title: Developmental genome rearrangements in ciliates: a natural genomic subtraction mediated by non-coding transcripts.
abstract: Several classes of non-protein-coding RNAs have recently been identified as epigenetic regulators of developmental genome rearrangements in ciliates, providing an interesting insight into the role of genome-wide transcription. In these unicellular eukaryotes, extensive rearrangements of the germline genome occur during the development of a new somatic macronucleus from the germline micronucleus. Rearrangement patterns are not dictated by the germline sequence, but reproduce the pre-existing rearrangements of the maternal somatic genome, implying a homology-dependent global comparison of germline and somatic genomes. We review recent evidence showing that this is achieved by a natural genomic subtraction, computed by pairing interactions between meiosis-specific, germline scnRNAs (small RNAs that resemble metazoan piRNAs) and longer non-coding transcripts from the somatic genome. We focus on current models for the RNA-based mechanisms enabling the cell to recognize the germline sequences to be eliminated from the somatic genome and to maintain an epigenetic memory of rearrangement patterns across sexual generations.
authors: Ecole Normale Supérieure, Laboratoire de Génétique Moléculaire, 75005 Paris, France. Sandra.Duharcourt@ens.fr
authors: Sandra
authors: S
authors: Duharcourt
authors: Gersende
authors: G
authors: Lepère
authors: Eric
authors: E
authors: Meyer
mesh_terms: D000818:Animals; D016798:Ciliophora / Q000235:genetics* / Q000254:growth & development*; D044127:Epigenesis, Genetic; D015321:Gene Rearrangement; D016678:Genome / Q000235:genetics*; D005854:Germ Cells / Q000378:metabolism; D022661:RNA, Untranslated / Q000235:genetics*
chemical_list: D022661:RNA, Untranslated