RESUMO

We analyze the invisibility of fisheries and inadequacy of fishers' participation in the process of hydropower development in the Amazon, focusing on gaps between legally mandated and actual outcomes. Using Ostrom's institutional design principles for assessing common-pool resource management, we selected five case studies from Brazilian Amazonian watersheds to conduct an exploratory comparative case-study analysis. We identify similar problems across basins, including deficiencies in the dam licensing process; critical data gaps; inadequate stakeholder participation; violation of human rights; neglect of fishers' knowledge; lack of organization and representation by fishers' groups; and lack of governmental structure and capacity to manage dam construction activities or support fishers after dam construction. Fishers have generally been marginalized or excluded from decision-making regarding planning, construction, mitigation, compensation, and monitoring of the social-ecological impacts of hydroelectric dams. Addressing these deficiencies will require concerted investments and efforts by dam developers, government agencies and civil society, and the promotion of inter-sectorial dialogue and cross-scale participatory planning and decision-making that includes fishers and their associations.

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RESUMO

In order to investigate the relationship between the primary structure of Orpotrin, a vasoactive peptide previously isolated from the freshwater stingray Potamotrygon gr. orbignyi, and its microcirculatory effects, three Orpotrin analogs were synthesized. The analogs have a truncated N-terminal with a His residue deletion and two substituted amino acid residues, where one Nle is substituted for one internal Lys residue and the third analog has a substitution of a Pro for an Ala (Orp-desH(1) , Orp-Nle and Orp-Pro/Ala, respectively). Only Orp-desH(1) could induce a lower vasoconstriction effect compared with the natural Orpotrin, indicating that besides the N-terminal, the positive charge of Lys and the Pro residues located at the center of the amino acid chain is crucial for this vasoconstriction effect. Importantly, the suggestions made with bioactive peptides were based on the molecular modeling and dynamics of peptides, the presence of key amino acids and shared activity in microcirculation, characterized by intravital microscopy. Moreover, this study has demonstrated that even subtle changes in the primary structure of Orpotrin alter the biological effects of this native peptide significantly, which could be of interest for biotechnological applications.

Assuntos

RESUMO

In order to investigate the relationshipbetween theprimary structure of Orpotrin, a vasoactive peptidepreviously isolated from the freshwater stingray Potamotrygon gr. orbignyi, and its microcirculatory effects, three Orpotrin analogs were synthesized. The analogs have a truncated N-terminal with a His residue deletion and two substituted amino acid residues, where one Nle is substituted for one internal Lys residue and the third analog has a substitution of a Pro for an Ala (Orp-desH1, Orp- Nle and Orp-Pro/Ala, respectively). Only Orp-desH1 could induce a lower vasoconstriction effect compared with the natural Orpotrin, indicating that besides the N-terminal, the positive charge of Lys and the Pro residues located at the center of the amino acid chain is crucial for this vasoconstriction effect. Importantly, the suggestions made with bioactive peptides were based on the molecular modeling and dynamics of peptides, the presence of key amino acids and shared activity in microcirculation, characterized by intravital microscopy. Moreover, this study has demonstrated that even subtle changes in the primary structure of Orpotrin alter the biological effects of this native peptide significantly, which could be of interest for biotechnological applications.

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RESUMO

Brazilian freshwater stingrays, Potamotrygon gr. orbigyni, are relatively common in the middle-western regions of Brazil, where they are considered an important public health threat. In order to identify some of their naturally occurring toxin peptides available in very low amounts, we combine analytical protocols such as reversed-phase high-performance liquid chromatography (RP-HPLC), followed by a biological microcirculatory screening and mass spectrometry analysis. Using this approach, one bioactive peptide was identified and characterized, and two analogues were synthesized. The natural peptide named Porflan has the primary structure ESIVRPPPVEAKVEETPE (MW 2006.09 Da) and has no similarity with any bioactive peptide or protein found in public data banks. Bioassay protocols characterized peptides as presenting potent activity in a microcirculatory environment. The primary sequences and bioassay results, including interactions with the membrane phospholipids, suggest that these toxins are a new class of fish toxins, directly involved in the inflammatory processes of a stingray sting.

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In order to evaluate aspects of the reproductive biology of Rhaphiodon vulpinus in the Upper and Middle Tocantins River, samples were taken monthly from October, 1999 through September, 2001, by means of gill nets. Males, which were more abundant than females (chi2 146.87: df=1: p<0.05), matured at a smaller size. The reproductive period of the species extended essentially from November through January, with a peak of activity in November. Fecundity, with an estimated mean value of 98,185 oocytes, varied from 38,177 to 215,841 oocytes, and it did not correlate with the length of the individual female analyzed (r=0.4663: p=0.206). Relative fecundity was 130.6 oocytes/g total weight. Mature oocytes had a mean diameter of 0.98 mm, corresponding to a volume of 0.50 mm³(AU)

Visando avaliar aspectos da biologia reprodutiva de Rhaphiodon vulpinus, foram realizadas coletas mensais no período de outubro de 1999 a setembro de 2001, no alto e médio rio Tocantins utilizando redes de espera. Os machos foram mais abundantes que as fêmeas (chi2 146,87: gl=1: p<0,05) e alcançaram o tamanho de primeira maturação em comprimentos menores. O período reprodutivo da espécie se estendeu, essencialmente, de novembro até janeiro, com pico de atividade no primeiro mês. A fecundidade, com valor médio estimado de 98185 ovócitos, variou de 38177 a 215841. A correlação entre o comprimento padrão das fêmeas e a fecundidade não foi significativa (r=0,4663: p=0,206). A fecundidade relativa foi de 130,6 ovócitos/g de peso total. O diâmetro médio dos ovócitos maduros foi 0,98 mm, correspondendo a volume de 0,50 mm³(AU)

Assuntos

RESUMO

In order to evaluate aspects of the reproductive biology of Rhaphiodon vulpinus in the Upper and Middle Tocantins River, samples were taken monthly from October, 1999 through September, 2001, by means of gill nets. Males, which were more abundant than females (chi2 146.87: df=1: p<0.05), matured at a smaller size. The reproductive period of the species extended essentially from November through January, with a peak of activity in November. Fecundity, with an estimated mean value of 98,185 oocytes, varied from 38,177 to 215,841 oocytes, and it did not correlate with the length of the individual female analyzed (r=0.4663: p=0.206). Relative fecundity was 130.6 oocytes/g total weight. Mature oocytes had a mean diameter of 0.98 mm, corresponding to a volume of 0.50 mm³

Visando avaliar aspectos da biologia reprodutiva de Rhaphiodon vulpinus, foram realizadas coletas mensais no período de outubro de 1999 a setembro de 2001, no alto e médio rio Tocantins utilizando redes de espera. Os machos foram mais abundantes que as fêmeas (chi2 146,87: gl=1: p<0,05) e alcançaram o tamanho de primeira maturação em comprimentos menores. O período reprodutivo da espécie se estendeu, essencialmente, de novembro até janeiro, com pico de atividade no primeiro mês. A fecundidade, com valor médio estimado de 98185 ovócitos, variou de 38177 a 215841. A correlação entre o comprimento padrão das fêmeas e a fecundidade não foi significativa (r=0,4663: p=0,206). A fecundidade relativa foi de 130,6 ovócitos/g de peso total. O diâmetro médio dos ovócitos maduros foi 0,98 mm, correspondendo a volume de 0,50 mm³

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RESUMO

Characterization of the peptide content of venoms has a number of potential benefits for basic research, clinical diagnosis, development of new therapeutic agents, and production of antiserum. In order to analyze in detail the peptides and small proteins of crude samples, techniques such as chromatography and mass spectrometry have been employed. The present study describes the isolation, biochemical characterization, and sequence determination of a novel peptide, named Orpotrin from the venom of Potamotrygon gr. orbignyi. The natural peptide was shown to be effective in microcirculatory environment causing a strong vasoconstriction. The peptide was fully sequenced by de novo amino acid sequencing with mass spectrometry and identified as the novel peptide. Its amino acid sequence, HGGYKPTDK, aligns only with creatine kinase residues 97-105, but has no similarity to any bioactive peptide. Therefore, possible production of this peptide from creatine kinase by limited proteolysis is discussed. Taken together, the results indicate the usefulness of this single-step approach for low molecular mass compounds in complex samples such as venoms.

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Four new species of the Diplectanidae from the gills of freshwater sciaenid species (Pachyurinae) in Brazil are described and two new genera, Anoplectanum n. g. and Spinomatrix n. g., are proposed. These are: Diplectanum copiosum n. sp. from Pachyurus junki and Petilipinnis grunniens; Anoplectanum haptorodynatum n. g., n. sp. from Pachyurus junki and Petilipinnis grunniens, and A. microsoma n. g., n. sp. from Petilipinnis grunniens, all in the Tocantins Basin; and Spinomatrix penteormos n. g., n. sp. from Pachyurus adspersus in the Rio Doce Basin. Anoplectanum is proposed to accommodate diplectanids lacking squamodiscs and having a superficial root of the ventral anchor as long or longer than the deep root. Spinomatrix is proposed for species having a haptoral and peduncular armature composed of spines, hooks, anchors, squamodiscs and armed muscular pads.

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RESUMO

Stingrays of the family Potamotrygonidae are widespread throughout river systems of South America that drain into the Atlantic Ocean. Some species are endemic to the most extreme freshwater environment of the Brazil and cause frequent accidents to humans. The envenomation causes immediate, local, and intense pain, soft tissue edema, and a variable extent of bleeding. The present study was carried out in order to describe the principal biological and some biochemical properties of the Brazilian Potamotrygon fish venoms (Potamotrygon cf. scobina and P. gr. orbignyi). Both stingray venoms induced significant edematogenic and nociceptive responses in mice. Edematogenic and nociceptive responses were reduced when the venom was incubated at 37 or 56 degrees C. The results showed striking augments of leukocytes rolling and adherent cells to the endothelium of cremaster mice induced by both venoms. The data also presented that injection of both venoms induced necrosis, low level of proteolytic activity, without inducing haemorrhage. But when the venoms of both stingray species were injected together with their mucus secretion, the necrotizing activity was more vigorous. The present study provided in vivo evidence of toxic effects for P. cf. scobina and P. gr. orbignyi venoms.

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