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51.
Valcilaine T. Barbosa Joyelanne K. C. Souza Valter Alvino Mario R. Meneghetti Pedro P. Florez-Rodriguez Rui E. Moreira Gustavo V. B. Paulino Melissa F. Landell Irinaldo D. Basílio-Júnior Ticiano G. do Nascimento Luciano A. M. Grillo Camila B. Dornelas 《Biotechnology progress》2019,35(6):e2888
Biological methods have been used to synthesize silver nanoparticles through materials such as bacteria, fungi, plants, and propolis due to their reducing properties, stabilizer role and environmentally friendly characteristic. Considering the antimicrobial activity of propolis as well as the broad-spectrum antibacterial effects of silver nanoparticles, this study aim to describe the use of Brazilian propolis to synthesize silver nanoparticles (AgNP-P) and investigate its antimicrobial activity. The synthesis was optimized by factorial design, choosing the best conditions for smaller size particles. AgNP-P demonstrated a maximum absorbance at 412 nm in ultraviolet-visible spectra, which indicated a spherical format and its formation. Dynamic light scattering demonstrated a hydrodynamic size of 109 nm and polydispersity index less than 0.3, showing a good size distribution and stability. After its purification via centrifugation, microscopy analysis corroborates the format and showed the presence of propolis around silver nanoparticle. X-ray diffraction peaks were attributed to the main planes of the metallic silver crystalline structure; meanwhile infrared spectroscopy demonstrated the main groups responsible for silver reduction, represented by ∼22% of AgNP-P indicates by thermal analysis. Our product revealed an important antimicrobial activity indicating a synergism between propolis and silver nanoparticles as expected and promising to be an effective antimicrobial product to be used in infections. 相似文献
52.
A new 5-deoxyflavone glycoside, identified as 7-O-(alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl)-3',4',7-trihydroxyflavone (1), was isolated from the aerial parts of Calea clausseniana. Its structure was determined by spectral analysis. 相似文献
53.
Habitat fragmentation, variable edge effects, and the landscape-divergence hypothesis 总被引:2,自引:0,他引:2
Laurance WF Nascimento HE Laurance SG Andrade A Ewers RM Harms KE Luizão RC Ribeiro JE 《PloS one》2007,2(10):e1017
Edge effects are major drivers of change in many fragmented landscapes, but are often highly variable in space and time. Here we assess variability in edge effects altering Amazon forest dynamics, plant community composition, invading species, and carbon storage, in the world's largest and longest-running experimental study of habitat fragmentation. Despite detailed knowledge of local landscape conditions, spatial variability in edge effects was only partially foreseeable: relatively predictable effects were caused by the differing proximity of plots to forest edge and varying matrix vegetation, but windstorms generated much random variability. Temporal variability in edge phenomena was also only partially predictable: forest dynamics varied somewhat with fragment age, but also fluctuated markedly over time, evidently because of sporadic droughts and windstorms. Given the acute sensitivity of habitat fragments to local landscape and weather dynamics, we predict that fragments within the same landscape will tend to converge in species composition, whereas those in different landscapes will diverge in composition. This 'landscape-divergence hypothesis', if generally valid, will have key implications for biodiversity-conservation strategies and for understanding the dynamics of fragmented ecosystems. 相似文献
54.
Marciane Danniela Fleck Ervandil Corrêa Costa Maristela Machado Araujo Karine Schoeninger Leonardo Mortari Machado Jéssica Maus da Silva Leandra Pedron Dayanna do Nascimento Machado Jardel Boscardin 《Revista Brasileira de Entomologia》2019,63(3):212-216
Forest species can have their seeds damaged by granivorous insects, especially by those in their larval stage. In this context, this study aims to report the occurrence of Amblycerus species in Cordia trichotoma seeds, to describe their main damage to seeds and effects on germination, as well as their associated hymenopteran parasitoids. Therefore, seven trees were selected in the municipality of Taquaruçu do Sul, RS, Brazil. Fruits were collected weekly from the medium third of the tree crown, from the beginning of their formation until total dehiscence. To examine the damage caused by granivorous insects within the fruits, 15 fruits from each tree were sectioned with a scalpel. Furthermore, 10 fruits from each tree were stored individually in clear plates to verify the occurrence and identification of granivorous insect species. Evidence of the damage caused to seeds was verified through the germination test by comparing preserved and damaged seeds, with four repetitions of 25 seeds each. The species Amblycerus longesuturalis and Amblycerus profaupar (Chrysomelidae: Bruchinae) were found associated with fruits of C. trichotoma. Female insects predominantly laid eggs on the superior part between the marcescent calyx and the fruit, and larvae perforated the fruit tegument to start consuming seed embryos and reserves. Bruquine larvae are parasitized by Hymenoptera of Bracon, Mirax, Omeganastatus and Triapsis genera. In conclusion, the germination of C. trichotoma seeds is significantly affected by emergence orifices caused by granivorous species. 相似文献
55.
Carlos Henrique de Vasconcelos Nascimento Rafael Pereira-Silva Iris Gabrielly Arruda dos Santos Gilberto Gonçalves Rodrigues 《水生昆虫》2019,40(2):146-172
New records and distributional notes of Chironomidae (Insecta, Diptera) are provided for four protected areas in the state of Pernambuco, northeastern Brazil. Additionally, we also present new records and update of distributional ranges from Brazil and the Neotropical Region. In total, 810 specimens belonging to 35 genera within the subfamilies Chironominae (22 taxa), Tanypodinae (11 taxa) and Orthocladiinae (2 taxa) were found. The subfamilies Chironominae and Tanypodinae predominated. Axarus Roback, 1980 and the Tanytarsus ortoni-group were recorded for the first time in the state of Pernambuco, while Nanocladius Kieffer, 1913a was recorded for the first time in the Northeast Region of Brazil. Our results make evident how much and where current knowledge of the northeastern Brazil chironomids remains fragmentary. 相似文献
56.
de Oliveira Hellen Oliveira de Castro Gledson Luiz Salgado Correa Lorena Oliveira Silvestre Walter Vellasco Duarte do Nascimento Sidney Vasconcelos da Silva Valadares Rafael Borges de Oliveira Guilherme Corrêa Santos Rodolfo Inacio Nunes Festucci-Buselli Reginaldo Alves Pinheiro Hugo Alves 《Photosynthesis research》2019,140(2):189-205
Photosynthesis Research - This study examined whether drought sensitivity in açaí (Euterpe oleracea Mart.) is associated with reductions in photosynthesis and increasing oxidative stress... 相似文献
57.
Thais Maia Torres Priscila Silva de Almeida-Monteiro Renata Vieira do Nascimento Vanessa Alves Pereira Yasmim Maia Ferreira Jessica Sales Lobato Romulo Roberto Ribeiro Pinheiro Yara Silvino Sales Assis Rubens Montenegro Carminda Sandra Brito Salmito-Vanderley 《Animal Reproduction》2022,19(1)
The action of substances with non-permeable cryoprotectant potential, besides glucose, has not yet been studied for the species Prochilodus brevis. The objective of this work was to evaluate the action of four non-permeable cryoprotectants on this species sperm cryopreservation. Five pools were cryopreserved in a solution of 5% glucose and 10% dimethyl sulfoxide (Me2SO) associated or not (control) with cryoprotectants egg yolk (5, 10 or 12%), soy lecithin (2.5, 7.5 or 10%), sucrose (5, 10 or 20%) and lactose (5, 8 or 15%). After thawing, samples were evaluated for sperm kinetics (total motility, motility duration, velocities, and wobble - WOB), morphology and membrane and DNA integrity. The treatments containing egg yolk improved significantly (P<0.05) results when compared the control for the membrane integrity parameter. When compared to other treatments, egg yolk, at any concentration, presented higher results (P<0.05) for membrane integrity, total motility, curvilinear velocity (VCL) and average path velocity (VAP) parameters. Egg yolk also showed the best results for WOB, but it did not differ from 5% and 8% lactose and 5% and 20% sucrose. Soy lecithin had the lowest percentages of morphologically normal sperm (P<0.05), while the other treatments did not differ from each other. There was no difference regarding DNA integrity data. Thus, 5% egg yolk is indicated as a non-permeable cryoprotectant for P. brevis, in association with 5% glucose and 10% Me2SO. 相似文献
58.
Tempone AG Andrade HF Spencer PJ Lourenço CO Rogero JR Nascimento N 《Biochemical and biophysical research communications》2001,280(3):620-624
Leishmaniasis is an endemic tropical disease in South America, with few therapeutic approaches. Snake venoms are complex protein mixtures with biological actions that could be used as tools for drug development. Here we show that Bothrops moojeni crude venom presented a killing effect in vitro against Leishmania spp. promastigotes, but not with amastigotes, as determined by a viability assay using the mitochondrial oxidative function. Purification of active fractions from crude venom was performed by molecular exclusion and ion exchange chromatography. Anti-Leishmania and l-amino acid oxidase (L-AAO, EC.1.4.3.2.) activities co-eluted in the same fractions. The molecular weight of the active enzyme was estimated to be 140 kDa by molecular exclusion chromatography, and 69 kDa by SDS--PAGE, with a 4.8 isoelectric point. Using substrate subtraction and catalase for scavenging, the action of L-AAO was demonstrated to be hydrogen-peroxide-dependent. 相似文献
59.
Nantes IL Zucchi MR Nascimento OR Faljoni-Alario A 《The Journal of biological chemistry》2001,276(1):153-158
Recently cytochrome c has been mentioned as an important mediator in the events of cellular oxidative stress and apoptosis. To investigate the influence of charged interfaces on the conformation of cytochrome c, the CD and magnetic circular dichroic behavior of ferric and ferrous cytochrome c in homogeneous medium and in phosphatidylcholine/phosphatidylethanolamine/cardiolipin and dicetylphosphate liposomes was studied in the 300-600 and 200-320 nm wavelength region. EPR spectra demonstrate that the association of cytochrome c with membranes promotes alterations of the crystal field symmetry and spin state of the heme Fe(3+). The studies also include the effect of P(i), NaCl, and CaCl(2). Magnetic circular dichroism and CD results show that the interaction of both ferrous and ferric cytochrome c with charged interfaces promotes conformational changes in the alpha-helix content, tertiary structure, and heme iron spin state. Moreover, the association of cytochrome c with different liposomes is sensitive to the heme iron valence state. The more effective association with membranes occurs with ferrous cytochrome c. Dicetylphosphate liposomes, as a negatively charged membrane model, promoted a more pronounced conformational modification in the cytochrome c structure. A decrease in the lipid/protein association is detected in the presence of increasing amounts of CaCl(2), NaCl, and P(i), in response to the increase of the ionic strength. 相似文献
60.
de Oliveira EM Suzuki MF do Nascimento PA da Silva MA Okazaki K 《Mutation research》2001,476(1-2):109-121
Among various environmental genotoxins, ionizing radiation has received special attention because of its mutagenic, carcinogenic and teratogenic potential. In this context and considering the scarcity of literature data, the objective of the present study was to evaluate the effect of 90Sr beta-radiation on human cells. Blood cells from five healthy donors were irradiated in vitro with doses of 0.2-5.0Gy from a 90Sr source (0.2Gy/min) and processed for chromosome aberration analysis and for comet assay. The cytogenetic results showed that the most frequently found aberration types were acentric fragments, double minutes and dicentrics. The alpha and beta coefficients of the linear-quadratic model, that best fitted the data obtained, showed that 90Sr beta-radiation was less efficient in inducing chromosome aberrations than other types of low linear energy transfer (LET) radiation such as 3H beta-particles, 60Co gamma-rays, 137Cs and 192Ir and X-rays. Apparently, 90Sr beta-radiation in the dose range investigated had no effect on the modal chromosome number of irradiated cells or on cell cycle kinetics. Concerning the comet assay, there was an increase in DNA migration as a function of radiation dose as evaluated by an image analysis system (tail moment) or by visual classification (DNA damage). The dose-response relation adequately fitted the non-linear regression model. In contrast to the cytogenetic data, 90Sr beta-radiation induced more DNA damage than 60Co gamma-radiation when the material was analyzed immediately after exposures. A possible influence of selective death of cells damaged by radiation was suggested. 相似文献