Effect of ethylenebis (dithiocarbamic acid)disodium salt(nabam)and ethylenebis(dithiocarbamato)manganese(maneb) on Xenopus laevis development.

Abstract

AbstractThe fungicides ethylenebis [dithiocarbamic acid] (nabam) and ethylenebis [dithiocarbamato] manganese (maneb) were dissolved in a modified Holtfreter's solution at concentrations of 0.1–5 ppm. Thirty to 60 yolk‐plug Xenopus laevis embryos were placed for 1–10 days in 200 ml of different concentrations of the fungicide solution. Treated and control (Holtfreter's only) embryos were fixed in Bouin's fluid or formalin for light microscopy, and in glutaraldehyde‐formaldehyde for electron microscopy. Gross morphological and histological observations were made. The first changes observed in experimental embryos was a slight growth retardation and a transient absence or reduction in melanogenesis in the eye and on the rest of the body. The tail was shortened and the notochord had a distinct waviness. Animals in higher concentrations were unable to swim as well as controls. Histological examination, both light and electron microscopic, showed a general decrease in melanin content of the melanosomes in the pigmented retina. The notochord was increased in diameter; in sagittal sections the foldings were obvious. These results indicate that minute doses of these commonly used fungicides are harmful to the normal development of amphibian embryos.