Scientific accident results in creation of six-legged mouse without genitals

Lisbon, Portugal

A rare mouse embryo, which has six legs and no genitals, was created by scientists in an accident. This never-before-seen creation reflected how changes made to the DNA can have severe impacts on development.

A team of scientists from Portugal's Gulbenkian Science Institute was trying to understand how a specific protein works in the middle stages of embryo growth. 

Embryos at the beginning are only a bundle of identical cells. When they develop, the cells specialise and start forming different body parts. Generally, the development starts from the head and goes back towards the tail. The human embryos also have tails in the early days, however, they disappear after roughly eight weeks. 

It is well-known to scientists that in most four-limbed mammals, both the hind limbs and the external genitalia (the penis or clitoris) get developed from the same early structures.

The research team, headed by developmental biologist Moises Mallo, emphasised one particular receptor protein known as Tgfbr1.  

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The protein, which is officially known as transforming growth factor beta receptor I, has involvement in the expression of genes. It helps in deciding which ones to be activated in what place and what each cell should turn into - a blood cell, muscle tissue or a nerve cell. 

Receptor protein plays a key role in magical creation

In this groundbreaking study, Tgfbr1 was inactivated by the researchers in mouse embryos roughly halfway through development to understand how the spinal cord's development was affected.

The researchers discovered an embryo which had developed extra limbs and had no genitals. Also, various organs were growing outside of its body. 

It appeared that in the absence of this protein, other genes came into action and the cells grew into more legs and not genitals.

The scientists are now hoping that more research into this will help them determine if Tgfbr1 and its relatives can affect DNA in other systems, like metastatic cancer.

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In the journal Nature Communications, the scientists said, "Identification (the) mechanisms and determining whether they also operate in other physiological and pathological processes under the control of members of the (Tgfbr1) family might have far-reaching implications for our understanding of morphogenetic processes and disease."

The DNA of the tumours is already targetted by existing cancer treatments which can give a better understanding of how they work and help scientists create new and better options.

(With inputs from agencies)