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Mayank Bharti
1 July 2024 |
On 5 July 1996, Dolly, a female sheep, became the first mammal cloned from an adult somatic cell, marking a groundbreaking achievement in biotechnology. Associates in Scotland’s Roslin Institute led by Keith Campbell and Ian Wilmut, used the process of somatic cell nuclear transfer (SCNT) to extract the nucleus from a mammary gland cell of an adult sheep and combine it with an enucleated egg cell from a donor ewe.
Dolly: A scientific milestone, and a new beginning
The process that brought Dolly into existence, known as somatic cell nuclear transfer (SCNT), began with the extraction of the nucleus from a mammary gland cell of an adult sheep. This hybrid cell, now with its newly implanted nucleus, was coaxed into dividing and developing into an embryo, which was subsequently implanted into a surrogate mother. The result was Dolly, genetically identical to the sheep that donated the mammary cell nucleus. This experiment not only proved the feasibility of cloning from adult cells but also demonstrated the ability to reprogram a differentiated cell into a totipotent state, capable of developing into any type of cell.
The cloning ignited a wave of research and technological advancements in genetic engineering and biotechnology. One major achievement following Dolly was the refinement of SCNT procedures, which increased efficiency and reduced the occurrence of anomalies. Other animals were soon cloned, including cows, pigs, and even endangered species like the gaur. The principles underlying Dolly’s creation also paved the way for advancements in stem cell research, regenerative medicine, and synthetic biology.
Dr Robert Lanza of Advanced Cell Technology highlighted Dolly’s impact, stating, "Dolly's cloning was the spark that ignited the stem cell revolution." The ability to reprogram somatic cells to an embryonic state laid the foundation for induced pluripotent stem cells (iPSCs), a discovery that earned Shinya Yamanaka a Nobel Prize in 2012.
The cloning of Dolly resonated globally, influencing scientific circles, public policy, and ethical debates. In agriculture, animal cloning offers the potential to preserve genetic lines of valuable livestock, increase food production, and ensure the propagation of animals with desirable traits. For instance, cloned cattle with higher milk yields or disease resistance could revolutionize the dairy and meat industries.
Cloning technology also has significant implications for conservation biology. Cloning endangered species can help stabilize dwindling populations, providing a genetic lifeline to animals on the brink of extinction. However, the commercial cloning of pets, such as the well-known cloned cat "Cc," has created a niche market for cloning services, reflecting both technological advancements and public fascination with replication.
From Dolly to Present: Cloning’s Evolution
Since Dolly, animal cloning has made substantial progress. The cloning of the first endangered species, a gaur named Noah, in 2001 was a notable achievement, despite Noah’s death shortly after birth due to an infection. More recently, in 2020, scientists successfully cloned a Przewalski's horse, an endangered wild horse species, using frozen cells. This milestone, achieved by Revive & Restore and ViaGen Pets and Equine, illustrates how cloning technology can be harnessed for conservation purposes.
Researchers are also exploring the use of gene-editing tools like CRISPR-Cas9 in conjunction with cloning to correct genetic defects and enhance traits, expanding the scope of genetic manipulation. Cloning has become invaluable in scientific research, particularly in creating animal models for human diseases, enabling precise studies on genetic disorders and potential treatments.
The benefits of animal cloning are numerous and potentially transformative. In agriculture, cloning can lead to more consistent and predictable animal production, enhancing food security and quality. Cloning animals with superior traits, such as higher milk or meat productivity, ensures a steady supply of high-quality food.
Cloning also holds promise in medicine. Genetically modified cloned animals can produce drugs in their milk, a process known as "pharming." According to the FDA, "biopharmaceuticals from transgenic animals could revolutionize treatment for a variety of conditions." Cloning also enables xenotransplantation, where organs from genetically engineered pigs are used for human transplants, addressing the critical shortage of human organs for transplantation.
Ethical and Practical Concerns
Despite its potential, animal cloning raises significant ethical, practical, and welfare concerns. Cloning remains inefficient, with high rates of failure, developmental anomalies, and premature aging, as seen with Dolly, who developed arthritis and died at the age of six. This inefficiency raises animal welfare issues, as many cloned animals suffer health problems.
Cloning also sparks ethical debates about the extent of human intervention in natural processes and the moral status of cloned beings. Critics argue that cloning commodifies animals and threatens biodiversity by focusing on a narrow genetic pool. The commercial cloning of pets has been criticized for fostering a profit-driven industry rather than addressing necessity. Bioethicist Dr. Arthur Caplan emphasizes that the ethical issues surrounding animal cloning are complex, involving animal welfare, biodiversity, and the potential consequences of "playing God."
The cloning of Dolly the sheep was a watershed moment in science, propelling it into new realms of possibility. It spurred significant advancements in biotechnology, impacting global agriculture, conservation efforts, and biomedical research, while also raising ethical debates and underscoring the need for responsible use of such technologies. As we build on this pioneering success, it is crucial to balance the potential of cloning with the ethical concerns and practical challenges it entails, ensuring that this powerful tool is used carefully and compassionately.
In the series:
01 July 2002: The Rome Statute establishes the International Criminal Court
05 July 1962: Algeria declares its independence, ending 132 years of French occupation
06 June 1944: Allied forces land in Normandy, turning the tide in World War-II
21 May 1991: LTTE human bomb assassinates Rajiv Gandhi
20 May 1948: Vasco da Gama, a Portuguese explorer lands in Calicut in India’s west coast
20 May 2002: East Timor becomes an independent country
30 April 1975: Saigon falls to North Vietnam troops, leading to the reunification of Vietnam
21 April 1526: The First Battle of Panipat leads to the emergence of the Mughal Empire in India
17 April 1895: The Treaty of Shimonoseki ends the first Sino-Japan War (1894-95)
17 April 1975: Khmer Rouge captures Phnom Penh in Cambodia, establishing the Pol Pot regime
16 April 1917: Lenin issues “April Theses”
04 April 1968: Martin Luther King Jr assassinated
18 March 2014: Russia annexes Crimea
14 March 1879: Albert Einstein born in Germany
14 March 1849: The Sikh Army surrenders to the British
12 March 1918: Lenin shifts the capital to Moscow
11 March 1985: Mikhail Gorbachev becomes the General Secretary of the Communist Party of the Soviet Union
About the author
Mayank Bharti is an undergraduate student from Kristu Jayanti College, Autonomous, Bengaluru.
