Man’s “super” best friend: Chinese scientists genetically engineer muscular dogs


Man’s best friend is all set to become his super friend – if a seemingly oddball research scope from Chinese scientists comes to large-scale fruition. According to a team of such researchers from the Key Laboratory of Regenerative Biology (at the Guangzhou Institutes of Biomedicine and Health), they have been successfully able to create the world’s first ‘gene-edited’ dogs. Simply put, these dogs possess double the muscle mass than an average-joe dog – which further pertains to enhanced running stamina tailored to better hunting and police work.

The biological working scope of this gene-editing entailed the introduction of certain chemicals into 60 dog embryos (of beagle variety) – including a DNA snipping enzyme, Cas9, and a guide molecule that targets a specific section of the DNA. The aim of these chemicals was to damage or eliminate both copies of the myostatin gene. This in turn would deter the dog’s body from producing any muscle-inhibiting protein that is originally generated by the myostatin gene.


When it came to the assessment phase, out of the 60 ‘edited’ embryos, 27 puppies were born. But only two specimens among these (one male and one female) showcased disruptive tendencies affecting the myostatin. However on later analysis, the male dog named ‘Hercules’ was still found to have continued (albeit slowed) production of the muscle-inhibiting gene. This left out the female dog named ‘Tiangou’, and she was the only specimen who demonstrated complete disruption of the myostatin. As a result, Tiangou developed her new-found muscled body, with the thigh area showing obvious growth when compared to other dogs.

Now, the prime question that arises when it comes to such processes, pertains to – isn’t a gene-editing and disruption procedure harmful to the animal? Well, the answer is – apparently no. In fact, there are also natural examples of losing the myostatin gene – which leads to some ‘beefy’ outcomes, like in the case of the Belgian Blues cattle (see below). Such mutations sometimes also occur naturally in the whippet variety of dogs, and these muscled specimens are called bully whippets.


Belgian Blues cattle

In very rare cases, the mutations also extend to humans, with one particular case in 2004 describing how a newborn had the appearance of being ‘extraordinarily muscular, with protruding muscles in his thighs and upper arms.’ And, by the time the male child grew to be 4 years old, he could easily maneuver his arms while holding 6.6 lbs dumbbells. Scientists have taken note of this apparently harmless nature of myostatin-disruption, and as such are attempting similar blocking measures in gene-therapy experiments that might reverse conditions like Duchenne muscular dystrophy in humans.

Lastly, in an interesting turn of events, when the DNA modifications are inducted during the embryonic stage, the alterations can also affect the sperm and eggs carried forth by the animal. Simply put, as the Chinese scientists found out, the animal can pass the myostatin mutation onward from next generation to generation. This scope once again raises the larger debate on evolution; and how instead of gradual change, the mode of evolution can be altered almost immediately by human-made procedures. Anyhow, in this particular instance, the team has made it clear that they don’t have any intention of breeding the extra-muscular beagles as pets.


Source: MITTechnologyReview

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