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1.
Braz. arch. biol. technol ; 52(6): 1431-1441, Nov.-Dec. 2009. ilus, graf, tab
Article in English | LILACS | ID: lil-539110

ABSTRACT

Piaractus mesopotamicus is a freshwater native fish from rivers of the Paraná-Paraguay Basin and of the Pantanal region and has been used for repopulation programs in Brazil. Juvenile fishes were exposed to the sub-lethal dose of 1.08mg/L of the OP Azodrin®400 containing 0.43µL/L of the active principle monocrotophos for 96 h. A frequent pathology in the gills at all times of exposure was epithelial detachment, from minimal until 24 h of exposure, to intense after 48 h of contamination. Deformed pillar cells in the respiratory lamellae leading to irregular blood spaces and blood congestion, as well as hyperplasia and lamellar fusion were observed. These histopathologies suggested that 48 h after T0 was an important time when a reduction in the capability for gaseous exchange with consequent weakening of the fishes' condition could occur. This could impair growth and development of juveniles introduced in water bodies for repopulation programs.


Piaractus mesopotamicus é um peixe de água doce encontrado na Bacia Paraná-Paraguai e na região do Pantanal, tendo sido usado em programas de repovoamento no Brasil. Peixes juvenis foram expostos por 96 horas à dose sub-letal de 1.08mg/L do organofosforado (OP) Azodrin®400 que contém 0,43µL/L do principio ativo monocrotofós. A patologia freqüente nas brânquias foi o descolamento epitelial que variou de mínimo nas primeiras 24 horas a severo ou intenso após 48 horas de contaminação. Deformações e degeneração de células pilares nas lamelas respiratórias levando à formação de espaços sanguíneos irregulares e congestão sanguínea, hiperplasia e fusão lamelar também foram observadas. Sugere-se que 48 horas após o T0 é um tempo crítico após exposição a níveis subletais de OP, pois a capacidade de trocas gasosas poderá ter diminuído, levando ao enfraquecimento dos peixes. Os sintomas poderão prejudicar o desenvolvimento dos juvenis introduzidos em corpos de água em programas de repovoamento.

2.
Ecotoxicol Environ Saf ; 71(3): 821-9, 2008 Nov.
Article in English | MEDLINE | ID: mdl-18468684

ABSTRACT

This study has the aim of verifying the morphologic alterations in the hepatic tissue of Rhamdia quelen juveniles when exposed to 0.01 mL/L of Folidol 600. Techniques of light microscopy and transmission electronic microscopy were used. The liver was target for the Folidol 600 action after 4h of contamination. Loss of cellular contour, picnotic nucleus and decharacterization of the endothelium and of the rough endoplasmic reticulum were observed. Focuses of necrosis increased significantly when compared to the control sample at the exposure times of 48 and 72 h to the organophosphate. The density of hepatocytes increased significantly in every experimental time when compared to the control sample. The number of hepatocytes with biliary pigment increased significantly in the first 72 h of exposure when compared to the control. Folidol 600 was responsible for serious alterations in the hepatic tissue of the Rhamdia quelen.


Subject(s)
Catfishes/physiology , Chemical and Drug Induced Liver Injury/pathology , Insecticides/toxicity , Liver/drug effects , Methyl Parathion/toxicity , Animals , Liver/pathology , Liver/ultrastructure , Water Pollutants, Chemical/toxicity
3.
Braz. arch. biol. technol ; 46(3): 361-372, Jun. 2003. ilus
Article in English | LILACS | ID: lil-351413

ABSTRACT

Gills are vital structures for fish, since they are the main site for gaseous exchange as well as partially responsible for osmorregulation, acid-basic balance, excretion of nitrogenous compounds and taste. Chemicals in the water may alter the morphology of branchial cells of fish that are, therefore, a useful model for environmental impact and ecotoxicology studies. In order to investigate the effects of an organophosphorous compound, methyl parathion, on the gills of the fish, samples of Metynnis roosevelti were exposed to lethal (7ppm) and sublethal (1ppm) doses of Mentox 600 CE. Through light and scanning electron microscopy, shrinking of the branchial epithelium, followed by detachment and hyperplasia were observed. Externally, the branchial filaments presented the gradual disappearance of microridges. Even in sublethal doses, the organophosphorous reduced the health and fitness of these fish, as consequence of secondary effects derived from changes in the branchial epithelium, impairing oxygenation and ionic balance of the organism

4.
Ecotoxicol Environ Saf ; 54(2): 119-30, 2003 Feb.
Article in English | MEDLINE | ID: mdl-12550089

ABSTRACT

The effects of contamination, through water or food, of a sublethal dose of the organophosphate methyl parathion were analyzed in tissues that are responsible for absorption (gills, intestine) and metabolism (liver), in the freshwater fish Corydoras paleatus. In gill respiratory lamellae, epithelial hyperplasia, edema, and detachment occurred, diminishing sooner after contamination by food than after contamination through water. In the intestine, lipoid vacuolization of enterocytes, apical cytoplasm, and an increase in goblet cell activity occurred mainly after ingestion of contaminated food. The liver exhibited cloudy swelling, bile stagnation, focal necrosis, atrophy, and vacuolization after contamination through both absorption routes, the highest degeneration being between T(8) and T(24). Metabolic processes that depend on liver function were equally impaired by the two routes of contamination, but secondary effects vary with gill and intestine pathologies as a consequence of water and food contamination, respectively. Therefore, a "safe" sublethal dose of methyl parathion causes serious health problems in C. paleatus.


Subject(s)
Fishes/physiology , Gills/pathology , Insecticides/adverse effects , Liver/pathology , Methyl Parathion/adverse effects , Water Pollutants, Chemical/adverse effects , Absorption , Animals , Insecticides/pharmacokinetics , Liver/physiology , Methyl Parathion/pharmacokinetics , Tissue Distribution , Water Pollutants, Chemical/pharmacokinetics
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