999 resultados para Hormônios Peixes


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Para avaliar o efeito anestsico do leo de cravo em lambaris (Astyanax altiparanae), cinco grupos de 30 alevinos (0,6±0,1g) foram expostos s concentraes de 50, 75, 100, 125 e 150mg L-1, medindo-se, respectivamente: tempo de induo anestesia profunda (caracterizada pela perda de equilbrio, pela ausncia de natao, pela reduo dos movimentos operculares e pelas respostas apenas a estmulos tteis mais intensos), tempo de recuperao e taxa de mortalidade aps a exposio. Em uma segunda etapa (10 peixes/tratamento), registraram-se, para cada concentrao, os tempos de induo e de recuperao aps anestesia cirrgica (movimentos operculares lentos e irregulares e perda de reaes a estmulos), anotando-se a mortalidade aps seis minutos de exposio. Observou-se reduo linear no tempo de induo anestesia (0,01min mg-1 de anestsico acrescido) e aumento quadrtico do tempo de recuperao com a elevao da concentrao (resposta mxima estimada em 7,1 minutos). A anestesia profunda foi alcanada em tempo inferior a 1,5 minuto para todas as concentraes, com recuperao mais rpida e sem mortalidade para 50mg L-1. Para induo anestesia cirrgica, foram registrados menores tempos nas concentraes 75 e 100mg L-1; porm, com mortalidade de 80% e 100%, respectivamente. A concentrao 50mg L-1 promoveu anestesia cirrgica e recuperao em 3,29±0,71 e 4,97±0,63 minutos, respectivamente, sem mortalidade. Concluiu-se que o leo de cravo possui efeito anestsico para alevinos de lambari, sendo 50mg L-1 a concentrao eficiente e segura para induo anestesia profunda em at 1,5 minuto e de anestesia cirrgica em at 3,3 minutos de exposio.

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Flavobacterium columnare is the causative agent of columnaris disease in freshwater fish, implicated in skin and gill disease, often causing high mortality. The aim of this study was the isolation and characterization of Flavobacterium columnare in tropical fish in Brazil. Piracanjuba (Brycon orbignyanus), pacu (Piaractus mesopotamicus), tambaqui (Colossoma macropomum) and cascudo (Hypostomus plecostomus) were examined for external lesions showing signs of colunmaris disease such as greyish white spots, especially on the head, dorsal part and caudal fin of the fish. The sampling comprised 50 samples representing four different fish species selected for study. Samples for culture were obtained by skin and kidney scrapes with a sterile cotton swabs of columnaris disease fish and streaked onto Carlson and Pacha (1968) artificial culture medium (broth and solid) which were used for isolation. The strains in the liquid medium were Gram negative, long, filamentous, exhibited flexing movements (gliding motility), contained a large number of long slender bacteria and gathered into columns'. Strains on the agar produced yellow-pale colonies, rather small, flat that had rhizoid edges. A total of four Flavobacterium columnare were isolated: 01 Brycon orbignyanus strain, 01 Piaractus mesopotamicus strain, 01 Colossoma macropomum strain, and 01 Hypostomus plecostomus strain. Biochemical characterization, with its absorption of Congo red dye, production of flexirubin-type pigments, H2S production and reduction of nitrates proved that the isolate could be classified as Flavobacterium columnare.

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Neste trabalho, avaliou-se a adio de clulas ntegras de levedura e seus derivados em dietas para juvenis de tilpia do Nilo. Foram utilizados 144 juvenis machos de tilpia (peso mdio de 52,1g) distribudos em 12 tanques de fibra de vidro (250L), em delineamento inteiramente casualizado, composto por quatro tratamentos e trs repeties. Os peixes foram alimentados ad libitum, duas vezes ao dia durante 60 dias, com dietas isoproteicas (28% PB) e isocalricas (2.900kcal de ED kg-1) contendo levedura ntegra de cana-de-acar (LI), levedura autolisada (LA) e parede celular (PC) adicionados na proporo de 25% da protena bruta total, comparadas com uma dieta controle (CO), sem adio de levedura. No foram observadas diferenas significativas para converso alimentar aparente e taxa de eficincia protica. No entanto, o ganho em peso foi melhor nos peixes alimentados com as dietas LA (114,70g) e PC (131,03g), assim como em relao taxa de crescimento especfico (LA=1,79 e PC=1,93%), protena bruta no ganho de peso (LA=14,45 e PC=15,62%) e ao contedo corporal proteico (LA=14,89 e PC=15,67g 100g-1). As fraes, a parede celular e a levedura autolisada de cana-de-acar podem ser utilizadas em dietas para juvenis de tilpia.

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Avaliaram-se os efeitos da incluso de farelo de canola em dietas de juvenis de pacu (Piaractus mesopotamicus) sobre parmetros de crescimento e composio corporal. Um total de 192 alevinos (9 a 15g) foram estocados em 24 tanques de cimento, de 100l de capacidade, durante 103 dias. O farelo de canola foi utilizado em quatro propores: zero; 9,5%; 19% e 38% da dieta, com ou sem farinha de peixe (12%/dieta), totalizando oito tratamentos. A presena de farinha de peixe no afetou os parmetros de crescimento avaliados. A incluso de 38% de farelo de canola na dieta diminuiu o ganho de peso dos peixes, valores mdios de 28,74g a 50,70g, e piorou a converso alimentar aparente, de 1,66 para 2,85. A taxa de eficincia protica tambm foi menor nos peixes alimentados com 38% de farelo de canola. As vrias propores de farelo de canola das dietas alteraram os teores de umidade, protena bruta e lipdios dos peixes. A presena da farinha de peixe, nas dietas, somente influiu no teor de lipdios dos peixes alimentados com dietas contendo 9,5% de farelo de canola. Conclui-se que at 19% de farelo de canola pode ser adicionado s dietas de juvenis de pacu, sem que seu desenvolvimento seja prejudicado.

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Para verificar o efeito do estresse calrico (EC) nas concentraes plasmticas de testosterona, triiodotironina (T3) e tiroxina (T4), oito bodes, das raas Saanen (n=4) e Alpina (n=4), foram mantidos em cmara bioclimtica, sob condies de termoneutralidade (13,0C a 26,7C) durante 30 dias e, aps um perodo (60 dias) de descanso, submetidos ao EC (23,7C a 34,0C) por 30 dias. Para minimizar as variaes sazonais nos perfis hormonais devido ao fotoperodo, durante toda fase experimental, incluindo a de adaptao em condies de termoneutralidade (30 dias), o fotoperodo foi controlado utilizando-se alternncia de dias longos (16h de luz e 8h de escuro) e de dias curtos (8h de luz e 16h de escuro) a cada 30 dias. As amostras de sangue foram coletadas duas vezes por semana durante cinco semanas. No conjunto das raas, o EC no influenciou (P>0,05) as concentraes de testosterona (1,80,2 vs 1,30,2ng/ml) e nem a de T4 (52,72,8 vs 50,02,8ng/ml). Houve declnio (P<0,01) das concentraes de T3 nos animais submetidos ao experimento (1,30,1 vs 1,00,1ng/ml), mas a reduo foi observada somente nos bodes Saanen. Em ambas as raas, as concentraes de T3 e T4 variaram (P<0,01) conforme o dia da coleta das amostras de sangue. O EC foi suficiente para produzir uma resposta fisiolgica com reduo das concentraes plasmticas de T3 em bodes das raas Saanen, mas no da raa Alpina, assim como no foi capaz de alterar os nveis plasmticos de testosterona e nem de T4.

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Artificial reproduction and gamete fertilization were evaluated in Salminus hilarii wild and domesticated broodstocks. Wild and domesticated broodstocks were artificially induced to reproduction using a carp pituitary treatment. Four groups were considered: Group 1 (G1), fish caught in the wild maintained for three years in the same conditions as the domesticated broodstocks and spawned naturally; Group 2 (G2), broodstock born and raised in captivity and spawned naturally; Group 3 (G3), wild broodstocks, which were manually stripped for gamete collection and dry fertilization; and Group 4 (G4), domesticated males and females, also manually stripped. Oocytes, eggs, and larvae were sampled at different time intervals throughout embryonic development. Yolk sac absorption occurred approximately 24-29 h after hatching. Twenty-six h after hatching, the larvae mouths opened. Cannibalism was identified just 28-30 h after hatching. There was no morphological difference in embryonic development among all groups. The number of released eggs per gram of female was: G1: 83.3 24.5 and G2: 103.8 37.4; however, the fertilization success was lower in G2 (42.0 6.37 %) compared with G1 (54.7 3.02%) (P = 0.011). Hand-stripping of oocytes was not successful and the fertilization rate was zero. The reproduction of this species in captivity is viable, but it is necessary to improve broodstock management to enhance fertilization rates and obtain better fingerling production for restocking programs.

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Troglobitic (exclusively subterranean) organisms usually present, among their apomorphies related to the subterranean life (troglomorphisms), the regression of eyes and melanic pigmentation. The degree of regression varies among species, from a slight reduction to the complete loss of eyes and dark pigmentation, without a taxonomic correlation. While mechanisms of eye reduction have been intensively investigated in some troglobites such as the Mexican blind tetra characins, genus Astyanax, and the European salamander, Proteus anguinus, few studies have focused on pigmentation. The Brazilian subterranean ichthyofauna distinguishes not only by the species richness (23 troglobitic fishes so far known) but also by the variation in the degree of reduction of eyes and pigmentation. This study focused on Brazilian fishes completely devoid of melanic pigmentation: the characiform Stygichthys typhlops (Characidae) and the siluriforms Ancistrus formoso (Loricariidae), Rhamdiopsis sp.1 (Heptapteridae; from caves in the Chapada Diamantina, Bahia) and Rhamdiopsis sp. 2 (cave in Campo Formoso, Bahia). In order to investigate if such depigmentation is the result of blockage in some step in the melanogenesis, in vitro tests of administration of L-DOPA were done, using caudal-fin fragments extracted from living fish. Except for Rhamdiopsis sp. 2, all the studied species were DOPA(+), i.e., melanin was synthesized after L-DOPA administration. This indicates these fish do have melanophores but they are unable to convert L-tyrosine to L-DOPA. On the other hand, Rhamdiopsis sp. 2, like the albino specimens of Trichomycterus itacarambiensis previously studied (which correspond to one third of the population), are DOPA(-), either because the block of melanin synthesis occurs downstream in melanogenesis, which is probably the case with T. itacarambiensis (monogenic system in view of the phenotypic discontinuity), or because the so-called albinos do no possess melanophores. The physiological loss in the ability to synthesize melanin, apparently caused by different genetic processes in DOPA(+) and in DOPA(-) fishes, may co-exist in subterranean populations with a decrease in the density of melanophores, as observed in the pigmented two thirds of T. itacarambiensis population, a morphological reduction apparently controlled by polygenic systems producing a continuous phenotypic variation.

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OBJETIVO: Este artigo analisa e compara os dados de consumo alimentar de duas populaes ribeirinhas da Amaznia vivendo em ecossistemas contrastantes de floresta tropical: a vrzea estacional e a floresta de terra firme. MTODOS: Foi estudado o consumo alimentar de 11 unidades domsticas na vrzea (Ilha de Ituqui, Municpio de Santarm) e 17 na terra firme (Floresta Nacional de Caxiuan, Municpios de Melgao e Portel). O mtodo utilizado foi o recordatrio de 24 horas. As anlises estatsticas foram executadas com o auxlio do programa Statistical Package for Social Sciences 12.0. RESULTADOS: Em ambos os ecossistemas, os resultados confirmam a centralidade do pescado e da mandioca na dieta local. Porm, a contribuio de outros itens alimentares secundrios, tais como o aa (em Caxiuan) e o leite in natura (em Ituqui), tambm foi significante. Alm disso, o acar revelou ser uma fonte de energia confivel para enfrentar as flutuaes sazonais dos recursos naturais. Parece haver ainda uma maior contribuio energtica dos peixes para a dieta de Ituqui, provavelmente em funo da maior produtividade dos rios e lagos da vrzea em relao terra firme. Por fim, Ituqui revelou uma maior dependncia de itens alimentares comprados, enquanto Caxiuan mostrou estar ainda bastante vinculada agricultura e s redes locais de troca. CONCLUSO: Alm dos resultados confirmarem a importncia do pescado e da mandioca, tambm mostraram que produtos industrializados, como o acar, tm um papel importante nas dietas, podendo apontar para tendncias no consumo alimentar relacionadas com a atual transio nutricional e com a eroso, em diferentes nveis, dos sistemas de subsistncia locais.

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A new species of the relatively poorly known Neotropical freshwater stingray genus Plesiotrygon Rosa, Castello & Thorson, 1987 is described from the main channel and smaller tributaries (Ros Itaya and Pachitea) of the upper Amazon basin in Peru. The first specimen to be collected, however, was from much farther east in Rio Solimes in 1996, just down-river from Rio Purus (specimen unavailable for this study). Plesiotrygon nana sp. nov., is a very distinctive and unusually small species of freshwater stingray (Potamotrygonidae), described here mostly from three specimens representing different size classes and stages of sexual maturity. Plesiotrygon nana sp. nov., is distinguished from its only congener, P. iwamae Rosa, Castello & Thorson, 1987, by numerous unique features, including: dorsal coloration composed of very fine rosettes or a combination of spots and irregular ocelli; very circular disc and snout; very small and less rhomboidal spiracles; short snout and anterior disc region; narrow mouth and nostrils; denticles on dorsal tail small, scattered, not forming row of enlarged spines; adult and preadult specimens with significantly fewer tooth rows; fewer caudal vertebrae; higher total pectoral radials; very small size, probably not surpassing 250 mm disc length or width, males maturing sexually at around 180 mm disc length and 175 mm disc width; distal coloration of tail posterior to caudal stings usually dark purplish-brown; and features of the ventral lateral-line canals (hyomandibular canal very narrow, infraorbital and supraorbital canals not undulated, supraorbital and infraorbital loops small and narrow, supraorbital loop very short, not extending posteriorly to level of mouth, jugular and posterior infraorbital canals short, not extending caudally to first gill slits, subpleural loop very narrow posteriorly; absence of anterior and posterior subpleural tubules). To provide a foundation for the description of P. nana sp. nov., morphological variation in P. iwamae was examined based on all type specimens as well as newly collected and previously unreported material. Two specimens topotypic with the male paratype of P. nana sp. nov., referred to here as Plesiotrygon cf. iwamae, are also reported. Relationships of the new species to P. iwamae are discussed; further characters indicative of Plesiotrygon monophyly are proposed, but the genus may still not be valid. Plesiotrygon nana sp. nov., is commercialized with some regularity in the international aquarium trade from Iquitos (Peru), an alarming circumstance because nothing is known of its biology or conservation requirements.

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After an ichthyofaunistic survey conducted in May 2007 on surface (epigean) water bodies of Cordisburgo karst area, State of Minas Gerais, 13 species were recorded, mostly characiforms; in addition three non-troglomorphic (normally eyed and pigmented) and one troglomorphic catfish (siluriforms) species were recorded in two caves surveyed at different occasions, totaling 17 fish species for the area. All the nominal species herein reported for Cordisburgo area have been previously reported for the Rio das Velhas basin. None of the species observed in caves were found in epigean habitats and vice-versa. The four cave species are distributed throughout subterranean stream reaches, with individuals at different size/age classes. This, associated to the lack of conspicuous morphological differences in relation to epigean congeners, indicate that Trichomycterus brasiliensis, Gymnotus cf. carapo and Pimelodella cf. vittata are troglophiles (species encompassing individuals able to live and complete their life cycle either in the surface or in the subterranean environment) in the Morena Cave; the latter forms a large population and may be at the beginning of a differentiation process due to isolation in the subterranean habitat, as indicated by a slight reduction in eye size. Topographic isolation may be the cause for the incipient, but unmistakable troglomorphism of the Rhamdiopsis population found in the Salitre Cave, allowing for its classification as troglobite (exclusively subterranean species). The Cordisburgo area is subject to significant anthropic pressure, mainly represented by deforestation for agriculture, cattle raising and timbering. Tourism is an additional important threat for cave communities, calling for urgent protection measures.

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During the exploration and mapping of new caves in Serra do Ramalho karst area, southern Bahia state, cavers from the Grupo Bambu de Pesquisas Espeleolgicas - GBPE (Belo Horizonte) noticed the presence of troglomorphic catfishes (species with reduced eyes and/or melanic pigmentation), which we intensively investigated with regards to their ecology and behavior since 2005. Non-troglomorphic fishes regularly found in the studied caves were included in this investigation. We present here data on the natural history of two troglobitic (exclusively subterranean troglomorphic species) fishes - Rhamdia enfurnada Bichuette & Trajano, 2005 (Heptapteridae; Gruna do Enfurnado) and Trichomycterus undescribed species (Trichomycteridae; Lapa dos Peixes and Gruna da gua Clara), and non-troglomorphic Hoplias cf. malabaricus, probably a troglophile (able to form populations both in epigean and subterranean habitats) in the Gruna do Enfurnado, and Pimelodella sp., a species with a sink population in the Lapa dos Peixes.

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After an ichthyofaunistic survey in several epigean (surface) water bodies of the Serra do Ramalho, southern Bahia, conducted in May 2007, 44 species were recorded; in addition, three non-troglomorphic (normally eyed and pigmented) and two troglomorphic species were recorded only in caves, totaling 49 species of fishes for the area, which represents a little more than one fourth of the total registered in the literature for the entire Rio So Francisco basin. In these caves, which have been studied since 2005, eight non-troglomorphic species were sampled and their presence in both epigean and subterranean habitats, associated to the lack of morphological differences, indicate that they may be either troglophiles (species encompassing individuals able to live and complete their life cycle either in the surface or in the subterranean environment), trogloxenes (individuals regularly found in subterranean habitats, but which must return periodically to the surface in order to complete their life cycle) or even accidental in caves. In addition, two troglomorphic species (with reduced eyes and melanic pigmentation when compared to close epigean relatives), belonging respectively to the genera Rhamdia and Trichomycterus, were recorded exclusively in caves, thus classified as troglobites. Interestingly, no epigean representative of the genus Trichomycterus was collected. The new data are integrated into updated lists of Brazilian troglobitic and troglophilic fishes, based on published data and new records recently confirmed.

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The Paran-Paraguay basin encompasses central western Brazil, northeastern Paraguay, eastern Bolivia and northern Argentina. The Pantanal is a flooded plain with marked dry and rainy seasons that, due to its soil characteristics and low declivity, has a great water holding capacity supporting abundant fish fauna. Piaractus mesopotamicus, or pacu, endemic of the Paran-Paraguay basin, is a migratory species economically important in fisheries and ecologically as a potential seed disperser. In this paper we employ eight microsatellite loci to assess the population structure of 120 pacu sampled inside and outside the Pantanal of Mato Grosso. Our main objective was to test the null hypothesis of panmixia and to verify if there was a different structuring pattern between the Pantanal were there were no physical barriers to fish movement and the heavily impounded Paran and Paranapanema rivers. All loci had moderate to high levels of polymorphism, the number of alleles varied from three to 18. The average observed heterozygosity varied from 0.068 to 0.911. After the Bonferroni correction three loci remained significant for deviations from Hardy-Weinberg, and for those the frequency of null alleles was estimated. F ST and R ST pairwise comparisons detected low divergence among sampling sites, and differentiation was significant only between Paranapanema and Cuiab and Paranapanema and Taquari. No correlation between genetic distance and the natural logarithm of the geographic distance was detected. Results indicate that for conservation purposes and for restoration programs small genetic differences detected in the Cuiab and Paranapanema rivers should be taken in consideration.

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Investigou-se o efeito da adio de C18:2n6, por meio da incluso de leo de milho em dietas com dois nveis de protena bruta, sobre o processo de maturao de gametas de pintado, Pseudoplatystoma corruscans, mantidos em tanques-rede. Foram avaliados: taxa de sobrevivncia, relao peso x comprimento, fator de condio (K) e ndice gonadossomtico (IGS). O experimento foi realizado entre maro de 2004 e fevereiro de 2006, em 12 tanques-rede, distribudos em seis viveiros-escavados de 600m e densidade de estocagem de 20 peixes/tanque-rede. Utilizaram-se trs tratamentos (T) com duas repeties/viveiro: T1 com 28% de PB; T2 com 28% de PB + 5% leo de milho e T3 com 40% de PB. O crescimento foi ligeiramente mais alto nos peixes do T3. As taxas de sobrevivncia foram acima de 77%. Pode-se inferir que as raes ofertadas no causaram alteraes histomorfolgicas durante o processo de maturao gonadal dessa espcie. O IGS e o K foram ligeiramente mais altos nos animais alimentados com a rao enriquecida com leo de milho.

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Os autores discutem, a partir do conceito evolutivo, como a resposta de estresse, nas suas possibilidades de fuga e luta e de imobilidade tnica, pode levar a uma nova compreenso etiolgica do transtorno de estresse ps-traumtico. Atravs da anlise dos agrupamentos de sintomas desse diagnstico - revivncia, evitao e hiperexcitao -, procuram correlacionar os achados neurobiolgicos e evolutivos. As descobertas atuais sobre a gentica do transtorno de estresse ps-traumtico so resumidas e colocadas nessa perspectiva evolutiva, dentro de conceitos que possibilitam o entendimento da interao gene/ambiente, como a epigentica. Propem que a pesquisa dos fatores de risco do transtorno de estresse ps-traumtico deva ser investigada do ponto de vista fatorial, onde a somatria destes aumenta o risco de desenvolvimento do quadro, no sendo possvel a procura da causa do transtorno de forma nica. A pesquisa de genes candidatos no transtorno de estresse ps-traumtico deve levar em considerao todos os sistemas associados aos processos de respostas ao estresse, sistemas dos eixos hipotlamo-hipofisrio-adrenal e simptico, mecanismos de aprendizado, formao de memrias declarativas, de extino e esquecimento, da neurognese e da apoptose, que envolvem vrios sistemas de neurotransmissores, neuropeptdeos e neuro-hormônios.