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991.
F E Muñiz-Lozano G Domιnguez-Sánchez Y Dιaz-Viveros D M Barradas-Dermitz 《Journal of industrial microbiology & biotechnology》1998,21(6):296-299
A novel bacterial strain producing D-aminoacylase was isolated from organic waste and identified as Stenotrophomonas maltophilia ITV-0595. The isolation was performed using N-acetyl-D-phenylglycine (NAcDPG) as the sole source of C and N. The optimum pH for enzyme expression was 8 at 37°C. Using N-Ac-DPG
concentrations from 0.5 up to 3% w/v, it was observed that at the 1% level, the microorganism showed acceptable responses
in both enzyme activities and cell growth. From the different tested compounds N-acetyl-D-methionine (1%) was the best enzyme inducer (Sp. act. = 4.14 U mg−1 protein, Vol. act. = 0.17 U ml−1) and the only one that increased cell growth.
Received 13 June 1997/ Accepted in revised form 29 October 1998 相似文献
992.
Veena Prasad Asish Ray Chaudhuri Matthew Curcio Isao Tomita Fukutaro Mizuhashi Kyoji Murata Richard F. Ludueña 《The protein journal》1998,17(7):663-668
Tubulin, the subunit protein of microtubules, undergoes a time-dependent loss of functional properties known as decay. We
have previously shown that the drug 2-(4-fluorophenyl)-1-(2-chloro-3,5-dimethoxyphenyl)-3-methyl-6-phenyl-4(1H)-pyridinone (IKP104) accelerates decay, but that in the presence of colchicine, IKP104 becomes a stabilizer of tubulin. To
see if this is due to conformational effects specific to colchicine or simply to occupancy at the colchicine site, we examined
the effects of nocodazole and podophyllotoxin, two well-known competitive inhibitors of colchicine for binding to tubulin,
on IKP104’s acceleration of decay. We found that podophyllotoxin abolished IKP104’s accelerating effect and, like colchicine,
turned it into a stabilizer of tubulin. Nocodazole’s effects were similar to those of podophyllotoxin and colchicine, in that
it abolished IKP104-induced enhancement of decay; however, in the presence of nocodazole, IKP104 caused little or no stabilization
of tubulin. Since colchicine, nocodazole, and podophyllotoxin have very different interactions with tubulin, but all inhibit
the IKP104-induced enhancement of decay, our findings suggest that this inhibition arises from occupancy of the colchicine
site rather than from a direct conformational effect of these two drugs. 相似文献
993.
F. Roch F. Serras F. J. Cifuentes M. Corominas B. Alsina M. Amorós A. López-Varea R. Hernández D. Guerra S. Cavicchi J. Baguñá A. García-Bellido 《Molecular genetics and genomics : MGG》1998,257(2):103-112
We have carried out screens for lethal mutations on the second chromosome of Drosophila melanogaster that are associated with abnormal imaginal disc morphologies, particularly in the wing disc. From a collection of 164 P element-induced mutations with a late larva/pupa lethal phase we have identified 56 new loci whose gene products are required for normal wing disc development and for normal morphology of other larval organs. Genetic mosaics of these 56 mutant lines show clonal mutant phenotypes for 23 cell-viable mutations. These phenotypes result from altered cell parameters. Causal relationships between disc and clonal phenotypes are discussed. 相似文献
994.
B. Alsina F. Serras J. Baguñà M. Corominas 《Molecular genetics and genomics : MGG》1998,257(2):113-123
Proliferation in imaginal discs requires cell growth and is linked to patterning processes controlled by secreted cell-signalling molecules. To identify new genes involved in the control of cell proliferation we have screened a collection of P-lacW insertion mutants that result in lethality in the larval/pupal stages, and characterized a novel gene, patufet (ptuf). Inactivation of ptuf by a P element insertion in the 5′ untranslated region leads to aberrant imaginal disc morphology characterized by a reduction in mass of discs and disorganisation of disc cells where no folding or patterning can be detected. Moreover, apoptotic cells can be observed in these small and abnormal mutant discs. To examine the role of ptuf we have studied its clonal behaviour in genetic mosaics generated by mitotic recombination. The mutation causes reduced cell viability, smaller cell size and stops vein differentiation. Non-autonomous effects, such as abnormal differentiation of wild-type cells surrounding the clones, are also observed. We have cloned the ptuf gene of Drosophila melanogaster and found that it encodes a selenophosphate synthetase, which is the first identified in insects. Mutant flies transformed with the full-length cDNA show complete reversion of lethality and disc phenotype. Northern blot analysis and in situ hybridization indicate that the ptuf gene is expressed in imaginal discs as well as at different stages of development. The synthesis of selenoproteins by the selenophosphate synthetase, the role of selenoproteins in the maintenance of the oxidant/antioxidant balance of the cell and its possible implications in imaginal disc morphogenesis are discussed. 相似文献
995.
Nobel Park S. Zhang Hehui Sharifi Rasoul Castañeda Miguel Greenhouse Barry 《Photosynthesis research》1998,56(1):67-73
Encelia farinosa is one of the most abundant and highly studied species of the Sonoran Desert, yet characteristics of its leaf development and long-term photosynthetic capacity are relatively unknown. The net CO2 uptake rate and the Rubisco activity per unit leaf area for E. farinosa in a glasshouse increased in parallel for about 18 days after leaf emergence (leaf area was then 5 cm2), after which both were constant, suggesting that Rubisco levels controlled net CO2 uptake. Instantaneous net CO2 uptake rates at noon for well-watered E. farinosa in the glasshouse at different temperatures and light levels correctly predicted differences in daily net CO2 uptake at four seasonally diverse times for transplanted plants under irrigated conditions in the field but overpredicted the daily means by 13%. After this correction, seasonally adjusted net CO2 uptake per unit leaf area multiplied by the estimated monthly leaf area predicted that 42% of the net carbon gain was incorporated into plant dry weight over a 17-month period. The ecological success of E. farinosa apparently reflects an inherently high daily net CO2 uptake and retention of a substantial fraction of its leaf carbon gain. 相似文献
996.
The appearance of the electroretinogram was established during the development of two species of opilionids, an epigaeic species, Pachylus chilensis, and a cavernicolous one, Ischyropsalis luteipes. In nymphs and adults of the two species, electroretinograms of about the same amplitude can be recorded. During embryonic and larval development they are quite different. In Ischyropsalis luteipes, it is impossible to record an electrical response before hatching. In Pachylus chilensis on the other hand an initial inconstant and very small response occurs from the 50th hour of development of the retina and can always be recorded from the 72nd hour. In older embryos, the response has a progressively greater amplitude, but remains a simple negative wave. On the tenth day, when the first synaptic relays appear, the electroretinogram takes the shape of that of the adult. Given that transmission electronic microscopy cannot detect differences between the microvilli of these two species, it is tempting to compare Ischyropsalis luteipes lack of response with that of the mutant norp A of Drosophila melanogaster in which transmission electron microscopy shows no marked difference, whereas freeze-etching shows a very low number of intramembranous particles. 相似文献
997.
Fernando Granado-Lorencio Carmer Herrero-Barbudo Begoña Olmedilla-Alonso Inmaculada Blanco-Navarro Belén Pérez-Sacristán 《The Journal of nutritional biochemistry》2010,21(2):133-139
We assessed the bioavailability of lutein from lutein-fortified fermented milk using in vivo and in vitro approaches. Twenty-four volunteers were randomized to take lutein-fortified fermented milk at two levels of fortification. Single-dose bioavailability study (2×100 ml, ca. 8 or 16 mg of lutein) was performed using a three-point approach (baseline, 3.5 and 6.5 h). Multiple-dose study consisted of consuming one serving/day (ca. 4 or 8 mg/100 ml) for 14 days. Blood samples for biochemical, hematological and lutein analysis were drawn at baseline, Day 7 and Day 14. In vitro bioaccessibility was assessed by a static gastrointestinal digestion model. Lutein content, in vitro ester hydrolysis and micellarization, and lutein concentrations achieved in serum were analyzed by HPLC. In vivo, post-prandial response was higher using the high content fermented milk, but the percentage of absorption was not different according to the dose consumed. Net increments at Day 7 and Day 14 were significantly higher on consuming the high-dose milk as well. In vitro, lutein ester hydrolysis was incomplete regardless of the amount initially present. Free lutein released was higher using the high-dose fermented milk, but the percentage of hydrolysis was similar at both levels of fortification. In the micellar phase, the percentage of free and total lutein was not different according to the dose. Our results support the suitability of the fermented milk as a carrier of lutein esters and an in vivo dose-dependent effect upon regular consumption and suggest the usefulness of in vitro models to provide relevant information to predict in vivo responses. 相似文献
998.
Nancy Argüelles Eugenia Sánchez-Sandoval Aarón Mendieta Lourdes Villa-Tanaca Leticia Garduño-Siciliano Fabiola Jiménez María del Carmen Cruz José L. Medina-Franco Germán Chamorro-Cevallos Joaquín Tamariz 《Bioorganic & medicinal chemistry》2010,18(12):4238-4248
A series of α-asarone-based analogues was designed by conducting docking experiments with published crystal structures of human HMG-CoA reductase. Indeed, synthesis and evaluation of this series showed a highly hypocholesterolemic in vivo activity in a murine model, as predicted by previous docking studies. In agreement with this model, the polar groups attached to the benzene ring could play a key role in the enzyme binding and probably also in its biological activity, mimicking the HMG-moiety of the natural substrate. The hypolipidemic action mechanism of these compounds was investigated by developing a simple, efficient, and novel model for determining HMG-CoA reductase inhibition. The partial purification of the enzyme from Schizosaccharomyces pombe allowed for testing of α-asarone- and fibrate-based analogues, resulting in positive and significant inhibitory activity. 相似文献
999.
Rocio Duque‐Jamaica Azucena Arévalo‐Galvis Raúl A. Poutou‐Piñales Alba A. Trespalacios 《Helicobacter》2010,15(4):303-312
Background: Colonization of the gastric mucosa by Helicobacter pylori is one of the most important causes of acute and chronic gastric pathologies in humans. Achieving the growth of H. pylori in liquid media is of great importance in the development of clinical studies. In this study, we developed a sequential optimization strategy based on statistical models to improve the conditions of liquid culture of H. pylori. Materials and Methods: Four statistical models were sequentially used. First, a Box‐Behnken design was used to select the best process conditions (shaking speed, inoculum concentration, and final volume of culture). Secondly, a general factorial design was used to evaluate the influence of adding gel blocks or gel beads (shape and composition). Then a D‐optimal reduce design was carried out to allow the selection of the most influential factors in increasing the cell concentration (culture media components). Finally, another Box‐Behnken design was used to optimize the concentration of the culture media components previously selected. Results: After 12 hours of liquid culture a concentration of 25 × 108 cells per mL (9.4 log10 cells per mL) of H. pylori was obtained, compared with a predicted 32 × 108 (9.5 log10 cells per mL), which means between 1 and 5 log10 units higher than some previous reports. Conclusions: The sequential statistical approach increased the planktonic H. pylori cell culture. The final culture media and conditions were: Brain Heart Infusion, blood agarose (1.5% w/v), lamb’s blood (3.18% v/v), DENT (0.11% v/v), and Vitox (0.52% v/v) at 60 rpm and 37 °C with filtered CO2 (5% v/v) bubbled directly into the culture media in a final volume of 76.22 mL. 相似文献
1000.