Glowing Beacon towards Transgenic Cloning
A cloned beagle named Ruppy – short for Ruby Puppy – is the world's first transgenic dog. She and four other beagles all produce a fluorescent protein that glows red under ultraviolet light. A group of scientists at the Seoul National University in South Korea created the dogs by cloning fibroblast cells that express a red fluorescent gene produced by sea anemones.
Two of the scientists in the group; Byeong-Chun Lee and Woo Suk Hwang were part of the original team who created the first cloned dog named Snuppy in 2005
This experiment basically is splicing fluorescent genes from the sea anemones with a beagle dog egg. This has an absent nucleus due to the insertion of a virus which allowed the fluorescent gene from the sea anemones into the beagle eggs and allowed it to begin dividing. Once embryotic cycle kicked in they inserted the embryos which were dividing on a Petri dish into surrogate mothers.
Though the process and result seem pointless in the short term, these experiments don’t just produce a “glowing dog” but rather opened up new pathways of using dogs as models to help with research of diseases, certain cancers and blindness. These model dogs could pave the way in discovering new vaccines for diseases, showing the world that cloning and transgenesis can be applied to a wide range of animals.
However, other researchers who study domestic dogs as stand-ins for human disease are less certain that transgenic dogs will become widespread in research.
Dogs already serve as models for diseases such as narcolepsy, certain cancers and blindness. And a dog genome sequence has made the animals an even more useful model by quickening the search for disease-causing genes. Most dog genetics researchers limit their work to gene scans of DNA collected from hundreds of pet owners.
Besides the low efficiency of cloning – just 1.7 per cent of embryos came to term – another challenge to creating transgenic dogs is controlling where in the nuclear DNA a foreign gene lands. Using retrovirus to transfer the genes to the fibroblast cells works when getting the gene into the cell but there is no way to control the virus and where it inserts the selected fluorescent gene within the cell.
"I do not know of specific situations where the ability to produce transgenic dogs represents an immediate experimental opportunity," Barsh adds. But transgenic dogs will give researchers another potential tool to understand disease.
However, Nathan Sutter, a geneticist specialising in dogs at Cornell University in Ithaca, New York, says "transgenesis is labourious, expensive and slow".
Add the expense of caring for laboratory-reared dogs and negative public perceptions and it could mean few researchers turn to transgenic dogs like Ruppy, he says: "it's not on my horizon as a dog geneticist at all."
Journal reference: genesis (DOI: 10.1002/dvg.20504)