title: Telomeric trans-silencing in Drosophila melanogaster: tissue specificity, development and functional interactions between non-homologous telomeres.
abstract: BACKGROUND
  The study of P element repression in Drosophila melanogaster led to the discovery of the telomeric Trans-Silencing Effect (TSE), a homology-dependent repression mechanism by which a P-transgene inserted in subtelomeric heterochromatin (Telomeric Associated Sequences, "TAS") has the capacity to repress in trans, in the female germline, a homologous P-lacZ transgene located in euchromatin. TSE can show variegation in ovaries, displays a maternal effect as well as an epigenetic transmission through meiosis and involves heterochromatin and RNA silencing pathways.
  
  
  RESULTS
  Here, we analyze phenotypic and genetic properties of TSE. We report that TSE does not occur in the soma at the adult stage, but appears restricted to the female germline. It is detectable during development at the third instar larvae where it presents the same tissue specificity and maternal effect as in adults. Transgenes located in TAS at the telomeres of the main chromosomes can be silencers which in each case show the maternal effect. Silencers located at non-homologous telomeres functionally interact since they stimulate each other via the maternally-transmitted component. All germinally-expressed euchromatic transgenes tested, located on all major chromosomes, were found to be repressed by a telomeric silencer: thus we detected no TSE escaper. The presence of the euchromatic target transgene is not necessary to establish the maternal inheritance of TSE, responsible for its epigenetic behavior. A single telomeric silencer locus can simultaneously repress two P-lacZ targets located on different chromosomal arms.
  
  
  CONCLUSIONS
  Therefore TSE appears to be a widespread phenomenon which can involve different telomeres and work across the genome. It can explain the P cytotype establishment by telomeric P elements in natural Drosophila populations.
authors.affiliation: Laboratoire "Dynamique du Génome et Evolution", Institut Jacques Monod, UMR7592, CNRS-Universités Paris 6 et 7, Paris, France.
authors.forename: Thibaut
authors.initials: T
authors.lastname: Josse
authors.forename: Corinne
authors.initials: C
authors.lastname: Maurel-Zaffran
authors.forename: Augustin
authors.initials: A
authors.lastname: de Vanssay
authors.forename: Laure
authors.initials: L
authors.lastname: Teysset
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Todeschini
authors.forename: Valerie
authors.initials: V
authors.lastname: Delmarre
authors.forename: Nicole
authors.initials: N
authors.lastname: Chaminade
authors.forename: Dominique
authors.initials: D
authors.lastname: Anxolabéhère
authors.forename: Stéphane
authors.initials: S
authors.lastname: Ronsseray
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D004251:DNA Transposable Elements; D004331:Drosophila melanogaster / Q000235:genetics*; D044127:Epigenesis, Genetic; D005786:Gene Expression Regulation; D020868:Gene Silencing; D008954:Models, Biological; D008957:Models, Genetic; D010641:Phenotype; D034622:RNA Interference; D016615:Telomere / Q000648:ultrastructure*; D013696:Temperature; D019076:Transgenes
chemical_list: D004251:DNA Transposable Elements