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881.
The aim of this study was to test if serological distinction between patients with active and inactive neurocysticercosis (NCC), could be accomplished by the recognition of immunodominant peptides in total saline antigenic extract of Taenia solium metacestodes by IgG antibody in cerebrospinal fluid (CSF) and serum paired samples. CSF and serum samples of 10 each, active NCC patients, inactive NCC, and individuals with other neurological disorders, were used to recognize the antigenic peptides by western blot (WB). In the active NCC the 28-32 and 39-42 kDa peptides were more frequently detected in CSF than in sera (p < 0.05). The 47-52, 64-68, and 70 kDa antigens showed high frequencies in both samples from patients with active NCC. All the CSF samples of inactive NCC and other neurological disorder (control) patients tested negative, while serum samples from these last two groups recognized mainly the 80, 86, 95, and 98 kDa bands. This finding eliminates the use of the high molecular weigh bands (>or= 80 kDa) for diagnosis of NCC. The final conclusions were that the difference between active and inactive NCC may be done with the detection of peptides only in the CSF samples and that the 47-52, 64-68, and 70 kDa bands may be included as specific markers for active NCC when detected in CSF samples by WB using total saline extract of T. solium metacestode.  相似文献   
882.
Researchers consider predation rates by terrestrial animals to be lower in the case of arboreal primates, particularly among large-bodied species. We recorded the consumption of black-and-gold howlers (Alouatta caraya) by cougars (Puma concolor) as evidence of predation on an island of the upper Paraná River. We collected and processed fecal samples of the felid in 2004 and 2005. We identified items in the laboratory by comparison with museum specimens. We considered each species in a fecal sample as a single occurrence. Based on analysis of the cuticle scale pattern, we identified the felid as cougar. Howlers occurred in 4 out of the 8 fecal samples (40% of the occurrences). In addition to howlers, we also recorded 5 occurrences of agouti (Dasyprocta azarae; 50%) and a small unidentified sigmodontine rodent (10%). The abundance of howlers and the low forest canopy in a successional vegetation might have facilitated the predation of the large primates by a primarily terrestrial predator. The versatility of cougars is corroborated by the consumption of prey species that were abundant in the region and that were available in different forest strata, such as howlers and agoutis.  相似文献   
883.
The yeast Kluyveromyces marxianus presents several interesting features that make this species a promising industrial yeast for the production of several compounds. In order to take full advantage of this yeast and its particular properties, proper tools for gene disruption and metabolic engineering are needed. The Cre-loxP system is a very versatile tool that allows for gene marker rescue, resulting in mutant strains free of exogenous selective markers, which is a very important aspect for industrial application. As the Cre-loxP system works in some non-conventional yeasts, namely Kluyveromyces lactis, we wished to know whether it also works in K. marxianus. Here, we report the validation of this system in K. marxianus CBS 6556, by disrupting two copies of the LAC4 gene, which encodes a beta-galactosidase activity.  相似文献   
884.
In this work three piezoelectric sensors modified with anti-HIV-1 Vif (virion infectivity factor) single fragment antibodies (4BL scFV), single domains (VH) and camelized single domains (VHD) were constructed and used to detect HIV1 Vif in liquid samples. Dithio-bis-succinimidyl-undecanoate (DSU) and 11-hydroxy-1-undecanethiol (HUT) mixed self assembled monolayers (SAM) were generated at the sensors surface onto which the antibodies were immobilized. All sensors detected specifically the target HIV1-Vif antigen in solution and no unspecific binding was monitored. Impedance analysis was performed to quantify electroacoustic and viscoelastic interferences during antibody immobilization and antigen recognition. The elimination of such interferences enabled the quantitative use of the piezoelectric immunosensors to estimate the antibody surface density as well as antigen binding and equilibrium constants. In spite of the possible limitation regarding mass transport and other related molecular phenomena, which were not considered in the binding model used, this work demonstrates the usefulness of piezoelectric biosensors in biorecognition analysis and evidences the advantages on using simultaneous impedance analysis to bring analytical significance to measured data, and thus to improve piezoelectric sensors sensitivity and applicability.  相似文献   
885.
Transgenic trees currently are being produced by Agrobacterium-mediated transformation and biolistics. Since trees are particularly suited for long-term evaluations of the impact of the technology, Prunus subhirtella autumno rosa (PAR) was chosen as model fruit tree species and transformed with a reporter gene (uidA) under the control of the 35S promoter. Using Southern and GUS fluorometric techniques, we compared transgene copy numbers and observed stability of transgene expression levels in 34 different transgenic plants, grown under in vitro, greenhouse and screenhouse conditions, over a period of 9 years. An influence of grafting on gene expression was not observed. No silenced transgenic plant was detected. Overall, these results suggest that transgene expression in perennial species, such as fruit trees, remains stable in time and space, over extended periods and in different organs, confirming the value of PAR as model species to study season-dependent regulation in mature stone fruit tissues. While the Agrobacterium-derived Prunus transformants contained one to two copies of the transgenes, 91% of the transgenic events also contained various lengths of the bacterial plasmid backbone, indicating that the Agrobacterium-mediated transformation is not as precise as previously perceived. The implications for public acceptance and future applications are discussed.  相似文献   
886.
We describe simple and cost-effective methods using carbohydrates to improve the in vitro viability of dermatophytes. Glucose and sucrose in different concentrations (3, 6, 9 and 12%) were used to maintain fifteen strains of M. canis and T. mentagrophytes var. mentagrophytes at 4 and -20 degrees C. The strains were phenotypically analyzed before storage and reevaluated at 1, 3, 6 and 9 months. At 1 and 3 months, any alterations in the viability or phenotype pattern of the stored strains were noted. At 6 months, both dermatophytes were 100% viable, when preserved in glucose (3, 6, 9 and 12%) at -20 degrees C. All T. mentagrophytes strains were also viable in sucrose (12%), at 4 degrees C and -20 degrees C. However, sucrose failed to improve the viability of M. canis at both temperatures. At 9 months, the higher viabilities without pleomorphism were seen for both dermatophytes preserved in glucose (9 and 12%) at -20 degrees C.  相似文献   
887.
In this work, it is shown that in a deterministic context, a threshold policy can induce cyclic behavior in an otherwise exploited stable population. These dynamics ensue as a result of the combination of the degree of harvesting pressure and more protective threshold densities. Virtual equilibrium in variable structure systems plays a determinant role in this dynamical outcome.  相似文献   
888.
The Guaíba Basin is a source of drinking water for Porto Alegre (RS, Brazil). The water from this basin receives industrial, urban, and rural waste from many sources. The mussel species Limnoperna fortunei was chosen based on population data, distribution, and sensitivity. Previous tests with comet assay and micronuclei frequency in this freshwater mussel have shown to be successful in biomonitoring studies. The aim of this study was to evaluate the genotoxic contamination of the Guaíba Lake Hydrographic Region, through the determination of damage by the micronuclei and comet assays in L. fortunei (golden mussel). Nine sampling sites were evaluated in three different seasons: five sites in the mouths of the main rivers that flow into Guaíba lake; one site at the mouth of a stream; one major site of sewage discharge; two sites at Guaíba lake, near a sewage discharge; and the control site in a preservation area. DNA damage was detected by the single cell gel assay, as well as the frequency of micronuclei in hemocytes of mussels exposed under laboratory conditions for 7 days to water and sediment samples. Significant results were found in different seasons in almost all sampling sites (P<0.05, ANOVA Dunnet's test). Most of the positive results were found in samples affected mainly by urban effluents. It was possible to observe that there was a weak relation between mutagenic and genotoxic responses and mussels inorganic elements contents. Seasonal variation was observed at different sampling sites, but always indicating a huge contamination near urban sewage discharge. These results are consistent with previous studies, allowing us to infer that urban contamination is the biggest problem in this region. It is also possible to infer that L. fortunei is a good sentinel organism for the Guaíba Basin.  相似文献   
889.
The purpose of this study was to determine the seasonal water use patterns of dominant macrophytes coexisting in the coastal Everglades ecotone. We measured the stable isotope signatures in plant xylem water of Rhizophora mangle, Cladium jamaicense, and Sesuvium portulacastrum during the dry (DS) and wet (WS) seasons in the estuarine ecotone along Taylor River in Everglades National Park, FL, USA. Shallow soilwater and deeper groundwater salinity was also measured to extrapolate the salinity encountered by plants at their rooting zone. Average soil water oxygen isotope ratios (δ 18O) was enriched (4.8 ± 0.2‰) in the DS relative to the WS (0.0 ± 0.1‰), but groundwater δ 18O remained constant between seasons (DS: 2.2 ± 0.4‰; WS: 2.1 ± 0.1‰). There was an inversion in interstitial salinity patterns across the soil profile between seasons. In the DS, shallow water was euhaline [i.e., 43 practical salinity units (PSU)] while groundwater was less saline (18 PSU). In the WS, however, shallow water was fresh (i.e., 0 PSU) but groundwater remained brackish (14 PSU). All plants utilized 100% (shallow) freshwater during the WS, but in the DS R. mangle switched to a soil–groundwater mix (δ 55% groundwater) while C. jamaicense and S. portulacastrum continued to use euhaline shallow water. In the DS, based on δ 18O data, the roots of R. mangle roots were exposed to salinities of 25.4 ± 1.4 PSU, less saline than either C. jamaicense (39.1 ± 2.2 PSU) or S. portulacastrum (38.6 ± 2.5 PSU). Although the salinity tolerance of C. jamaicense is not known, it is unlikely that long-term exposure to high salinity is conducive to the persistence of this freshwater marsh sedge. This study increases our ecological understanding of how water uptake patterns of individual plants can contribute to ecosystem levels changes, not only in the southeast saline Everglades, but also in estuaries in general in response to global sea level rise and human-induced changes in freshwater flows.  相似文献   
890.
The sucrose binding protein (SBP) belongs to the cupin family of proteins and is structurally related to vicilin-like storage proteins. In this investigation, a SBP isoform (GmSBP2/S64) was expressed in E. coli and large amounts of the protein accumulated in the insoluble fraction as inclusion bodies. The renatured protein was studied by circular dichroism (CD), intrinsic fluorescence, and binding of the hydrophobic probes ANS and Bis-ANS. The estimated content of secondary structure of the renatured protein was consistent with that obtained by theoretical modeling with a large predominance of beta-strand structure (42%) over the alpha-helix (9.9%). The fluorescence emission maximum of 303 nm for SBP2 indicated that the fluorescent tryptophan was completely buried within a highly hydrophobic environment. We also measured the equilibrium dissociation constant (K(d)) of sucrose binding by fluorescence titration using the refolded protein. The low sucrose binding affinity (K(d)=2.79+/-0.22 mM) of the renatured protein was similar to that of the native protein purified from soybean seeds. Collectively, these results indicate that the folded structure of the renatured protein was similar to the native SBP protein. As a member of the bicupin family of proteins, which includes highly stable seed storage proteins, SBP2 was fairly stable at high temperatures. Likewise, it remained folded to a similar extent in the presence or absence of 7.6M urea or 6.7 M GdmHCl. The high stability of the renatured protein may be a reminiscent property of SBP from its evolutionary relatedness to the seed storage proteins.  相似文献   
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