623 resultados para Astyanax (Peixe)


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B chromosomes occur in several Neotropical fish species. Cytogenetic analysis of 27 specimens (15 females and 12 males) of Astyanax scabripinnis paranae from the Araqua river (a small headwater tributary of the Tiete river) shows that this population has 2n = 50 chromosomes (4M + 30 SM + 4ST + 12A), two chromosome pairs with NORs and conspicuous C-band positive blocks in the terminal position of the long arm of four chromosome pairs. In this population, eight females presented 2n = 51 chromosomes and the extra chromosome was a large metacentric similar in size and morphology to the first chromosome pair in the karotype. This accessory chromosome is entirely heterochromatic in C-banded metaphases and shows a late replication pattern evidenced by BrdU incorporation. There was no significant correlation between the presence of B chromosomes and increased NOR activity at the P >0.05 level. Some aspects related to these B chromosomes are discussed.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Toxic effects of phytosanitary surfactants for jewel tetra (Hyphessobrycon eques). Surfactants are amphipatic molecules that reduce the surface tension of water and make up the inert components of pesticide formulations. Thus, the objectives of this study were: to estimate the lethal concentration (LC(I)50;96h); classify and evaluate water quality during testing of the following surfactants: Agral[registered trademark], Aterbane[registered trademark]BR, Ag-bem[registered trademark], Energic[registered trademark], Fixade[registered trademark] and Gotafix[registered trademark] for jewel tetra (Hyphessobrycon eques); and the signs of intoxication in the animals. For this, the fish were acclimated for ten days in the bioassay room. The animals were exposed to the surfactants in an entirely randomized design with three replications. The LC(I)(50;96h) of surfactant Agral[registered trademark] was 3.29 mg L-1; Aterbane[registered trademark] BR 8.21 mg L-1; Energic[registered trademark] 2.34 mg L-1; Gotafix[registered trademark] 4.37 mg L-1; Fixade[registered trademark] 3.38 mg L-1; and Ag-bem[registered trademark] 34.95 mg L-1. The variables of water quality were unchanged. The fish showed an increase in the opercular beating after exposure; 4 and 24 hours, loss of gasping ability; 48 hours, slow opercular beating; and 72 and 96 hours later, recovery. The surfactants Energic[registered trademark], Agral[registered trademark], Gotafix[registered trademark], Aterbane[registered trademark] BR and Fixade[registered trademark] can be classified as moderately toxics, and Ag-Bem[registered trademark] as slightly toxic for H. eques; this organism shows similar intoxication signs for all surfactants.

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Cytogenetic studies performed on 17 specimens (11 females and six males) of Astyanax scabripinnis paranae from the Cascatinha stream showed that this population has 2n = 50 chromosomes (8M + 22SM + 10ST + 10A), two chromosome pairs with NORs and conspicuous C-band positive blocks in the terminal position of the long arm of five chromosome pairs. Three females presented 2n = 51 chromosomes and the extra chromosome was a large metacentric similar in size and morphology to the first chromosome pair in the karyotype. This accessory chromosome was entirely heterochromatic in C-banded metaphases, which permitted its classification as a supernumerary chromosome. Some aspects related to the morphology of such macro B-chromosomes are discussed.

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This work characterized the feeding of Astyanax altiparanae in the sub-basin of Corumbataí river and in the basin of Jacaré-pepira river with a focus on the ingestion of Croton urucurana seeds. The food items of Astyanax altiparanae were, in decreasing APD (Alimentary Preference Degree) order: allochthonous insects, allochthonous plant material, Croton urucurana seeds, autochthonous insects, sediments, autochthonous plant material, scales, oocytes and arachnidans. Croton urucurana seeds occurred during the summer, in the flood period. Lambari, Astyanax altiparanae, could be a secondary disperser of Croton urucurana seeds, however, the intensity and effectiveness of this dispersion may be still investigated.

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This paper presents the identification of tectonic deformation through the application of the stream-gradient index (slope x length) method in the Rio do Peixe hydrographic basin, located in western State of Sã o Paulo. The main principle used is that river valleys are the best tools for this type of analysis because of their fast adjustment to even the most gentle crustal deformations. This type of analysis for structural studies is extremely useful in the western region of the State of São Paulo, where deep chemical weathering results in a thick regolith and scarce outcrops. The stream length index is the ratio of the altimetric amplitude of each drainage and the natural logarithm of its length. The value obtained is plotted on maps at the median point of each drainage, allowing the drawings of lines with the same values (isodefs). Three anomalies (A, B and C) were identified along the Rio do Peixe valley representing uplift sectors indicated by the formation and distribution of Upper Quaternary deposits in terraces and modern fluvial plains and alluvial fans. In correlation with known tectonic data for this region it is possible to attribute the A and B anomalies to the Ribeirão Preto and Presidente Prudente crustal sutures, respectively. The smaller C anomaly needs further field investigation, but it could be associated with the Três Lagoas crustal suture. It must be emphasised that these sutures are inherited from the Precambrian Basement which had a strong influence on the Phanerozoic evolution in the whole sedimentary and volcanic stratigraphic pile of the Paraná Basin and on the dominant structural lineaments directions developed therein .The A, Band C anomalies are suggestive of renewed uplift as a result of neotectonic action in modern times.

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This work evaluates the impact of the pink shrimp Farfantepenaeus paulensis (Perez-Farfante, 1967) fishery on fish and crab assemblages of Lagoa do Peixe National Park, Brazil. We observed that composition of catches is similar to shrimp fisheries using fyke-net at others estuaries of Rio Grande do Sul State: pink shrimp (53%), accessory catches (24%) and bycatch (23%). However, fishery composition showed distinct differences along the saline gradient of the main park's lagoon. Regarding only fish species, the most impacted species in this fishery were Brevoortia pectinata (Jenyns, 1842), Micropogonias furnieri (Desmarest, 1823), and Jenynsia multidentata (Jenyns, 1842). In others estuaries from Rio Grande do Sul, in contrast, the most impacted species were M. furnieri, Genidens barbus (Lacepède, 1803) and Genidens genidens (Cuvier, 1829). The potential impact of the pink shrimp fishery at Lagoa do Peixe National Park seemed to be weaker when compared to shrimp fisheries elsewhere. We believe that the decision to prohibit this fishery at the Lagoa do Peixe National Park should not be based on its potential damage to the fish and crab assemblages but based on the simple fact that Brazilian laws do not allow fisheries inside National Parks.

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Running water is one of the most important of all the physical processes which fashion the landscape, allowing gravity to operate along the valley floors. Besides this, the streams show a fast adjustment to the crustal deformations, even to the most gentle ones. This geologic behavior turns them a potential tool for neotectonic studies, specially the analysis of morphotnetric parameters associated with hydraulic gradient and discharge, this second factor being directly proportional to the extension of the streams. Both elements, gradient and stream length, can be combined in the SL index. The purpose of this paper is to show the RDE index application in the neotectonics analysis of the Rio do Peixe hydrographic basin and to compare the obtained values with the geologic basement incised by the streams. This basement encompasses Cretaceous sedimentary rocks of post-Serra Oeral Formation magmatism (Caiuá and Bauru groups) and Quaternary deposits that include chiefly recent alluvial plains and some Pleistocene terrace deposits. In the final part of this paper, an attempt is made in order to correlate the RDE results and the neotectonic framework admitted to this portion of the São Paulo State territory, as well as with field geologic, seismologic and paleoseismologic known elements. The results indicate the presence of two groups of anomalies: The first set corresponds to the Marília-Exaporã Plateau border, and the second one, located in the central portion of the hydrographic basin, is correlated to the Presidente Prudente seimogenic zone.

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Cytogenetical data in 3 populations of characid fish assigned to the complex of Astyanax scabripinnis from São Francisco river basin and Grande river basin, Minas Gerais State, Brazil, are presented for the first time. The same diploid number, 2n=50, was detected in the 3 populations, which has conspicuous differences involving karyotype morphology: 8M, 20SM, 6ST and 16A (Cambeba stream), 6M, 28SM, 6ST and 10A (Machado headwater), 6M, 24SM, 8ST and 12A (Pedra Branca stream). Differences involving amount and/or locations of heterochromatin blocks, number and position of nucleolar organizer regions (NORs) and CMA3 positive signals were also observed. Some aspects related to the chromosome diversification of Astyanax scabripinnis are discussed. © 2007 The Japan Mendel Society.

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Haematological investigation is an important part of disease diagnosis. The techniques used for mammals are generally applicable for fishes with slight modification. The presence of nucleated erythrocytes and thrombocytes in fish may cause some confusion in the identification of blood cells, mainly in total leukocytes count. This work evaluated two different methods (direct and indirect) of leukocytes counting. Specimens of tilapia were divided randomly into four groups of 48 fish each. Each group was further randomized into three replicate experiments of 16 fish per replicate in 40 L aquarium and maintained for 10 days. Counting of leukocytes in peripheral blood was determined in six fishes per group at the times: 0, 3, 7 and 10 days. The direct method in Neubauer chamber showed a large dispersion of data in regard to the average, the opposite was observed in indirect method determined in blood smears that showed more homogeneity among groups. Due to this factor the indirect method can be considered more accurate than the direct method for counting leukocytes in fishes.

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The study was carried out to evaluate the inclusion of increasing levels (0, 3,0 and 6.0%) of fish silage (SSFP), in the ration. The parameters studied were urea, uric acid, total protein, triglycerides, total cholesterol and lipoproteins (LDL, HDL and VLDL). Eighteen female piglets Moura weighting and crossbred Duroc x Moura, were used with 24,0± 3,0 kg in average weight and 90 days of age and eighteen male pigs Moura and crossbred Duroc x Moura, with 31,5±5,0 kg in average weight and 70 days of age in a randomized design with 3 treatments. The results showed no effect to the addition up to 6,0% of SSPF in the swine diet neither for in growth, nor to the serum parameters, even if had been found alteratum on the urea plasmatic concentrations experiments. All the parameters was closed to the normal value recommended in the literature.

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One specimen of the lophiid white anglerfish, Lophiodes beroe was collected for the second time in Brazilian waters, which far extends the limit distribution of the species to southeastern region (25°00'08).

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Fish hydrolyzed (HP), poultry manure (CF), shrimp skin (CC), cattle manure (EB), sewage sludge (LE) and castorbean presscake (TM) were evaluated for their effect of aqueous extracts with and without autoclaving, on mycelial growth and conidial germination of Cylindrocladium spathiphylli. The effect of mixtures of residues with potting mixes and their volatile compounds were also evaluated on the mycelial growth of the pathogen. To evaluate the effect of HP in the suppressiveness to Cylindrocladium spathiphylli, HP was added in potting mix artificially infested, at concentrations of 0, 10, 20, 30, 40 and 50% of the volume of water required to reach the water retention capacity of the potting mix. The mixtures were incubated for 10 days and transferred to pots containing one plug of Spathiphyllum Opal per pot. In the experiments in vitro, aqueous extracts and mixtures containing HP showed the highest suppressiveness against the pathogen. In the Spathiphyllum growing, the suppressiveness occurred at concentrations higher than 20% of fish hidrolyzed.