How Y chromosomes become genetically inert.
We have investigated the mechanistic aspects of inactivation of the major larval cuticle protein genes (Lcp1-4) in Drosophila miranda during Y chromosome evolution. The Lcp genes are located on the X2 and neo-Y chromosomes in D. miranda but are autosomally inherited in all other Drosophila species investigated so far. In the neo-Y chromosome all four Lcp loci are embedded within a dense cluster of transposable elements. The X2 Lcp1-4 loci are expressed, while the Y chromosomal Lcp3 locus shows only reduced activity and the Lcp1, Lcp2, and Lcp4 are completely inactive. Our results suggest that Lcp1 and Lcp3 loci on the degenerating Y chromosome of D. miranda are silenced by neighboring transposable elements. These observations support our assumption that the first step in Y chromosome degeneration is the successive silencing of Y chromosomal loci caused by trapping and accumulation of transposons.
Steinemann
M
M
Institut für Genetik und Mikrobiologie, Universität München, Federal Republic of Germany.
Steinemann
S
S
Lottspeich
F
F
D000595:Amino Acid Sequence; D000818:Animals; D002874:Chromosome Mapping; D004251:DNA Transposable Elements; D004330:Drosophila / Q000235:genetics*; D015870:Gene Expression; D007621:Karyotyping; D008297:Male; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D021382:Protein Sorting Signals / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics*; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D014170:Transformation, Genetic; D014960:X Chromosome; D014998:Y Chromosome
D004251:DNA Transposable Elements; D021382:Protein Sorting Signals; D011506:Proteins