[Hidden polyteny in giant embryonic nuclei of Drosophila melanogaster gnu mutants]

Drosophila melanogaster embryos, whose mothers are homozygous for the gnu (a recessive lethal mutation with maternal effect) undergo DNA synthesis but are defective in nuclear division. This leads to formation of giant nuclei in the syncytial blastoderm. The interior spatial chromatin organization and possibility of obtaining polytene chromosomes in these nuclei was analysed. Partial conjugation of homologous chromatids, which is an evidence for cryptic polyteny in the gnu embryos nuclei, was shown.