An unusual source offers insight into human health problems, as researchers from Monash University used the naturally fused neck vertebrae of sharks to study neck development gone awry in humans.
As published in PLOS ONE, the study may bring new light to the development or disorders such as Klippel-Feil syndrome, in which the vertebrae of the neck harden together. However, in other animals, like sharks and rays, a neck encased in bone is the norm. And so the team studied the development of fused necks in elephant sharks (otherwise known as Australian ghost shark).
“In some animal species, part of the animal’s body mimics what we see in a human disease. These species are known as ‘evolutionary mutants,’ and analyzing them provides unprecedented access to information in a healthy individual,” said lead researcher Catherine Boisvert of Monash University’s Australian Regenerative Medicine Institute in a Futurity statement.
“We are gaining a better understanding on how these morphologies develop and what developmental pathways (genes and their networks) are involved in producing them. This knowledge may help us better understand the disease in humans.”
The team raised the elephant sharks themselves, hatching them from eggs laid in captivity in Mornington Peninsula, Victoria, Australia. They stained the sharks in order to visualize their cartilage and muscle development.
Necks fused after development
The common belief was that the individual vertebrae of the sharks failed to form in early development, leading to a long, fused chain of vertebrae. But, using microscopic imaging, the scientists discovered that the opposite actually holds true: The neck formed normally, and then fused.
In fact, the way the sharks’ necks formed appeared to be quite similar to another human disease known as fibrodysplasia ossificans progressiva, in which the soft tissues of the body turn into bone.
“Sharks don’t have true bone—instead they have a hard kind of cartilage called prismatic calcified cartilage—and we don’t fully understand yet if the vertebra fusion is due to overdevelopment of cartilage, or if the soft tissue between the vertebrae becomes transformed into cartilage, resulting in fusion,” said Boisvert.
“These sorts of ‘metaplastic’ transformations of the spine have been observed in farmed salmon, and exciting new research is beginning to unravel the genes involved in these transformations. Our goal is to do the same for elephant sharks, rays, and skates.
“All in all, we are coming closer to understanding how a fused neck develops normally or under stressful conditions (as is the case for farmed salmon) in a range of vertebrates at the base of our ancestry.”
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Feature Image: Wikimedia Commons
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