In biology, a clone is a cell or an organism that is genetically identical to another cell or organism. Many simple organisms such as bacteria reproduce themselves by copying their DNA and splitting in half. The two bacteria that result from this form of asexual reproduction are genetically identical; they are clones of each other. In contrast, during the process of sexual reproduction, the nucleus of a sperm cell, which carries the father's DNA, fuses with the nucleus of the egg cell, which contains the mother's DNA. The resulting offspring carry genetic material from both parents and are not identical to either parent. Usually, when scientists clone an animal, they take the nucleus of a cell, which contains chromosomes made of deoxyribonucleic acid (DNA) and proteins and place it into an egg cell (also called an oocyte) from which the nucleus has been removed. The egg cell then divides to produce an embryo that develops into an animal.

Three different types of cloning technologies are used (1) recombinant DNA technology or DNA cloning, (2) reproductive cloning, and (3) therapeutic cloning. The terms "recombinant DNA technology," "DNA cloning," "molecular cloning," or "gene cloning" all refer to the same process: the transfer of a DNA fragment of interest from one organism to a self-replicating genetic element such as a bacterial plasmid. The DNA of interest can then be propagated in a foreign host cell. Reproductive cloning is a technology used to generate an animal that has the same nuclear DNA as another currently or previously existing animal. In a process called "somatic cell nuclear transfer" (SCNT), scientists transfer genetic material from the nucleus of a donor adult cell to an egg whose nucleus, and thus its genetic material, has been removed. Once the cloned embryo reaches a suitable stage of cell division, it is transferred to the uterus of a female host where it continues to develop until birth. Therapeutic cloning, mean for the treatment of disease like diabetes and Alzheimer’s without problem of rejection. Each of the newly created stem cell lines is genetically identical to one of Hwang’s patients so any new tissue derived from that patient’s cell line can be injected into that individual without causing an immune reaction. The customized stem cells opened the door to therapeutic cloning, which has been touted as a futuristic remedy for hard-to-cure diseases.

Next, they revealed World’s first cloned dog, SNUPPY (a combination of Seoul National University and Puppy) a male Afghan Hound that was born in April 2005. Snuppy is the latest mammal to be cloned after sheep, mice, cats, rats, cows, goats, pigs, horses, rabbits and a mule. To create the world’s first dog clone, Hwang’s team used somatic cell nuclear transfer, merging somatic cells with enucleated eggs to produce clones. DNA analysis of the puppies revealed them to be genetically identical to the donor dog, the Afghan Hound Tai. Successful nuclear transfer in dogs has been elusive until now because it is difficult to get egg cells to mature in the lab. Dog eggs have been problematic because they are released from the ovary at an earlier, less mature stage than in other mammal. Therefore, the technique is still very inefficient because as many as 1,095 eggs and 123 surrogate dogs were used to create just three pregnancies. One of the three was miscarried and among the two cloned baby Afghan Hounds who saw the light, one died of pneumonia a mere 22 days after its birth.

Scottish embryologist Scot Wilmut banked on the method to make the first cloned mammal, Dolly the Sheep, in 1997. They were trying to find ways to produce livestock that carry specific genetic traits by creating Dolly. With the success of dog cloning, Korean scientists proved that they retain the best technologies and know-how as far as animal cloning is concerned. Dog cloning research is of great value because cloned dogs can be used as a model to study the pathogenesis and treatment of human diseases since dogs and humans share many physiological characteristics.

The cloning technology generally provides the benefits of preserving rare species and

Contributed by: Mohammad Abul Farah, Ph.D.

He attended Aligarh Muslim University in India where he received his M.Sc. and Ph.D. in Zoology with specialization in Genetics. He also served as Senior Research Fellow of Council of Scientific and Industrial Research, India. At present, he is working as a Research Scientist in Proteonik Inc., a biotechnology venture company based in Seoul, South Korea, on Diabetes research focusing on insulin signaling pathway.

NOTE

This article was contributed in October 2005, later those landmark papers were found to be exposed as a fabrication, and become one of the biggest scientific frauds of recent history. The Seoul National University Investigation Committee, initially organized to investigate the claims of scientific misconducts by professor Woo Suk Hwang and co-workers reports that Professor Hwang's research team possesses neither the patient-specific embryonic stem (ES) cell line described in 2005 publication nor the NT-1 ES cell line, the forerunner cloned cell line described in 2004 publication. The data in 2004 publication are also fabricated as can be seen by the non-match between the donor A and NT-1. Such act is none other than

also called "embryo cloning," is the production of human embryos for use in research. The goal of this process is not to create cloned human beings, but rather to harvest stem cells that can be used to study human development and to treat disease. Stem cells are important to biomedical researchers because they can be used to generate virtually any type of specialized cell in the human body.

A stem cell is a cell that has the ability to divide (self replicate) for indefinite periods-often throughout the life of the organism. Stem cells have two important characteristics that distinguish them from other types of cells. First, they are unspecialized cells that renew themselves for long periods through cell division. The second is that under certain physiologic or experimental conditions, they can be induced to become cells with special functions such as the beating cells of the heart muscle or the insulin-producing cells of the pancreas. Embryonic stem cells, which have been cultured under in vitro conditions that allow proliferation without differentiation for months to years. Scientists primarily work with two kinds of stem cells from animals and humans: embryonic stem cells and adult stem cells, which have different functions and characteristics that can be used for stem cell therapy.

Recently, Professor Hwang Woo-suk and his colleagues in the Seoul National University, South Korea, made two stunning scientific landmark with his successful cloning of dogs and making patient specific stem cells. Professor Hwang is a stem cell pioneer and also known as ‘king of cloning’, who successfully cloned human embryo last year. First, they have established 11 human embryonic stem cell lines by somatic cell nuclear transfer of skin cells from patient with disease or injury into donated oocytes. The resultant cells were a perfect match for the individuals and could

therapeutic cloning. Once dog embryonic stem cells become available, this technology could become a useful research tool for studying the genetics of outcrossed population. Studying stem cells will help us understand how they transform into the dazzling array of specialized cells that make us what we are. Some of the most serious medical conditions, such as cancer and birth defects, are due to problems that occur somewhere in this process. A better understanding of normal cell development will allow us to understand and perhaps correct the errors that cause these medical conditions. Another potential application of stem cells is making cells and tissues for medical therapies. Today, donated organs and tissues are often used to replace those that are diseased or destroyed. Stem cells offer the possibility of a renewable source of replacement cells and tissues to treat a myriad of diseases, conditions, and disabilities including Parkinson's and Alzheimer's diseases, spinal cord injury, stroke, burns, heart disease, diabetes, osteoarthritis and rheumatoid arthritis.

Hailing these breakthroughs, it would be expected that the medical feat opens the door to gene therapy, as transplanting developed stem cells back into patients with degenerative diseases such as Alzheimer’s, Parkinson’s and diabetes may be possible.



deceiving the scientific community and the public at large. The investigation's findings have stunned the scientific world and South Koreans, in particular. However, the panel said that the creation of first cloned dog, Snuppy was genuine.

Timeline of scandal:

Feb 2004 Hwang Woo-suk's team declares they have created 30 cloned human embryos and harvested stem cells from one of them.
May 2005 Team says it has made 11 pateint specific stem cell lines from skin cells.
Aug 2005 Hwang and colleagues announces in Nature that they have cloned the first dog, an Afghan Hound, called SNUppy.
Nov 2005 Hwang apologises for using eggs from his own researchers
Dec 15 A colleague claims stem cell research was faked
Dec 23 Academic panel finds results were 'intentionally fabricated'
Dec 29 Panel finds no data to back study
To read full report of investigation committee on Dr. Hwang stem cell research scandal please visit:
http://www.snu.ac.kr/engsnu/