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ABSTRACT This study investigated the diversity of metazoan parasites in Colossoma macropomum from the Jari River, in the eastern Amazon, northern Brazil. We collected a total of 4966 parasites from 34 fishes, including monogeneans (Anacanthorus spathulatus, Mymarothecium boegeri, Notozothecium janauachensis and Linguadactyloides brinkmanni), nematodes (Spectatus spectatus larvae, Contracaecum sp. larvae andProcamallanus (Spirocamallanus) inopinatus), digeneans (Cladorchiidae metacercariae), acanthocephalans (Neoechinorhynchus buttnerae), crustaceans (Ergasilus turucuyus, Argulus multicolor, Perulernaea gamitanae and Braga patagonica), mites and leeches. The dominance was of monogenean species, found in the gills of the hosts. The parasites exhibited high... Tipo: Info:eu-repo/semantics/article Palavras-chave: Aggregation; Diversity; Endoparasites; Freshwater fish. Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672018000300211 Parasitic diversity of a wild Satanoperca jurupari population, an ornamental cichlid in the Brazilian Amazon 36 TAVARES-DIAS,Marcos; OLIVEIRA,Marcos Sidney Brito; GONÇALVES,Raissa Alves; NEVES,Lígia Rigor. ABSTRACT Assessment of biodiversity is fundamental for the understanding of ecological interactions, but fish parasites were neglected in biodiversity estimates for a long time. The aim of this paper was to investigate the diversity of parasites in Satanoperca jurupari in the Amazon River system in Brazil. Of the fish examined, 90.0% were parasitized by one or more species of protozoans and metazoans, and a total of 3,110,094 parasites were collected. Ichthyophthirius multifiliis, Piscinoodinium pillulare, Sciadicleithum juruparii, Clinostomum marginatum, Posthodiplostomum sp., Genarchella genarchella, Argulus multicolor and Ergasilus coatiarus were found. However, I. multifiliis and P. pillulare were the most prevalent, abundant and dominant parasites,... Tipo: Info:eu-repo/semantics/article Palavras-chave: Aggregation; Cichlidae; Freshwater fish; Parasites. Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672017000200155 ECOLOGICAL ASPECTS OF THE PARASITES IN Cichlasoma bimaculatum (CICHLIDAE), ORNAMENTAL FISH FROM THE BRAZILIAN AMAZON 37 TAVARES-DIAS,Marcos; ALVES GONÇALVES,Raissa; BRITO OLIVEIRA,Marcos Sidney; RIGÔR NEVES,Ligia. ABSTRACT This study investigated the parasitic fauna of Cichlasoma bimaculatum of a tributary from the Amazon River system, northern Brazil. The prevalence of infection was 94.6 % and, in total, 428 267 parasites, such as Ichthyophthirius multifiliis, Piscinoodinium pillulare (Protozoa), Gussevia arilla (Monogenoidea), Posthodiplostomum sp. (Digenea) and Procamallanus (Spirocamallanus) inopinatus (Nematoda) were collected. However, the dominance was mainly of I. multifiliis, while P. (S.) inopinatus was the parasite species with the lower levels of prevalence and abundance of infection. These parasite species showed an aggregated dispersion pattern. The parasitic fauna was characterized by the presence of few species of parasites with high prevalence and... Tipo: Info:eu-repo/semantics/article Palavras-chave: Aggregation; Endoparasites; Freshwater fish; Infection. Ano: 2017 URL: http://www.scielo.org.co/scielo.php?script=sci_arttext&pid=S0120-548X2017000200006 Spatial distribution, association patterns and richness of tree species in a seasonal forest from the Serra Geral formation, southern Brazil 39 Sühs,Rafael Barbizan; Budke,Jean Carlos. This study aimed to determine the spatial distribution of the most abundant tree species, to look for relationships that may be responsible for their distribution and to compare the expected richness along the Serra Geral formation in the state of Rio Grande do Sul , Brazil. An one-hectare plot was divided in 100 contiguous 10 x 10 m sampling units and all individuals with at least 4.8 cm diameter at breast high were measured and identified. Each sampling unit received a description of the spatial position through metric coordinates (x,y) in order to quantify the spatial pattern. Later, an association index among species was applied. The observed richness was rarefied and compared to other surveys located on the slopes of Serra Geral in Rio Grande do Sul.... Tipo: Info:eu-repo/semantics/article Palavras-chave: Rarefaction; Diversity metrics; Spatial association; Aggregation. Ano: 2011 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062011000300014 Physiopathological modulators of amyloid aggregation and novel pharmacological approaches in Alzheimer's disease 42 DEFELICE,FERNANDA G.; FERREIRA,SÉRGIO T.. The biological mechanisms underlying the neuropathology of Alzheimer's disease (AD) are complex, as several factors likely contribute to the development of the disease. Therefore, it is not surprising that a number of different possible therapeutic approaches addressing distinct aspects of this disease are currently being investigated. Among these are ways to prevent amyloid aggregation and/or deposition, to prevent neuronal degeneration, and to increase brain neurotransmitter levels. Here, we discuss possible roles of endogenous modulators of Abeta aggregation in the physiopathology of AD and some of the strategies currently under consideration to interfere with brain levels of beta-amyloid, its aggregation and neurotoxicity. Tipo: Info:eu-repo/semantics/article Palavras-chave: Alzheimer's disease; Abeta peptide; Aggregation; Neurotoxicity; Physiopathological modulators. Ano: 2002 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652002000200006 Diversity of parasites in wild Astronotus ocellatus (Perciformes, Cichlidae), an ornamental and food fish in Brazil 42 TAVARES-DIAS,MARCOS; NEVES,LIGIA R.. ABSTRACT The community composition of parasites was characterized in Astronotus ocellatus from a tributary of the Amazon River, northern Brazil. The prevalence was 87.9%, and a total of 526,052 parasites were collected, with a mean of 15,941 parasites per host. Nine taxa of ecto- and endo-parasites were identified, but Ichthyophthirius multifiliis was the dominant species, while Piscinoodinium pillulare, Clinostomum marginatum and Argulus multicolor were the least prevalent parasites. The parasite community was characterized by a low species richness, low diversity and low evenness. Host body size was not found to influence the composition of the parasite community, and there was no significant correlation between abundance of any parasite species and host... Tipo: Info:eu-repo/semantics/article Palavras-chave: Aggregation; Amazon; Ectoparasites; Endoparasites; Freshwater fish. Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652017000502305 Dispersal of Cotesia flavipes in sugarcane field and implications for parasitoid releases 53 Dinardo-Miranda,Leila Luci; Fracasso,Juliano Vilela; Costa,Viviane Pereira da; Lopes,Diego Olympio Teixeira. Diatraea saccharalis Fabr. (Lepidoptera: Crambidae) is a major sugarcane pest in Brazil. The management of infested areas is based on the release of Cotesia flavipes (Cameron) (Hymenoptera: Braconidae), a parasitoid of D. saccharalis larvae, but there are doubts about the effectiveness of C. flavipes, primarily regarding its rate of dispersal in sugarcane fields. Thus, the objective of this study was to evaluate the dispersal of C. flavipes in a sugarcane field and suggest a release method that provides higher parasitoid efficiency. The study was carried out in four areas of approximately 1 ha, in which stalk pieces containing 20 D. saccharalis larvae were distributed in a rectangular grid, and 12,000 C. flavipes adults were released at four points, that... Tipo: Info:eu-repo/semantics/article Palavras-chave: Sugarcane borer; Diatraea saccharalis; Biological control; Aggregation; Pest management. Ano: 2014 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052014000200011 Volume and energy folding landscape of prion protein revealed by pressure 56 Cordeiro,Y.; Kraineva,J.; Winter,R.; Silva,J.L.. The main hypothesis for prion diseases proposes that the cellular protein (PrP C) can be altered into a misfolded, ß-sheet-rich isoform, the PrP Sc (from scrapie). The formation of this abnormal isoform then triggers the transmissible spongiform encephalopathies. Here, we discuss the use of high pressure as a tool to investigate this structural transition and to populate possible intermediates in the folding/unfolding pathway of the prion protein. The latest findings on the application of high pressure to the cellular prion protein and to the scrapie PrP forms will be summarized in this review, which focuses on the energetic and volumetric properties of prion folding and conversion. Tipo: Info:eu-repo/semantics/article Palavras-chave: Prion; High pressure; Structural conversion; Aggregation. Ano: 2005 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2005000800006 Stabilization of partially folded states in protein folding/misfolding transitions by hydrostatic pressure 56 Ferreira,S.T.; Chapeaurouge,A.; De Felice,F.G.. In the last few years, hydrostatic pressure has been extensively used in the study of both protein folding and misfolding/aggregation. Compared to other chemical or physical denaturing agents, a unique feature of pressure is its ability to induce subtle changes in protein conformation, which allow the stabilization of partially folded intermediate states that are usually not significantly populated under more drastic conditions (e.g., in the presence of chemical denaturants or at high temperatures). Much of the recent research in the field of protein folding has focused on the characterization of folding intermediates since these species appear to be involved in a variety of disease-causing protein misfolding and aggregation events. The exact mechanisms of... Tipo: Info:eu-repo/semantics/article Palavras-chave: High pressure; Protein folding; Misfolding; Amyloid; Aggregation. Ano: 2005 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2005000800009 Genomics and X-ray microanalysis indicate that Ca2+ and thiols mediate the aggregation and adhesion of Xylella fastidiosa 56 Leite,B.; Ishida,M.L.; Alves,E.; Carrer,H.; Pascholati,S.F.; Kitajima,E.W.. The availability of the genome sequence of the bacterial plant pathogen Xylella fastidiosa, the causal agent of citrus variegated chlorosis, is accelerating important investigations concerning its pathogenicity. Plant vessel occlusion is critical for symptom development. The objective of the present study was to search for information that would help to explain the adhesion of X. fastidiosa cells to the xylem. Scanning electron microscopy revealed that adhesion may occur without the fastidium gum, an exopolysaccharide produced by X. fastidiosa, and X-ray microanalysis demonstrated the presence of elemental sulfur both in cells grown in vitro and in cells found inside plant vessels, indicating that the sulfur signal is generated by the pathogen surface.... Tipo: Info:eu-repo/semantics/other Palavras-chave: Xylella fastidiosa; Aggregation; Adhesion; Methionine sulfoxide reductase; Biofilm. Ano: 2002 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2002000600003 Relationship between raindrops and ultrasonic energy on the disruption of a Haplic Cambisol 64 Ribeiro,Bruno Teixeira; Lima,José Maria de; Mello,Carlos Rogério de; Sá,Marcos Aurélio Carolino de; Oliveira,Geraldo César de. The aim of this work was to compare aggregate disruption of undisturbed soil samples by ultrasonic energy to aggregate disruption caused by the energy of simulated raindrops, to provide equations that can describe this relationship, and to evaluate whether aggregate stability, expressed by sonication method, may be used to estimate the effect that raindrops have on undisturbed soil samples. Undisturbed soil samples from A, Bi and C horizons of a Cambisol were submitted to different levels of ultrasonic energy and simulated raindrops. Sieved samples (aggregates) were also submitted to different levels of ultrasonic energy so that both disturbed and undisturbed conditions of samples could be compared. The results showed that the method using ultrasonic... Tipo: Info:eu-repo/semantics/article Palavras-chave: Aggregation; Soil structure; Ultrasound. Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542009000300021 Influencia de diferentes manejos agrícolas sobre el crecimiento radical y su relación con la agregación del suelo. 32 Torres Guerrero, Carlos Alberto. Los suelos de México han sido degradados en los últimos años en buena parte por la acción del hombre. Debido a las prácticas agronómicas empleadas en la mayor parte del país (labranza convencional, monocultivos y remoción de residuos vegetales de cosechas anteriores) los suelos con potencial agrícola se han visto disminuidos en su productividad. La Agricultura de Conservación (AC) ofrece un aprovechamiento sustentable del recurso suelo, asegurando su estabilidad y estructura, con el propósito de aumentar los rendimientos de los cultivos. El experimento que se reporta es de larga duración. Se inició en 1991 en el Batán Texcoco, Estado de México, en el Centro Internacional de Mejoramiento de Maíz y Trigo (CIMMYT) y consta de 32 parcelas con diferentes... Palavras-chave: Labranza; Agricultura de conservación; Raíces; Agregación; Maestría; Edafología; Tillage; Conservation agriculture; Roots; Aggregation. Ano: 2012 URL: http://hdl.handle.net/10521/1755 The aggregation of Chauliognathus species (Coleoptera, Cantharidae) and its possible role for coexistence and mimicry 76 Machado,Vilmar; Araújo,Aldo Mellender de. The relative population sizes of a species complex of Chauliognathus are reported, as well as their spatial distribution associated with different patches of food plants. Field work was done at Fazenda Santa Isabel, municipality of Guaíba, State of Rio Grande do Sul, Brazil. The results suggest that two mechanisms account for the reduction in food competition among the species involved: one is asynchrony in the appearance of the species in the area, and the other is aggregation in different patches of food plants. Since the species here reported show a similar colour pattern (yellow-black) the possibility of the occurrence of serial mimicry in this complex of species is dicussed. Tipo: Info:eu-repo/semantics/article Palavras-chave: Chauliognathus; Aggregation; Competition; Mimicry; Coleoptera. Ano: 2001 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0073-47212001000200002 Determinação da agregação do solo - metodologia em uso na Embrapa Agropecuária Oeste. 14 SALTON, J. C.; SILVA, W. M.; TOMAZI, M.; HERNANI, L. C.. Tipo: Folhetos Palavras-chave: Avaliação; Agregação; Evaluation; Aggregation; Analisys; Análise; Solo; Soil. Ano: 2012 URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/952808 Predation has no competition: factors influencing space and resource use by echinoids in deep-sea coral habitats, as evidenced by continuous video transects 5 Stevenson, Angela; Mitchell, Fraser J. G.; Davies, Jaime S.. Predation and competition are highly influential factors determining space use in foraging animals, and ultimately contribute to the spatial heterogeneity observed within habitats. Here we investigated the influence of competition and predation on space and resource use via continuous video transect observations – a tool that has not previously been employed for this purpose. This study therefore also evaluates video data as a pragmatic tool to study community interactions in the deep sea. Observations were compiled from 15 video transects spanning five submarine canyons in the Bay of Biscay, France. Substrate choice, positioning on the coral, echinoid aggregate size, and the presence/absence of predators (e.g. fish and decapods) as well as competitors... Tipo: Text Palavras-chave: Aggregation; Bay of Biscay; Cidaris cidaris; Community interactions; Deep sea; Echinothuriidae; NE Atlantic; Refuge; Space use. Ano: 2015 URL: http://archimer.ifremer.fr/doc/00242/35303/33829.pdf Examples of spatial and temporal variations of some fine-grained suspended particle characteristics in two Danish coastal water bodies 5 Mikkelsen, Oa. In June and September of 1999, a LISST-100 in situ laser diffraction particle sizer was used to analyse the temporal and spatial variation of the beam attenuation coefficient, the in situ median particle (aggregate) diameter and the median volume concentration of suspended matter in two Danish coastal water bodies. One of the study sites was generally exposed to wind, while the other was quite sheltered. Measurements of the mass concentration of total suspended matter and chl a were made simultaneously. The in situ median effective density, settling velocity and vertical flux of the suspended matter are computed. Results demonstrate that in September, the in situ median aggregate diameter, settling velocity and vertical flux was smaller (by a factor of up... Tipo: Text Palavras-chave: Agrégation; Diffraction laser; Spectre de taille des particules; Dimension fractale; Vitesse de sédimentation; Aggregation; Laser diffraction; Particle size spectra; Fractal dimension; Settling velocity. Ano: 2002 URL: http://archimer.ifremer.fr/doc/00322/43328/42899.pdf Use of a disjunctive kriging to model areas of high pelagic fish density in acoustic fisheries surveys 5 Petitgas, Pierre. Schooling fish may aggregate in very high densities covering very small areas. Thus the probability of hitting such high-density spots during a large-scale sampling is very low. The sampling fluctuations of the tail of the histogram are thought to be very significant. The stock biomass estimate and its precision rely greatly on how precisely the tail of the histogram can be sampled. In order to acquire elements for improving survey designs and abundance estimators wc study here the relation in space that the high values have with the other values. A disjunctive kriging approach is used. Different quantiles of the histogram are coded by indicators. The spatial structure of each indicator and its spatial covariation with the others are studied by computing... Tipo: Text Palavras-chave: Distribution spatiale; Agrégation; Abondance; Estimation; Géostatistique; Échantillonnage; Spatial distribution; Aggregation; Abundance estimation; Geostatistics; Sampling. Ano: 1993 URL: http://archimer.ifremer.fr/doc/00190/30076/28564.pdf Phytoplankton morphology controls on marine snow sinking velocity 5 Laurenceau-cornec, Emmanuel C.; Trull, Thomas W.; Davies, Diana M.; De La Rocha, Christina L.; Blain, Stephane. During the second KErguelen Ocean and Plateau compared Study (KEOPS2) in October-November 2011, marine snow was formed in roller tanks by physical aggregation of phytoplankton assemblages sampled at 6 stations over and downstream of the Kerguelen Plateau. Sinking velocities, morphology, bulk composition (transparent exopolymer particles, biogenic silica, particulate organic carbon), and phytoplankton contents were measured individually on 66 aggregates to identify controls on sinking velocities. Equivalent spherical diameters (ESD) ranged from 1 to 12 mm, and the particle aspect ratios, Corey shape factors, and fractal dimensions (D-F1 = 1.5, D-F2 = 1.8) were close to those of smaller natural aggregates (0.2 to 1.5 mm) collected in polyacrylamide... Tipo: Text Palavras-chave: Sinking velocity Marine snow; Aggregation; Phytoplankton; Porosity. Ano: 2015 URL: https://archimer.ifremer.fr/doc/00352/46275/46044.pdf Association between bluefin tuna schools and oceanic features in the western Mediterranean 5 Royer, Francois; Fromentin, Jean-marc; Gaspar, P. We present an analysis of the distribution of bluefin tuna Thunnus thynnus schools spotted during aerial surveys in the Gulf of Lions, in relation to oceanographic features. Bio-optical and thermal properties of the sea surface derived from high-resolution sensors (AVHRR and SeaWiFS) were studied on a daily basis, and an edge-detection technique was applied to detect frontal zones. Geostatistics and point-process analyses were used to evaluate the role of the environment in structuring the spatial pattern of bluefin tuna (BFT). The distribution of schools spotted was strongly non-stationary both in space and time; this is believed to be an effect of the survey design (transect sampling) and the influence of transient oceanographic structures (surface... Tipo: Text Palavras-chave: Thunnus thynnus; Gulf of Lions; Point process analysis; Front detection; Sea surface temperature; Ocean colour; Aggregation. Ano: 2004 URL: http://archimer.ifremer.fr/doc/00000/10786/7585.pdf Surface functionalization determines behavior of nanoplastic solutions in model aquatic environments 5 Tallec, Kevin; Blard, Océane; González-fernández, Carmen; Brotons, Guillaume; Berchel, Mathieu; Soudant, Philippe; Huvet, Arnaud; Paul-pont, Ika. Plastic debris are classified as a function of their size and recently a new class was proposed, the nanoplastics. Nano-sized plastics have a much greater surface area to volume ratio than larger particles, which increases their reactivity in aquatic environment, making them potentially more toxic. Only little information is available about their behavior whereas it crucially influences their toxicity. Here, we used dynamic light scattering (DLS) to explore the influence of environmental factors (fresh- and saltwater, dissolved organic matter) on the behavior (surface charge and aggregation state) of three different nano-polystyrene beads (50 nm), with (i) no surface functionalization (plain), (ii) a carboxylic or (iii) an amine functionalization. Overall,... Tipo: Text Palavras-chave: Nanoplastic; Dynamic light scattering; Behavior; Aggregation; Salinity; Organic matter. Ano: 2019 URL: https://archimer.ifremer.fr/doc/00485/59652/62684.pdf Registros recuperados: 57 Primeira ... 1 2 3 ... Última

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