MATERNAL AND ZYGOTIC INTERACTIONS BETWEEN THE ABNORMAL OOCYTE MUTATION AND THE SCUTE⁴ INVERSION IN DROSOPHILA MELANOGASTER

C. Malva ¹, T. Labella ¹, A. Manzi ¹, G. Salzano ¹, G. Lavorgna ¹, L. De Ponti ¹, and F. Graziani ¹

¹ International Institute of Genetics and Biophysics, Consiglio Nazionale delle Ricerche, 80125 Naples, Italy

The authors have studied the interaction between the abnormal oocyte mutation and an inversion of the X chromosome, In( 1)sc⁴, which has a proximal breakpoint in or near the heterochromatic region (ABO) that maternally interacts with the abo product. It has been demonstrated that the presence of X chromosomes carrying this inversion, besides a marked increase in the severity of the maternal effect of the abo mutation, produces a zygotic effect resulting in the lethality of the progeny of stocks homozygous for abo and sc⁴. These results indicate that the sc⁴ inversion carries an abnormal region indispensable for the development of abo zygotes from sc⁴;abo mothers.