The activation of a neocentromere in Drosophila requires proximity to an endogenous centromere.

摘要: The centromere is essential for proper segregation and inheritance of genetic information. Centromeres are generally regulated to occur exactly once per chromosome; failure do so leads chromosome loss or damage linked material. mechanism faithful regulation activity number unknown. presence ectopic centromeres (neocentromeres) has allowed us probe the requirements characteristics activation, maintenance, structure. We utilized derivatives that placed a 290-kilobase “test segment” in three different contexts within Drosophila melanogaster genome—immediately adjacent (1) centromeric chromatin, (2) centric heterochromatin, (3) euchromatin. Using irradiation mutagenesis, we freed this test segment from source genetically assayed whether liberated fragment” exhibited activity. observed fragment behaved differently with respect when chromosomal contexts, despite an apparent sequence identity. Test segments juxtaposed active produced fragments neocentromere activity, whereas far did not. Once established, was stable. imposition on DNA supports hypothesis identity capable spreading epigenetically.