Evidence for multiple forms of heritable RNA silencing.

Heritable gene silencing has been proposed to rely on DNA methylation, histone modifications, and/or non-coding RNAs in different organisms. Here we demonstrate that multiple RNA-mediated mechanisms with distinct and easily detectable molecular signatures can underlie heritable silencing of the same open-reading frame in the nematode . Using two-gene operons, we reveal three cases of gene-selective silencing that provide support for the transmission of heritable epigenetic changes through different mechanisms of RNA silencing independent of changes in chromatin that would affect all genes of an operon equally.

Heritable epigenetic changes at single genes: challenges and opportunities in Caenorhabditis elegans.

Organisms rely on stereotyped patterns of gene expression for similar form and function in every generation. The analysis of epigenetic changes in the expression of different genes across generations can provide the rationale for measured actions in one generation that consider impact on future generations.

Mating can initiate stable RNA silencing that overcomes epigenetic recovery.

Stable epigenetic changes appear uncommon, suggesting that changes typically dissipate or are repaired. Changes that stably alter gene expression across generations presumably require particular conditions that are currently unknown. Here we report that a minimal combination of cis-regulatory sequences can support permanent RNA silencing of a single-copy transgene and its derivatives in C.