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51.
Valdez-Cruz NA Dávila S Licea A Corona M Zamudio FZ García-Valdes J Boyer L Possani LD 《Biochimie》2004,86(6):387-396
Current literature concerning the taxonomic names of two possibly distinct species of scorpions from the genus Centruroides (sculpturatus and/or exilicauda) is controversial. This communication reports the results of biochemical, genetic and electrophysiological experiments conducted with C. exilicauda Wood of Baja California (Mexico) and C. sculpturatus Ewing of Arizona (USA). The chromatographic profile fractionation of the soluble venom from both species of scorpions is different. The N-terminal amino acid sequence for nine toxins of C. exilicauda was determined and compared with those from C. sculpturatus. Lethality tests conducted in mice support the idea that C. exilicauda venom should be expected to be medically less important than C. sculpturatus. Thirteen genes from the venomous glands of the scorpion C. exilicauda were obtained and compared with previously published sequences from genes of the species C. sculpturatus. Genes coding for cytochrome oxidase I and II of both species were also sequenced. A phylogenetic tree was generated with this information showing important differences between them. Additionally, the results of electrophysiological assays conducted with the venom from both species on the Ca(2+)-dependent K(+)-channels, showed significant differences. These results strongly support the conclusion that C. exilicauda and C. sculpturatus are in fact two distinct species of scorpions. 相似文献
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53.
The Purruja mangrove (Golfito, Costa Rica) has an estimated area of 70 ha. A socio-biological research was the ground to set initial goals to manage the resources and to identify the mangrove biological condition. Community participation and the local organization were key factors in developing an integrated model for the management of natural resources. Constant monitoring and institutional networks were the other two factors to manage the mangrove. The constant profesional support was a tool to facilitate the acomplishment of goals and to establish an institucional network to promote local group iniciatives for collaborative management of the Purruja mangrove. 相似文献
54.
Synaptotagmin is considered a calcium-dependent trigger for regulated exocytosis. We examined the role of synaptotagmin VII (Syt VII) in the calcium-dependent exocytosis of individual lysosomes in wild-type (WT ) and Syt VII knockout (KO ) mouse embryonic fibroblasts (MEFs) using total internal reflection fluorescence microscopy. In WT MEFs, most lysosomes only partially released their contents, their membrane proteins did not diffuse into the plasma membrane, and inner diameters of their fusion pores were smaller than 30 nm. In Syt VII KO MEFs, not only was lysosomal exocytosis triggered by calcium, but all of these restrictions on fusion were also removed. These observations indicate that Syt VII does not function as the calcium-dependent trigger for lysosomal exocytosis. Instead, it restricts the kinetics and extent of calcium-dependent lysosomal fusion. 相似文献
55.
Captive muntjac fed on vegetation had a daily defecation rate of 7 to 8.2.pellet groups. Even in the cold month of February 97.6% of pellets decayed within 80 days but for 8 other months the range was 4 to 23 days. Emphasis is given to the need for site-specific information when decay rate is required to assess population size from dung counts. The morphology, dimensions, weight and group size of pellets are described as an aid to distinguish them from the faeces of other cervids. 相似文献
56.
Stability of enzymes and proteins in dried glassy systems: effect of simulated sunlight conditions 总被引:2,自引:0,他引:2
The purpose of the present work was to study the effects of simulated sunlight conditions on enzyme inactivation and structural damage in dehydrated glassy systems. Freeze-dried samples containing different enzymes (lactase, invertase, lysozyme and amyloglucosidase) were exposed to light using a medium-pressure metal halide HPA 400 W lamp. After 1 h of light exposure, the samples showed a significant reduction (more than 50%) in the denaturation peak area as analyzed by DSC, and this could be attributed to protein denaturation. For most of the pure enzymes, the loss of enzymic activity after 1 h of light exposure was around 50%. In the case of enzymes included in anhydrous model systems (trehalose, raffinose, maltodextrin, and dextran), the remaining activity also decreased dramatically during the light treatment. We showed that the light exposure in dehydrated systems generated both the loss of enzymic activity and structural changes such as denaturation (observed by DSC) and protein fragmentation and aggregation (observed by electrophoresis). Overall, we can conclude that a short exposure to the light produces dramatic changes in the enzymic activity in dehydrated systems with or without protective matrices. 相似文献
57.
José?Pedraza-ChaverríEmail author Diana?Barrera Perla?D?Maldonado Yolanda?I?Chirino Norma?A?Macías-Ruvalcaba Omar?N?Medina-Campos Leticia?Castro Marcos?I?Salcedo Rogelio?Hernández-Pando 《BMC clinical pharmacology》2004,4(1):5
Background
Oxidative and nitrosative stress have been involved in gentamicin-induced nephrotoxicity. The purpose of this work was to study the effect of S-allylmercaptocysteine, a garlic derived compound, on gentamicin-induced oxidative and nitrosative stress and nephrotoxicity. In addition, the in vitro reactive oxygen species scavenging properties of S-allylmercaptocysteine were studied. 相似文献58.
Pokkuluri PR Londer YY Duke NE Erickson J Pessanha M Salgueiro CA Schiffer M 《Protein science : a publication of the Protein Society》2004,13(6):1684-1692
The structure of a novel c(7)-type cytochrome domain that has two bishistidine coordinated hemes and one heme with histidine, methionine coordination (where the sixth ligand is a methionine residue) was determined at 1.7 A resolution. This domain is a representative of domains that form three polymers encoded by the Geobacter sulfurreducens genome. Two of these polymers consist of four and one protein of nine c(7)-type domains with a total of 12 and 27 hemes, respectively. Four individual domains (termed A, B, C, and D) from one such multiheme cytochrome c (ORF03300) were cloned and expressed in Escherichia coli. The domain C produced diffraction quality crystals from 2.4 M sodium malonate (pH 7). The structure was solved by MAD method and refined to an R-factor of 19.5% and R-free of 21.8%. Unlike the two c(7) molecules with known structures, one from G. sulfurreducens (PpcA) and one from Desulfuromonas acetoxidans where all three hemes are bishistidine coordinated, this domain contains a heme which is coordinated by a methionine and a histidine residue. As a result, the corresponding heme could have a higher potential than the other two hemes. The apparent midpoint reduction potential, E(app), of domain C is -105 mV, 50 mV higher than that of PpcA. 相似文献
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60.
Biancalana V Caron O Gallati S Baas F Kress W Novelli G D'Apice MR Lagier-Tourenne C Buj-Bello A Romero NB Mandel JL 《Human genetics》2003,112(2):135-142
X-linked myotubular myopathy is characterised by neonatal hypotonia, muscle weakness and respiratory distress in affected males, leading often to early death, although prolonged survival is observed in milder forms, or as a result of prolongation of ventilation support. It is caused by mutations in the MTM1 gene, which encodes a phosphatase called myotubularin, which has been highly conserved during evolution, down to yeasts ( S. cerevisiae and S. pombe). To date, 251 mutations have been identified in unrelated families, corresponding to 158 different disease-associated mutations, which are widespread throughout the gene. We have found additional mutations in 77 patients, including 35 novel ones. We identified a missense mutation N180K in a 67-year-old grandfather (the oldest known patient with an MTM1 mutation), previously suspected to have autosomal centronuclear myopathy, and in his two grandsons also mildly affected. Mild and moderate phenotypes associated with novel missense mutations and with a translation initiation defect mutation are discussed, as well as severe phenotypes associated with particular novel mutations. With the present report, 192 different mutations in the MTM1 gene have been described in 328 families. The spectrum of mutations is now enlarged from the very severe classic neonatal phenotype to very mild phenotype allowing survival to the age of 67 years. 相似文献