Walking monozygotic twin sisters in the snow are sharing an umbrella. They share the same genotype; however, they seem to have a different personality and taste as their kimono. It has been pointed out that the difference in epigenome would cause such difference in personality. The data printed on their sleeves that was obtained with the bisulfite sequencing (a method that can detect methylation of individual cytosine residues in DNA) and is showing their methylation patterns at a certain locus of the genome suggests that there are epigenetic differences between them. Our knowledge of the relationship between presumed hereditary traits or diseases and epigenetics will increase through studies of monozygotic twin-pairs of which one twin has such traits or diseases.
In recent years, sirtuin family genes have attracted attention because it has been reported that their activation extended lifespan in some animal species and yeast. Sirtuin family consists of several classes, and the majority of them encode NAD+-dependent deacetylase. The arrow in this picture is called 'hamaya,' which is one of Japanese New Year's good luck charms. It is decorated with two 'ema's (wooden votive plaques) likened five-membered ring of ribose with drawings of a crane and a turtle, common symbols of longevity in Japan. The arrow as a whole is mimicking the structure of NAD+, which is required for sirtuin's deacetylase activity.