RESUMO

Potentially toxic cyanobacterial blooms (cyanoHABs) have become a problem in public water supply reservoirs. Temperature rise caused by climate change can increase the frequency and intensity of blooms, which may influence the cyanotoxins concentration in the environment. This study aimed to evaluate the effect of the temperature on the responses of a Neotropical catfish exposed to a neurotoxin-rich cyanobacterial crude extract (Raphidiopsis raciborskii T3). Juveniles of Rhamdia quelen were exposed to four treatments, based on study data: control at 25 °C (C25), control at 30 °C (C30), crude extract equivalent to 105 cells.mL-l of R. raciborskii at 25 °C (CE25) and 30 °C (CE30). After 96 h of exposure, the fish were anesthetized and blood was taken. After euthanasia, the gill, posterior kidney, brain, muscle, liver and gonad were sampled for hematological, biochemical, genotoxic and histopathological biomarker analysis. Liver was sampled for proteomic analysis for identification of proteins related to energy production. Water samples were collected at the beginning and the end of the experiment for neurotoxins quantification. Different parameters in both males and females were altered at CE25, evidencing the effects of neurotoxins in freshwater fish. At CE30, a water warming scenario, more effects were observed in females than at 25 °C, such as activation of saxitoxin metabolism pathway and genotoxicity. More damage to macromolecules was observed in females at the higher temperature, demonstrating that the increase in temperature can aggravate the toxicity of neurotoxins produced by R. raciborskii T3.

Assuntos

RESUMO

Phytoremediation has been a potential solution for the removal of pharmaceuticals from water. Here, we evaluated the toxicological safety of ciprofloxacin-contaminated water treated by 96 h with Salvinia molesta. The Neotropical catfish Rhamdia quelen was used as a model, and the potential of the phytoremediation technique for mitigating the drug accumulation in the fishes was also studied. Fish exposed to Cipro (1 and 10 µg·L-1) in untreated water showed toxic responses (alteration of hematological, genotoxicity, biochemical, and histopathological biomarkers) and accumulated Cipro in their muscles at concentrations high for human consumption (target hazardous quotient > 1). Fish exposed to water treated with S. molesta showed no toxic effect and no accumulation of Cipro in their tissues. This must be related to the fact that S. molesta removed up to 97% of Cipro from the water. The decrease in Cipro concentrations after water treatment with S. molesta not only prevented the toxic effects of Cipro on R. quelen fish but also prevented the antimicrobial accumulation in fish flesh, favouring safe consumption by humans. For the very first time, we showed the potential of phytoremediation as an efficiently nature-based solution to prevent environmental toxicological effects of antimicrobials to nontarget organisms such as fish and humans. The use of S. molesta for Cipro-removal from water is a green technology to be considered in the combat against antimicrobial resistance.

Assuntos

RESUMO

Metals are one of the contaminants released from the increase of anthropic activities. They can be classified as endocrine disruptors once they can affect the reproductive parameters of different organisms. The aim of the study was to evaluate the potential effects of cadmium on regulatory reproduction axis (Hypothalamic-Pituitary-Gonadal-Liver, the HPGL axis) in females of Rhamdia quelen exposed to nominal concentrations of 0.1; 1; 10 and 100 µg.L-1 of cadmium. After 15 days, tissues were collected for hormonal quantification, brain aromatase (cyp19a1b), hepatic vitellogenin (vtg) gene expression, and biomarkers analysis. Cadmium was quantified in water, gonad and liver samples. The plasma levels of estradiol, testosterone and gonad and hepatosomatic indexes did not changed after Cd exposure. The cyp19a1b was not different among the groups. Cadmium was detected at higher concentrations in the liver compared to the gonads. No genotoxicity was observed, only erythrocytes nuclear alterations. Metallothionein was reduced at 10 µg.L-1 in the liver and 10 and 100 µg.L-1 in the gonad. Hepatic superoxide dismutase activity increased and this can lead to a hydrogen peroxide increase, one of reactive oxygen species. This increase without a compensation of other enzymes of the antioxidant system can lead to lipoperoxidation, as occurred at 100 µg.L-1. Hepatic vitellogenin gene expression increased as well as the injury index at 0,1 and 100 µg.L-1. The tested cadmium concentrations have been found in the freshwater ecosystems and can affect the female reproductive regulation axis HPGL of the Neotropical species R. quelen.

Assuntos

RESUMO

Toxic metals and silver nanoparticles (AgNPs) are of great importance as pollutants and their frequent use increases the risk of exposure to biota, but few studies have described co-toxic effects in aquatic organisms. In fish, the method using early stages of development are interesting parameters to validate ecotoxicological studies, and more recently, the use of mathematical models has substantially increased the efficiency of the method. Post hatching stages of native catfish Rhamdia quelen were exposed to single or combined mixtures of toxic metals (Mn, Pb, Hg or AgNPs) in order to study its effects. Fertilized eggs were exposed for 24, 48, 72, and 96 h, where hatching and survival rates, malformation frequency, and neuromast structure damages were evaluated. The results showed alterations in hatching rate after single and combined exposure to metals, but mixtures showed effects more severe comparatively with the single exposures. A similar result including a time-dependent effect was observed in survival rates and incidence of deformities. Overall, embryos and larvae were sensitive to toxic metals exposure while the mathematical modeling suggested a population reduction size including risk of local extinction.

Assuntos

RESUMO

Rhamdia quelen, a Neotropical fish with hybridization between highly divergent mitochondrial DNA (mtDNA) lineages, represents an interesting evolutionary model. Previous studies suggested that there might be demographic differences between coastal lagoons and riverine environments, as well as divergent populations that could be reproductively isolated. Here, we investigated the genetic diversity pattern of this taxon in the Southern Neotropical Basin system that includes the La Plata Basin, Patos-Merin lagoon basin and the coastal lagoons draining to the SW Atlantic Ocean, through a population genomics approach using 2b-RAD-sequencing-derived single nucleotide polymorphisms (SNPs). The genomic scan identified selection footprints associated with divergence and suggested local adaptation environmental drivers. Two major genomic clusters latitudinally distributed in the Northern and Southern basins were identified, along with consistent signatures of divergent selection between them. Population structure based on the whole set of loci and on the presumptive neutral vs. adaptive loci showed deep genomic divergence between the two major clusters. Annotation of the most consistent SNPs under divergent selection revealed some interesting candidate genes for further functional studies. Moreover, signals of adaptation to a coastal lagoon environment mediated by purifying selection were found. These new insights provide a better understanding of the complex evolutionary history of R. quelen in the southernmost basin of the Neotropical region.

Assuntos

RESUMO

ABSTRACT: The aim of the present study was to evaluate the zootechnical performance, intestinal mucosa, and reaction to infestation by the parasite Ichthyophthirius multifiliis in jundiá Rhamdia quelen larvae supplemented with Mentha piperita essential oil or sodium butyrate in their diets. Five diets were used over 30 days: diet free of additive inclusion, 0% (control); inclusion of 1% or 2% of M. piperita essential oil: EO1% and EO2%, respectively; and inclusion of 0.25% or 0.50% of sodium butyrate: SB0.25% and SB0.50%, respectively. The different diets were not able to inhibit I. multifiliis infestation. Supplementation with SB0.50% in their diets presented better performance in all zootechnical parameters analyzed, including a 54% increase in final weight and 70% in survival, and increased (P<0.05) both the villi width and the amount of goblet cells present in the intestinal mucosa by approximately 50%. In view of these results, dietary supplementation of R. quelen larvae with 0.50% sodium butyrate for 30 days is recommended.

RESUMO: O objetivo do presente estudo foi avaliar o desempenho zootécnico, a mucosa intestinal, a resistência ao estresse e a reação à infestação pelo parasita Ichthyophthirius multifiliis em larvas de jundiá Rhamdia quelen suplementadas com óleo essencial de Mentha piperita ou butirato de sódio em suas dietas. Foram utilizadas cinco dietas por 30 dias: dieta livre de inclusão de aditivos, 0% (controle); inclusão de 1% ou 2% de óleo essencial de M. piperita, EO1% e EO2%, respectivamente; e inclusão de 0,25% ou 0,50% de butirato de sódio, SB0.25% e SB0.50%, respectivamente. As diferentes dietas não foram capazes de inibir a infestação por I. multifiliis. A suplementação com SB0.50% em suas dietas apresentou melhor desempenho em todos os parâmetros zootécnicos analisados, incluindo um aumento do peso final em 54% e a sobrevivência em 70%, e aumentou ​​(P<0,05) a largura das vilosidades e a quantidade de células caliciformes presentes na mucosa intestinal em aproximadamente 50%. Em vista desses resultados, recomenda-se a suplementação dietética de larvas de R. quelen com butirato de sódio a 0,50% por 30 dias.

RESUMO

The aim of the present study was to evaluate the zootechnical performance, intestinal mucosa, and reaction to infestation by the parasite Ichthyophthirius multifiliis in jundiá Rhamdia quelen larvae supplemented with Mentha piperita essential oil or sodium butyrate in their diets. Five diets were used over 30 days: diet free of additive inclusion, 0% (control); inclusion of 1% or 2% of M. piperita essential oil: EO1% and EO2%, respectively; and inclusion of 0.25% or 0.50% of sodium butyrate: SB0.25% and SB0.50%, respectively. The different diets were not able to inhibit I. multifiliis infestation. Supplementation with SB0.50% in their diets presented better performance in all zootechnical parameters analyzed, including a 54% increase in final weight and 70% in survival, and increased (P 0.05) both the villi width and the amount of goblet cells present in the intestinal mucosa by approximately 50%. In view of these results, dietary supplementation of R. quelen larvae with 0.50% sodium butyrate for 30 days is recommended.(AU)

O objetivo do presente estudo foi avaliar o desempenho zootécnico, a mucosa intestinal, a resistência ao estresse e a reação à infestação pelo parasita Ichthyophthirius multifiliis em larvas de jundiá Rhamdia quelen suplementadas com óleo essencial de Mentha piperita ou butirato de sódio em suas dietas. Foram utilizadas cinco dietas por 30 dias: dieta livre de inclusão de aditivos, 0% (controle); inclusão de 1% ou 2% de óleo essencial de M. piperita, EO1% e EO2%, respectivamente; e inclusão de 0,25% ou 0,50% de butirato de sódio, SB0.25% e SB0.50%, respectivamente. As diferentes dietas não foram capazes de inibir a infestação por I. multifiliis. A suplementação com SB0.50% em suas dietas apresentou melhor desempenho em todos os parâmetros zootécnicos analisados, incluindo um aumento do peso final em 54% e a sobrevivência em 70%, e aumentou (P 0,05) a largura das vilosidades e a quantidade de células caliciformes presentes na mucosa intestinal em aproximadamente 50%. Em vista desses resultados, recomenda-se a suplementação dietética de larvas de R. quelen com butirato de sódio a 0,50% por 30 dias.(AU)

Assuntos

RESUMO

Abstract Background: The cost of feed in fish farming can exceed 70% of the total costs. Thus, the feed industry have sought to formulate balanced diets including low-cost by-products. Objective: To evaluate sunflower meal as a partial substitute (0, 10, and 20%) for soybean meal, with or without phytase supplementation (1,500 FTU/kg) in isoproteic (27% crude protein (CP)) and isoenergetic diets (3,400 kcal/ED/kg of feed) for silver catfish (Rhamdia quelen) juveniles. Methods: A total of 360 fish (weight: 15.77 ± 0.56 g) were randomly distributed in 24 tanks in a completely randomized design following a factorial scheme (3x2) with 4 replicates. The fish were evaluated on the following variables after 90 days: productive performance, hematological variables, histology of intestinal tissue, bromatological composition of carcass, and composition of bone mineral matter. Results: 20% dietary inclusion of sunflower meal improved weight gain and protein efficiency. No difference was observed in the other treatments and no interactions were observed between the other factors. Conclusion: 20% sunflower meal can be included in the feed of silver catfish as a substitute for soybean meal. Phytase inclusion (1,500 FTU/kg) did not improve the nutritional value of the treatments.

Resumen Antecedentes: El costo de la alimentación en piscicultura pueden superar el 70% del costo total. Las industrias de alimentos para peces han intentado formular dietas balanceadas con subproductos de menor valor en el mercado para minimizar costos. Objetivo: Evaluar la harina de girasol como sucedáneo parcial (0, 10 y 20%) de la torta de soya, suplementada o no con fitasa (1.500 FTU/kg) en dietas isoprotéicas (27% de PB) e isoenergéticas 3400 kcal / ED / kg de ración) para bagre (barbudo, Col.; Rhamdia quelen). Métodos: Los peces, 360 juveniles (15,77 ± 0,56 g), se distribuyeron aleatoriamente en 24 unidades experimentales, en un diseño completamente al azar, en esquema factorial (3x2) y 4 repeticiones. A los 90 días se evaluó: desempeño productivo, variables hematológicas, histología de tejido intestinal y composición bromatológica de la carcasa y de la materia mineral de los huesos. Resultados: La inclusion de 20% de harina de girasol mejoró la ganancia de peso de los peces y la tasa de eficiencia proteica de la ración, sin diferencia para las otras evaluaciones ni interacción entre los demás factores evaluados. Conclusión: La harina de girasol se puede utilizar en un 20% de la ración del bagre (barbudo, Col.) como sucedáneo a la harina de soja. La inclusión de fitasa (1.500 FTU/kg) no mejoró el valor nutritivo de estas raciones.

Resumo Antecedentes: Os custos relativos a alimentação na piscicultura pode ultrapassar 70% do custo final, neste sentido, as indústrias de rações têm procurado formular dietas balanceadas com subprodutos de menor valor de mercado para minimizar estes custos. Objetivo: Esse estudo objetivou avaliar o farelo de girassol como sucedâneo parcial (0, 10 e 20%) do farelo de soja, suplementado ou não com a fitase (1.500 FTU/kg), em dietas isoprotéicas (27% de PB) e isoenergéticas (3400 kcal/ED/kg de ração) para o jundiá (Rhamdia quelen). Métodos: Os peixes, 360 juvenis (15,77 ± 0,56 g) foram distribuídos aleatoriamente em 24 unidades experimentais, num delineamento inteiramente casualizado, em esquema fatorial (3x2) e 4 repetições. Após 90 dias foram avaliados: desempenho produtivo, variáveis hematológicas, histologia de tecido intestinal, composição bromatológica da carcaça e de matéria mineral dos ossos. Resultados: O emprego de 20% de farelo de girassol melhorou o ganho de peso dos peixes e a taxa de eficiência protéica da ração, sem diferença nas outras avaliações, ou para a interação entre os demais fatores avaliados. Conclusão: Pode-se concluir que o farelo de girassol pode ser utilizado em 20% da ração do jundiá, como sucedâneo ao farelo de soja e, que a inclusão de fitase (1,500 FTU/kg) não melhorou o valor nutritivo destas rações.

RESUMO

Aeromonosis is a fish disease that leads to haemorrhagic septicaemia and high mortality. The detection of early behavioural changes associated to this disease could be helpful in anticipating the initiation of treatment, increasing the probability of success. The influence of this disease on the hypothalamic-pituitary-interrenal (HPI) axis and on the brain expression of heat shock proteins (HSP) is little known. Therefore, the aim of this study was to evaluate the effect of Aeromonas hydrophila infection on individual behaviour and brain expression of genes related to stress (slc6a2, hsp90, hspa12a, hsd20b, hsd11b2, crh) in silver catfish (Rhamdia quelen). Thirty fish were divided into healthy and infected groups. The fish of the infected group were inoculated intramuscularly with 50 µL of bacterial suspension (6.4 × 108 CFU/mL), while control animals received 50 µL of saline. On day five post-infection, animals were submitted to the novel tank test, euthanized, and the brain was collected for molecular analysis. Infected fish swam more in the unknown aquarium and presented an increase in brain expression of genes related to HSP (hspa12a) and the route of cortisol synthesis (crh) when compared to uninfected fish. Therefore, this disease causes hyperlocomotion related to stress.

Assuntos

RESUMO

In fish farming, the use of alternative ingredients has been studied, so that alternative sources can be used to minimize feed costs. This study evaluated the incorporation of grape, orange, guava, and fig residues in diets for silver catfish and its effects on growth, digestive enzymes and body composition. A total of 180 fish (initial mean weight = 22.93±0.75 g) were reared in a recirculation aquaculture system. There was no difference (P>0.05) in the parameters of growth, dry matter, mineral matter, plasma protein, cholesterol, triglycerides, lipase, and trypsin of fish. Glucose levels were higher in fish fed diets containing fig, orange, and grape residue (P<0.05). Lipase activity was higher in fish fed orange residue, compared to guava (P<0.05). Diets containing guava and fig provided more body protein in silver catfish. The fish fed with diet containing orange residue had a higher content of body lipids. It can be concluded that the tested fruit residues can be used in silver catfish feeding.(AU)

Na piscicultura, o uso de ingredientes alternativos vem sendo estudado, de modo que seja possível utilizar fontes alternativas para minimizar custos com a alimentação. Neste estudo, foi avaliada a incorporação de resíduos de uva, laranja, goiaba e figo em rações para jundiá e seus efeitos no crescimento, em enzimas digestivas e na composição corporal. Foram utilizados 180 peixes (peso médio inicial = 22,93±0,75 g), criados em sistema de recirculação. Não houve diferença (P>0,05) nos parâmetros de crescimento, matéria seca, matéria mineral, proteína plasmática, colesterol, triglicerídeos, lipase e tripsina dos peixes. Os níveis de glicose foram maiores nos peixes alimentados com dietas contendo figo, laranja e uva (P<0,05). A atividade de lipase foi maior nos peixes alimentados com resíduo de laranja, comparado com o de goiaba (P<0,05). As dietas contendo goiaba e figo proporcionaram mais proteína corporal nos jundiás. Os jundiás alimentados com dieta contendo resíduo de laranja apresentaram maior teor de lipídeos corporal. Conclui-se que os resíduos de frutas testados podem ser usados na alimentação do jundiá.(AU)

Assuntos