Sunday, December 16, 2012
What have fingers and toes got to do with genitalia?: The Turing mechanism
A research team at the Institut de Recherches Cliniques de Montreal (IRCM) worked with others in a multidisciplinary research project to identify the mechanism responsible for generating fingers and toes. By combining genetic studies with mathematical modeling, the scientists provided experimental evidence supporting a theoretical model for pattern formation known as the Turing mechanism. In 1952, mathematician Alan Turing proposed mathematical equations for pattern formation, which describes how two uniformly-distributed substances, an activator and a repressor, trigger the formation of complex shapes and structures from initially-equivalent cells. By studying the role of Hox genes (HOXA13 gene ) during limb development, the team were able to demonstrate the patterning process to generate fingers and toes relies on a Turing-like mechanism. In humans, as in other mammals embryo's development is controlled, in part, by "architect" genes known as Hox genes. These genes are essential to the proper positioning of the body's architecture, and define the nature and function of cells that form organs and skeletal elements. Hox genes act as modulators of a Turing-like mechanism, which was further supported by mathematical tests performed by other researchers. The study published in Science was a collaborative project between the teams supervised by Drs. Marie Kmita (IRCM), James Sharpe (CRG Barcelona) and Maria A. Ros (University of Cantabria , Spain). The research conducted at the IRCM was funded by the Canadian Institutes of Health Research and the Canada Research Chairs Program.
Previously the University of Michigan revealed the human HOX gene function is also responsible for genital development with gene mutation responsible for genital, as well as limb, abnormalities. This may explain why so many vertebrates have five digits on their hands and feet - a number favored for over 300 million years of evolution. With one gene regulating both the number of digits and reproductive function, the one trait (digit number) will continue to be expressed in those individuals capable of reproducing.
Rushikesh Sheth et al (2012) Hox Genes Regulate Digit Patterning by Controlling the Wavelength of a Turing-Type Mechanism Science Vol. 338 no. 6113 pp. 1476-1480.