Abstract:Methyl mercury (MeHg) is highly neurotoxic, affecting visual function in addition to other central nervous system functions. The effect of mercury intoxication on the amplitude of horizontal cell responses to light was studied in the retina of the fish Hoplias malabaricus. Intracellular responses were recorded from horizontal cells of fish previously intoxicated with MeHg by intraperitoneal injection (IP group) or by trophic exposure (T group). Only one retina per fish was used. The doses of MeHg chloride admi… Show more
“…There is some evidence that tropical fish have a much faster uptake of mercury and a higher bio-accumulation factor (Oliveira Ribeiro et al 2000). Tanan et al (2006) reported effects on the retina of the tropical Hoplias malabaricus at methylmercury levels that may be encountered in the field. Possible effects from mercury on the fish population of the PWS area are not visible at present; the CI AquaRAP ichthyologists described the fishes as being ''in excellent condition; the predators such as S. rhombeus and H. aimara were abundant and of very large size; the colors of the ornamental fishes were brilliant; there were almost no parasites or infections found on the fishes'' (Mol et al 2006).…”
Mercury levels in sediment and predatory fish were measured for 53 localities in Suriname. The average mercury level in bottom sediment surpassed the Canadian standard for sediment in most localities, except the coastal plains. Of the predatory fish, 41 % had a mercury level above the European Union standard for human consumption of 0.5 lg g -1 . Highest mercury levels were found in fish from the Brokopondo Reservoir and from the Upper Coppename River. High levels of mercury in fish in pristine areas are explained by atmospheric transportation of mercury with the northeastern trade winds followed by wet deposition. Contrary to gold mining areas, where mercury is bound to drifting sediments, in ''pristine'' areas the mercury is freely available for bio-accumulation and uptake. Impacts on piscivorous reptiles, birds, and mammals are unknown, but likely to be negative.
“…There is some evidence that tropical fish have a much faster uptake of mercury and a higher bio-accumulation factor (Oliveira Ribeiro et al 2000). Tanan et al (2006) reported effects on the retina of the tropical Hoplias malabaricus at methylmercury levels that may be encountered in the field. Possible effects from mercury on the fish population of the PWS area are not visible at present; the CI AquaRAP ichthyologists described the fishes as being ''in excellent condition; the predators such as S. rhombeus and H. aimara were abundant and of very large size; the colors of the ornamental fishes were brilliant; there were almost no parasites or infections found on the fishes'' (Mol et al 2006).…”
Mercury levels in sediment and predatory fish were measured for 53 localities in Suriname. The average mercury level in bottom sediment surpassed the Canadian standard for sediment in most localities, except the coastal plains. Of the predatory fish, 41 % had a mercury level above the European Union standard for human consumption of 0.5 lg g -1 . Highest mercury levels were found in fish from the Brokopondo Reservoir and from the Upper Coppename River. High levels of mercury in fish in pristine areas are explained by atmospheric transportation of mercury with the northeastern trade winds followed by wet deposition. Contrary to gold mining areas, where mercury is bound to drifting sediments, in ''pristine'' areas the mercury is freely available for bio-accumulation and uptake. Impacts on piscivorous reptiles, birds, and mammals are unknown, but likely to be negative.
“…42,43 Furthermore, retinal damage has been found in methylmercury intoxication as a reduction of the density in amacrine and bipolar cells, and alterations of the horizontal cells by electrophysiological measurements. 44,45 In humans exposed to Hg vapor, electrophysiological evidence for impairment of the peripheral retina has been found in full-field electroretinogram responses, and in the central retina by multifocal electroretinogram responses. 5 The authors argued that the involvement of the central retina, in addition to the retinal periphery, was in line with psychophysical results showing losses of central visual functions (luminance spatial contrast sensitivity and color vision), 5 confirmed by the present study.…”
“…7.5b mostra uma dessas imagens. Para cada imagem os colaboradores identificaram as coordenadas espaciais dos neurônios com a ajuda do software NIH Scion No caso da intoxicação por baixas doses, outros trabalhos descrevem que ocorre um aumento da resposta eletrofisiológica nas células horizontais [65] e também um pequeno aumento no número de células [6]. Nesses casos, não ocorrem alterações significativas no arranjo espacial das células da retina, conforme demonstrado peloíndice de hexagonalidade.…”
Section: Análise Da Hexagonalidade Em Retinas De Hoplias Malabaricusunclassified
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