In the advanced world, consistently there has been a remarkable social tool for comprehending and assessing scientific, ethical, moral, and social consequences of new innovations. Cloning is one such new technology which is a major development in the field of Genetics, such as Human Genome Project for making identical copies of an organism. Cloning is the term broadly meaning natural or artificial development of two or more genetically identical cells or organisms. Scientists use the term cloning with variable implications, although all uses suggest getting duplicates precisely of a biological entity. Cloning Dolly was a significant achievement, motivating researchers to keep improving cloning innovation as well as to pursue new concepts in stem cell research. More than any other reproductive technique, cloning evokes questions about identity and uniqueness. The reason for developing cloning in animals is to study and identify genetic diseases and indeed genetic development more generally.
Cloning is the outcome of the hard works on use of genetic engineering in animal breeding, treatment of hereditary diseases in human and replicating organisms. In the last aspect of the nineteenth century, August Weismann believed that differentiation results from the differential and successive portioning of the genome as the cells divide. Wilhelm Roux, in an 1888 analysis, executed one cell (blastomere) of a two-cell embryo and found that a half-embryo created, suggesting that a few genes are lost during cell replication. However, in 1892, Hans Driesch found that if the blastomeres of two-cell sea urchin were genuinely isolated, whole embryo shaped from every blastomere; comparative outcomes were gotten when amphibian blastomeres were isolated, given that they contained a portion of cytoplasm known as gray crescent material. Subsequently, the genome was not lessened, but instead reproduced during cell division.
Blastomere partition of embryos beyond the 2-to 16-cell stage (depending upon species) was noninformative for testing genomic potential in light of the fact that the cells had too little cytoplasm. But, in 1894, Jacques Loeb randomly observed that fertilized sea urchin eggs sometimes ruptured when exposed to hypotonic solutions. The expelled portion of the egg was typically dispossessed of a nucleus and remained uncleaved. Sporadically, nuclei navigated the isthmus between the cleaving egg and the expelled cytoplasmic material. In such cases, the expelled cytoplasm separated alongside the fundamental mass, resulting in the formation of two whole embryos. In 1914, Hans Spemann played out a thoughtfully identical experiment on an amphibian egg. He constricted a zygote with a noose made of baby hair, making the egg assume the shape of a dumbbell. When on separating (nucleated) portion reached at the 8-or 16-cell stage, he extricated the constriction and allowed a nucleus to move to the non-nucleated cytoplasmic part. Here, as well, the non-nucleated portion separated and framed a clone of its nuclear donor. These primitive nuclear transplantation (cloning) tests confirmed the view that the total genome is duplicated during cell division, at least during early cleavage. The stage was currently set for modern day cloning experiments to analyze the genomic capability of older embryonic cells.
Parturition of Dolly
Dolly the sheep, as the first mammal to be cloned from an adult cell, is by far the world's most famous clone. So, when scientists working at the Roslin Institute in Scotland produced Dolly, the only lamb born from 277 attempts, it was a major news story around the world. Animal cloning from an adult cell is much more difficult than from an embryonic cell. To produce Dolly, scientists used a mammary gland cell from a six-year-old Finn Dorset white sheep. In order for the mammary cell nucleus to be accepted and functional within the host egg, the cell first had to be induced to abandon the normal cycle of growth and division and enter a quiescent stage. They needed to figure out how to 'reinvent' the udder cells - to keep them alive however stop them developing – which they accomplished by changing the growth medium. At that point they infused the cell into an unfertilized egg cell which had its nucleus eliminated (oocyte), and made the cells replicate by utilizing electrical pulses. The unfertilized egg cell cytoplasm originated from a Scottish Blackface ewe. When the research group had figured out how to fuse the nucleus from the adult white sheep cell with the egg cell from the dark faced sheep, they expected to ensure that the subsequent cell would form into an embryo. They cultured it for six or seven days to check whether it partitioned and developed normally, before implanting it into a surrogate mother, another Scottish Blackface ewe. From 277 cell fusions, 29 early embryos developed and were implanted into 13 surrogate mothers. But only one pregnancy went to full term, and the 6.6 kg Finn Dorset lamb 6LLS (alias Dolly) was born after 148 days. She was Born on 5 July 1996, Dolly had a white face. Dolly remained alive and well long after her birth, with a functional heart, liver, brain, and other organs, all derived genetically from the nuclear DNA of an adult mammary gland cell. Dolly was the culmination of hundreds of cloning experiments that, for example, showed diploid embryonic and fetal cells could be parents of offspring. Dolly demonstrated that adult somatic cells also could be used as parents. Thus, one could know the characteristics of the animal being cloned. Dolly was euthanized on 14 February 2003, aged six and a half by veterinarians after being found to suffer from progressive lung disease. Her body was preserved and displayed at the National Museum of Scotland in Edinburgh. The technique used to produce Dolly later became known as somatic cell nuclear transfer (SCNT). SCNT has since been used to generate a wide variety of mammalian clones, from different types of adult cells, it succeeded in producing clones of primates.
The initial step identifies with recognizing an appropriate nuclear donor cell from which to clone. Although donor cells can be obtained legitimately from an animal, primary cells are normally propagated in vitro already to facilitate control and storage. Donor nuclei are regularly treated before transfer to synchronize the cells at the GI/GO phase of the cell cycle. This is significant when oocytes that have been captured at the metaphase stage at the time of fusion are utilized as recipients(hosts). The most well-known system to synchronize the cell cycle is to expose cells for a few days to culture medium containing low degrees of serum (serum starvation). Since numerous cells quit cycling because of contact inhibition. Transfection of nuclear donor cells to produce transgenic animals through cloning can be performed by random integration. Techniques for transfection are like those applied to immortalized somatic cell lines that is, by utilizing the cationic lipid reagent, lipofectamine, which enables the transport of the exogenous DNA (transgene) through the plasma and nuclear membranes. Enucleation is normally performed by microsurgical aspiration of a part of the cytoplasm encompassing the first polar body and is affirmed by DNA vital staining and ultraviolet (UV) illumination. The use of UV irradiation can be avoided by enucleating after the secondary oocyte has been exposed to an artificial stimulus for activation, at the time of 2nd polar body extrusion (telophase stage). Nuclear transfer is most performed by introducing a single donor cell into the perivitelline space of an enucleated oocyte, followed by plasma membrane fusion with a direct current electric shock. Donor cells need to be placed in close contact with the enucleated oocyte to achieve fusion. Host oocytes that have been halted in the metaphase of the cell cycle are usually chosen because their mitosis promoting factor (MPF)-kinase activity, which induces donor nuclear membrane breakdown immediately after fusion, is high at this stage of the cell cycle. If nuclei are not undergoing DNA replication (S-phase of the cell cycle) at the time of fusion, nuclear membrane breakdown enables a rapid remodeling of chromatin. However, when nuclear donor cells are in the S-phase, the chromatin will undergo premature chromosome condensation and pulverization (PCC), which is detrimental to further development. Reconstructed oocytes are either cultured in vitro to the blastocyst stage or transferred soon after fusion to a temporary recipient for development in vivo. Finally, selected morula- and blastocyst-stage embryos are transferred to synchronized recipients and allowed to develop to term.
Work on cloning techniques has progressed our knowledge on developmental science, especially early human development. Cells created by Somatic Cell Nuclear Transfer (SCNT) are helpful in exploration of the causes of diseases, and as model frameworks for drug disclosure and can also be used in cell transplantation, or for production of organs in transplantation, called regenerative medication. Advantages of cloning include being able to make tissue and organs that specialists can utilize when required for medical procedure on the first. Other benefits include growing stem cells, cloning lab mice genetically engineered for the examination, bringing back extinct species, replicating a pet that died and cloning domesticated animals for food. It can propagate genes and save newborns from hereditary diseases, Replicating and propagating plants and animals, it can reproduce the ambulated limbs and replicating them to culture and replace the destroyed organs such as liver, heart. One of the advantages can be that the cloned limbs have full genetic adaptation with the recipient individual who is the donor of the stem cells, Infertile people or same-sex couples could have children produced from cloned cells. After editing or removing bad genes, cloning could lead engineered humans for explicit characteristics. Cloning could enhance and advance human development.
As the technology is new and its outcome is not public and common yet, the damages and losses are sometimes resulted as internal damages by nature of the operation and the process of cloning. One of the main drawbacks of cloning is that if the original organism has genetic defects, these transfer to the clone as a copy of the original. The first developed clone “Dolly the sheep” lived to six years than original average life’s expectancy due to presence of tumors in lungs which may have been in genome of original. Human cloning could be a violation of the clone's individual human rights. 99% of attempts to clone human may result in creation of monsters, Cloning raises the question of a moral or human right to an exclusive identity. Human cloning could produce psychological distress for the clone and society. It is least effective way to produce offspring and expensive. It reduces the genetic diversity of species. Cloning animals will develop a history of creating abnormal pregnancies and it can create long-term health issues to manage, sterility issues, more cancer-related issues, and higher levels of embryo destruction. External damages include belief damages, Human moral damages, it is against divine nature.
In the second half of the 20th century, as dramatic advances were taking place in genetic knowledge, as well as in the genetic technology often referred to as Genetic Engineering, some utopian proposals suggested that persons of great intellectual or artistic achievement or of great virtue can be cloned. But cloning technology has not yet been developed to an extent that would make possible to produce a healthy human individual by cloning. Ethical, social, and religious values will become possibly the most important factor when looking to choose whether an individual may be permitted to be cloned. Most people are likely to disapprove. Indeed, many countries have prohibited human cloning. The Human Fertilization and Embryology Act of 2008 unequivocally prohibited reproductive cloning, however permitted experimental stem cell research for treating diabetes, Parkinson's infection, and Alzheimer's illness. In the United States, there are currently no federal laws that ban cloning completely. Thirteen states (Arkansas, California, Connecticut, Iowa, Indiana, Massachusetts, Maryland, Michigan, North Dakota, New Jersey, Rhode Island, South Dakota, and Virginia) ban reproductive cloning, and three states (Arizona, Maryland, and Missouri) prohibit use of public funds for research on reproductive cloning.
Human cloning refers to therapeutic and reproductive cloning which means cloning of embryonic cells and use of somatic cell nuclear transfer (SCNT) to obtain organs for transplantation or to treat any diseases and to obtain eggs that could develop into adult individuals respectively. Reproductive cloning is the process where asexual cells are transferred to an egg while its DNA has been removed and after the development of an embryo, it is placed into the recipient uterus. This process can result in production of a human while the cloned individual would totally be identical to the genetic donor. Therapeutic cloning is intended for production of cloned human, but the culture of cells used in researches and treatment purposes in regenerative medicine.
There is no evidence that anyone has successfully cloned a human, but the hoped-for therapeutic breakthroughs have also been slow to emerge. And despite the hype and controversy, somatic cell nuclear transfer remains a relatively marginal research activity. The low pace of cloning achievement may improve later in future. It might be that the organ and different failures of those that reach birth will be adjusted by specialized advances. Human cloning would at present face moral complaints from a larger part of concerned individuals, as well as opposition from various religions. Also, it may be conceivable to clone an individual's genes, yet the individual cannot be cloned. The character, personality, and the features other than anatomical and physiological that make up the individual are not precisely determined by the genotype.
Legality and Ethics
The publication of Dolly the sheep's existence had a quick and for the most part negative impact on public opinion around the world and started off a whirlwind of prohibitive administrative action. Some argue that cloning is wrong because it departs from natural, sexual procreation. There is an ethical objection on human reproductive cloning as it is production of a person using nuclear transfer. It is anticipated as psychological damage to clones from societal prejudice and enough to ban the practice. Therapeutic cloning is ethically less contentious because a new person is not produced. It is illegal in many countries where legislation prevents the use of human eggs for therapeutic research. This prohibits therapeutic cloning using unfertilized eggs, even though a nuclear-transplant embryo would be used to make embryonic stem-cell-like cells, and so would have no potential for survival because it would not be implanted. In united states no such legislation except federal funds cannot be used for reproductive cloning, nor can they be used in generating embryos for therapeutic cloning. It is illegal to use human eggs for any purpose where the intention is to create an embryo, even if only for cell replacement. This can be permitted by grant from Secretary of State for Science to present Human Embryology act.
Scientists believe that this fundamental principle of cloning should be effective in the case of humans. In fact, the attempt to clone a man was done with the intention of getting embryonic stem cells. Cloning for this purpose is called therapeutic cloning. In the absence of compelling arguments against human cloning, we can bid Dolly. We surely have sufficient reasons to permit experiments on human embryos to proceed, provided, as with any such experiments, the embryos are destroyed at an early stage. While we stand by to see regardless of whether the method will actually be set up as safe, we ought to think about the most ideal approaches to manage its uptake until we are in a situation to recognize what will emerge both by method of advantages and as well as disadvantages.
- José van Dijck (1999) Cloning humans, cloning literature: genetics and the imagination deficit, New Genetics and Society, 18:1, 9-22, DOI: 10.1080/14636779908656887.
- Harris J 'Goodbye Dolly?' The ethics of human cloning. Journal of Medical Ethics 1997; 23:353-360.
- Nabavizadeh, S. L., Mehrabani, D., Vahedi, Z., & Manafi, F. (2016). Cloning: A Review on Bioethics, Legal, Jurisprudence and Regenerative Issues in Iran. World journal of plastic surgery, 5(3), 213–225.
- Ayala F. J. (2015). Cloning humans? Biological, ethical, and social considerations. Proceedings of the National Academy of Sciences of the United States of America, 112(29), 8879–8886. https://doi.org/10.1073/pnas.1501798112.
- Wilson EB. 1928. The Cell in Development and Heredity. 3rd ed. New York: Macmilla.
- Spemann H. 1938. Embryonic Development and Induction. New Haven (CT): Yale University Press.
- Briggs R, King TJ. 1952. Transplantation of living nuclei from blastula cells into enucleated frogs' eggs. Proceedings of the National Academy of Sciences of the United States of America 38: 455-463.
- Robert G. McKinnell, Marie A. Di Berardino, The Biology of Cloning: History and Rationale, Bioscience, Volume 49, Issue 11, November 1999, Pages 875 885, https://doi.org/10.2307/1313647.
- AnimalResearch.info, The global resource for scientific evidence and research, http://www.animalresearch.info/en/medical-advances/timeline/cloning-dolly-the-sheep.
- Judith L. Fridovich-Keil. August 13, 2020.Dolly, Encyclopædia Britannica, Inc. https://www.britannica.com/topic/Dolly-cloned-sheep.
- Smith, L. C., Bordignon, V., Babkine, M., Fecteau, G., & Keefer, C. (2000). Benefits and problems with cloning animals. The Canadian veterinary journal = La revue veterinaire canadienne, 41(12), 919–924.
- Caulfield, Timothy. “Human cloning a decade after Dolly.” CMAJ: Canadian Medical Association journal = journal de l'Association medicale canadienne vol. 176,5 (2007): 613. doi:10.1503/cmaj.070182.
- John Harris, 'Goodbye Dolly?' The ethics of human cloning, Journal of Medical Ethics 1997; 23: 353-360.
- Siniša Franjić, Dolly and the History of Cloning, Ec Clinical and Medical Case Reports, June 25, 2019. https://www.ecronicon.com/eccmc/pdf/ECCMC-02-00044.pdf.
- Gurdon, J., Colman, A. The future of cloning. Nature 402, 743–746 (1999). https://doi.org/10.1038/45429.