Researchers in South Korea have announced the creation of four healthy puppies that glow bright red under UV light. Reported in the journal Genesis, the team from the College of Veterinary Medicine at Seoul National University claim the new model will be of importance in the study of human genetic disease.
Using SCNT (somatic cell nuclear transfer), the procedure used to create Dolly the sheep, the team took DNA from a dog skin cell and 'implanted' it inside an egg from another dog that had been stripped of its own genetic material, before implanting the resulting embryo back into a surrogate mother. However, in preparing the DNA for transfer, the team used a virus to deliver the gene for the red fluorescent protein (RFP) into the skin cells. Only those skin cells expressing RFP were chosen for SCNT. Remarkably, the gene was duplicated as the fertilised egg divided, until all tissues carried a copy.
From a total of 344 embryos transplanted into 20 surrogate dogs, six pregnancies went full-term, though two of these died during birth. Autopsies revealed that brain, spinal cord, heart, testis, lung, kidney, muscle, intestine, thymus, spleen, skin, adrenal gland, bone, liver, bladder and stomach all glowed intensely under UV light, as photographs in the report confirm. RFP was so strongly expressed that even in daylight, the puppy's skin and nails have a reddish hue.
'What's significant in this work is not the dogs expressing red colours, but that we planted genes into them', says Professor Lee Byeong-chun, who led the research. Defective copies of genes, implicated in conditions such as Parkinson's, might be similarly expressed in canine models, which could serve as relevant models for drug design, for example.
Similar models have previously been created in mice, pigs and cats. The paper makes the case that whilst transgenic mice are commonly created for the study of human disease, 'the size, genetic and physiological differences between humans and rodents have put limitations on applying the findings from the rodent study to the human'. Moreover, the authors state that many genetic diseases are shared between man and dog (224 in total), making a transgenic dog a useful tool for research.
Professor Byeong-chun has announced that his team has started to design transgenic dogs expressing a more relevant gene, however no further details have so far been released. Byeong-chun was previously a researcher with the Hwang Woo-Suk team, who in 2006 was indicted with claims of embezzlement linked to faked stem cell research. The same team had reported the world's first cloned dog in 2005, a claim later verified by independent reviewers.
Sources and References
South Korean scientists create glowing cloned dogs (press release)