EFFECTS OF 2, 4-DINITROPHENOL ON THE EARLY DEVELOPMENT OF THE TELEOST, ORYZIAS LATIPES

¹ From the Thompson Biology Laboratory, Williams College, Williamstown, Mass.

A study has been made of the effect of 2, 4-dinitrophenol on the development of four embryonic stages of the teleost, Oryzias latipes, i.e. early and late cleavage, closure of the blastopore and optic vesicle stages. Both the sensitivity of the whole organism and constituent parts to the drug decreases with age and differentiation. The general effect is cumulative and proportional to the concentration and length of exposure. In addition to inhibitory and retardative effects, other developmental abnormalities include those of the heart and blood vessels, myotomes, nervous system, body shape, etc.

Concentrations of 1:10,000 up to 1:1,900,000 were used, but the most significant results appeared at concentrations from 1:40,000 to 1:200,000. When the chorion is pricked there is some difference in the effective concentrations. No evidence of any stimulation was seen either in the developmental rate or in the hatching time. Gastrulation was either inhibited or retarded and no examples of exogastrulation were seen. If exposure has not been too long, recovery takes place to a more or less extent in fresh water.

Some of the results of the present study have been duplicated in the amphibia by various agents and in fish by X-rays. In general no special type of teratological embryo was produced but the results are fairly consistent and reproducible. It does not seem possible to attribute the effects to a specific action of this drug and hence to increased metabolic and respiratory rates alone, unless the change produces toxic products of which the embryo is unable to rid itself.