A possible maternal-effect mutant of Xenopus laevis I. Cytological and biochemical analyses of the unfertilized eggs and embryos.

In an effort to define the cause of the developmental arrest of offspring from a certain Xenopus female (designated as No. 65), we have examined eggs and embryos from the female both cytologically and biochemically. Light and electron microscopic observations revealed that all of the blastomeres from embryos of female No. 65 had multiple small spherical nuclei, while wild-type counterparts had a single lobulated nucleus. Two-dimensional gel electrophoretic analyses demonstrated that a major acidic protein, whose molecular weight was 38 kDa, was always found in samples from wild-type unfertilized eggs and embryos, but was not recognizable in those from female No. 65. These facts, coupled with the death of the offspring at gastrulation, suggest the possibility that female No. 65 carries a mutation of the ova-deficient type.