These mutant rabbits walk on two legs, and geneticists now know why


A sauteur d'Alfort rabbit walking on its front legs, the result of a genetic mutation.

TO sauteur d’Alfort rabbit walking on its front legs, the result of a genetic mutation.
Photo: S. Boucher

A whole lineage of French rabbits has been doing a handstand for almost a century. The acrobatic bunnies are not performing a stunt but a product of stunted genetics, according to an article. published this week in PLOS Genetics.

First discovered in a domesticated rabbit that lived in a suburb of Paris in 1935, the recessive trait is the product of a genetic mutation that could have has been hidden in the genetic code of animals for generations, only to surface then. It is not a superpower. The variety of rabbit, the “sauteur d’Alfort,“Or” the Alfort jumper “- you are also more likely to develop cataracts and go blind.

“The strain has been around ever since to study ocular malformations and pathological locomotion,” said co-author Miguel Carneiro, a geneticist at the University of Porto in Portugal, in an email. “Rabbits carrying this mutation could not survive long in the wild due to its harmful effects.”

Bunnies are bipedal and often blind.

Bunnies are bipedal and often blind.
Image: Carneiro et al. 2021 (Other)

Rabbits walk on all fours when moving slowly but in a hurry, turn to the handstand. method. Now, a team of geneticists has identified the root of all these problems in the Breed DNA.

Illustration for the article titled These Mutant Rabbits Walk on Two Legs, and Geneticists Now Know Why

Photo: S. Boucher

To discover the origins of the animal’s anomalies, the team of geneticists and developmental biologists bred the Alfort jumper with rabbits that jump normally and sequenced the DNA of their offspring. They found that the rabbits that turned out to be bipedal had a mutation on the first chromosome; specifically, a deformed gene called RORB, which expresses a protein of the same name.

“With modern technology, it’s easy to go from a simple recessive disorder to finding the genes,” said co-author Leif Andersson, a geneticist at Uppsala University in Sweden, in a video call. “The expectation was that something was wrong with the spinal cord, because they don’t coordinate their front and back legs. “

Among the jumping Alfort rabbits (perhaps a misnomer, given that bunnies don’t have hops), this was shown to be true. The RORB protein is a transcription factor, which means that it intervenes in several genes, which end up being expressed in traits. Proteins are normally produced on inhibitory interneurons that stop communications moving through the body. (Imagine an operator who refuses to take your calls.) In the strangerwalking rabbits, the interneurons were less present or completely absent, and, in the latter case, the rabbits flexed their hind legs too much, rendering them unable to jump.

“What happens when you move is that these neurons fire all the time and coordinate muscle contractions and receive information about the balance of different limbs,” Andersson said. “This coordination of muscle contraction is not correct in these rabbits.”

You may think that the rabbit handstand is not itself the mutation, but a solution to a debilitating inhibition of the animal’s iconic means of locomotion. Andersson said the two-legged locomotion did not cause the animals any pain that he was aware of.

It is not the only animal that experiences gait interruption due to genetic mutations. Similar behavior was observed in mice with a RORB mutation, and previous work de Andersson found that a mutation in the DMRT3 gene alters the gait of mice and horses. (Interestingly, it’s that mutation at work when you look at the different gait patterns of certain horse breeds, from Tennessee Walkers to Louisiana Fox Trotters.)

Tthanks to genetic science, are mysteries can be deciphered on microscopic scales and could help in better understand the communication centers of our own (human) spinal cord, so that medical research advances.

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