Strazdas,Lori A.; Borders,Rebecca S.; Kilani,Ramsey K.; Yool,Andrea J.; Sherman,Scott J.. |
| High-density cultures of mammalian neurons offer a model system for studies of brain development, but the morphological features of individual neurons is difficult to ascertain. We show that a herpes virus vector expressing a bioluminescent protein allows detailed morphometric analyses of living neurons in complex culture environments. Expression of enhanced green fluorescent protein (eGFP) was constitutively driven in neurons using the herpes simplex virus amplicon system. This system allowed us to make novel observations regarding development in high-density cultures from rat hippocampus and cerebellum. After the phase of initial neurite outgrowth, maturing neurons continue to show rapid remodeling of the neurite branches (0.79 ± 0.11 mum/h per neurite;... |
| Tipo: Journal article |
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| Ano: 2001 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000100004 |
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| Zaldívar,Mercedes; Velásquez,Juan Carlos; Contreras,Inés; Pérez,Luz María. |
| A mutant of the native fungus Trichoderma aureoviride, 7-121, selected for its overproduction of extracellular cellulase and ß-glucosidase (cellobiase) was obtained. In shake flask cultures, production of endoglucanase, filter paper activity and cellobiase increased two to four- fold as compared with the wild type strain. The mutant strain is stable and grows rapidly in liquid as well as in solid culture media. Enzyme yields were best when pH was controlled so that it did not fall bellow pH 3.5. Cellobiase production by this mutant is particularly high (approximately 5 U/ml) as compared to other Trichoderma, strains, which makes it a suitable candidate for waste cellulose degradation. In addition, the mutant strain showed enhanced production of fungal cell... |
| Tipo: Journal article |
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| Ano: 2001 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000300011 |
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| Rousseau,Marthe; Batista,Irineu; Le Gal,Yves; Fouchereau-Peron,Martine. |
| Calcitonin gene related peptide (CGRP) related molecules were purified from sardine hydrolysates prepared using 0.1% alcalase and two hours of hydrolysis. Gel exclusion chromatography and HPLC performed purification of these molecules. The purified molecules were characterised using specific CGRP radioimmunoassays and radioreceptoraasays. From 22 mg of crude extract, we obtained 14 µg of CGRP related molecules, the molecular weight determined by mass spectrophotometry was 6000 daltons. The biological activity of these molecules was analysed using the ability of CGRP to stimulate the adenylate cyclase activity in rat liver membranes. The purified molecules induced an inhibition of the CGRP stimulated adenylate cyclase activity, this effect was specific as... |
| Tipo: Journal article |
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| Ano: 2001 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000100003 |
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| Canales,Mauricio; Westermeyer,Linda; Carvajal,Nelson. |
| By using molecular dynamics (MD) simulations and crystallographic data for rat liver arginase, the substrate positions in the active sites of native and mutant forms of the enzyme, were compared and correlated with known kinetic consequences of mutations. The mutants compared were His 141<IMG SRC="/content/vol4/issue3/full/6/flecha2.gif" WIDTH=12 HEIGHT=9>Phe and His 141<IMG SRC="/content/vol4/issue3/full/6/flecha2.gif" WIDTH=12 HEIGHT=9>Asn. The simulations show that mutation His141<IMG SRC="/content/vol4/issue3/full/6/flecha2.gif" WIDTH=12 HEIGHT=9>Asn gives the greatest divergence from the atomic coordinates, when compared with the control native enzyme. The mutant Asp128<IMG SRC="/content/vol4/issue3/full/6/flecha2.gif" WIDTH=12... |
| Tipo: Journal article |
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| Ano: 2001 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000300010 |
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| Juang,Der-Fong; Morgan,Joe M.. |
| The purpose of this study was to test the applicability of the API 20E and API Rapid NFT systems for the identification of some predominant gram-negative and gram-positive bacteria isolated from lab-scale activated sludge treatment systems. In this study, one lab-scale sequencing batch reactor (SBR) and one lab-scale continuous-flow stirred tank reactor (CFSTR) were setup. After both reactors had reached equilibrium, many pure cultures isolated from the activated sludge in both systems were obtained and many morphological, biochemical, physiological tests were conducted to identify each pure culture. The API 20E system is a standardized, miniaturized version of conventional procedures for rapid identification of Enterobacteriaceae and other gram-negative... |
| Tipo: Journal article |
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| Ano: 2001 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000100002 |
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| Patnaik,Debasis; Khurana,Paramjit. |
| Due to the inherent difficulties associated with gene delivery into regenerable explants and recovery of plantlets with the introduced transgene, wheat was the last among cereals to be genetically transformed. This review attempts to summarize different efforts in the direction of achieving genetic transformation of wheat by various methods. Particle bombardment is the most widely employed procedure for the introduction of marker genes and also for the generation of transformed wheat with introduction of agronomically important genes for quality improvement, engineering of nuclear male sterility, transposon tagging, resistance to drought stress, resistance against fungal pathogens and insect resistance. The other methods of choice of gene delivery into... |
| Tipo: Journal article |
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| Ano: 2001 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000200007 |
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| Federici,María Teresa; Vaughan,Duncan; Norihiko,Tomooka; Kaga,Akita; Xin,Wang Wang; Koji,Doi; Francis,Marta; Zorrilla,Gonzalo; Saldain,Nestor. |
| Weedy rice is a serious problem in Uruguayan rice fields since intensification of rice production started about 10 years ago. The genetic diversity of 26 weedy accessions of weedy rice and 6 Uruguayan cultivars were analyzed using AFLP (amplified fragment length polymorphisms) methodology. Abundant polymorphisms were found among samples tested. Using different methods of analysis three groups of samples were revealed. A relationship was found between three groups and morphological traits. One group had a black hull, purple apex and long awn (wild type traits) while another group had straw hull and apex, and short or no awn (domestication traits). The third group included the cultivars analyzed and some weedy rice samples. The weedy rice in this third group... |
| Tipo: Journal article |
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| Ano: 2001 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000300008 |
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| Afaq,Sarah; Iqbal,Jawaid. |
| A method for immobilization of papain has been selected based on the interaction between its histidine, cysteine and tryptophan residues with the immobilized metal ion (IMI) carrier for maximum binding on a small volume of the carrier. The immobilized papain retained high activity has improved thermal stability and the carrier could be recovered from the spent bound enzyme, to be reused. Reimmobilization of papain on the regenerated matrix was equally effective with the retention of maximum enzyme activity. |
| Tipo: Journal article |
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| Ano: 2001 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000300006 |
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| Registros recuperados: 8.909 | |
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