Activation of Eggs by Oxidation-Reduction Indicators

Abstract

Eggs of Urechis caupo and Strongylocentrotus purpuratus were placed in sea water containing oxidation-reduction dyes whose E''o values at pH 7.0 ranged from + .195 to [long dash].258, giving an rH from 20.5 to 5.2. The eggs were immersed from 1 min. to 24 hrs. and then replaced in sea water. Samples -were taken out at intervals. Activation was seen when eggs were exposed chiefly from 1-20 mins. In S. purpuratus, development progressed to the pluteus stage in 1-2% of the eggs; in U. caupo, it progressed to the trochophore stage in 50% of the eggs. The maximum percentage of activation varied from 70% in Urechis to 10% in S. purpuratus. In the latter sp., the best results were obtained with indigo monosulfonate, which has an rH of 8.7. The rH of the sperm of this sea urchin was 9.0-9.5. In Urechis, methylene blue and indigo tetrasulfonate gave the best results. The rH values of these dyes are 14.4 and 12.1, respectively, while that of the sperm of Urechis is 13-14. In a few cases, neutral red produced fertilization membranes. o-Cresol and Janus green showed no results. Development in all cases was slower than that of eggs fertilized by sperm and a smaller proportion developed. The results show that there is a direct relation between the oxidation-reduction potential and the fertilization of eggs.