Creating a six-legged mouse for the first time

In Portugal, a team of scientists has created a 6-legged mouse embryo with an extra pair of hind legs instead of external genitalia. Moisés Mallo, a biologist at the Gulbenkian Institute of Sciences in Oerias, Portugal, and his colleagues are studying a receptor protein called Tgfbr1, which plays a role in embryonic development. They stopped the activity of the Tgfbr1 gene in mouse embryos during pregnancy to study its effects on spinal cord development.

The Tgfbr1 gene codes for a protein called transforming growth factor beta type 1 receptor, which is involved in cellular responses like cell growth and division. Mutations in this gene can increase the risk of skin cancer. The researchers discovered that inactivating the Tgfbr1 gene in mouse embryos led to the development of hind legs instead of external genitalia.

The team found that Tgfbr1 dictates whether structures develop into genitals or legs. This means that inactivating the protein can alter the activity of other genes, resulting in mice with extra legs and no external genitalia. The researchers plan to investigate how Tgfbr1 and related genes affect other systems, such as cancer metastasis, and whether similar processes occur in reptiles with double penises.

In order to study this phenomenon further, the team analyzed embryos collected from mice aged 3-6 months without any distinguishing between male and female embryos since their external genitalia do not differ. The research will focus on understanding the broader implications of the Tgfbr1 gene in development and disease.

Overall, this discovery raises questions about how genetic factors can affect development and potentially lead to new treatments for diseases like skin cancer.

By Aiden Johnson

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