排序方式: 共有137条查询结果,搜索用时 140 毫秒
71.
72.
V.?C.?Sarmento T.?P.?Souza A.?M.?Esteves P.?J.?P.?SantosEmail author 《Coral reefs (Online)》2015,34(3):955-966
Despite the increasing risk that ocean acidification will modify benthic communities, great uncertainty remains about how this impact will affect the lower trophic levels, such as members of the meiofauna. A mesocosm experiment was conducted to investigate the effects of water acidification on a phytal meiofauna community from a coral reef. Community samples collected from the coral reef subtidal zone (Recife de Fora Municipal Marine Park, Porto Seguro, Bahia, Brazil), using artificial substrate units, were exposed to a control pH (ambient seawater) and to three levels of seawater acidification (pH reductions of 0.3, 0.6, and 0.9 units below ambient) and collected after 15 and 30 d. After 30 d of exposure, major changes in the structure of the meiofauna community were observed in response to reduced pH. The major meiofauna groups showed divergent responses to acidification. Harpacticoida and Polychaeta densities did not show significant differences due to pH. Nematoda, Ostracoda, Turbellaria, and Tardigrada exhibited their highest densities in low-pH treatments (especially at the pH reduction of 0.6 units, pH 7.5), while harpacticoid nauplii were strongly negatively affected by low pH. This community-based mesocosm study supports previous suggestions that ocean acidification induces important changes in the structure of marine benthic communities. Considering the importance of meiofauna in the food web of coral reef ecosystems, the results presented here demonstrate that the trophic functioning of coral reefs is seriously threatened by ocean acidification. 相似文献
73.
The pharmacological activity of insulin-loaded dextran sulfate/chitosan nanoparticles was evaluated following oral dosage in diabetic rats. Nanoparticles were mucoadhesive and negatively charged with a mean size of 500 nm, suitable for uptake within the gastrointestinal tract. Insulin association efficiency was over 70% and was released in a pH-dependent manner under simulated gastrointestinal conditions. Orally delivered nanoparticles lowered basal serum glucose levels in diabetic rats around 35% with 50 and 100 IU/kg doses sustaining hypoglycemia over 24 h. Pharmacological availability was 5.6 and 3.4% for the 50 and 100 IU/kg doses, respectively, a significant increase over 1.6%, determined for oral insulin alone in solution. Confocal microscopic examinations of FITC-labeled insulin nanoparticles showed adhesion to rat intestinal epithelium, and internalization of insulin within the intestinal mucosa. Encapsulation of insulin into dextran sulfate/chitosan nanoparticles was a key factor in the improvement of the bioavailability of its oral delivery over insulin solution. 相似文献
74.
75.
76.
Human trampling is a common type of disturbance associated with outdoor recreational activities in coastal ecosystems. In
this study, the effect of trampling on the meiofaunal harpacticoid copepod assemblage inhabiting turfs on a coral reef was
investigated. In Porto de Galinhas, northeastern Brazil, reef formations near the beach are one of the main touristic destinations
in the country. To assess trampling impact, two areas were compared: a protected area and an area subject to intensive tourism.
Densities of total Harpacticoida and of the most abundant harpacticoid species showed strong reductions in the trampled area.
An analysis of covariance revealed that the loss of phytal habitat was not the main source of density reductions, showing
that trampling affected the animals directly. In addition, multivariate analysis demonstrated differences in the structure
of harpacticoid assemblages between areas. Of the 43 species identified, 12 were detected by the Indicator Species Analyses
as being indicators of the protected or trampled areas. Moreover, species richness was reduced in the area open to tourism.
At least 25 harpacticoids are new species for science, of these, 20 were more abundant or occurred only in the protected area,
while five were more abundant or occurred only in the trampled area; thus, our results highlight the possibility of local
extinction of still-unknown species as one of the potential consequences of trampling on coral reefs. 相似文献
77.
Jamie L. Wasilenko Luciana Sarmento Stephen Spatz Mary Pantin‐Jackwood 《Biotechnology progress》2010,26(2):542-547
Yeast is an ideal organism to express viral antigens because yeast glycosylate proteins more similarly to mammals than bacteria. Expression of proteins in yeast is relatively fast and inexpensive. In addition to the convenience of production, for purposes of vaccination, yeast has been shown to have natural adjuvant activity making the expressed proteins more immunogenic when administered along with yeast cell wall components. Development of genetic systems to display foreign proteins on the surface of yeast via fusion to glycosylphosphatidylinositol‐anchored (GPI) proteins has further simplified the purification of recombinant proteins by not requiring harsh treatments for cellular lysis or protein purification. We have expressed the hemagglutinin protein from a highly pathogenic avian influenza (HPAI) virus [A/Egret/HK/757.2/02], subtype H5N1, on the surface of the yeast strain Pichia pastoris, as an anchored C‐terminal fusion with the Saccharomyces cerevisiae GPI‐anchored cell wall protein, α‐agglutinin. Surface expression of the hemagglutinin fusion protein was demonstrated by immunofluorescence microscopy. Functionally, the fusion protein retained hemagglutinin agglutinating activity, and oral vaccination with the yeast resulted in production of virus neutralizing antibodies. This study represents the first steps in the generation of a yeast‐based vaccine for protection against highly pathogenic strains of avian influenza. Published 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 相似文献
78.
Teresa Cardoso Armando Teixeira-Pinto Pedro Pereira Rodrigues Irene Arag?o Altamiro Costa-Pereira António E. Sarmento 《PloS one》2013,8(7)
Purpose
To develop a clinical staging system based on the PIRO concept (Predisposition, Infection, Response and Organ dysfunction) for hospitalized patients with infection.Methods
One year prospective cohort study of all hospitalized patients with infection (n = 1035), admitted into a large tertiary care, university hospital. Variables associated with hospital mortality were selected using logistic regressions. Based on the regression coefficients, a score for each PIRO component was developed and a classification tree was used to stratify patients into four stages of increased risk of hospital mortality. The final clinical staging system was then validated using an independent cohort (n = 186).Results
Factors significantly associated with hospital mortality were • for Predisposition: age, sex, previous antibiotic therapy, chronic hepatic disease, chronic hematologic disease, cancer, atherosclerosis and a Karnofsky index<70; • for Insult/Infection: type of infection • for Response: abnormal temperature, tachypnea, hyperglycemia and severity of infection and • for Organ dysfunction: hypotension and SOFA score≥1. The area under the ROC curve (CI95%) for the combined PIRO model as a predictor for mortality was 0.85 (0.82–0.88). Based on the scores for each of the PIRO components and on the cut-offs estimated from the classification tree, patients were stratified into four stages of increased mortality rates: stage I: ≤5%, stage II: 6–20%, stage III: 21–50% and stage IV: >50%. Finally, this new clinical staging system was studied in a validation cohort, which provided similar results (0%, 9%, 31% and 67%, in each stage, respectively).Conclusions
Based on the PIRO concept, a new clinical staging system was developed for hospitalized patients with infection, allowing stratification into four stages of increased mortality, using the different scores obtained in Predisposition, Response, Infection and Organ dysfunction. The proposed system will likely help to define inclusion criteria in clinical trials as well as tailoring individual management plans for patients with infection. 相似文献79.
Maria J. Sarmento Ana Coutinho Aleksander Fedorov Manuel Prieto Fabio Fernandes 《生物化学与生物物理学报:生物膜》2014
Calcium has been shown to induce clustering of PI(4,5)P2 at high and non-physiological concentrations of both the divalent ion and the phosphatidylinositol, or on supported lipid monolayers. In lipid bilayers at physiological conditions, clusters are not detected through microscopic techniques. Here, we aimed to determine through spectroscopic methodologies if calcium plays a role in PI(4,5)P2 lateral distribution on lipid bilayers under physiological conditions. Using several different approaches which included information on fluorescence quantum yield, polarization, spectra and diffusion properties of a fluorescent derivative of PI(4,5)P2 (TopFluor(TF)-PI(4,5)P2), we show that Ca2 + promotes PI(4,5)P2 clustering in lipid bilayers at physiological concentrations of both Ca2 + and PI(4,5)P2. Fluorescence depolarization data of TF-PI(4,5)P2 in the presence of calcium suggests that under physiological concentrations of PI(4,5)P2 and calcium, the average cluster size comprises ~ 15 PI(4,5)P2 molecules. The presence of Ca2 +-induced PI(4,5)P2 clusters is supported by FCS data. Additionally, calcium mediated PI(4,5)P2 clustering was more pronounced in liquid ordered (lo) membranes, and the PI(4,5)P2-Ca2 + clusters presented an increased affinity for lo domains. In this way, PI(4,5)P2 could function as a lipid calcium sensor and the increased efficiency of calcium-mediated PI(4,5)P2 clustering on lo domains might provide targeted nucleation sites for PI(4,5)P2 clusters upon calcium stimulus. 相似文献
80.
Steven Loiselle Andrés Cózar Enyew Adgo Thomas Ballatore Geoffrey Chavula Jean Pierre Descy David M. Harper Frank Kansiime Ismael Kimirei Victor Langenberg Ronghua Ma Hugo Sarmento Eric Odada 《PloS one》2014,9(4)
The Great Lakes of East Africa are among the world’s most important freshwater ecosystems. Despite their importance in providing vital resources and ecosystem services, the impact of regional and global environmental drivers on this lacustrine system remains only partially understood. We make a systematic comparison of the dynamics of the bio-optical and thermal properties of thirteen of the largest African lakes between 2002 and 2011. Lake surface temperatures had a positive trend in all Great Lakes outside the latitude of 0° to 8° south, while the dynamics of those lakes within this latitude range were highly sensitive to global inter-annual climate drivers (i.e. El Niño Southern Oscillation). Lake surface temperature dynamics in nearly all lakes were found to be sensitive to the latitudinal position of the Inter Tropical Convergence Zone. Phytoplankton dynamics varied considerably between lakes, with increasing and decreasing trends. Intra-lake differences in both surface temperature and phytoplankton dynamics occurred for many of the larger lakes. This inter-comparison of bio-optical and thermal dynamics provides new insights into the response of these ecosystems to global and regional drivers. 相似文献