Science & Technology

Seeing double: An overview of cloning, past and present

The scientific tool of cloning, which allows humans to duplicate organisms, has soared since the birth of first-ever mammalian clone Dolly the sheep. But how has this now commonplace discipline evolved, and where might it head in the future? Scientists must continue to grapple with the ethics of such a sensitive subject, especially considering cloning’s growing potential as a commercial endeavour.

In essence, to clone an organism, scientists take the desired genomic material from a somatic cell and insert it into an enucleated oocyte—or a female sex cell whose nucleus has been removed—in a process called somatic cell nuclear transferase (SCNT). 

“This is the fundamental principle of cloning from somatic cells,” Vilceu Bordignon, an associate professor within McGill’s animal science department, in an interview with The McGill Tribune. “It has to go back to the cytoplasm of the oocyte.” 

Despite the variety of highly technical methods available, such as powerful microscopes, stereoscopes, or even “handmade cloning,” Bordignon points out that one of the most complex parts of the cloning process is related to the oocyte itself.  

“The protocols for using in vitro [are] not as good in vivo because there is a part of the development that is made in oocytes that we still don’t know what it needs, and what the oocyte stores into the cytoplasm,” Bordignon said.

For this reason, Bordignon mentioned that even if scientists select the best candidate for an oocyte, the cell could still be missing some key components that are essential for controlling development.  

“The real factors affecting these reprogramming efficiencies are epigenetic factors,” Bordignon said. Epigenetics is the study of how the environment influences gene expression without altering the DNA sequence.  “For example, one of the experiments we’ve done is produce 25 piglets from the same cell culture, so […] theoretically, they are identical twins, but if you look at them, just at the difference in the size and the difference in the viability, you reasonably understand that just having the same genome sequences is not enough to make an identical animal.”

Though many epigenetic mechanisms are poorly understood, Bordignon remains hopeful about the prospects of applying scientific knowledge to improve the efficiency of cloning. 

“The message is simple. The more we understand how the cell differentiates, which pathways [it] controls, and how they restrict the functions to become specialized, the more we can understand how to act on those pathways to bring them back to an embryonic state,” Bordignon explained.

Similar protocols for cloning have been applied in other fields, like plant science. Though the ancient use of clonal propagation in plants—taking branches or pieces of a plant to regrow the species as its own organism—replaces the direct need for SCNT, the science of cloning and epigenetics can help create transgenic plants, which have a variety of applications. 

Jean-Benoit Charron, an associate professor in the Department of Plant Science at McGill, explained that, similar to cloning processes conducted in animals, scientists must use undifferentiated cells—grouped in a mass called a callus—to effectively create a plant with an altered genome that can be passed down to future offspring. 

“The oocyte is reproductive tissue […] that can allow the genetic information to pass to the next generation,” Charron said in an interview with the Tribune. “With plants, we do exactly the same thing. If you just [alter] a leaf, you will […] transform that leaf for the time that it is alive. The callus [is] a tissue that has the possibility of transferring the genetic information that you are adding to the next generation. The overall strategy I would say is identical.” 

Applications of these laboratory processes are simultaneously expanding, especially in the domain of transgenic crops. 

“The first wave of transgenic produce that were put on the market was mostly to […] help the grower achieve a higher yield at a reduced cost,” Charron said.  “So now we’re seeing a wave […] where we are trying to improve the nutritional value of all of the products and all the produce, or to limit the losses due to pathogens. And to do this, […] they take a wild variety that resists well to a virus or pathogen, they identify the gene responsible for that, and they transfer this gene into [another variety].”

While Charron says that transgenic crops would still take a couple of years to produce, when it comes to improving crop yield and resilience, the applications are endless. However, such tools can lead to unintended negative consequences when used to attack one specific problem 

“A transgenic plant producing an insecticide that kills insects reducing the yield of the crop […] was mostly to reduce the production cost,” Charron said. “This worked so well that it created a lot of monoculture, so people started to depend a lot on this.” 

Though transgenic crops have already been integrated into industrial farming, the use of cloning has not been similarly implemented, likely due to the continuing ethical debate surrounding it. Among its prospective uses, though, is the creation of superior livestock for meat and the potential to rescue endangered species. 

“Breeding is just a way to reprogram the genome and produce the next generation, and we can achieve that by cloning as well. Should we or should we not clone for production perspectives?” Bordignon asked. 

Bordignon went on to say that when the FDA compared the alimentary products of cloned animals to regularly farmed ones, they did not find any significant difference in nutritional value. Charron says that genetically modified organisms (GMOs) present in crops are also unfairly stigmatized despite the DNA alteration being so minuscule. 

“Instead of a big chunk of the chromosomes being transferred, here we are transferring only a thousand base pairs,” Charron said. “It’s surgical, almost. At the end [of the day], DNA is DNA.” 

As cloning technology grows more sophisticated, different industries can apply it towards new commercial endeavours. For a considerable price, many companies now offer cloning to pet owners who wish to create a genetic twin of their cat or dog. One such company is ViaGen Pets, which extends cloning services not only to pet owners, but also to zoos and wildlife conservation groups. 

“We have many clients who wish to enjoy a genetic twin to a beloved companion animal. This is an amazing opportunity if you think about it,” a spokesperson for ViaGen Pets said in an email to the Tribune. “A cloned companion animal is not the same animal, but shares many of the same traits [….] We also utilize our resources to help in the world of conservation where we work closely with […] conservation-minded groups.” 

While there are certainly positives to such technology, whether we are capable of handling it responsibly remains to be seen. Evidently, cloning and similar technologies, such as those involved in the creation of transgenic plants, span a large range of practices and are considerably difficult to evaluate ethically. These questions remain unanswerable for now and require additional research and consideration before implementing cloning technologies into new contexts, whether it be in the corn fields or at the pet store.

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