Hunting for Darwin's gemmules and Lamarck's fluid: transgenerational signaling and histone methylation.

Recent studies have discovered phenotypes induced by a transient treatment or mutation that persist for multiple generations without mutations in DNA. Both invertebrates and vertebrates exhibit such inheritance, and a range of environmental factors can act as a trigger. Now referred to as transgenerational epigenetic inheritance or TEI, this emerging field faces a big challenge-what molecular mechanisms account for inheritance of TEI phenotypes? This review describes examples of TEI and focuses on the possible role of histone methylation and small RNAs in mediating TEI.