O cachara, Pseudoplatystoma fasciatum, é um siluriforme carnívoro da América do Sul. Apesar da importância da espécie para pesca e piscicultura, não há uma dieta específica e nem as exigências nutricionais determinadas. O objetivo deste projeto foi determinar a digestibilidade aparente da energia e proteína de diferentes alimentos de origem animal e vegetal e, com os valores da digestibilidade dos ingredientes, elaborar rações para determinar as exigências em proteína, energia e relação energia:proteína para o cachara. Para o ensaio de digestibilidade, 105 juvenis de cachara (82,35 ± 17,7 g; 23,04 ± 1,6 cm) foram distribuídos em 21 gaiolas cilíndricas plásticas de 80 L e alimentados até a saciedade aparente em duas refeições diárias (20h00min e 22h00min) com dietas teste obtidas a partir da adição de 0,1% de óxido crômico III e substituição de 30% de uma ração referência (RR; 46% proteína bruta; 4600 kcal energia bruta) pelos seguintes ingredientes: farinha de peixe, farinha de carne e ossos, farinha de vísceras, farinha de penas, farinha de sangue, farelo de soja, farelo de trigo, milho moído e glutenose de milho. Após a última refeição, os peixes eram transferidos para os aquários cônicos (200 L) acoplados a recipientes refrigerados para a coleta de fezes por sedimentação. Os melhores coeficientes de digestibilidade aparente da proteína (99,36%) e energia (86,25%) foram registrados para a farinha de vísceras de aves e farinha de carne e ossos, respectivamente, consideradas fontes alternativas adequadas para substituir com eficiência a farinha de peixe, ingrediente padrão para formulação de rações para o cachara. Em um segundo experimento foram determinados os melhores níveis de energia e proteína nas dietas para juvenis de cachara (53,6 ± 1,30 g e 20,1 ± 1,06 cm), distribuídos aleatoriamente em 75 gaiolas (210 L) alojadas em tanques de alvenaria (12 m3) com constante renovação de água e aeração e alimentados duas vezes ao dia (06h30m e 18h30m) por 60 dias com 25 dietas formuladas para conter cinco níveis de proteína digestível (32, 36, 40, 44 e 48%) e cinco níveis de energia digestível (3600, 3725, 3850, 3975 e 4100 kcal kg-1), em um delineamento inteiramente casualizado com um esquema fatorial 5 x 5 (n = 3). A energia e proteína dietética afetaram o ganho de peso, taxa de crescimento específico, consumo de ração, conversão alimentar, taxa de eficiência proteica, retenção de proteína, índice hepatossomático, índice lipossomático, índice viscerossomático, proteínas totais séricas e triglicerídeos no soro. A energia dietética afetou a retenção de energia pelo cachara, mas a retenção de fósforo e a composição do peixe inteiro não foram influenciadas pela dieta. Com os resultados é possível concluir que os níveis de 3600 kcal kg-1 de ED, 39% de PD e a relação ED:PD de 9,23 kcal g-1 garantem ótimo desempenho e retenção de nutrientes pelo cachara. / Striped surubim, Pseudoplatystoma fasciatum is a South American carnivore catfish of economic importance for fisheries and fish culture alike. However, in spite of its importance for the Brazilian aquaculture, there is no specific diet neither nutritional requirement determined for this specie. The aim of this study was thus determination of apparent digestibility coefficients of selected feedstuff and their use in diets for determination of protein, energy and energy:protein requirements of juvenile striped surubim. Juvenile striped surubim (82.35 ± 17.7 g and 23.04 ± 1.6 cm) were distributed in 21 cylindrical, plastic cages (80 L) and conditioned to a two daily meals (20h00m and 22h00m) feeding regimen on a practical, reference diet (RD) (460.0 g kg-1 crude protein (CP); 19.23 kJ g-1 gross energy (GE)). Test diets were obtained by adding 0.1% chromium III oxide and substituting 30% of one the following feedstuffs in RD: fish meal, meat and bone meal, poultry by-product meal, feather meal, blood meal, soybean meal, wheat bran, corn and corn gluten meal. After the last daily meal, fish were transferred to cylindrical-conical bottomed aquaria (200 L), coupled to refrigerated plastic bottles for feces collection by sedimentation. Best apparent digestibility coefficients of protein (99.36%) and energy (86.25%) were recorded for poultry by-product meal and meat and bone meal, respectively, so deemed ideal surrogate feedstuffs to fish meal, the standard protein source for the formulation and processing of diets for carnivore fish. For determination of best energy and protein level, juvenile striped surubim (53.6 ± 1.30 g and 20.1 ± 1.06 cm) were randomly distributed in 75 cages (210 L), housed in 12 m3 concrete tanks under constant water flow and aeration, and hand fed two daily meals (06h30m and 18h30m) for 60 days. Twenty-five diets were formulated to contain five levels of digestible protein (DP) (32, 36, 40, 44 and 48%) and five levels of digestible energy (DE) (3600, 3725, 3850, 3975 and 4100 kcal kg-1) in a randomized design, 5 x 5 factorial scheme (n = 3). The dietary energy and protein affected the weight gain, specific growth rate, feed intake, feed conversion rate, protein retention, hepatosomatic, liposomatic and viscerosomatic index, serum total protein and triglycerides, but energy retention was affected only by dietary energy. Phosphorus retention and whole body composition were not affected by diets. Estimated dietary requirement for the best performance and best nutrient retention of striped surubim were 3600 kcal kg-1 of DE, 39% of DP and a 9.23 kcal g-1 of DE:DP ratio.

The aim of this study was to determine the mean lethal concentration (96 h) for waterborne copper (LC50), as well as the effect of the exposure to copper on growth, metabolic parameters (glycogen, glucose, lactate, and protein) in some tissues, activity of acetylcholinesterase (AChE) (brain and muscle), amylase and maltase (intestine) in silver catfish (Rhamdia quelen). The LC50 for copper was 0.4 mg/L. On growth experiments fish were exposed to 10 and 20% LC50, i.e., 0.04 and 0.08 mg/L respectively. Exposure to copper did not change growth parameters (weight, length and biomass). In the liver, lactate levels increased in juveniles exposed to 0.04 mg/L and decreased in those maintained at 0.08 mg/L, while protein levels decreased in those exposed to both concentrations compared to unexposed specimens. Glycogen levels in the muscle were lower in fish exposed to both concentrations, glucose and lactate were higher in those exposed to 0.04 mg/L and decreased in juveniles maintained at 0.08 mg/L, while protein was higher in those exposed to 0.08 mg/L. Glucose and lactate plasma levels were higher in juveniles exposed to 0.04 mg/L, but protein levels were lower in those maintained at both copper concentrations. Amylase activity was lower in juveniles exposed to both concentrations, but maltase was higher in those exposed to 0.04 mg/L than control group. Brain AChE activity was lower in fish exposed to both concentrations while muscle AChE activity was not affected after 45 days of exposure. It can be concluded that copper can change several metabolic parameters and enzymes of toxicological and feeding interest even at sublethal concentrations. / O objetivo deste estudo foi verificar a concentração letal média em 96 h (CL50) para o cobre, bem como o efeito da exposição ao cobre sobre o crescimento, parâmetros metabólicos (glicogênio, glicose, lactato e proteína) em alguns tecidos (fígado, músculo e cérebro) e a atividade da acetilcolinesterase (AChE) (cérebro e músculo), amilase e maltase (intestino) em jundiás (Rhamdia quelen.). A CL50 para o cobre foi 0,4 mg/L. Nos experimentos de crescimento os peixes foram expostos durante 45 dias a 10 e 20% da CL50, ou seja, 0,04 e 0,08 mg/L respectivamente. A adição de cobre não alterou os parâmetros de crescimento avaliados (peso, comprimento e biomassa). No fígado, os níveis de lactato aumentaram nos exemplares expostos a 0,04 mg/L e diminuíram nos mantidos em 0,08 mg/L, enquanto que os níveis de proteína diminuíram em ambas as concentrações em relação ao grupo controle. No músculo houve redução na atividade do glicogênio nos exemplares mantidos nas duas concentrações testadas, a glicose e o lactato aumentaram nos expostos a 0,04 mg/L e diminuíram nos expostos a 0,08 mg/L, e a proteína aumentou nos mantidos em 0,08 mg/L. Os níveis de glicose e lactato no plasma foram maiores nos exemplares mantidos em 0,04 mg/L e diminuíram os níveis de proteína nos expostos a ambas as concentrações de cobre. A atividade da amilase foi menor nos juvenis expostos a ambas as concentrações, enquanto a da maltase foi maior em 0,04 mg/L quando comparada ao grupo controle. A atividade da AChE cerebral foi menor nos exemplares expostos a ambas concentrações, enquanto que a AChE muscular não sofreu alterações após os 45 dias de exposição. Conclui-se que o cobre mesmo em concentrações subletais pode alterar diversos parâmetros metabólicos e enzimas de interesse toxicológico e alimentar.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The use of herbicides has increased in agriculture and pisciculture for controlling plant weeds, but the indiscriminate use can cause contamination to organisms such as fish. Therefore, the aim of this study was to evaluate the effects to commercial formulations of glyphosate and clomazone affects oxidative stress parameters in silver catfish (Rhamdia quelen). Silver catfish were exposed to: 0 (control), 0.45 or 0.95 mg/L of glyphosate (480 g/L) and 0 (control), 0.45 or 0.91 mg/L of clomazone for eight days and after transferred to water without the herbicide to equal period. The parameters analyzed were lipid peroxidation estimated by a TBARS levels (thiobarbituric acid reactive species), protein carbonyl and the antioxidants activity such as catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), ascorbic acid and non-protein thiols. The results showed that fish exposed to glyphosate presented increased of TBARS levels in liver and muscle at the higher concentration, whereas in brain this increase was observed in the two concentrations used. When exposed to clomazone caused an enhanced in TBARS levels in muscle at both concentrations, in liver in the higher concentration, while in the brain showed no alterations. The protein carbonyl increased in the liver of silver catfish after exposure to both concentrations of two herbicides. In silver catfish exposed to glyphosate activities of CAT and SOD did not change, while GST reduced at the concentrations of 0.45 and 0.95 mg/L. The ascorbic acid levels in the liver did not change after exposure to the herbicide and the non-protein thiols levels reduced the concentration of 0.95 mg/L. In fish exposed to clomazone the CAT activity did not change and the SOD increased in the liver at the concentration 0.91 mg/L. The GST activity, ascorbic acid and non-protein thiols increased in the liver at the concentrations of 0.45 and 0.91 mg/L. In the recovery period most of the altered parameters recovered to both herbicides, after eight days in water without herbicide, except for the GST enzyme and ascorbic acid levels after exposure to clomazone. The results obtained in this study may suggest that in a short period of time the herbicides glyphosate and clomazone are able of inducing oxidative stress in the silver catfish, being these changes transient and reversible. / O uso de herbicidas tem aumentado na agricultura e na piscicultura para o controle de plantas daninhas, porém o uso indiscriminado pode causar contaminação a organismos, como os peixes. Sendo assim, o objetivo deste estudo foi avaliar o efeito das formulações comerciais de glifosato e clomazone sobre parâmetros de estresse oxidativo em jundiás (Rhamdia quelen). Jundiás foram expostos à: 0 (controle), 0,45 e 0,95 mg/L de glifosato (480 g/L) e 0 (controle), 0,45 e 0,91 mg/L de clomazone (500 g/L) por oito dias e após, transferidos para água sem o herbicida por igual período. Os parâmetros analisados foram peroxidação lipídica através dos níveis de TBARS (substâncias reativas ao ácido tiobarbitúrico), carbonilação de proteínas e a atividade de antioxidantes como a catalase (CAT), superóxido dismutase (SOD), glutationa S-transferase (GST), ácido ascórbico e tióis não protéicos. Os resultados mostraram que os peixes expostos ao glifosato apresentaram aumento nos níveis de TBARS em fígado e músculo na maior concentração, enquanto que no cérebro este aumento foi observado nas duas concentrações usadas. Quando expostos ao clomazone ocorreu aumento nos níveis de TBARS em músculo em ambas as concentrações, em fígado na maior concentração, enquanto que no cérebro não foram observadas alterações. A proteína carbonil aumentou no fígado dos jundiás após a exposição a ambas as concentrações dos dois herbicidas. Nos jundiás expostos ao glifosato, as atividades das enzimas CAT e SOD não alteraram, enquanto que a GST diminuiu nas concentrações de 0,45 e 0,95 mg/L. Os níveis de ácido ascórbico no fígado não alteraram após a exposição ao herbicida e os níveis de tióis não protéicos reduziram na concentração de 0,95 mg/L. Nos peixes expostos ao clomazone, a atividade da CAT não alterou e a SOD aumentou no fígado na concentração de 0,91 mg/L. A atividade da GST, ácido ascórbico e tióis não protéicos aumentaram no fígado nas concentrações de 0,45 e 0,91 mg/L. No período de recuperação a maioria dos parâmetros alterados foi recuperada para ambos os herbicidas, após oito dias em água sem o herbicida, com exceção da enzima GST e dos níveis de ácido ascórbico após exposição ao clomazone. Com os resultados obtidos neste trabalho, pode-se sugerir que em curto período de tempo os herbicidas glifosato e clomazone são capazes de induzir estresse oxidativo nos jundiás, sendo essas alterações transitórias e reversíveis.

Calcified teeth comprise the hardest vertebrate tissues (enamel and dentine) and they undoubtedly represent a key evolutionary advantage for their users. Nevertheless, teeth have been lost many times and they were often replaced by keratinised structures, such as rhamphoteca of birds or of turtle beaks, or labial tooth structures and scratching laminae of many aquatic vertebrates. This thesis is intended to analyse levels of similarities among keratinised teeth and structures of three phylogenetically distinct lineages of amniotes and to compare them to morphogenesis of true teeth. Detailed developmental and structural characteristics of oral apparatus possessing keratinous teeth of lampreys, Loricarid cathfishes and frog tadpoles were identified and distinguished. Keratinous structures of cathfishes include only horny projections from single cell surface (unculi), whereas in frog tadpoles both horny jaw sheet and unicellular labial teeth composed by cell columns were found; the lamprey oral apparatus consists of multicellular teeth and laminae instead. Disparate phenotypes of these keratinous structures can, however, developmentally derive from a general process of keratinization: morphological disparities arise by distinct gradual accretion of keratinous layers and collumns during development. My...

D.Phil. / The endocrine system regulates important physiological processes in an organism. Numerous natural and synthetic chemicals are released into the environment and can disrupt the normal functioning of the endocrine system, influencing physiological processes even at relatively low concentrations. These chemicals are known as endocrine disrupting chemicals (EDCs). These compounds are highly persistent in nature due to a resistance to biodegradation, and because of their hydrophobicity. EDCs bio-accumulate especially in the fatty tissue of aquatic and terrestrial organisms. Developmental and reproductive disorders are potentially harmful effects of exposure. EDC sources include agricultural and urban runoff, and industrial effluent discharges that eventually pass through sewage- and wastewater treatment plants. These chemicals degrade at various rates and to varying extents during treatment processes, forming many new chemicals. Methods to predict the occurrence of endocrine disruption include the occurrence of intersex, and changes in spermatogenesis and secondary sexual characteristics (SSCs) of supposedly exposed organisms. The urogenital papilla (UGP) is a SSC whose development and morphology is hormonally controlled and may be influenced when exposed to EDCs. The sharptooth catfish (Ciarias gariepinus) is often used in environmental toxicity studies. Sex is determined by the external dimorphic UGP found only in males. Intersex has been observed in this species in South African freshwater systems. A field study was carried out in the Rietvlei (RVD) and Marais (MD) dams in the Rietvlei Nature Reserve (RNR). MD acts as a sedimentation dam before water enters RVD, and is theoretically more polluted. The RNR system receives effluent from various domestic and industrial sources including agriculture, industries, informal settlements and municipal sewage treatment plants. Four sampling surveys, two low and two high flow, were carried out over a period of two years. Supposedly male catfish (n=97) were collected and identified as male or possible intersex based on the UGP. Water and sediment was collected for target EDC and endocrine disrupting metal (EDM) analyses. Fish length and mass, and UGP length and width were measured. Laparotomy was performed and gonads were inspected macroscopically for alterations. A section of the gonad and the entire UGP was removed and processed according to standard techniques for histological analysis. The gonadosomatic- (GSI), hepatosomatic- (HSI) and UGP length (UGPLI) indices were calculated. Fish fat was removed and analysed for target EDCs.

Dos peixes peçonhentos encontrados no Brasil os bagres destacam-se pelo número de acidentes provocados. O objetivo deste trabalho foi caracterizar os componentes tóxicos presentes na peçonha e no muco. Obtivemos uma média protéica de 3,1 mg/mL (peçonha) e 1,4 mg/mL (muco). O perfil eletroforético da peçonha e do muco possui poucas bandas protéicas. O fracionamento isolou 11 frações para peçonha e 13 frações para o muco. Com relação às atividades biológicas avaliadas, as frações peptídicas induziram danos teciduais ao passo que as frações protéicas induziram processo inflamatório. Isolamos duas frações com atividade antimicrobiana para cada secreção. Isolamos uma toxina de 65,1 kDa que apresenta homologia com Wap65 e análise por microscopia intravital revelou que esta proteína causa aumento dos leucócitos rolantes assim como a presença de leucócitos aderidos ao endotélio. Nossos resultados indicam uma diferença entre os componentes protéicos e peptídicos do muco e da peçonha. Finalmente, conseguimos isolar e caracterizar a proteína Wap65 da peçonha deste peixe. / Of the venomous fish found in Brazil, catfish noteworthy for the number of accidents they cause. The objective of this study was to characterize the toxic compounds present in the venom and mucus. We obtained an average protein intake of 3,1 mg / mL (venom) and 1,4 mg / mL (mucus). The electrophoretic profile of venom and mucus has a few protein bands. Fractionation isolated 11 fractions to the venom and 13 fractions to the mucus. With respect to biological activities evaluated, the peptide fractions induced tissue damage while the protein fractions induced inflammation. We isolated two fractions with antimicrobial activity for each sample. We isolated a toxin of 65,1 kDa which shows homology with Wap65 and intravital microscopy analysis revealed that this protein causes an increase in leukocyte rolling as well as the presence of leukocytes adhered to the endothelium. Our results indicate a difference between the peptide and protein components of mucus and venom. Finally, we isolate and characterize the protein Wap65 from the venom of this fish.

Catfish fillets that were enhanced with salt and various phosphate treatments through vacuum tumbling or multi-needle injection were evaluated for yield, protein exudate (only tumbling), surface color, pH, cooking loss, tenderness, purge loss and shelf-life. An agglomerated sodium phosphate blend (AGSP) was the optimum treatment for both vacuum tumbling and multi-needle injection and was further utilized in conjunction with potassium lactate (PL) and/or potassium acetate (PA) through vacuum tumbling to determine their effect on the quality, shelf-life and sensory characteristics of enhanced catfish fillets. In addition, the combination of AGSP and PA+PL that maximized shelf-life was further utilized in conjunction with liquid or wood smoking to evaluate the quality and inhibition of L. monocytogenes growth in ready-to-eat (RTE) smoked catfish fillets. All phosphate treatments increased (P<0.05) tenderness, but AGSP that contained mono-, tri-, and polyphosphates increased (P<0.05) pH and yield and decreased (P<0.05) yellowness in both tumbling and injection systems when compared to the control treatment. In addition, AGSP decreased (P<0.05) protein exudate when fillets were tumbled and increased (P<0.05) solution pick-up when injected. Psychrotrophic plate counts (PPC) for all phosphate treatments were similar to the control at each storage time and reached 7 log CFU/g by day 7 of storage; however, when AGSP was used in conjunction with PA+PL, PPC and sensory spoilage scores of raw catfish fillets were lower (P<0.05) than the control at each storage time. Marinating with a combination of 0.25% PA and 0.58% PL increased shelf-life (P<0.05) to between 10 and 14 days when compared to the control which had a shelf-life between 7 and 10 days. In addition, consumers preferred (P<0.05) fried catfish fillets that were treated with AGSP with and without PA+PL when compared to non-marinated controls with respect to appearance, flavor and overall acceptability. In conclusion, AGSP optimized yield and improved the quality of refrigerated catfish fillets, and extended shelf-life three days over other treatments when combined with PA+PL. This combined treatment also enhanced sensory properties of fried catfish fillets and had a synergistic effect with wood smoke constituents that inhibited the growth of L. monocytogenes on RTE smoked catfish fillets.

Microcystin-LR is a hepatotoxin produced by cyanobacteria. Aeromonas hydrophila and Edwardsiella piscicida infections are leading causes of losses in market-sized channel catfish (Ictalurus punctatus). These older fish should have natural immunity in place and a predisposing factor is likely a prerequisite for these disease outbreaks. While microcystin-LR rarely causes mortality in warm-water aquaculture, we believe it may be a predisposing factor that leads to bacterial disease outbreaks during the summer months due to its ability to damage the liver. Our study investigated microcystin-LR’s effects on channel catfish susceptibility to these pathogens. We found that a sublethal dose of microcystin-LR induced substantial damage to multiple immune organs. In our challenges with both the toxin and bacteria, we saw a significant increase in mortality of fish. Our findings suggest that microcystin-LR increases channel catfish susceptibility to Aeromonas hydrophila and Edwardsiella piscicida infections.

No description available.

The digenetic trematode, Bolbophorus damnificus, poses a substantial threat to catfish aquaculture, causing significant economic losses. Infestations lead to suppressed feed consumption, secondary bacterial infections and poor production performance. Survey data reveals widespread infestation in the in the southeastern United States. Current control strategies involve the application of a concentrated copper sulfate solution to reduce snail populations which serve as the first intermediate host of the trematode life cycle. This study aimed to improve treatment efficacy by developing a granular copper sulfate application system. A modified Gandy fertilizer applicator, equipped with a programmable control system, demonstrated accurate distribution of copper sulfate crystals along pond margins at various speeds. Granular copper sulfate was effective in killing snails along the pond margins at treatment rates between 1-3 ppm. The innovative system offers a practical, single-pass solution to combat trematode infestations in catfish ponds and minimizes logistical challenges associated with multiple applications.