According to Nature Medicine, researchers discovered that the interplay of two proteins, one of which drives ridge formation and the other of which inhibits it, causes ridges to sprout in periodic waves from three different places on the fingertip.
A unique fingerprint pattern is formed when waves clash in precisely defined zones. Denis Headon, a developmental biologist at the University of Edinburgh and co-author of the study, claims that “the key isn’t just the chemical elements” when developing complex patterns like arches, loops, and whorls.
Although fingerprint patterns have long been used for identifying and diagnosing particular developmental problems, many individuals feel they aid with grip and sensitivity. Last year, researchers Headon and colleagues discovered that some genes involved in limb development are also crucial in determining fingerprint patterns. However, several of these genes exhibited limited activity during fingerprint development, suggesting that they did not play an essential role in forming ridges.
Headon and his colleagues observed prenatal fingerprint development to understand more about fingerprint patterns. Gene activity investigations of cells forming fingerprint ridges have revealed that their growth is initially similar to that of a hair follicle. Ridge cells, unlike follicle cells, did not incorporate dermal cells in their gene activity pattern.
The findings supported the idea of a “turning reaction-diffusion system,” in which the starting molecule promotes itself and the inhibiting molecule. According to Marian Ros, a developmental biologist at the Institute of Biomedicine and Biotechnology of Cantabria in Santander, Spain, the outcome is a self-organizing system that forms periodic patterns.
Alan Turing, a mathematician, proposed such systems in 1952 as a chemical explanation for developmental processes such as the arrangement of leaves on a plant or tentacles on microscopic aquatic animals known as hydras.
Many typical biological traits, such as the vivid coloring of some tropical fish scales and the intricate patterns seen on bird feathers, have been linked to Turing reaction-diffusion processes in the years after. Headon and colleagues studied the ridges on mice toes and human cells cultivated in 3D cultures to determine what molecules control fingertip patterning.
Researchers discovered that the WNT protein, previously known to promote hair follicle growth, also promotes the production of ridges. They are part of the BMP-regulated Turing reaction-diffusion system. The ridges may be traced to one of three points on the finger: the tip, the finger bend, or the middle of the tip (see “How prints are patterned” for more on this).
Headon and his colleagues constructed wave patterns such as arches, loops, and whorls by varying the wave’s onset timings, angle offsets, and origin places. According to Cheng-Ming Chuong, a developmental biologist and professor at USC Los Angeles, these waves will inevitably meet. When these particles meet, they cause turbulence, contributing to distinct fingerprint patterns.
