Transposons (transposable elements), discovered in maize by Barbara McClintock in 1948, are DNA sequences that can change their positions within the genome. Transposition of transposons can introduce mutations in the host genome. Actually, there was a close and astonishing relationship between transposons and the culture of the Edo era. In late Edo, a large number of mutant Asagaos (Japanese morning glory) were isolated, and it became popular to cultivate them; in fact, many mutations were caused by transposons. These mutant Asagaos have been collected by researchers and are currently maintained by a group led mainly by Kyushu University. See the website of National BioResource Project (NBRP) “Asagao” (http://www.shigen.nig.ac.jp/asagao/) for further details.
One of the highlights of the month of July in Japan is Tanabata (Star Festival). Tanabata, a festival to pray to the stars in the Milky Way in summer, was imported from ancient China. People in Edo era started to decorate bamboo branches with ‘tanzaku’ (small pieces of paper) on which they wrote their wishes, and to pray the wishes would come true. The bamboo branches in this drawing are likened to histone tails (H2A, H2B, H4 and H3 from the left). The tanzakus represent epigenetic modifi cations (acetylation, methylation and phosphorylation) of amino acid residues in histone tails. If you use this histone bamboo, mind that you have to phrase your wishes with the types, positions and combinations of decorations (or modifications). You need a textbook to perform modifi cations correctly.