Hypoxia adaptation in fish of the Amazon: a never-ending task

In addition to seasonal long-term changes in dissolved oxygen and carbon dioxide, water bodies of the Amazon present periodic short-term episodes of hypoxia and even anoxia. To preserve gas exchange and acid base balance, fish of the Amazon have developed multiple adaptive solutions which occur at all biological levels. These solutions are thought to represent adaptive convergence rather than phylogenetic relatedness. Fish of the Amazon exposed to different experimental conditions adjust, for example, several parameters to improve oxygen transfer from the gas-exchange site to the tissues. These parameters include morphological changes such as the development of the lower lip in Colossoma, changes in ventilation rates, changes in circulatory parameters, increased circulating red blood cells, decreased levels of intraerythrocytic phosphates, and adjustments of intraerythrocytic pH (pHi). These adjustments that allow fish to survive both short- and long-term hypoxia occur in different degrees in different fish species and may or may not occur simultaneously. In addition, these adjustments in oxygen transfer affect many other parameters, particularly acid-base status. We suggest that these adjustments are initiated as soon as the animal detects the environmental change in oxygen availability and are mediated by a single factor, possibly one of the catecholamines. In this paper we aim to show that adaptation to hypoxia is a never-ending task for the fish of the Amazon

Anoxia- and hypoxia-induced expression of LDH-A* in the Amazon Oscar, Astronotus crassipinis

Adaptation or acclimation to hypoxia occurs via the modulation of physiologically relevant genes, such as erythropoietin, transferrin, vascular endothelial growth factor, phosphofructokinase and lactate dehydrogenase A. In the present study, we have cloned, sequenced and examined the modulation of the LDH-A gene after an Amazonian fish species, Astronotus crassipinis (the Oscar), was exposed to hypoxia and anoxia. In earlier studies, we have discovered that adults of this species are extremely tolerant to hypoxia and anoxia, while the juveniles are less tolerant. Exposure of juveniles to acute hypoxia and anoxia resulted in increased LDH-A gene expression in skeletal and cardiac muscles. When exposed to graded hypoxia juveniles show decreased LDH-A expression. In adults, the levels of LDH-A mRNA did not increase in hypoxic or anoxic conditions. Our results demonstrate that, when given time for acclimation, fish at different life-stages are able to respond differently to survive hypoxic episodes

Rio Amazonas: tesouro descoberto

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Metabolic adjustments in two Amazonian cichlids exposed to hypoxia and anoxia.

The effects of graded hypoxia on the physiological and biochemical responses were examined in two closely related species of cichlids of the Amazon: Astronotus crassipinnis and Symphysodon aequifasciatus. Ten fish of each species were exposed to graded hypoxia for 8 h in seven oxygen concentrations (5.92, 3.15, 1.54, 0.79, 0.60, 0.34, and 0.06 mg O2 L- 1), with the aim to evaluate hypoxia tolerance and metabolic adjustments, where plasma glucose and lactate levels, hepatic and muscle glycogen contents, and maximum enzyme activities (PK, LDH, MDH and CS) in skeletal and cardiac muscles were measured. Another experimental set was done to quantify oxygen consumption (MO2) and opercular movements in two oxygen concentrations. Hypoxia tolerance differed between the two species. Astronotus crassipinnis was able to tolerate anoxia for 178 min while S. aequifasciatus was able to withstand 222 min exposure in deep hypoxia (0.75 mg O2 L- 1). Suppressed MO2 was observed during exposure to 0.34 (A. crassipinnis) and 0.79 mg O2 L- 1 (S. aequifasciatus), while opercular movements increased in both species exposed to hypoxia. Higher levels of muscle and liver glycogen and larger hypoxia-induced increases in plasma glucose and lactate were observed in A. crassipinnis, which showed a higher degree of hypoxia tolerance. Changes in enzyme levels were tissue-specific and differed between species suggesting differential abilities in down-regulating oxidative pathways and increasing anaerobic metabolism. Based on the present data, we conclude that these animals are good anaerobes and highly adapted to their environment, which is allowed by their abilities to regulate metabolic pathways and adjust their enzyme levels

Validation of a suite of biomarkers of fish health in the tropical bioindicator species, tambaqui (Colossoma macropomum)

Here we explore the dose-dependent response of the tropical fish tambaqui (Colossoma macropomum) to intraperitoneal injection of benzo[a]pyrene (BaP) at doses of 0 (carrier control), 1, 10, 100 and 1000 µmolar BaP Kg-1 Hepatic ethoxyresorufin-O-deethylase (EROD) activity showed a bell-shaped dose-dependent response curve, where the highest injected BaP dose caused enzyme inactivation. Activities of hepatic catalase (CAT) and superoxide dismutase (SOD) increased at the highest dose relative to the carrier control group. Lipid peroxidation (LPO), serum-sorbitol dehydrogenase (s-SDH) and DNA damage in blood cells were higher for all BaP doses when compared to the carrier control group. At high dosage, the production of BaP metabolites was paralleled by induced activity of the antioxidant enzyme SOD, and high levels of DNA damage in blood cells. In a similar way, high LPO was concomitant to elevated s-SDH in the bloodstream, suggesting that lipid peroxidation caused the loss of membrane integrity and leakage of s-SDH from hepatocytes into the bloodstream. These biomarkers were also positively co-correlated. The results demonstrate the potential use of a suite of biomarkers for tambaqui living in contaminated tropical aquatic environments. In particular, we recommend the analysis of DNA damage in blood cells, as this was highly correlated with all other biomarkers. © 2016 Elsevier Lt

Revisitando a obra de Padre João Daniel. Redescobrindo o Tesouro

This review is about a revisit to the work Discovered Treasure at the maximum Amazon River (volumes I and II). After having read it for over ten years and drafted two reviews, one in the year of its own publication by Editora Contraponto at the request of the SBPC, and another in 2005, at the invitation of the magazine Ambiente & Sociedade, published by Unicamp. In those two documents, we deal with biodiversity and environment, precious things that Priest João Daniel described, providing us with a detailed and precise narrative that seems current to the reader today, although written in the eighteenth century. In this paper we recall some points and we highlight two parts where he describes the amphibian fish, treating all aquatic animal biodiversity that breathe air. After this revisit, we bring a part not covered in the other reviews, in which Priest João Daniel describes the Indians ("natural" as he also calls them) and their physical characteristics and social organization. It also deals with the relation of the European man (Spanish and Portuguese people) with the Indian. It is striking how there is a strong parallel between the hierarchical and social relations that existed at the time of colonization and still persists in the present time. It is worth to feel the affection that the author had while living as a Jesuit in the Amazon and how he could have been a great historian, philosopher and biologist in the present times.Esta reseña revisita la obra Tesouro Descoberto no máximo Rio Amazonas (volúmes I y II). Más de diez años después de haber leído la obra y redactado dos reseñas, una en el año de su publicación por la editorial Contraponto, por encargo de la SBPC, y otra, en 2005, por invitación de la revista Ambiente & Sociedade, editada por la Unicamp, esta tercera reseña trae una lectura distinta en relación a las dos anteriores. En las dos primeras tratamos de la biodiversidad y el ambiente, tesoros que el Padre João Daniel describió, brindándonos una narrativa detallada y precisa que parece actual al lector de hoy, a pesar de haber sido escrita en el siglo XVIII (1757-1776). En esta reseña recordamos algunos puntos y resaltamos dos partes del texto donde el autor describe los peces anfíbios y la diversidad acuática animal que respira oxígeno. Después de esta revisión, presentamos una parte no abordada en las reseñas anteriores, en la que el Padre João Daniel describe a los índios (naturales, como les llama) y sus características físicas y organización social. Igualmente, la relación del hombre europeo (españoles y portugueses) con el índio. Impresiona la fuerte correlación entre las relaciones jerárquicas y sociales que hubo en la época de la colonización y que todavía persisten en el presente. Vale la pena sentir el cariño que el autor tiene en cuanto vive como un jesuíta en la Amazonia y como podría haber sido, hoy en día, un gran historiador, filósofo y biólogo.Esta resenha trata de uma revisita à obra Tesouro Descoberto no máximo Rio Amazonas (volumes I e II). Após termos lido a mesma há mais de dez anos e redigido duas resenhas, uma no ano da própria publicação pela Editora Contraponto a pedido da SBPC, e outra em 2005, a convite da revista Ambiente & Sociedade, na ocasião, editada pela Unicamp, esta terceira traz uma leitura diferente. Naqueles dois documentos, tratamos da biodiversidade e ambiente, preciosidades que Padre João Daniel descreveu, brindando-nos com uma narrativa detalhada e precisa que parece atual ao leitor de hoje, apesar de escrita no século XVIII (1757-1776). No presente documento recordamos alguns pontos e ressaltamos duas partes onde ele descreve os peixes anfíbios, tratando toda a biodiversidade aquática animal que respira ar. Após esta revisita, trazemos uma parte não abordada nas demais resenhas, na qual Padre João Daniel descreve os índios (naturais como também os chama) e suas características físicas e organização social. Trata também da relação do homem europeu (espanhóis e portugueses) com o índio. Impressiona como há um forte paralelo entre as relações hierárquicas e sociais que houve na época da colonização e ainda persiste nos dias atuais. Vale à pena sentir o carinho que o autor teve enquanto viveu como jesuíta na Amazônia e como ele poderia ter sido, nos tempos de hoje, um grande historiador, filósofo e biólogo

Revisitando la obra del Padre João Daniel. Redescubriendo el Tesoro

Esta resenha trata de uma revisita à obra Tesouro Descoberto no máximo Rio Amazonas (volumes I e II). Após termos lido a mesma há mais de dez anos e redigido duas resenhas, uma no ano da própria publicação pela Editora Contraponto a pedido da SBPC, e outra em 2005, a convite da revista Ambiente & Sociedade, na ocasião, editada pela Unicamp, esta terceira traz uma leitura diferente. Naqueles dois documentos, tratamos da biodiversidade e ambiente, preciosidades que Padre João Daniel descreveu, brindando-nos com uma narrativa detalhada e precisa que parece atual ao leitor de hoje, apesar de escrita no século XVIII (1757-1776). No presente documento recordamos alguns pontos e ressaltamos duas partes onde ele descreve os peixes anfíbios, tratando toda a biodiversidade aquática animal que respira ar. Após esta revisita, trazemos uma parte não abordada nas demais resenhas, na qual Padre João Daniel descreve os índios (naturais como também os chama) e suas características físicas e organização social. Trata também da relação do homem europeu (espanhóis e portugueses) com o índio. Impressiona como há um forte paralelo entre as relações hierárquicas e sociais que houve na época da colonização e ainda persiste nos dias atuais. Vale à pena sentir o carinho que o autor teve enquanto viveu como jesuíta na Amazônia e como ele poderia ter sido, nos tempos de hoje, um grande historiador, filósofo e biólogo.This review is about a revisit to the work Discovered Treasure at the maximum Amazon River (volumes I and II). After having read it for over ten years and drafted two reviews, one in the year of its own publication by Editora Contraponto at the request of the SBPC, and another in 2005, at the invitation of the magazine Ambiente & Sociedade, published by Unicamp, we bring a different view in this one. In those two documents, we deal with biodiversity and environment, precious things that Priest João Daniel described, providing us with a detailed and precise narrative that seems current to the reader today, although written in the eighteenth century (1757-1776). In this paper we recall some points and we highlight two parts where he describes the amphibian fish, treating all aquatic animal biodiversity that breathe air. After this revisit, we bring a part not covered in the other reviews, in which Priest João Daniel describes the Indians (“natural” as he also calls them) and their physical characteristics and social organization. It also deals with the relation of the European man (Spanish and Portuguese people) with the Indian. It is striking how there is a strong parallel between the hierarchical and social relations that existed at the time of colonization and still persists in the present time. It is worth to feel the affection that the author had while living as a Jesuit in the Amazon and how he could have been a great historian, philosopher and biologist in the present times

Aspectos biológicos de peixes amazônicos. IV. Padrões eletroforéticos de hemoglobinas de 22 espécies coletadas na ilha da Marchantaria (Manaus - AM).

The hemoglobin patterns of hemolysates from 22 fish species belonging to Manchantaria island (Solimões river , Manaus, AM) had been characterized by starch gel and agarstarch gel electrophresis. High interespecific hemoglobin heterogeneity was observed, similarly to those described for sub-tropical and temperate fish species. The resolution power of the electrophoretic supports was considered. The adaptability question of the multiple hemoglobin systems was regarded.Foram estudados hemolisados de 22 espécies de peixes coletados na Ilha da Marchantaria (rio Solimões, Manaus - AM), através de eletroforeses em gel de amido e gel de ágar-amido. Uma grande heterogeneidade hemoglobínica interespecífica foi detectada, a exemplo do observado para espécies de zona subtropical e temperada. A capacidade de resolução de dois suportes eletroforéticos é discutida. Os resultados são discutidos em função da possível adaptabilidade conferida pelos sistemas de múltiplas hemoglobinas