Developmental arrest in Japanese medaka (Oryzias latipes) embryos exposed to sublethal concentrations of atrazine and arsenic trioxide.
Embryos of the Japanese medaka (Oryzias latipes) were exposed to serial concentrations of atrazine (0, 25, 50, and 100 ppm) and arsenic trioxide (0, 0.025, 0.05, 0.1 ppm) until hatching. Stasis of circulation, blood islands, titanic convulsions, tube heart and mortality were observed in atrazine-treated embryos. Each endpoint exhibited a concentration-response relationship. Only 4% of the embryos hatched in the 25 ppm, and none in the 50 and 100 ppm, probably due to cell death attributed to the embryos' inability to break from the chorion. With arsenic exposure, hatching was inversely correlated to chemical concentration: 86%, 75% and 54% for 0.025, 0.05 and 0.1 ppm, respectively. Hatching periods were also reduced from 7-13 days in controls to 7-11 days in arsenic-treated embryos. This observation was more pronounced with the 0.05 ppm concentration, showing a reduction of about 4 days. Despite this shortage in hatching time, there were no observable morphological abnormalities, as seen with atrazine. The ecological significance of these findings and implications for the development of sublethal toxicity tests using Japanese medaka embryos are important.
Department of Natural Sciences, University of Maryland Eastern Shore, Carver Hall, Princess Anne, MD 21853, USA.
Ali B
AB
Ishaque
Paul B
PB
Tchounwou
Barbara A
BA
Wilson
Teresa
T
Washington
D000014:Abnormalities, Drug-Induced; D000818:Animals; D000077237:Arsenic Trioxide; D001152:Arsenicals; D001280:Atrazine / Q000633:toxicity*; D016923:Cell Death / Q000187:drug effects*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000187:drug effects*; D004781:Environmental Exposure; D005260:Female; D007928:Lethal Dose 50; D009990:Oryzias; D010087:Oxides / Q000633:toxicity*; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D001152:Arsenicals; D010087:Oxides; D014874:Water Pollutants, Chemical; D001280:Atrazine; D000077237:Arsenic Trioxide