Mitochondria-rich cells changes induced by nitrite exposure in tambaqui (Colossoma macropomum Cuvier, 1818)

ABSTRACT The gill mitochondria-rich cells of the juvenile Amazonian fish Colossoma macropomum were analyzed using light and scanning and transmission electron microscopy after 96 h exposure to 0.04 and 0.2 mM nitrite. Although the number of mitochondria-rich cells decreased significantly in the lamellar epithelium, no decrease was found in the interlamellar region of the gill filament. Nitrite exposure caused significant reduction on the apical surface area of individual mitochondria-rich cells (p < 0.05), with a resulting reduction of the fractional area of these cells in both the lamellar and filament epithelium. Swelling of endoplasmic reticulum cisternae, nuclear envelope and mitochondria were the main changes found in the mitochondria-rich cells. Cristae lysis and matrix vacuolization characterized the mitochondrial changes. The overall ultrastructural changes indicated cellular functional disruption caused by exposure to nitrite. The changes observed in the gill indicate that the cellular structures involved in the process of energy production become severely damaged by exposure to nitrite indicating irreversible damage conducting to cell death.

Physiological effects of gasoline on the freshwater fish prochilodus lineatus (characiformes: prochilodontidae)

The purpose of this work was to evaluate the effects of the water-soluble fraction of gasoline (WSFG) on the Neotropical freshwater fish Prochilodus lineatus. The WSFG was prepared by mixing gasoline in water (1:4) and animals were exposed for 6, 24 and 96h to 5% diluted WSFG or only to water. After exposure, blood was collected from the caudal vein and the gills were removed. The following parameters were analyzed: hematological (hemoglobin, hematocrit, number of red blood cells), osmo-ionic (plasma Na+, Cl- and K+ and plasma osmolarity), metabolic (total plasma proteins and glucose), endocrine (cortisol), density and distribution of chloride cells [CC] in the gills (immunohistochemistry), and branchial Na+/K+-ATPase (NKA) activity. Hemolysis was found to occur after 96h exposure to WSFG, as indicated by the decrease in the hematological parameters analyzed, followed by an increase in plasma K+. Secondary stress response was revealed by the occurrence of hyperglycemia in the three periods of exposure, despite the absence of significant increases in the plasma cortisol. The exposure to WSFG also caused an increase in the quantity of CC and in plasma Na+, after 24h, as well as in the enzymatic activity of NKA and plasma osmolarity, after 24h and 96h. These results indicate that fish exposed to the WSFG showed physiological adjusts to maintain their osmotic balance. However, the increase in the quantity of CC in the lamellae may interfere in the gas exchange impairing respiration.

O objetivo deste trabalho foi avaliar os efeitos da fração solúvel da gasolina (FSG) em Prochilodus lineatus. A FSG foi preparada misturando-se a gasolina à água (1:4) e os animais foram expostos por 6, 24 e 96h à FSG diluída 5% ou apenas à água. Após a exposição, o sangue foi coletado pela veia caudal e as brânquias foram retiradas. Os seguintes parâmetros foram analisados: hematológicos (hemoglobina, hematócrito, quantidade de células vermelhas), osmo-iônicos (concentrações plasmáticas de Na+, Cl-, K+ e osmolaridade), metabólicos (concentrações plasmáticas de proteínas totais e glicose), endócrino (cortisol plasmático), densidade e distribuição de células-cloreto [CC] nas brânquias (imunohistoquímica) e a atividade da enzima Na+/K+-ATPase (NKA) branquial. Hemólise foi observada após 96h de exposição à FSG, indicada pela diminuição dos parâmetros hematológicos analisados, seguido pelo aumento do K+ plasmático. Houve resposta secundária de estresse visualizada pela ocorrência da hiperglicemia nos três tempos de exposição, apesar da ausência de diferenças significativas na concentração plasmática do cortisol. A exposição à FSG também provocou aumento na quantidade das CC e na concentração de Na+, após 24h, e na atividade enzimática da NKA e osmolaridade, após 24h e 96h. Esses resultados indicam que peixes expostos à FSG apresentaram ajustes fisiológicos para manter o equilíbrio osmótico. Entretanto, o aumento na quantidade de CC nas lamelas pode ter interferido nas trocas gasosas prejudicando a respiração.

Effects of deltamethrin pyrethroid on the respiratory metabolism of the neotropical spirostreptid millipedes Gymnostreptus olivaceus and Plusioporus setiger

The effects of deltamethrin on the respiratory metabolism of Gymnostreptus olivaceus and Plusioporus setiger were investigated. Acetone solutions corresponding to half the LD50 values, i.e., 20 mg.g-1 for G. olivaceus and 4.40 mg.g-1 for P. setiger, were used. Metabolism was determined with a Warburg respirometer at 25ºC. Respirometric measurements were performed 1, 3 and 6 hours after administration of the pyrethroid to the same groups of millipedes. After 24 hours, daily respirometric measurements lasting 1 hour each were made on different millipede groups for a period of 10 days. Significant differences were detected only between the groups treated with the pyrethroid and the two control groups. In G. olivaceus, respiratory rates increased by about 1.65-fold compared to normal immediately after administration of the pyrethroid, followed by a gradual decrease up to 72 hours and a return to normal levels thereafter. In P. setiger the increase was about 1.1-fold compared to normal, with a decrease up to 96 hours and a return to normal thereafter. Although increased oxygen consumption was observed, a detoxification process occurred in both species, so that the possible metabolism of the pyrethroid may justify the low toxicity of deltamethrin for G. olivaceus and P. setiger

Toxidade do carbonato methiocarb para os diplópodos gymnostreptus olivaceus e plusioporus setiger / Toxicity of methiocarb carbamat on millipedes Gimnostreptus olivaceus e Plusioporus setiger

A toxidade por aplicação tópica, do carbamato Methiocarb foi avaliada para os diplódos Gymnostreptus olivaceus e Plusioporus setiger. Os valores das DL50 foram Altos para as duas espécies:515;216;137 e 93mg.g1 para G. olivaceus e 489;222;108 e 71 para P. setiger, respectivamente, 24,48,72 e 96 horas após aplicação do Methiocarb, indicando baixa toxidade. A baixa toxidade do Methiocarb, em diplópodos, pode estar relacionada à dificuldade de penetração do produto principalmente em animais na fase adulta que possuem um exoesqueleto calcificado e rígido. Os resultados sugerem a necessidade de um melhor conhecimento do modo de ação de defensivos químicos em diplópodos, a fim de adequar a sua aplicação e vitar riscos de contaminação ambiental pela utilização dos mesmos