The role of the genome in the development of the haploid syndrome in Anura

Homozygous diploid embryos were obtained by using Subtelny’s method of nuclear transplantation of haploid nuclei and selection of the eggs which were delayed in first cleavage. Genetically uniform clones of homozygous diploids were produced by serial transplantation and their uniformity assessed as tadpoles. Homozygous diploid nuclear transplant embryos are quite variable within clones, about 20% normal and 80% with the ‘haploid syndrome’. Hetero-zygous diploid transplant embryos are uniform and normal. It is concluded that lack of heterozygosity leads to developmental insta-bility of which the ‘haploid syndrome’ is an expression.