Snail shell spiral switched
Nov 26, 2009 3 comments
Researchers in Japan have altered the destiny of a rout of snails by changing the chirality of their shells before birth. By delicately manipulating a batch of developing embryos, the scientists successfully reversed the spiral shells of over 100 Lymnaea stagnalis. The results illustrate the importance of developing embryo structure in determining the physical appearance of snail newborns, say the researchers.
Chirality or "handedness" is a property of those physical systems that cannot be superposed on their mirror images. This property crops up time and again throughout nature from the human hand to DNA to the spin of sub-atomic particles.
The spiral shells of snails are often used as a textbook example of biological structures that possess chirality. Shell-coiling is important because a snail's sexual organs are usually twisted and it is difficult for snails of opposite handedness to reproduce. In addition, the way a snail catches prey depends on the handedness of the micro-organism or plant. The handededness of a snail's shell is inherited from its mother but the gene that gives snail shells their chirality in the first place is yet to be identified.
In this latest research, Reiko Kurodo of the University of Tokyo and her colleagues investigated chirality in Lymnaea stagnalis – a large, air-breathing freshwater snail. They isolated a series of developing embryos that had already acquired a particular handedness – either "dextralized" (right-handed) or "sinistralized" (left-handed). By adding two glass nanorods to an 8-cell bundle they were able to alter its cleavage — the plains along which it sub-divides — to reverse its handedness. Nearly 78% (71 out of 91) of sinistral embryos were reversed to dextral, and 78% (67 out of 86) of dextral embryos were reversed to sinistral.
Reiko told physicsworld.com that she hopes this research will help his team to isolate the gene responsible for giving this snail its handedness. She hopes this knowledge could help researchers to shed light on some of the mystery that still surrounds chirality in nature. "In everyday life, the effects of medicinal drugs, agricultural chemicals and food sweeteners are all dependent on the handedness of their molecules," she said. "Even the origin of life can be explained from the point of chirality."
Henri Brunner, an inorganic chemist at the University of Regensburg, is impressed with the new research describing it as an "extremely interesting result". "Chirality is not only a basic concept for biology and chemistry but also for physics," he said.
This research is published in the latest edition of Nature.
About the author
James Dacey is a reporter for physicsworld.com