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排序方式: 共有574条查询结果,搜索用时 15 毫秒
1.
Paula Veríssimo Cristina Esteves Carlos Faro Euclides Pires 《Biotechnology letters》1995,17(6):621-626
The flowers of cardoon (genus Cynara) are traditionally used in Portugal for cheese making. In this work the vegetable rennet of the species Cynara cardunculus L. was characterized in terms of enzymic composition and proteolytic specificity of its proteinases (cardosin A and cardosin B). Cardosin A was found to cleave insulin B chain at the bonds Leu15-Tyr16, Leu17-Val18 and Phe25-Tyr26. In addition to the bonds mentioned cardosin B cleaves also Glu13-Ala14, Ala14-Leu15 and Phe24-Phe25 indicating that it has a broader specificity. The kinetic parameters for the hydrolysis of the synthetic peptide Leu-Ser-Phe(NO2)-Nle-Ala-Leu-oMe were also determined and compared to those of chymosin and pepsin. The results obtained indicate that in terms of specificity and kinetic parameters cardosin A is similar to chymosin whereas cardosin B is similar to pepsin. It appears therefore that the enzyme composition of cardoon rennet closely resembles that of calf rennet. 相似文献
2.
A F de Andrade M J Esteves J Angluster M Gonzales-Perdomo S Goldenberg 《Journal of general microbiology》1991,137(12):2845-2849
Highly purified lectins with specificities for receptor molecules containing sialic acid, N-acetylglucosamine (D-GlcNAc), N-acetylgalactosamine (D-GalNAc), galactose (D-Gal), mannose-like residues (D-Man) or L-fucose (L-Fuc), were used to determine changes in cell-surface carbohydrates of the protozoal parasite Trypanosoma cruzi during metacyclogenesis under chemically defined conditions. Of the D-GalNAc-binding lectins, BS-I selectively agglutinated metacyclic trypomastigotes, MPL was selective for replicating epimastigotes, whereas SBA strongly agglutinated all developmental stages of T. cruzi. WGA (sialic acid and/or D-GlcNAc specific) was also reactive with differentiating epimastigotes and metacyclic trypomastigotes but displayed a higher reactivity with replicating epimastigote forms. A progressive decrease in agglutinating activity was observed for jacaline (specific for D-Gal) during the metacyclogenesis process; conversely, a progressive increase in affinity was observed for RCA-I (D-Gal-specific), although the reactivity of other D-Gal-specific lectins (PNA and AxP) was strong at all developmental stages. All developmental stages of T. cruzi were agglutinated by Con A and Lens culinaris lectins (specific for D-Man-like residues); however, they were unreactive with the L-fucose-binding lectins from Lotus tetragonolobos and Ulex europaeus. These agglutination assays were further confirmed by binding studies using 125I-labelled lectins. Neuraminidase activity was detected in supernatants of cell-free differentiation medium using the PNA hemagglutination test with human A erythrocytes. The most pronounced differences in lectin agglutination activity were observed between replicating and differentiating epimastigotes, suggesting that changes in the composition of accessible cell-surface carbohydrates precede the morphological transformation of epimastigotes into metacyclic trypomastigotes. 相似文献
3.
The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs. 相似文献
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AB Zarafi AM Emechebe AD Akpa O Alabi 《Archives Of Phytopathology And Plant Protection》2013,46(4):261-268
Pearl millet downy mildew (DM) incidence, severity and yield losses of two pearl millet varieties (local and improved) due to the disease were determined in the field. Significant differences in the disease incidence and severity were recorded in the plots sown with metalaxyl-treated seeds and those sown with non-treated seeds, indicating the efficacy of the fungicide on the fungus. Yield losses due to non-treatment of seeds with metalaxyl was 40.88 and 45.39% in a local variety and 43.00 and 18.60% in an improved variety in the 2000 and 2001 cropping seasons respectively. Significant differences between plots sown with metalaxyl-treated and those sown with non-treated seeds were obtained for other yield components such as 1000-grains weight, panicle length and weight. 相似文献
8.
Nat��lia Furlan Katharina Eichbaum Esteves Gilson Alves Quin��glia 《Environmental Biology of Fishes》2013,96(1):77-92
The rivers and streams of the large urban centers in Southeast Brazil are increasingly being degraded, demanding expanded conservation efforts. This study was conducted in the Grande River, one of the main tributaries of the Billings Complex, a reservoir that is a strategic fresh water resource for the S?o Paulo metropolitan region. Water quality, habitat features and fish fauna were investigated at seven sites along the longitudinal gradient with the aim of identifying the distribution patterns and relative contributions of the environmental factors. The water samples and environmental characteristics were recorded, and fish were collected during the rainy (January to March) and dry seasons (July and August) of 2009. The water quality varied along the river, with higher values of conductivity, fecal coliforms and total phosphorus in the lower reach, indicating a strong influence of the urban area. Twenty-two fish species were recorded, two of which are considered endangered. A canonical correspondence analysis (CCA) indicated marked differences in species composition between the river??s upper and lower reaches, which was mainly attributed to vegetation cover and the presence of different meso-habitats, such as riffles and pools. Trychomycterus spp. and Astyanax paranae were associated with the upper reaches, while Astyanax fasciatus and Astyanax bockmanni, Cyphocharax modestus, Hoplias malabaricus and Hypostomus ancistroides occurred in the lower reaches. Despite the disturbance in water quality and riparian vegetation in the lower river section, no detectable changes in community structure were observed. However, the presence of some tolerant species, such as Astyanax fasciatus, Hoplosternum littorale and Hypostomus ancistroides, may indicate that the community is experiencing initial stages of disturbance. 相似文献
9.
Spores from 19 species of the subgenus Aloma Kindb. of the moss genus Fissidens were analyzed by light and scanning electron microscopy. Aloma is the largest subgenus of Fissidentaceae and is characterized by the presence of a peristome of scariosus type. The spores of the subgenus Aloma are present in monads, size small to very small, heteropolar, plano-convex, with a proximal aperture region, and the sporoderm is formed by a perine, exine, and intine. The intine is not stratified, the exine is psilate, and the perine granulated. The ornamentation elements may occur singly or grouped on the surface of the spore. The aperture region shows irregular contours, ranging from circular to elongated, due to the weakness of the sporoderm proximal pole. The observed variations among species are related to different patterns of distribution of the sporoderm granules and nanogranules. Quantitative analysis combined with qualitative results did not allow all species of the subgenus Aloma to be distinguished. The results of this study demonstrate that the spore is a useful tool for taxonomic studies, and suggest that its characters be included in phylogenetic analyses, to assist in the reconstruction of the evolutionary history of mosses. 相似文献
10.
Mirelle Lomar Viana Rosana das Graças Carvalho dos Santos Simone de Vasconcelos Generoso Jacques Robert Nicoli Flaviano dos Santos Martins José Augusto Nogueira-Machado Rosa Maria Esteves Arantes Maria Isabel Toulson Davisson Correia Valbert Nascimento Cardoso 《Amino acids》2013,45(5):1089-1096
This study investigated the nitric oxide (NO) role as a mediator of arginine on bacterial translocation (BT) and gut damage in mice after intestinal obstruction (IO). The effects of pretreatment with arginine with or without NO inhibition on the systemic and local immunological response were also assessed. Mice were categorized into four groups. Group ARG received chow containing 2 % arginine, while group ARG + l-NAME received the same diet plus l-NAME (N-nitro-l-arginine methyl ester) by gavage. The IO and Sham groups were fed standard chow. After 7 days, animals were gavaged with radiolabeled Escherichia coli, anesthetized and subjected to IO, except the Sham group. Animals were euthanized after 18 h, and BT was evaluated in the mesenteric lymph nodes, blood, liver, spleen and lungs. In another experiment, the intestinal injury was assessed regarding intestinal permeability and ileum histological analyses. Intestinal secretory immunoglobulin A (sIgA) levels, serum IFN-γ and IL-10 cytokines were assessed. Arginine reduced BT, but NO inhibition enhanced BT compared with the ARG group (p < 0.05). Intestinal permeability in the ARG and ARG + l-NAME groups was similar but decreased when compared with the IO group (p < 0.05). Histological preservation was observed. Arginine treatment increased IL-10 and sIgA levels when compared with the Sham and IO groups (p < 0.05). The cytokines and sIgA concentrations were similar in the ARG + l-NAME and Sham groups. Arginine appeared to reduce BT and its effects on the modulation of cytokines and secretory IgA in mice after IO are mediated by NO production. 相似文献