Research Product

Embryos of the inland silverside Menidia beryllina were exposed to 3 teratogens: (1) 2,4-dinitrophenol, (2,4-DNP), (2) 'produced water' (PW), and (3) naphthalene (NPH). Tests were conducted by placing single embryos in glass tissue culture tubes containing 6 ml of saline exposure media. Twenty tubes were used for each exposure concentration and for controls. A severity-index based upon craniofacial, cardiovascular, and skeletal terata was used to rank response each day. The compounds tested caused teratogenic expressions in embryos and larvae exposed from the 2- to 4-cell and blastula stage through 7 to 8 d post-fertilization. However, combined survival in control embryos and larvae, and those exposed to respective teratogens, were not significantly different in 5 of 6 tests, except the 2- to 4-cell embryos exposed to 2,4-DNP. There was a marked increase in the relative frequency of terata with increasing nominal exposure concentrations of each compound. Post-hoc comparison of mean rank scores for severity of expression between control and exposed individuals revealed statistically significant (a= 0.05) levels of terata at 1.8 and 3.2 mg 2,4-DNP 1-1; 10 and 20% PW; and 5.6 and 10 mg NPH 1-1.