The Sonic Hedgehog (Shh) gene is a fundamental component in developmental biology. This gene and its encoded protein play a crucial role in orchestrating the formation of an organism from a single cell. What makes this gene particularly memorable is its unusual and intriguing name. The origin of the “Sonic Hedgehog” moniker is a curious tale that highlights the often-unconventional naming conventions found within scientific discovery.
The Story Behind the Name
The journey to the Sonic Hedgehog name began with discoveries in the fruit fly, Drosophila melanogaster. In 1980, geneticists Christiane Nüsslein-Volhard and Eric Wieschaus identified the original hedgehog (hh) gene during screens for genes controlling embryonic development. When this gene was mutated, the fruit fly embryos developed a distinctive appearance. Instead of their normal segmented pattern, the embryos were covered with small, pointy projections, or denticles, resembling a hedgehog.
As research progressed, scientists began searching for similar genes, known as homologs, in vertebrates. They discovered several such genes, including “desert hedgehog” and “Indian hedgehog,” named after actual hedgehog species. A third vertebrate homolog needed a distinctive name. Robert Riddle, a postdoctoral fellow in Cliff Tabin’s lab, is credited with naming this gene “Sonic Hedgehog.” His inspiration came from the popular Sega video game character, Sonic the Hedgehog, after he encountered an advertisement or comic book featuring the speedy blue character.
The Gene’s Role and Its Link to the Name
The Sonic Hedgehog (SHH) gene encodes a protein that acts as a vital signaling molecule during embryonic development. This protein is instrumental in guiding cell growth, specialization, and the precise patterning of various body structures. Its widespread influence helps establish the blueprint for an organism, ensuring that organs and limbs develop in their correct positions and forms.
Specifically, Sonic Hedgehog is involved in the formation of the central nervous system, including the brain and spinal cord, and plays a role in the development of limbs and digits. For instance, it helps separate the single eye field in the early embryo into two distinct eyes. The “hedgehog” part of the name subtly relates to its function in establishing boundaries and patterns, much like the segmented or spiky appearance observed in the original mutant fruit flies. The “Sonic” prefix, while inspired by a video game character, reflects the gene’s rapid and far-reaching signaling activity, which is crucial for orchestrating complex developmental processes across the embryo.