DEVELOPMENTAL DEFECTS OF EMRYONIC ORIC-IN IN NULLOSOMY AND TETRASOMY OF CHROMOSOME 3 IN DROSOPHILA MELANOGASTER

1. 1. From the translocation strain A(3L)3,ri; A(3R)3,sr arise nullosomies and tetrasomies of the whole or half 3rd chromosome of Drosophila melanogaster. All these mutations of the genome are lethal at embryological developmental stages. The results are interpreted as follows: 2. 2. Nullosomy of the whole 3rd chromosome (nullo-3-zygotes) or of one distinct half (half 1") of the 3rd chromosome blocks the fertilization spindle at metaphase. 3. 3. Nullosomy of the other half ("half 2") of the 3rd chromosome disturbs regular migration of cleavage nuclei into the periplasm at the egg surface. 4. 4. Tetrasomy of the whole 3rd chromosome (tetra-3-zygotes) or of one distinct half ("half 1") of the 3rd chromosome causes lethality at the blastoderm stage. 5. 5. Tetrasomy of "half 2" of the 3rd chromosome leads to developmental abnormalities at the phase of germ band contraction and subsequent organ differentiation. © 1969."