Estudo estereológico em fígado de tambaqui (Colossoma macropomum): efeito tóxico do nitrito

Durante o cultivo intensivo de peixes, desequilíbrios nos processos de transformação da amônia podem acarretar elevados níveis de nitrito (NO2-) no meio aquático, o nitrito logo é absorvido através das brânquias que em poucas horas acumula-se no sangue e tecidos dos animais, e a concentração chega a ser muito superior da encontrada no ambiente. Das consequências devido a intoxicação pelo nitrito, pode se ressaltar duas: a primeira se da à direta ação do NO2- sobre a molécula da hemoglobina (Hb) transformando-a em metahemoglobina (MetHB) onde a mesma torna-se incapaz de de ligar e liberar oxigênio O2 aos tecidos. A partir disso alguns órgãos vitais para a homeostase enfrentam períodos de severa hipóxia devido a exposição ao nitrito. Dentre esses órgãos destaca-se o fígado, mas embora a espécie do tambaqui ser amplamente utilizada em meios de aquacultura, não se tem informações a respeito dos efeitos tóxicos do nitrito sobre a organização hepática do tambaqui. O presente projeto tem a finalidade de fazer uma análise morfométrica do fígado de tambaqui submetidos à exposição por nitrito, para se poder ter mais informações sobre a histologia quantitativa desta espécie.FAPEA

Embryonic development of the Giant South American River Turtle, Podocnemis expansa (Testudines: Podocnemididae)

Knowledge of embryonic development is important for choosing strategies for nest conservation, and reducing negative effects on eggs and embryos of turtle species subject to human and natural interference, as is the case of Podocnemis expansa in the Amazon. Nine P. expansa nests located in Balbina, Amazonia, Brazil, were used to describe embryonic development. An embryo was collected each day, totaling 240 embryos. The specimens were fixed in Bouin’s and Karnovsky’s solutions for macroscopic analysis and scanning electron microscopy, respectively. The incubation period lasted between 58 and 64 days with a mean nest incubation temperature of 30.3 °C. The main characteristics used for description and comparison of embryonic development were: development of the eyes, the mandibular process, limbs, carapace and plastron. We found that the timing of appearance and disappearance of structures in P. expansa were more advanced than in other turtle species. Furthermore, P. expansa displays some unique characteristics during its normal development, such as craniofacial morphology, frontonasal groove and carapace and plastron characteristics. © 2017, Springer-Verlag GmbH Germany

Cross-reactivity between Potamotrygon motoro antivenoms and dorsal and stinger extracts of others stingrays (Chondrichthyes: Potamotrygonidae) from the Amazon basin

In this study, two mouse hyperimmune sera were produced, one using extract from the stinger of the stingray Potamotrygon motoro and the other using extract from the dorsal region of the same species and their cross-reactivity with extracts from the following species of stingrays from the Amazon basin was investigated using Western blot and dot ELISA: Paratrygon aiereba, Plesiotrygon iwamae, Potamotrygon orbignyi and Potamotrygon schroederi. The results show that the dorsal extract was as immunogenic as the stinger extract and induced high levels of antibodies, which reacted with homologous and heterologous antigens, indicating that both types of extract may be suitable for use in the production of antivenom to treat victims of envenomation by stingrays. © 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group

The effects of stocking density on the hematology, plasma protein profile and immunoglobulin production of juvenile tambaqui (Colossoma macropomum) farmed in Brazil

Farming of Amazonian native fish species holds great promise. One species whose characteristics make it suitable for intensive farming is tambaqui (Colossoma macropomum). However, there is a lack of consensus about the most suitable stocking density (SD) for intensive farming. More information on the physiology of fish in farming systems is thus required, as this would increase our understanding of the effects of stress on these fish. The aim of this study was therefore to evaluate the effect of different SDs on the hematology and plasma protein profile of tambaqui. To this end, juvenile tambaqui were exposed to the following different SDs (kg/m3) for 96 h: SD1 = 2.11; SD2 = 8.31; SD3 = 16.34; and SD4 = 27.40. Water quality was monitored, and blood was collected for hematological analysis and electrophoresis (SDS-PAGE) to analyze plasma protein and immunoglobulin profiles. Gill filaments were removed and the number of parasites (monogenoids) was counted. Multivariate PCA analysis revealed a strong positive association between the highest SDs (SD3 and SD4) and parasite count, immune cells (eosinophils, thrombocytes, monocytes and lymphocytes) and water ammonia and nitrite levels. Conversely, the highest SDs were negatively associated with water quality variables (pH, turbidity, conductivity and O2 content) and blood hematocrit. The results show that the highest SDs contributed to a deterioration in water quality, leading to increased MetHb levels, gill parasitism, an increase in the number of defense cells, altered protein profile and stimulation of immunoglobulin production. These changes suggest that the welfare of tambaqui is adversely affected by high SDs and increase our understanding of the effects of crowding stress on the physiology of the species. © 201