Rabbits typically either jump or walk. However, the sauteur d’Alfort breed can only walk — both on all four legs and on two. Jumping is impossible for it: instead, it lifts its body and moves on its front legs, resembling a circus acrobat walking on their hands.
Researchers from the University of Porto report in the journal PLoS Genetics that the cause of this is a mutation in the RORB gene. It was discovered as a result of crossing acrobatic rabbits with New Zealand rabbits, which are capable of jumping normally.
The offspring turned out to be diverse: some individuals jumped, while others moved on their "hands." By comparing the genomes of both groups, the scientists identified a genetic defect that prevented sauteur d’Alfort rabbits from jumping like their relatives. Essentially, their movement on their front legs is a failed jump: the hind legs push off, while the front legs forget what to do.
The protein encoded by the RORB gene is necessary for spinal cord neurons to coordinate signals from motor neurons. While the rabbit is simply walking slowly, the neurons with the defective RORB function normally, but at the moment it tries to jump, the neurons cannot coordinate the movements of the hind and front legs. Mice with a similar mutation also stand on their front legs when they are about to run. Studying acrobatic rabbits may help better understand certain hereditary musculoskeletal disorders in humans.
