COMPARISON OF THE EFFECTS OF ANTICOAGULANTS USED IN BLOOD COLLECTION TO DETERMINE BLOOD PARAMETERS OF FREE-LIVING STINGRAYS FROM THE Potamotrygon GENUS (ELASMOBRANCHII: POTAMOTRYGONIDAE)

Este estudo avaliou a eficácia de três anticoagulantes em parâmetros sanguíneos de arraias cururu Potamotrygon sp. O sangue de dez animais foi coletado e diluído nos anticoagulantes: EDTA 5% e 10%, heparina 2.500 e 5.000 UI e citrato de sódio 3,2%, outra parte do sangue também foi analisada sem anticoagulante.  O sangue de 20% e 30% das amostras de sangue que não continha anticoagulante e citrato de sódio (3,2%), respectivamente, coagularam.  Grumos de células foram observados durante a contagem de eritrócitos em 30% das amostras com EDTA 10%, 40% das amostras com heparina 2.500 UI e 60% das amostras com heparina 5.000 UI. Não foram observadas alterações no eritrograma da arraia cururu com diferentes anticoagulantes, os valores da glicose plasmática foram semelhantes em todos os grupos, enquanto os níveis de proteínas totais foram menores nas amostras coletadas com EDTA 5% e 10%. Em arraias Potamotrygon sp., para a conservação de amostras de sangue não é recomendado o uso de citrato de sódio 3.2%, porém, para a determinação da glicose plasmática e do eritrograma os anticoagulantes usados não influenciaram os parâmetros analisados. Portanto, esses resultados indicam que para evitar qualquer sinal de coagulação do sangue deve ser coletadas amostras diretamente com qualquer uma dessas concentrações de anticoagulantes.Palavras-chave: potamotrigonídeos, anticoagulantes, sangue, hematologia.This study assessed the effectiveness of three anticoagulants in blood parameters of "cururu" stingrays Potamotrygon cf. histrix. Blood from ten individuals were collected and diluted with anticoagulants EDTA 5% and 10%, heparin 2500 and 5000 UI and sodium citrate 3.2%. A blood sample without anticoagulant was also evaluated. The blood of samples without anticoagulant and with sodium citrate 3.2% coagulated in 20% and 30% of the cases, respectively. Clumps of cells were observed during erythrocyte counting in 30% of samples with EDTA 10%, 40% of samples with heparin 2500 IU and 60% of samples with heparin 5000 IU. No alterations were observed on the erythrogram of "cururu" stingrays with different anticoagulants, the values of plasma glucose were similar in all groups and total protein levels were lower in the samples with EDTA 5% and 10%. The use of sodium citrate 3.2% is not recommended for blood sample conservation of Potamotrygon cf. histrix. stingrays, but anticoagulants did not affect the parameters analyzed in the determination of plasma glucose and erythrogram. Therefore, these results indicate that in order to blood coagulation the samples should be collected directly with any of these anticoagulants concentrations.Keywords: potamotrygonid; anticoagulants; blood; hematology

Estresse oxidativo em duas espécies de teleósteos amazônicos, Astronotus ocellatus e Colossoma macropomum, expostos a diferentes tensões de oxigênio: uma abordagem comparativa

This study describes the antioxidant defenses of acará-açu (Astronotus ocellatus) and tambaqui (Colossoma macropomum) exposed to long term hypoxia, normoxia and hyperoxia. Superoxide dismutase, catalase and the oxidized cell products (measured as TBARS) were measured in liver and blood of A. ocellatus and C. macropomum. Methemoglobin and glutathione contents were evaluated only in the blood and glutathione peroxidase only in the liver. These species exhibit different responses for the analysed parameters. Acclimation to hypoxia resulted in increased methemoglobin and liver superoxide dismutase levels in C. macropomum. Glutathione peroxidase also increased in both species, whereas reduced glutathione decreased in hypoxia exposed animals. Colossoma macropomum exhibited acatalasemia in normoxia and hypoxia, while catalase decreased in A. ocellatus exposed to hypoxia. Under hyperoxia, most of the analyzed parameters were changed significantly in both liver (increased TBARS, superoxide dismutase and glutathione peroxidase levels, and a possible inhibition of catalase) and blood (increased methemoglobin, TBARS and superoxide dismutase levels) of C. macropomum. In addition, a high production of intraerythrocytic oxidized glutathione was also observed in C. macropomum. Astronotus ocellatus exhibited slight changes in antioxidant defenses and no cellular damage in both liver and blood. This cichlid species is hypoxia tolerant and is also able to survive many hours under anoxia, whereas C. macropomum relies preferentially on aerobic metabolism, and is able to improve many adaptive solutions to maintain an adequate oxygen supply to the tissues. We suggest that the responses observed for these fish species to hypoxia and hyperoxia are in agreement to their oxygen needs, where C. macropomum is more susceptible to oxidative stress, specially under hyperoxia.O presente trabalho objetivou identificar as respostas fisiológicas e bioquímicas manifestadas pelo sistema de proteções antioxidantes de Astronotus ocellatus (acará-açu) e Colossoma macropomum (tambaqui), frente às variações na disponibilidade de oxigênio. Exemplares de ambas as espécies foram aclimatados, por 15 dias consecutivos, a três diferentes condições experimentais: hipóxia, normóxia e hiperóxia. Os parâmetros analisados incluiram as proteções antioxidantes enzimáticas (superóxido dismutase, catalase e glutationa peroxidase), do fígado e do sangue, os parâmetros hematalógicos, os níveis de glutationa sanguínea, o consumo de oxigênio do fígado e os níveis endógenos de produtos celulares oxidados de ambos os tecidos. Procurou-se também investigar se situações extremas, como hipóxia e hiperóxia, levam ao estabelecimento de uma situação de estresse oxidativo. Distintas características, como a ausência de catalase no sangue do tambaqui e, principalmente, diferenças quantitativas nas defesas antioxidantes foram observadas entre as duas espécies na condição normóxica. Na exposição à hipóxia, as respostas manifestadas pelas mesmas foram distintas em sua maioria. Colossoma macropomum demonstrou uma maior susceptibilidade, revelando níveis elevados de metahemoglobina e de produtos celulares oxidados no sangue, em contraste com A. ocellatus, onde estas modificações não foram constatadas. Na aclimatação à hiperóxia, a mesma tendência foi observada. Em C. macropomum, as alterações observadas nos diversos parâmetros analisados, como o aumento no conteúdo da superóxido dismutase em ambos os tecidos, a drástica diminuição dos níveis de glutationa reduzida e, provavelmente, uma inibição da catalase no fígado, foram acompanhadas por um aumento significativo no processo de dano celular. Por outro lado, em A. ocellatus apenas alguns parâmetros foram modificados, e nenhuma evidência de dano celular foi demonstrada por esta espécie. Isso indica que C. macropomum encontrou na condição hiperóxica, uma situação de elevado estresse oxidativo, enquanto A. ocellatus demonstrou ser tolerante não somente à hipóxia, mas também à hiperóxia. As distintas estratégias adotadas em relação às proteções antioxidantes pelas duas espécies estudadas coadunam-se com suas respectivas características ecológicas

Testicular structure and spermatogenesis of Amazonian freshwater cururu stingray Potamotrygon cf. histrix

The cururu stingray Potamotrygon cf. histrix, a new and endemic Amazonian freshwater species, presents appropriate characteristics for fish keeping and is exploited from its natural environment. The present study identified the testicular structure and spermatogenesis of this species. Gonads from adult male specimens were dissected, fixed and processed for histological analysis. The testes were of testicular/epigonial type. The presence of germinal papillae was observed in the upper portion of organ with primordial germ cells and Sertoli cell precursors. The testis was lobular with zonal organization and cystic gametogenesis, with the occurrence of spermatoblasts. The Sertoli cells underwent morphological modifications over the course of gamete formation. The spermatozoids had long heads and were spiraled on their own axis. Information on the reproductive biology will serve as basis for studies on the reproduction and phylogeny of this peculiar group of cartilaginous fish

The influence of dietary vitamin C and E supplementation on the physiological response of pirarucu, Arapaima gigas, in net culture

This study evaluated the efficacy of dietary vitamin C (ascorbic acid or AA), vitamin E (α-tocopherol or α-T), and C + E supplementation on the blood parameters of Arapaima gigas grown in net cages for 45 days. Four treatments were tested: control (commercial feed); C800; E500 and C + E (800 + 500) with supplementation of 800 mg AA kg- 1, 500 mg α-T kg- 1 and 800 + 500 mg AA + α-T kg- 1, respectively. Hematocrit (Ht), red blood cells (RBC), and hemoglobin concentration (Hb) (oxidative status indicators), thrombocytes and leukocytes (immunological indicators), plasma protein and glucose were evaluated. Fish fed vitamin C and C + E supplemented diets showed greater weight gain and survival. Dietary vitamin C and C + E diet supplementation resulted in increased Ht, Hb, RBC, MCHC, total leukocytes, total proteins, thrombocytes and eosinophils compared to the control and α-T. The α-tocopherol-supplemented diet reduced the number of total thrombocytes, lymphocytes and neutrophils and increased glucose and eosinophils relatively to the control. In general, leukocytes and thrombocytes were good indicators of the efficiency of vitamin on the defense mechanism of the A. gigas reared in cages. Results indicate that high α-T diet supplementation provides no benefit for the maintenance of the oxidative or the immunological status of A. gigas. However, it was demonstrated that high dietary AA improves A. gigas immunological status. Red blood cell indices and immune system indicators showed no synergistic effect between the vitamins after supplementing the A. gigas diet with α-T + AA. © 2006 Elsevier Inc. All rights reserved

Benefits of using the probiotic Efinol((R))L during transportation of cardinal tetra, Paracheirodon axelrodi (Schultz), in the Amazon

The objective of this experiment was to test the probiotic Efinol((R))L during transportation of cardinal tetra, Paracheirodon axelrodi (Schultz). For the transportation, fish were distributed in 18 plastic tanks, of which nine contained the Efinol((R))L (10 mg L-1; probiotic treatment) and the remaining had no probiotic (control treatment). Transport lasted 24 h and three different boxes of each treatment were sampled at 3, 12 and 24 h. Up to the 12-h sampling period, no significant difference in the survival was observed; on the other hand, survival was higher at the end of the transport (24 h) in the probiotic treatment. No significant difference was found in dissolved oxygen and temperature between treatments. Conductivity, pH and alkalinity increased along the transport, but without a difference between treatments. Ammonia increased in all treatments, although it was significantly lower in the probiotic group at 24 h. Cortisol levels were significantly higher in all transported fish when compared with the basal values. At 24 h, cortisol levels in control fish were significantly higher than those in the probiotic treatment. With the observed results, we are able to conclude that the probiotic Efinol((R))L is efficient during cardinal transport, lowering the mortality and helping maintain water quality possibly by lowering metabolic wastes.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Body color pattern and aggressiveness related to behavioral context and light intensity in an Amazonian cichlid, Laetacara fulvipinnis

The aim of this study was to describe agonistic interaction and color patterns relative to social status and to evaluate the effects of light on aggressiveness in Laetacara fulvipinnis. Eight agonistic events were observed: frontal display, mouth fight, nipping, chase, parallel display, threat, undulation, and flight. Four body color patterns were related to the social context. Two light levels were also tested: groups of juveniles were maintained for 15 days under low (228 ± 38.60 lx) or high (1435.92 ± 481.40 lx) light. Color pattern a was mainly observed during escalating agonistic interactions. Other patterns were exhibited during flight, rest, and attack. High light decreased the latency to fighting; increased the frequency of threats, total attacks, and flight; and destabilized the social hierarchy. These findings indicate that light intensity increases aggressiveness, interferes with the stability of hierarchies, and may result in a stressful situation with negative effects on animal welfare. © 2017 Informa UK Limited, trading as Taylor & Francis Group