Quantitation of type II topoisomerase in oocytes and eggs of Xenopus laevis.

We have generated a monoclonal antibody and a polyclonal antiserum specific for Xenopus laevis topoisomerase II. Using quantitative immunoprecipitation and Western blotting techniques, we have determined the content of topoisomerase II in X. laevis oocytes during oogenesis and in unfertilized eggs. An average stage I oocyte contains 6 pg of topoisomerase II. The content of topoisomerase II per oocyte increases throughout oogenesis to 1.5 ng per stage VI oocyte. The topoisomerase II protein in stage VI oocytes is stored in the germinal vesicles. The cellular content of type II topoisomerase increases significantly when stage VI oocytes are hormonally stimulated to mature into unfertilized eggs.