PRODUCTION OF TRIPLOID AND GYNOGENETIC DIPLOID XENOPUS BY COLD TREATMENT

Methods are described for producing triploids and gynogenetic diploids of Xenopus laevis. A high frequency of triploids was obtained when the eggs were refrigerated at 2-3 C for 15 min, starting 10–16 min after insemination. By this procedure, the suppression of second polar body emission was cytologically evident. The occurrence of triploidy was confirmed by chromosome and nucleolar counts, as well as microspectrophotomctric determination of nuclear DNA contents. Thus, more than 60% of the feeding tadpoles were triploids. Using the refrigeration method for inducing triploids, gynogenetic diploids were produced by inseminating eggs by sperm previously irradiated with ultraviolet light. Triploids and gynogenelic diploids thus obtained developed normally beyond metamorphosis, and have been growing well for more than 1.5 years.