Maternal inheritance of P cytotype in Drosophila melanogaster: a "pre-P cytotype" is strictly extra-chromosomally transmitted

Mol Gen Genet. 1993 Oct;241(1-2):115-23. doi: 10.1007/BF00280208.


In Drosophila melanogaster, transposition of the P element is under the control of a cellular state known as cytotype. The P cytotype represses P transposition whereas the M cytotype is permissive for transposition. In the long-term, the P cytotype is determined by chromosomal P elements but over a small number of generations it is maternally inherited. In order to analyse the nature of this maternal inheritance, we tested whether a maternal component can be transmitted without chromosomal P elements. We used a stable determinant of P cytotype, linked to the presence of two P elements at the tip of the X chromosome (1A site) in a genome devoid of other P elements. We measured P repression capacity using two different assays: gonadal dysgenic sterility (GD) and P-lacZ transgene repression. We show that zygotes derived from a P cytotype female (heterozygous for P (1A)/balancer devoid of P copies) and which inherit no chromosomal P elements from the mother, have, however, maternally received a P-type extra-chromosomal component: this component is insufficient to specify the P cytotype if the zygote formed does not carry chromosomal P elements but can promote P cytotype determination if regulatory P elements have been introduced paternally. We refer to this strictly extra-chromosomally inherited state as the "pre-P cytotype". In addition, we show that a zygote that has the pre-P cytotype but which has not inherited any chromosomal P elements, does not transmit the pre-P cytotype to the following generation. The nature of the molecular determinants of the pre-P cytotype is discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Crosses, Genetic
  • DNA Transposable Elements*
  • Drosophila melanogaster / genetics*
  • Extrachromosomal Inheritance*
  • Female
  • Larva
  • Male


  • DNA Transposable Elements