Oxidative stress responses of juvenile tambaqui Colossoma macropomum after short-term anesthesia with benzocaine and MS-222

ABSTRACT The present study aimed to evaluate the effects of benzocaine and tricaine methanesulfonate on oxidative stress parameters of juvenile tambaqui tissues. Fish (n=80) were anesthetized with benzocaine (100 mg L-1) or tricaine (240 mg L-1) and two control groups were used (non-anesthetized fish and fish exposed to ethanol-only). After anesthetic induction 10 fish/anesthetic were euthanized after 3, 12 and 24 hours post-anesthesia and tissue samplings (gills, liver and brain) were performed. Samples were submitted to analyses of enzyme activity glutathione-S-transferase (GST), cellular lipid peroxidation (TBARS) and total antioxidant capacity (ACAP). ACAP increased in gills of benzocaine treatment after 12 hours. The liver showed a reduction in ACAP of tricaine treatment after 12 hours. Both anesthetic treatments showed an increase of ACAP at 24 hours compared to control group. The activity of the GST enzyme increased in the gills for treatments benzocaine and tricaine after 3 and 12 hours. Liver showed increased GST activity (benzocaine after 24 hours and tricaine after 3 and 24 hours). Lipid damage decreased in gills (both anesthetics) and brain (tricaine) after 24 hours. The results demonstrate that benzocaine and tricaine did not cause oxidative damage in juvenile tambaqui under the experimental conditions herein established.

Acclimation of juvenile Mugil liza Valenciennes, 1836 (Mugiliformes: Mugilidae) to different environmental salinities

Survival and physiological parameters associated with metabolism and osmoregulation were evaluated in juveniles of the Lebranche mullet Mugil liza acclimated to different water salinities (5, 10, 20, 30, and 40‰) for 15 days. Room temperature (25ºC) and photoperiod (12L:12D) were fixed. Fish were fed twice-a-day with commercial diet (28% crude protein) until satiation. After acclimation, whole body oxygen consumption was measured and fish were euthanized and sampled for blood, gills, and liver. Whole body oxygen consumption and plasma osmolality did not change in the range of salinities tested. The isosmotic point was estimated as 412.7 mOsmol kg-1 (13.5‰). Gill Na+,K+-ATPase activity tended to be lower at 20 and 30‰, while liver glycogen content was significantly higher at 20‰ than at 5 and 40‰. These results indicate that juvenile M. lizais able to acclimate for a short-period of time (15 days) to a wide range of salinities (5-40‰). This condition is achieved through adjustments in gill Na+,K+-ATPase activity and carbohydrate metabolism to regulate plasma osmolality and aerobic/energy metabolism. Therefore, our findings support the idea of catching juveniles M. lizain sea water and rear them in estuarine and marine waters.

A sobrevivência e parâmetros fisiológicos associados ao metabolismo e a osmorregulação foram avaliados em juvenis da tainha Mugil lizaaclimatada à diferentes salinidades (5, 10, 20, 30 e 40‰) por 15 dias. Foram fixadas a temperatura (25ºC) e o fotoperíodo (12L:12D) da sala onde os experimentos foram realizados. Os peixes foram alimentados duas vezes ao dia com ração comercial (28% de proteína bruta) até a saciedade. Após aclimatação, foi medido o consumo corporal de oxigênio e os peixes foram eutanasiados e foram coletadas amostras de sangue, brânquias e fígado. O consumo corporal de oxigênio e a osmolalidade plasmática não variaram na faixa de salinidade testada. O ponto isosmótico foi estimado em 412,7 mOsmol kg-1 (13,5‰). A atividade da Na+,K+-ATPase branquial tendeu a ser menor em 20 e 30‰, enquanto o conteúdo de glicogênio hepático foi significativamente maior em 20‰ do que em 5 e 40‰. Estes resultados indicam que o juvenil de M. liza é capaz de se aclimatar a uma ampla faixa de salinidade (5-40‰) por um curto período de tempo (15 dias). Esta condição é atingida através de ajustes na atividade da Na+,K+-ATPase branquial e no metabolismo de carboidratos para regular a osmolalidade plasmática e o metabolismo aeróbico/energético. Portanto, nossos achados suportam a ideia de que é possível capturar juvenis da tainha M. liza em água do mar e cultivá-los em águas estuarinas e marinhas.

Whole-body and muscle amino acid composition of Plata pompano (Trachinotus marginatus) and prediction of dietary essential amino acid requirements / Composición de aminoácidos de la carcasa y del músculo del Pámpano (Trachinotus marginatus) y estimación de las necesidades por aminoácidos esenciales / Composição de aminoácidos da carcaça e do músculo do Pampo prateado (Trachinotus marginatus) e estimativa das necessidades por aminoácidos essenciais

Background: knowing the essential amino acid (EAA) requirement values is fundamental to formulate good quality and cost-effective fish feeds. However, such requirements have been established for few fish species. The estimation of amino acid requirements based on amino acid composition of fish is a fast and reliable alternative. Objective: to determine whole-body and muscle amino acid composition of Plata pompano (Trachinotus marginatus) and estimate its EAA requirements. Methods: EAA requirements were estimated using A/E ratios [(Individual EAA / Total EAA) * 1000]. Results: hystidine, leucine, lysine and phenylalanine were present in higher concentrations in muscle tissue in comparison with the whole-body. On the other hand, arginine, isoleucine, methionine, tryptophan and valine concentration were not different between whole-body and muscle. A/E ratios for Plata pompano determined in the present study are similar to those reported in other fish species, although valine A/E ratios were slightly smaller. Conclusion: until dose-response experiments are conducted to precisely determine EAA requirements, the estimated EAA values using whole-body EAA-as proposed in this study-could be used to formulate diets for Plata pompano.

Antecedentes: conocer los requerimientos de aminoácidos esenciales (EAA) es fundamental para la formulación de raciones rentables y de buena calidad para peces. Sin embargo, dichos requerimientos se han establecido solo para unas pocas especies de peces. La determinación de las necesidades de aminoácidos basada en la composición de aminoácidos de los peces es un método alternativo rápido y viable. Objetivo: determinar la composición de aminoácidos del cuerpo completo y del músculo del Pámpano (Trachinotus marginatus) y estimar sus necesidades de EAA. Métodos: el requerimiento de aminoácidos esenciales se calculó utilizando el índice A/E [(Individual EAA/Total EAA) * 1000]. Resultados: la histidina, leucina, fenilalanina y lisina estaban en una mayor concentración en el músculo que en el cuerpo. Por otro lado, arginina, isoleucina, metionina, triptófano y valina no mostraron ninguna diferencia significativa entre la composición del músculo y el cuerpo. Los valores de A/E para Pámpano determinados en este estudio son similares a los reportados para otras especies de peces, pero no los de valina, que fue levemente menor. Conclusiones: hasta que no sean realizados experimentos de dosis-respuesta para determinar con precisión los requerimientos de EAA, el cálculo de los requerimientos de aminoácidos esenciales a partir de la concentración de aminoácidos del cuerpo -como se propone en este estudio- puede ser utilizado en la formulación de dietas para pámpano.

Antecedentes: estimar as necessidades por aminoácidos essenciais (AAE) é importante para formular dietas de boa qualidade e com bom custo-benefício. No entanto, poucas espécies de peixes possuem suas necessidades por (AAE) estabelecidas. A determinação das necessidades por (AAE) baseada na composição de aminoácidos do peixe é uma alternativa rápida e viável. Objetivo: determinar a composição de aminoácidos da carcaça e do músculo do Pampo prateado (Trachinotus marginatus) e estimar suas necessidades por (AAE). Métodos: as necessidades por AAE foi estimada usando o índice A/E [(AAE individual/AAE total) * 1000]. Resultados: histidina, leucina, lisina e fenilalanina estavam em maior concentração no músculo do que na carcaça. Por outro lado, arginina, isoleucina, metionina, triptofano e valina não apresentaram diferenças significativas entre a composição da carcaça e do músculo. O índice A/E determinado no presente estudo para o Pampo prateado é similar ao reportado para outras espécies de peixe, entretanto o valor do índice A/E para a valina foi ligeiramente menor. Conclusão: até que experimentos dose resposta sejam realizados para determinar com exatidão as necessidades por aminoácidos essenciais, os valores estimados para as necessidades por aminoácidos essenciais usando a composição da carcaça como proposto neste estudo pode ser usada na formulação de dietas para o Pampo prateado.

Micobacteriose por Mycobacterium marinum em "linguado" Paralichthys orbignyanus e em "barber goby" Elacatinus figaro: diagnóstico histopatológico e imuno-histoquímico / Micobacteriosis by Mycobacterium marinum in Brazilian flounder Paralichthys orbignyanus and barber goby Elacatinus figaro: histopathological and imunohistochemical diagnosis

As micobacterioses afetam várias espécies de peixes, tanto comerciais como ornamentais. É uma enfermidade sistêmica com formação de granulomas, conhecida como micobacteriose de peixes. O desenvolvimento da aquicultura tem aumentado o número de casos com essa enfermidade que muitas vezes é de difícil diagnóstico. Neste trabalho apresentamos dois casos de micobacterioses em Paralichthys orbignyanus e Elacatinus figaro provenientes do Laboratório de Piscicultura Estuarina e Marinha da Universidade Federal do Rio Grande (FURG). As micobactérias de peixes possuem menos ácidos graxos que as de mamíferos, por isso foi utilizado o protocolo de coloração de Fite-Faraco, uma vez que o protocolo de coloração clássico de Ziehl Neelsen pode resultar em falsos negativos. Para determinar o tipo de micobactéria foi utilizada a imuno-histoquímica com a qual se pode diagnosticar a presença de Mycobacterium marinum. A enfermidade pode ser transmitida para o homem e com esse trabalho ressalta-se a necessidade de fazer o diagnóstico correto e implantar medidas de proteção para as pessoas que estão em contato com os peixes infectados.

Mycobacteriosis affects various species of fish, including those cultured with commercial purposes. It is a chronic systemic with granuloma forming disease known as fish mycobacteriosis. In the last few years the interest of fish culture has been increasing due to the reduction of the natural fish stocks. However the intensification of fish culture has collaborated to the development of diseases such as mycobacteriosis, causing losses due to the chronic characteristics and difficult diagnosis. This study is to report two cases of mycobacteriosis observed at "Laboratório de Piscicultura Estuarina e Marinha of the Universidade Federal do Rio Grande (FURG)", one for Brazilian flounder Paralichthys orbignyanus and another for barber goby Elacatinus figaro. The Fite-Faraco staining protocol was used. Membranes of mycobacterial cells contain a waxy substance composed of mycolic acids. These are ß-hydroxy carboxylic acids with chain lengths of up to 90 carbon atoms. The property of acid fastness is related to the carbon chain length of the mycolic acid found in any particular species. The fish mycobacterium is much less acid and alcohol fast than the tubercle bacillus and the classic Ziehl-Neelsen Staining Protocol may give false results. The presence of mycobacterial antigen lesions was studied by immunohistological methods using monoclonal antibodies to Mycobacterium marinum. Humans may be infected by these bacteria and develop cutaneous granuloma. In this paper the necessity is stressed for a correct diagnosis of the disease, contributing to the prevention of its establishment in aquatic facilities, and thus, preserving cultured fish as well as human beings from infection.

Identifi cation, tissue distribution and evaluation of brain neuropeptide Y gene expression in the Brazilian fl ounder Paralichthys orbignyanus.

Neuropeptide Y (NPY) is one of the most potent stimulants of food intake in vertebrates, mammals and fi sh. However, the present knowledge about feeding behaviour in fi sh is still limited and based on studies in a few species. The Brazilian fl ounder Paralichthys orbignyanus is being considered for aquaculture, and it is important to understand the mechanisms regulating feeding in order to improve its performance in captivity. The objectives of this study were to clone NPY cDNA, evaluate the mRNA levels in different tissues of fl ounder, and also evaluate brain NPY expression to associate food intake with NPY expression levels. A 597 bp NPY cDNA was cloned from Brazilian fl ounder brain. NPY expression was detected in all the peripheral tissues analysed. No signifi cant differences were observed in brain NPY gene expression over 24 h after food intake at a temperature of 15 ± 3°C. No correlation was observed among plasma glucose, total protein, cholesterol, triglycerides and NPY expression levels during this 24 h period. On the other hand, mRNA levels were increased after two weeks of fasting at elevated temperatures. Our results suggest that NPY mRNA levels in Brazilian fl ounder are affected by temperature.