Acrobats involuntarily
A mutation has been discovered that causes rabbits to run on their front paws
Sergey Vasiliev, Naked Science
In the 1930s, breeders from the French Alfort bred a new breed of rabbits – Sauteur d'Alfort ("Alfort jumper"). The name was chosen, apparently, ironic: just jump these rabbits do not know how. If necessary, to accelerate, they rise on their front paws and move them, literally "walking on their hands." In addition, they often suffer from cataracts, up to complete blindness, and do not live long. These animals are used in laboratories to study the genetics of visual and motor disorders.
Earlier experiments have shown that the loss of the ability to jump is associated with a mutation in a single gene. And now a group of European scientists led by Leif Andersson from Uppsala University has managed to identify this gene and explain its strange effect on "gait". They write about this in an article published in the journal PLOS Genetics (Carneiro et al., A loss-of-function mutation in RORB disrupts saltatorial locomotion in rabbits).
Scientists crossed Sauteur d'Alfort rabbits with a New Zealand white breed capable of normal jumps, showing that the mutation is recessive, and both copies of the gene must be carried to manifest it. Next, the scientists sequenced the genome of the offspring and compared the DNA of those who are able to jump with those few who received both recessive alleles, and with them the need to move on their front paws.
This work pointed to the RORB gene encoding the ROR-beta protein ("orphan RAR-bound beta receptor"). Soon his role was confirmed on the genome of purebred Sauteur d'Alfort rabbits: they all carry a mutant copy of RORB. After analyzing the available data on the genomes of domestic and wild rabbits of different breeds, as well as other animals, scientists found that they do not have such a mutation.
The ROR-beta protein plays the role of a transcription factor: by binding to DNA, it controls the activity of certain genes and through this chain manifests itself in the corresponding external signs. RORB-controlled genes are active in inhibitory interneurons of the spinal cord. These cells of the nervous system play the role of an intermediate link in the transmission of signals between the brain, on the one hand, and motor and sensory neurons, on the other.
In rabbits with mutant RORB, these interneurons were less developed, or even absent altogether. It can be said that the brakes "broke down" in the control system of their movements, and the brain could not coordinate normal jumps with the simultaneous participation of right and left, front and rear limbs. With the usual slow crawling on the grass, it is almost imperceptible, but if the rabbit needs to accelerate, he has no choice but to resort to a new ridiculous method – "on his hands".
Portal "Eternal youth" http://vechnayamolodost.ru