Cloning has been used since very ancient times, however, it was used mostly to obtain a plant.
Nuclear transfer cloning is the future if not already a present for further development. However, there are two sides to the issue of mammal cloning; those who believe that it is the basis of human survival and those who believe that this will lead to destruction. The most famous experiment was precisely that of Dolly the sheep which was carried out for two reasons: the merely commercial one; which consisted of developing a tool for the rapid reproduction of identical animals for biotechnology and the second one that wanted simple scientific curiosity.
CLONING HISTORY:
Since ancient times, Aristotle recognized the importance of sexual reproduction and proposed two alternative models. Either the structure of the whole animal was already preformed in miniature within the ovum or the embryo, or new structures were emerging little by little. Despite the fact that Aristotle was inclined towards the second idea, he lacked technology and the debates regarding this idea continued.
Later in the 18th century in Europe Nicholas Hartsoeker proposed a structure of the fetus. Hartsoeker proposed that the head of the sperm grew to form the fetus, that the tail became the umbilical cord, and that the function of the ovum was only to provide a nest.
In the year of 1830 Joseph Jackson Lister invented the compound microscope and for the year of 1839 Theodor Schwann and Matthias Scheleiden demonstrated that living beings are made up of cells. Albrecht von Kolliker later showed that sperm and oocytes are also cells, but that they mysteriously interact to form a new organism.
Justus Von Liebig suggested that the sperm transmits its masculine qualities to the oocyte through the energetic vibration of its tails.
Cloning began in the 1950s when Briggs and King who obtained identical animals from frog pipiens blastula cells fused with vocites of the same species. Later, 30 years later, Illmense and Hope in the United States used cells from the intracellular massif obtained from mouse blasts as starting genetic material, which were fused by inactivated Sendai virus, with newly fertilized and enucleated single-celled zygotes.
In the second half of the 1980s, successful cloning of economically important species was achieved. The first important advances were made in 1986 by Willadsen, who worked with embryos and oocytes from sheep.
Below is a table containing the cloning history:
| SPECIES | YEAR | ORIGIN
CELLULAR |
CONTAINER |
| FROG | 1952 | Blastula | Oocytes |
| MOUSE | nineteen eighty one | ICM | Enucleated zygotes |
| SHEEP | 1986 | Blastomeres | Ripe oocytes |
| Bovines | 1987 | Blastomeres | Ripe oocytes |
| RABBITS | 1988 | Blastomeres | Ripe oocytes |
| PIGS | 1989 | Pronuclei | Enucleated zygotes mature oocytes |
| SPECIES | YEAR | CELLULAR ORIGIN | CONTAINER |
| XENOPUS | 1975 | Keratinocytes | Oocytes |
| MOUSE | 1993 | Powerful embryonic toti cells | Embryos
tetraploid |
| SHEEP | 1994 | Embryonic disc day 9 of culture | Ripe oocytes |
| SHEEP | nineteen ninety six | Embryonic fibroblasts day 26 | Ripe oocytes |
| SHEEP | 1997 | Mammary gland | Ripe oocytes |
CLONING:
"Cloning is the making of identical copies of some biological element. From the point of view of whole organisms, cloning refers to obtaining genetically identical beings. " (O Castro, 1997)
"The term cloning implies the formation of genetic copies that can be DNA strands, cells in culture or complete individuals" (Santos Huguet, 2004)
The most relevant case in the history of cloning so far was the case of Dolly, since it was the first time that a progeny was obtained from the cloning of a somatic cell inserted into an enucleated oocyte; that is to say that Dolly had no father and was derived from the cells of the mammary gland of her mother, without the mediation of a sperm or other more primitive form of male gametes at conception.
However, it is difficult to assign the biogenetic term to the reconstructed embryo from which Dolly was formed, since in the formation of the tissue of Dolly's mother if a father participated and therefore if there was an exchange of genetic material in each and every one of the somatic cells of the genetic mother.
"The efficiency of cloning is quite low in most species, since only 1 and 5% of the reconstructed embryos were born. Animals born by nuclear transfer can suffer diseases, but their young cannot, as in the case of
Bonny, Dolly's Lamb ”(KIND & SCHNIEKE)
The best known technique for obtaining cloned mammals is nucleus transfer.
CLONE:
"It indicates a genetic identity and can appear at the level of DNA molecules; cells or organisms. " (Barrios García)
"A group of genetically identical cells that are formed by mitotic division from an original cell." (Santos Huguet, 2004)
CLONING OF MAMMALS:
“Organism or group of organisms that derive from another through a process of asexual reproduction. The term is applied to both cells and organisms, so that a group of cells that come from a single cell is also considered a clone ”(BIOTECHNOLOGY, nd)
CLONED MAMMALS :
- CattleDeerCatDogHuronGoatGaurHorseMiceEuropean MuffinPigRabbitRatMonkey RhesusSheepIndian BuffaloWolf
CLONING TECHNIQUES:
- Embryo partitioning: It is based on obtaining twin embryos by bisection or by separation of blastomeres from embryos of 2 to 32 or more cells and the accommodation of the "halves" from another egg or in an artificial cover.
- Nucleus transfer known as SCNT: This technique is based on the transplantation of nuclei that come from blastomeres of a pre-implanted embryo and on the transport of nucleus from embryonic or fetal cells that are obtained from a primary culture or that grow in a culture. These nuclei are transferred to an enucleated ovum or to a zygote to which the pronuclei have been removed. In the end we get individuals almost identical to each other but not identical to their parents.
BIOMEDICINE IN ANIMALS:
Nuclear transfer has become one of the best methods for establishing genetically modified large animal lineages. There are two ways to produce transgenic animals:
- The first is by means of transgenic DNA being introduced directly into the zygote for incorporation into the genome. The second is to make genetic modifications to cultured cells and then use them to produce whole animals.
CLONED ANIMALS USED AS BIOREACTORS:
Cloned animals that are introduced with a human gene in the embryo stage are known as bioreactors. These allow the production of human proteins in animal body fluids that can be subsequently purified and used as medicines for the treatment of various genetic and non-genetic diseases.
genetic.
NUCLEAR TRANSFER, EMBRYONIC STEM CELLS AND REGENERATIVE MEDICINE:
"ES cells are usually isolated from blastocyst stage embryos. A blastocyst is a tiny fluid-filled ball of a hundred cells contained within a cluster of cells called the internal cell mass that gives rise to all the tissues in the body. The blasts, or isolated ICMs, are cultured and in a few days or a week colonies of small, highly concentrated cells emerge, which also continue to grow indefinitely; they are ES cells.
ES cells are often used as an appropriate substitute for early embryo study, but what they really are remains unclear. They can be a tissue culture artifact, something aberrant created in response to artificial growth conditions. ”
(KIND & SCHNIEKE)
UNDERSTAND REPROGRAMMING:
The human body is made up of hundreds of cell types, the identity of a cell, the speed with which it divides, the materials it synthesizes, the receptors, ribonucleic acid and protein molecules are responsible for producing different models of expression. genetics.
Each cell has the same genetic information; in humans about 3 billion base pairs of DNA and about 25,000 genes, but these are expressed differently. A parallel can be drawn with computer software and hardware.
GLOBAL IMPACT OF CLONING:
After the production of the cloned Dolly sheep was made public, many countries of the world declared their opinions on it.
The President of the United States at that time said that the discoveries that touch human creation is not only a matter of scientific research but also a moral and spiritual matter.
In the case of Great Britain, the European Parliament gave a unanimously approved resolution recommending to the member states the absolute prohibition of all experiments related to the cloning of human beings, including those for research purposes.
The world health organization is made up of 191 countries and declared in 1997 that human cloning is ethically unacceptable and contrary to human and moral integrity.
UNESCO in 1993 drafted a document stating that practices that are contrary to human dignity, such as cloning for reproductive purposes of human beings, should not be allowed.
Portugal has no problems with cloning plants and animals as long as the international rules governing these practices are respected. However, they consider the cloning of human beings unacceptable.
Argentina published a bulletin prohibiting human-related cloning experiments.
CONSEQUENCES OF CLONING OF MAMMALS:
- From an environmental point of view, cloning threatens the biodiversity and genetic variability of species. Negatively influences ecological balance. A positive consequence is to develop models to study biochemical and physiological mechanisms in the development of Genetic and Non-Genetic Diseases. Cloning opens the door for important scientific studies in the field of medicine Facilitates the use of this technique to satisfy whims such as perpetuating a pet The introduction of animals cloned with common animals may affect future biodiversity.
CLONING APPLICATIONS IN HUMAN BEINGS:
- Cloning for reproductive purposes: This application can be used as a whim to create human beings for various purposes, whether intellectual, for organ and tissue donors, genetic photocopies and loved ones or to create useful people to society due to their intellectual or moral capacity. This application of cloning can also be used as an assisted reproduction technique, that is, as an aid for couples with infertility.
We can say that cloning for reproductive purposes is ethically inadmissible and violates the following fundamental principles:
- Being conceived in a sexual way Not having a father and a mother Attempting against the biological independence of the original and the clone Using cloned embryos to obtain stem cells capable of differentiating in more than 200 different tissues for the purpose of cell transplantation ETHICAL ISSUES RELATING TO CLONING FOR THE REPRODUCTION OF HUMAN BEINGS: "Concern about eugenic practices. Technical and medical security. Weakening of the concept of reproduction and family. Ambiguous relationships of a cloned child with the parent. Confusion about the personal identity and damage to the psychological development of a clone. Conflict with human dignity. of design and human improvement ”(UNESCO, 2004)
CONCLUSIONS:
The advancement with human genetics and human cloning is affected by many important ethical aspects that range from health professionals, professionals in general, patients, relatives of patients and basically for every individual in society.
It is worth mentioning that progress is increasing and very quickly. All these advances provoke us to ask what the future holds for us, if science is playing at being a god and causing many ethical-moral contradictions.
THANKS:
I thank my alma mater the Orizaba Technological Institute, Professor Fernando
Aguirre and Hernández who teaches the subject of Fundamentals of Administrative Engineering for showing us that we are capable of writing articles on various topics, for promoting the habit of reading and above all for helping us realize what we are capable of achieving.
BIBLIOGRAPHY
- Barrios García, B. (sf). CLONING: A CHALLENGE TO THE RESPONSIBILITY OF MEN. LATIN AMERICAN JOURNAL OF BIOETHICS. BIOTECHNOLOGY. (sf). BIOTECHNOLOGY. Retrieved on APRIL 23, 2016, from https://sites.google.com/site/biotecnologianayra/tecnica/clonacion-de-miferosKIND, A., & SCHNIEKE, A. (sf). CLONING OF MAMMALS: SOMETHING MORE THAN A SIMPLE SHEEP. BORDERS OF SCIENCE, 185-201.O Castro, F. (1997). CLONING OF ADULT MAMMALS. THE INITIATED WAY. APPLIED BIOTECHNOLOGY, 275-280, Santos Huguet, P. (2004). HUMAN CLONING: BIOETHICAL AND LEGAL ASPECTS. MADRID: COMPLUTENSE UNIVERSITY OF MADRID.UNESCO. (2004). HUMAN CLONING: ETHICAL ISSUES. FRANCE: ORGANIZATION OF THE UNITED NATIONS FOR EDUCATION, SCIENCE AND CULTURE.
