CALCIUM BUFFER INJECTIONS INHIBIT OOPLASMIC SEGREGATION IN MEDAKA EGGS

Injection of the weak (K-D = 1.5 mu M) calcium buffer 5,5'-dibromo-BAP TA into fertilized medaka eggs inhibited the formation of the blastodi sc at the animal pole, the movement of oil droplets toward the vegetal pole, and cytokinesis. These inhibitory actions were dependent upon t he concentration of the buffer but were independent of free [Ca2+] in the injectate. Because this buffer has previously been shown to substa ntially suppress zones of elevated calcium at the animal and vegetal p oles of the medaka egg, the results of the present study suggest that these zones are necessary for normal segregation of the ooplasm and it s inclusions in the medaka egg.