RESUMO
Many different materials have been tested for ß-glucosidases immobilization. Such materials, however, often show a poor activity related to a low surface area of the support or even enzyme hindrance caused by entrapment inside porous matrix. In this context, the use of nanosized zeolites as enzymes support is quite new and may be an interesting alternative. The present work evaluates the immobilization of ß-glucosidases in nanosized silicalites by covalent coupling. The new biocatalyst was able to convert 100% of cellobiose into glucose in 18 h at 50 °C and pH 5, retaining 85% of its activity after five cycles of reuse. A detailed investigation of the published literature indicates that, apparently, this is the first work concerning the immobilization of ß-glucosidases on nanosized zeolites ever reported.
Assuntos
Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Nanoestruturas/química , Silicatos/química , beta-Glucosidase/química , beta-Glucosidase/metabolismo , Biocatálise , Hidrólise , Propriedades de SuperfícieRESUMO
AIMS: The objectives were to determine the variability and to compare the genetic diversity obtained using amplified fragment length polymorphism (AFLP) markers in analyses of wine, tequila, mezcal, sotol and raicilla yeasts. METHODS AND RESULTS: A molecular characterization of yeasts isolated from Mexican agave musts, has been performed by AFLP marker analysis, using reference wine strains from Italian and South African regions. CONCLUSIONS: A direct co-relation between genetic profile, origin and fermentation process of strains was found especially in strains isolated from agave must. In addition, unique molecular markers were obtained for all the strains using six combination primers, confirming the discriminatory power of AFLP markers. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of molecular characterization between yeasts isolated from different Mexican traditional agave-distilled beverages, which shows high genetic differences with respect to wine strains.
Assuntos
Bebidas Alcoólicas/microbiologia , Reação em Cadeia da Polimerase/métodos , Polimorfismo Genético , Saccharomyces/classificação , Saccharomyces/genética , Vitis/microbiologia , Vinho/microbiologia , Agave/química , Agave/microbiologia , DNA Fúngico/análise , Genótipo , México , Filogenia , RNA Ribossômico 18S/genética , Saccharomyces/isolamento & purificação , Vitis/químicaRESUMO
Mannose-6-phosphate receptors (MPRs) play a role in the selective transport of macromolecules bearing mannose-6-phosphate residue to lysosomes. To date, two types of MPRs have been described in most of cells and tissues: the cation-dependent (CD-MPR) and cation-independent mannose-6-phosphate receptor (CI-MPR). In order to elucidate their possible role in the central nervous system, the expression and binding properties of both MPRs were studied in rat brain along perinatal development. It was observed that the expression of CI-MPR decreases progressively from fetuses to adults, while the CD-MPR increases around the 10th day of birth, and maintains these values up to adulthood. Binding assays showed differences in the Bmax and KD values between the ages studied, and they did not correlate with the expression levels of both MPRs. Variations in lysosomal enzyme activities and expression of phosphomannosylated ligands during development correlated more with CD-MPR than with CI-MPR expression. These results suggest that both receptors play a different role in rat brain during perinatal development, being CD-MPR mostly involved in lysosome maturation.
Assuntos
Encéfalo/metabolismo , Cátions/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Receptor IGF Tipo 2/metabolismo , Fatores Etários , Animais , Animais Recém-Nascidos , Sítios de Ligação/efeitos dos fármacos , Sítios de Ligação/fisiologia , Western Blotting/métodos , Encéfalo/crescimento & desenvolvimento , Proteínas de Transporte , Relação Dose-Resposta a Droga , Embrião de Mamíferos , Glucuronidase/metabolismo , Glucuronidase/farmacocinética , Hidrólise , Substâncias Macromoleculares , Fosforilação , Ratos , Ratos Sprague-Dawley , Receptor IGF Tipo 2/classificação , Receptor IGF Tipo 2/genética , Frações Subcelulares/enzimologiaRESUMO
The mammalian epididymis is an organ particularly rich in acid hydrolases, consistent with a developed lysosomal apparatus. However, some of these enzymes could also play a role in an extracellular environment, since they are actively secreted by the epithelium. In this study the authors measured the activity of five acid hydrolases distributed between the epithelium, fluid, small vesicles, and spermatozoa of the rat cauda epididymis in adult rats, and compared with that distribution under conditions of deprivation of luminal testosterone and testicular compounds (hemicastration). Lysosomal enzymes are differently compartmentalized in rat cauda epididymis. Most of beta-galactosidase (beta-GAL) and aryl sulfatase (approximately 70%) were found in soluble form within the fluid. Some 60% of N-acetyl-beta-D-glucosaminidase (beta-NAG) and alpha-mannosidase (alpha-MAN) become transiently bound to sperm, and beta-glucuronidase (beta-GLU) was mostly concentrated in the epithelium. After remotion of testis this distribution changed, as the retention of alpha-MAN, beta-GAL, beta-GLU, and beta-NAG by the epididiymal tissue increased. The increase of beta-GLU followed an increase of synthesis of the enzyme. The distribution of enzymes in the epididymis from the contralateral side was similar to that in normal rats. The different roles for each enzyme in the epididymis are discussed.
Assuntos
Epididimo/enzimologia , Hidrolases/metabolismo , Lisossomos/enzimologia , Acetilglucosaminidase/metabolismo , Animais , Arilsulfatases/metabolismo , Epididimo/patologia , Células Epiteliais/metabolismo , Glucuronidase/metabolismo , Masculino , Manosidases/metabolismo , Orquiectomia , Proteínas/metabolismo , Ratos , Ratos Sprague-Dawley , Maturação do Esperma/fisiologia , Espermatozoides/metabolismo , Espermatozoides/fisiologia , alfa-Manosidase , beta-Galactosidase/metabolismoRESUMO
This review discusses some of the changes in sperm during maturation within the context of current concepts of membrane structure and fertilization. Mammalian sperm are surrounded by a limiting plasma membrane that undergoes remodeling during passage through the epididymis. This process confers on the gamete vigorous motility and the ability to fertilize the egg. The repositioning of some surface proteins may follow redistribution of lipids in the plasmalemma, and thus represent a critical step in the maturation of the gametes. Among the various affected proteins of the sperm plasmalemma, mannose-6-phosphate receptors undergo redistribution as the gametes transit through the epididymal duct. The authors summarize their studies of the redistribution of phosphomannosyl receptors during maturation of sperm and discuss possible roles of these glycoproteins in the fertilizing capability of sperm.
Assuntos
Epididimo/citologia , Receptor IGF Tipo 2/metabolismo , Espermatozoides/fisiologia , Animais , Humanos , MasculinoRESUMO
The aim of the present work was to study the distribution of the cation-independent (CI) and cation-dependent (CD) mannose-6-phosphate receptors (MPRs) in spermatozoa obtained from either rete testis or three regions of rat epididymis. We observed that both receptors underwent changes in distribution as spermatozoa passed from rete testis to cauda epididymis. CI-MPR was concentrated in the dorsal region of the head in rete testis sperm and that this labeling extended to the equatorial segment of epididymal spermatozoa. CD-MPR, however, changed from a dorsal distribution in rete testis, caput, and corpus to a double labeling on the dorsal and ventral regions in cauda spermatozoa. The percentages of spermatozoa that showed staining for either CI-MPR or CD-MPR increased from rete testis to epididymis. The observed changes were probably the result of a redistribution during transit rather than an unmasking of receptors. The fluorescence corresponding to CD-MPR and CI-MPR on the dorsal region disappeared when caudal spermatozoa underwent the acrosomal reaction. Receptors were localized on the plasmalemma of spermatozoa, as observed by immunoelectron microscopy. Changes in distribution may be related to a maturation process, which suggests new roles for the phosphomannosyl receptors.
Assuntos
Receptores Citoplasmáticos e Nucleares/metabolismo , Espermatozoides/crescimento & desenvolvimento , Espermatozoides/metabolismo , Animais , Epididimo/citologia , Técnica Indireta de Fluorescência para Anticorpo , Masculino , Microscopia Eletrônica , Ratos , Ratos Sprague-Dawley , Receptor IGF Tipo 2 , Testículo/citologiaRESUMO
El alto nivel de industrialización en Italia condujo, a partir de 1976, al surgimiento de regulaciones en la calidad de los efluentes industriales no solo para las descargas en aguas superficiales, sino también, en el sistema de alcantarillado público. Se describe principalmente las medidas tomadas en el área metropolitana de la ciudad de Turin
Assuntos
Itália , Efluentes Industriais , Redes de Esgoto , IndústriasRESUMO
The HLA-A and HLA-B phenotypes of 329 unrelated Haitian adults were determined and gene and haplotype frequencies were estimated. A summary of the data is presented together with a brief comparison with American Black, American White, and African Black populations. HLA gene and haplotype frequencies of Haitians are quite similar to those for American Blacks. The frequency of Aw34 appears to be smaller in Haitians than in American and African Blacks. No statistically significant differences were found in the frequencies of B-locus antigens.