, 102:409

Enigma of Y chromosome degeneration: Neo-Y and Neo-X chromosomes of Drosophila miranda a model for sex chromosome evolution

  • Manfred Steinemann
  • Sigrid Steinemann

DOI: 10.1023/A:1017058119760

Cite this article as:
Steinemann, M. & Steinemann, S. Genetica (1998) 102: 409. doi:10.1023/A:1017058119760


Y chromosome degeneration is characterized by structural changes in the chromosome architecture and expansion of genetic inertness along the Y chromosome. It is generally assumed that the heteromorphic sex chromosome pair has developed from a pair of homologues. Several models have been suggested. We use the unique situation of the secondary sex chromosome pair, neo-Y and neo-X (X2), in Drosophila miranda to analyze molecular mechanisms involved in the evolutionary processes of Y chromosome degeneration. Due to the fusion of one of the autosomes to the Y chromosome (about 2 Mya), a neo-Y chromosome and a neo-X chromosome, designated X2, were formed. Thus, formerly autosomal genes are inherited now on a pair of sex chromosomes in D. miranda. Analyzing DNA sequences from the X2 and neo-Y region, we observed a massive accumulation of DNA insertions on the neo-Y chromosome. From the analysis of several insertion elements, we present compelling evidence that the first step in Y chromosome degeneration is driven by the accumulation of transposable elements, especially retrotransposons. An enrichment of these elements along an evolving Y chromosome could account for the switch from a euchromatic into a heterochromatic chromatin structure.

Drosophila evolution sex chromosomes Y chromosome degeneration Y chromosome mutations 

Copyright information

© Kluwer Academic Publishers 1998

Authors and Affiliations

  • Manfred Steinemann
    • 1
  • Sigrid Steinemann
    • 1
  1. 1.Institut für GenetikHeinrich-Heine-UniversitätsseldorfGermany (Phone