A Review Article on Study of Cloning

 

Deepali Anand Sutar*, Mrs. Bhavana. U. Jain, Mr. Manish Kondawar

Department of Pharmaceutical Chemistry, Appasaheb Birnale College of Pharmacy, Sangli- 416416

District- Sangli, Maharashtra, India.

*Corresponding Author E-mail: dipalisutar604@gmail.com

 

ABSTRACT:

DNA cloning, that can be used to discover new ways of warding off diseases and ailments is good and by no means harmful. A group of genetically identical cells produced by mitotic division from an original cell. The production of genetically identical animals by 'embryo splitting'. This can occur naturally at the two cell stage to give identical twins. The type of cloning which we will focus on here is called Nuclear Transfer. Cloning requires specialized microsurgery tools. There are two ways to make an exact genetic copy of an organism in a lab artificial embryo twinning and somatic cell nuclear transfer. In 1996, the Roslin Institute, England cloned “Dolly,” a sheep to demonstrate that somatic cells were able to be used as donor cells for the procedure, prior to this blastoceles (stem cells) were used in nuclear transfer technology. Around 2004–2005, in South Korean scientists falsely claimed to have used somatic cell nuclear transfer to create embryonic stem cell lines, the scientific community demanded much stronger evidence that the procedure had actually been successful. Cloned buffalo gave birth to a baby buffalo in India. In 2007 Primate embryonic stem cells created by somatic cell nuclear transfer. A DNA from an organism is transferred to a self-replicating genetic element such as a bacterial plasmid. Reproductive cloning is the basis of most controversial debates regarding the Genetic Revolution. The California Advising Committee on Human Cloning found that: Attempts at cloning certain species such as monkeys, chickens, horses and dogs have been unsuccessful.

 

KEYWORDS: Somatic Cell Nuclear Transfer, DNA Cloning, Embryo Twinning, Embryonic stem cells, Mitotic division.

 

 


INTRODUCTION:

A group of genetically identical cells produced by mitotic division from an original cell is known as a clone. Clones are organisms that are exact genetic copies. Every single bit of their DNA is identical. Clone scan happen naturally-identical twins are just one of many examples or they can be made in the lab. Cloning occurs naturally in plants when bulbs colonize in the area around a parent plant.

 

This is where the cell creates a new set of chromosomes and splits into two daughter cells[1].

 

Somatic Cell Nuclear Transfer (SCNT): Also called nuclear transfer, uses a different approach than artificial embryo twinning, but it produces the same result: an exact genetic copy, or clone, of an individual. This was the method used to create Dolly the Sheep.

 

Somatic cell:

A somatic cell is any cell in the body other than sperm and egg, the two types of reproductive cells. Reproductive cells are also called germ cells. In mammals, every somatic cell has two complete sets of chromosomes, whereas the germ cells have only one complete set.

 

Nuclear:

The nucleus is a compartment that holds the cell's DNA. The DNA is divided into packages called chromosomes, and it contains all the information needed to form an organism. It is small difference in our DNA that makes each of us unique.

 

Transfer:

Moving an object from one place to another. To make Dolly, researchers isolated a somatic cell from an adult female sheep. Next they removed the nucleus and its entire DNA from an egg cell. Then they transferred the nucleus from the somatic cell to the egg cell. After a couple of chemical tweaks, the egg cell, with its new nucleus, was behaving just like a freshly fertilized egg. It developed into an embryo, which was implanted into a surrogate mother and carried to term.

 

 

Figure 1 Nuclear Transfer Cloning

 

TYPES OF CLONING:

1. DNA Cloning

In DNA Cloning, only the DNA of a cell is replicated. A DNA from an organism is transferred to a self-replicating genetic element such as a bacterial plasmid. In other words, a small piece of the DNA strand is removed and united with a plasmid which reproduces itself to create multiple copies of the same DNA code. This plasmid is also known as a vector. This copied DNA can then be propagated in a foreign host cell. After it is introduced into a suitable host cell, the recombinant vector can then be reproduced along with the host cell DNA

 

2. Reproductive Cloning:

Reproductive cloning is a technology used to generate an animal that has the same nuclear DNA as another currently or previously existing animal. Human cloning also falls into this category. Dolly was created by reproductive cloning technology. In a process called "somatic cell nuclear transfer", the DNA information from the nucleus of a donor adult cell is copied into a cell whose nucleus (thus also its genetic material) has been removed. Chemicals or electric current are used to stimulate cell division. Once the cells start dividing and the embryo reaches a suitable stage, it is planted into the uterus of a female host where it develops until birth.

 

3. Therapeutic Cloning:

Therapeutic cloning is like reproductive cloning, except that the embryos are not allowed to develop fully. The purpose of therapeutic cloning is to extract the stem cells from the embryos and study them. When the egg has been cloned and divided for 5 days, the stem cells are extracted from it. The embryos are destroyed due to the extraction process, which raises ethical concerns. Stem cells are unspecialized cells which can transform into any of the 220 cell types that are in the human body. Many researchers hope that one day stem cells can be used to serve as replacement cells to treat heart disease, Alzheimer's, cancer, and various other diseases.[2]

 

4. Human Cloning:

For the purposes of this report, the term “cloning” will refer to the production of genetically identical organisms via somatic cell nuclear transfer. “Somatic cell nuclear transfer” refers to the process in which the nucleus of a somatic cell of an existing organism is transferred into an oocyte from which the nucleus has been removed. “Human cloning” will be used to refer to the application of somatic nuclear transfer technology to the creation of a human being that shares all of its nuclear genes with the person donating the implanted nucleus. Cloning is distinct from techniques such as embryo splitting and twinning. Human cloning, as defined in this report does not include the use of somatic cells to create a pluripotent cell line that could, for instance, also be used for extra-uterine production of transplantable tissues without the creation of an entire being. Nor does it include the use of cloning technology for the production of human tissues or human proteins from transgenic mammals funding of human cloning research. This paper was prepared for National Bioethics Advisory Commission to assist in its deliberations and policy recommendations. [3]

 

 

Figure 2 Structure of DNA

Table No. 1:-Advantages and Disadvantages of Cloning [4]

Advantages

Disadvantages

·      Potential benefits to modern medicine

1. Elements of Uncertainty.

·      Helping infertile couples.

2. Inheriting diseases.

·      Reverse the aging process.

3. The potential for Abuse.

·      Protecting endangered species

4. Unforeseen consequences

·      Improving food supply.

5. Cloned people could be treated like cattle.

 

Risk of Cloning]:

There have been multiple arguments both for and against the process for plant, animal and human cloning.

 

Facts on the Risks of Cloning Animals:

The cloning of animals continues since the successful cloning of the sheep Dolly in 1996. Sheep, rabbits, cows, mice, pigs, goats and cats have been cloned both successfully and unsuccessfully since that time. Through this some risks have been uncovered.

1.     Reproductive cloning is very expensive and very inefficient–Over 90% of attempts fail.

2.     Cloned animals have highly compromised immune systems and infection rates are high.

3.     Large offspring syndrome and other debilitating conditions affect 30% of clones born alive.

 

Facts on the Risks of Cloning Humans:

Arguments in favour of cloning make some good points but in light of the fact that no human has been cloned it is difficult to know exactly what benefits society can achieve with the risky science. Even more so than trying to find the benefits, is it worth the risks involved to attempt to clone a human being.

1.     Due to poor success rates with animal cloning lean toward poor outcomes for human cloning.

2.     Since a human has never been cloned we have no known outcome on emotional and mental development or complications.

3.     Based on animal cloning there is a very high risk of miscarriage, deformity or debilitating conditions and unsuccessful attempts.

4.     With so many unknowns related to reproductive cloning in animals, it is considered to be very dangerous and unethical to consider human cloning.

5.     The risk of abuse of the technology for cloning humans for spare body parts and research is high.

 

Facts on the Risks of Cloning Plants:

The cloning of plants is not nearly as risky as that of animals and humans. It does have some risk involved. It is helpful to know that nature already clones itself in some plant life. The risks involved in cloning plants are risks that hopefully can be prevented.

1.     There is a risk of loss of genetic variation in the future and risk of DNA diversity.

2.     It is unknown if a cloned plant can reproduce naturally, without natural growth we are at risk for losing species completely. [5]

 

CONCLUSION:

To clone means to make identical copies. DNA cloning involves separating a specific gene or DNA segment from a larger chromosome, attaching it to a small carrier DNA. The resultant hybrid DNA is called recombinant DNA, which is transferred to a proper host (bacteria, virus or yeast) and replicated to make multiple copy of the selected gene.

 

I believe DNA cloning, that can be used to discover new ways of warding off diseases and ailments is good and by no means harmful. Regarding reproductive cloning, I believe it is far too early in the development of cloning organisms to even fathom cloning a human being. Because we are currently incapable of cloning complex organisms such as dogs, cats and primates, the ability to successfully clone a human seems to be even less likely. If we had the ability to clone a primate which has DNA that differs from humans’ by a mere 0.07%, it may be the case that cloning could work. As of now, the 90% failure rate is too unpromising and shows no potential for good Therapeutic cloning (i.e., stem cell research) has been supported by our government. While it may leave some people in discontent, I believe that one day people will be able to recognize the benefits of this type of research.

 

I believe that these types of cloning could be very beneficial to our society. While many people may disagree due to ethical concerns, I feel it is a chance we must take when tackling new ground of science. Furthermore, it is our moral duty to keep suffering at a minimum therefore we must shy away from reproductive cloning because results are too unpromising.

 

REFERENCES:

1.      Rockville, Maryland National Bioethics Advisory Commission. Cloning Human Being, Report and Recommendations of the National Bioethics Advisory Commission June 1997.

2.      Report from Council on Ethical and Judicial Affairs The Use of Minors as Organ and Tissue Donors House of Delegates Proceedings, American Medical Association. December 5-8, 1993. p. 231-240.

3.      Kass, L.R. The Wisdom of Repugnance. In: The Ethics of Human Cloning Kass, L.R. and Wilson, James Q. Washington, D.C.: American Enterprise Institute for Public Policy Research, 1998.

4.      Ethical questions raised by gene transfer for egg cell fertilization. Chicago Tribune Saturday, October 10, 1998, p. 16.

5.      Griswold V. C. 381 U.S. 479 (1965); Eisenstaedt v. Baird 405 U.S. 438 (1972).

 

 

 

 

Received on 22.04.2019            Modified on 28.04.2019

Accepted on 05.05.2019            © A&V Publications All right reserved

Asian J. Res. Pharm. Sci. 2019; 9(2): 148-150.

DOI: 10.5958/2231-5659.2019.00022.5