Stable and Reversible Transgenerational Inheritance of Chromatin States in Drosophila. Drosophila melanogaster strain:Oregon-R w1118

Transgenerational Epigenetic Inheritance (TEI) conveys the passage of epigenetically determined phenotypic traits through multiple generations. In most documented cases, TEI was reported to gradually decline and eventually vanish. The epigenetic state of a Polycomb Response Element (PRE) was previously shown to drive transgenerational inheritance of phenotypes in Drosophila melanogaster. Here, we established stable and isogenic epilines, demonstrating their ability to transmit two opposing chromatin states that can be reset to an intermediate naïve state. We show that the differential inheritance of Polycomb-mediated H3K27me3 mark is crucial for TEI. Furthermore, we show that the environment can modulate the expressivity of the epialleles and we extend our paradigm to naturally occurring genetic makeups. This work shows that the inheritance of genetically induced epialleles follows specific rules and can contribute to heritable phenotypic variability. Finally, the epilines described here constitute a powerful, reliable and simple model that is amenable for molecular and genetic investigations on TEI.