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991.
Carlos E. Da Costa Joo V. Comasseto Iracema H.-S. Crusius Leandro H. Andrade Andr L.M. Porto 《Journal of Molecular Catalysis .B, Enzymatic》2007,45(3-4):135-139
Aspergillus terreus CCT 3320 and A. terreus URM 3571 catalysed the biotransformations of organic β-hydroxyphenyl selenides through oxidation and methylation reactions. The kinetic resolution of (RS)-1-(phenylseleno)-2-propanol (1) via enantioselective oxidation produced (+)-(S)-1 in high enantiomeric excess (>99%) and in a yield of 50% as determined by product isolation. Oxidation of the R-enantiomer of 1, followed by elimination of the propyl moiety and subsequent methylation of the presumed intermediate, led to the formation of methylphenyl-selenide, which was isolated in a yield of 40%. Whole cells of A. terreus also biocatalysed transformations of diphenyldiselenide, benzeneseleninic acid, (RS)-1-(phenylseleno)-2-pentanol and (RS)-1-(phenylseleno)-3-methyl-2-butanol, but not of (RS)-1-(phenylseleno)-2-phenyl-methanol. This is the first report of the biomethylation of organoselenium compounds by whole cells of A. terreus. 相似文献
992.
Notch signaling is essential for ventricular chamber development 总被引:1,自引:0,他引:1
Grego-Bessa J Luna-Zurita L del Monte G Bolós V Melgar P Arandilla A Garratt AN Zang H Mukouyama YS Chen H Shou W Ballestar E Esteller M Rojas A Pérez-Pomares JM de la Pompa JL 《Developmental cell》2007,12(3):415-429
Ventricular chamber morphogenesis, first manifested by trabeculae formation, is crucial for cardiac function and embryonic viability and depends on cellular interactions between the endocardium and myocardium. We show that ventricular Notch1 activity is highest at presumptive trabecular endocardium. RBPJk and Notch1 mutants show impaired trabeculation and marker expression, attenuated EphrinB2, NRG1, and BMP10 expression and signaling, and decreased myocardial proliferation. Functional and molecular analyses show that Notch inhibition prevents EphrinB2 expression, and that EphrinB2 is a direct Notch target acting upstream of NRG1 in the ventricles. However, BMP10 levels are found to be independent of both EphrinB2 and NRG1 during trabeculation. Accordingly, exogenous BMP10 rescues the myocardial proliferative defect of in vitro-cultured RBPJk mutants, while exogenous NRG1 rescues differentiation in parallel. We suggest that during trabeculation Notch independently regulates cardiomyocyte proliferation and differentiation, two exquisitely balanced processes whose perturbation may result in congenital heart disease. 相似文献
993.
Reischl E Dafre AL Franco JL Wilhelm Filho D 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2007,146(1-2):22-53
In the present review, the sequences of hemoglobins (Hb) of 267 adult vertebrate species belonging to eight major vertebrate taxa are examined for the presence and location of cysteinyl residues in an attempt at correlation with their ecophysiology. Essentially, all vertebrates have surface cysteinyl residues in Hb molecules whereby their thiol groups may become highly reactive. Thiol-rich Hbs may display eight or more thiols per tetramer. In vertebrates so far examined, the cysteinyl residues occur in 44 different sequence positions in alpha chains and 41 positions in beta chains. Most of them are conservatively located and occur in only a few positions in Teleostei, Aves and Mammalia, whereas they are dispersed in Amphibia. The internal cysteinyl residue alpha104 is ubiquitous in vertebrates. Residue beta93 is highly conserved in reptiles, birds and mammals. The number of cysteine residues per tetramer with solvent access varies in vertebrates, mammalians and bony fish having the lowest number of external residues, whereas nearly all external cysteine residues in Aves and Lepidosauria are of the surface crevice type. In cartilaginous fish, amphibians, Crocodylidae and fresh water turtles, a substantial portion of the solvent accessible thiols are of the totally external type. Recent evidence shows that some Hb thiol groups are highly reactive and undergo extensive and reversible S-thiolation, and that they may be implicated in interorgan redox equilibrium processes. Participation of thiol groups in nitric oxide ((*)NO) metabolism has also been proved. The evidence argues for a new physiologically relevant role for Hb via involvement in free radical and antioxidant metabolism. 相似文献
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995.
The in vitro and in vivo characterization of cell-loaded immobilization devices is an important challenge in cell encapsulation technology for the long-term efficacy of this approach. In the present paper, alginate-poly-l-lysine-alginate (APA) microcapsules containing erythropoietin (Epo)-secreting C2C12 myoblasts have been elaborated, characterized, and tested both in vitro and in vivo. High mechanical and chemical resistance of the elaborated microcapsules was observed. Moreover, the in vitro cultured encapsulated cells released 81.9 +/- 8.2 mIU/mL/24 h (by 100 cell-loaded microcapsules) by day 7, reaching the highest peak at day 21 (161.7 +/- 0.9 mIU/mL/24 h). High and constant hematocrit levels were maintained over 120 days after a single subcutaneous administration of microcapsules and lacking immunosuppressive protocols. No major host reaction was observed. On the basis of the results obtained in our study, cell encapsulation technology might be considered a suitable therapeutic strategy for the long-term delivery of biologically active products, such as Epo. 相似文献
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999.
Vieira Maísa Carvalho Ortega Jean C. G. Vieira Ludgero Cardoso Galli Velho Luiz Felipe Machado Bini Luis Mauricio 《Hydrobiologia》2022,849(3):697-709
Hydrobiologia - Human activities may change beta diversity—the spatial variation in species composition—in different ways. Positive and negative trends in beta diversity are referred as... 相似文献
1000.
Martins Renato T. Brito Janaina Dias-Silva Karina Leal Ceclia G. Leito Rafael P. Oliveira Vivian C. Oliveira-Jnior Jos M. B. de Paula Felipe R. Roque Fabio O. Hamada Neusa Juen Leandro Nessimian Jorge L. Pompeu Paulo S. Hughes Robert M. 《Hydrobiologia》2022,849(10):2281-2298
Hydrobiologia - Stream degradation in Amazonia is outpacing our ability to effectively monitor it for three key reasons: (1) Many changes are cumulative and occur gradually; (2) Scientists have... 相似文献