Kagami-mochi (mirror rice cake) is a representative of Japanese New Year decorations. It usually consists of a couple of stacked large round-shaped mochi that resemble ancient bronze mirrors with one daidai (Japanese bitter orange) on top. This year, however, our kagami-mochi is somewhat different from the usual; it is a so-called ribosome-like kagami-mochi. Two stacked mochi likened the ribosome's large and small subunits bind to a gohei (a folded ribbon of paper) that resembles an mRNA encoding (DAIDAI)n amino acid sequence, and a chain of daidais extends upward from the mochi likened the large subunit. It looks like a polypeptide chain itself.
Mochi (rice cake) is indispensable to welcome the New Year in Japan. To use mochi for various purposes such as for food and for ornament, people firstly pound a large mochi and then divide it into small pieces according to the purposes. This process may be similar to that of producing various types of cells from fertilized eggs by asymmetric cell divisions. The woman in the front is dividing a large mochi asymmetrically such that beans that look like Sara (Smad anchor for receptor activation) endosomes and a crescent that looks like Numb (a cell fate-determining factor) are gathered only into the left half. The other woman on the back is preparing a decoration called mochi-bana (rice-cake flower). Note that she is trying to schematize a linage of stem cells and progeny. For drawing this image, we referred to Gonzalez (2015) Nature 528, 196-197, DOI: 10.1038/528196a.