Abstractions

摘要

The make-up of many animals - be it internal or external - Is asymmetrical. In vertebrates such as mice and chickens, two genes, nodal and Pitx, are known to control this left-right body asymmetry. It wasn't clear how far back in time these genes originated, although it was thought that nodal was restricted to deuterostomes, which include all vertebrates; sea urchins, starfish and their kin; and some worms. Nipam Patel (pictured) and his postdoctoral fellow Cristina Grande at the University of California, Berkeley, have found that a version of nodal also controls the directional spiral of snail shells. The duo's findings suggest that nodal's forerunner might have been present in the common ancestor of all bilateral organisms - those with a two-sided body plan. This would make it much more ancient than was originally believed, possibly dating back as far as 650 million years. Patel, an evolutionary developmental biologist, tells Nature about exploring new territory with snails.