Daily Archives: August 27, 2015

Photo by: Gernot Krautberger

Genetic engineering is any process by which genetic material (the building blocks of heredity) is changed in such a way as to make possible the production of new substances or new functions. As an example, biologists have now learned how to transplant the gene that produces light in a firefly into tobacco plants. The function of that genethe production of lighthas been added to the normal list of functions of the tobacco plants.

Genetic engineering became possible only when scientists had discovered exactly what is a gene. Prior to the 1950s, the term gene was used to stand for a unit by which some genetic characteristic was transmitted from one generation to the next. Biologists talked about a "gene" for hair color, although they really had no idea as to what that gene was or what it looked like.

That situation changed dramatically in 1953. The English chemist Francis Crick (1916 ) and the American biologist James Watson (1928 ) determined a chemical explanation for a gene. Crick and Watson discovered the chemical structure for large, complex molecules that occur in the nuclei of all living cells, known as deoxyribonucleic acid (DNA).

DNA molecules, Crick and Watson announced, are very long chains or units made of a combination of a simple sugar and a phosphate group.

Amino acid: An organic compound from which proteins are made.

DNA (deoxyribonucleic acid): A large, complex chemical compound that makes up the core of a chromosome and whose segments consist of genes.

Gene: A segment of a DNA molecule that acts as a kind of code for the production of some specific protein. Genes carry instructions for the formation, functioning, and transmission of specific traits from one generation to another.

Gene splicing: The process by which genes are cut apart and put back together to provide them with some new function.

Genetic code: A set of nitrogen base combinations that act as a code for the production of certain amino acids.

Host cell: The cell into which a new gene is transplanted in genetic engineering.

Human gene therapy (HGT): The application of genetic engineering technology for the cure of genetic disorders.

Nitrogen base: An organic compound consisting of carbon, hydrogen, oxygen, and nitrogen arranged in a ring that plays an essential role in the structure of DNA molecules.

Plasmid: A circular form of DNA often used as a vector in genetic engineering.

Protein: Large molecules that are essential to the structure and functioning of all living cells.

Recombinant DNA research (rDNA research): Genetic engineering; a technique for adding new instructions to the DNA of a host cell by combining genes from two different sources.

Vector: An organism or chemical used to transport a gene into a new host cell.

Attached at regular positions along this chain are nitrogen bases. Nitrogen bases are chemical compounds in which carbon, hydrogen, oxygen, and nitrogen atoms are arranged in rings. Four nitrogen bases occur in DNA: adenine (A), cytosine (C), guanine (G), and thymine (T).

The way in which nitrogen bases are arranged along a DNA molecule represents a kind of genetic code for the cell in which the molecule occurs. For example, the sequence of nitrogen bases T-T-C tells a cell that it should make the amino acid known as lysine. The sequence C-C-G, on the other hand, instructs the cell to make the amino acid glycine.

A very long chain (tens of thousands of atoms long) of nitrogen bases tells a cell, therefore, what amino acids to make and in what sequence to arrange those amino acids. A very long chain of amino acids arranged in a particular sequence, however, is what we know of as a protein. The specific sequence of nitrogen bases, then, tells a cell what kind of protein it should be making.

Furthermore, the instructions stored in a DNA molecule can easily be passed on from generation to generation. When a cell divides (reproduces), the DNA within it also divides. Each DNA molecule separates into two identical parts. Each of the two parts then makes a copy of itself. Where once only one DNA molecule existed, now two identical copies of the molecule exist. That process is repeated over and over again, every time a cell divides.

This discovery gave a chemical meaning to the term gene. According to our current understanding, a specific arrangement of nitrogen bases forms a code, or set of instructions, for a cell to make a specific protein. The protein might be the protein needed to make red hair, blue eyes, or wrinkled skin (to simplify the possibilities). The sequence of bases, then, holds the code for some genetic trait.

The Crick-Watson discovery opened up unlimited possibilities for biologists. If genes are chemical compounds, then they can be manipulated just as any other kind of chemical compound can be manipulated. Since DNA molecules are very large and complex, the actual task of manipulation may be difficult. However, the principles involved in working with DNA molecule genes is no different than the research principles with which all chemists are familiar.

For example, chemists know how to cut molecules apart and put them back together again. When these procedures are used with DNA molecules, the process is known as gene splicing. Gene splicing is a process that takes place naturally all the time in cells. In the process of division or repair, cells routinely have to take genes apart, rearrange their components, and put them back together again.

Scientists have discovered that cells contain certain kinds of enzymes that take DNA molecules apart and put them back together again. Endonucleases, for example, are enzymes that cut a DNA molecule at some given location. Exonucleases are enzymes that remove one nitrogen base unit at a time. Ligases are enzymes that join two DNA segments together.

It should be obvious that enzymes such as these can be used by scientists as submicroscopic scissors and glue with which one or more DNA molecules can be cut apart, rearranged, and the put back together again.

Genetic engineering requires three elements: the gene to be transferred, a host cell into which the gene is inserted, and a vector to bring about the transfer. Suppose, for example, that one wishes to insert the gene for making insulin into a bacterial cell. Insulin is a naturally occurring protein made by cells in the pancreas in humans and other mammals. It controls the breakdown of complex carbohydrates in the blood to glucose. People whose bodies have lost the ability to make insulin become diabetic.

The first step in the genetic engineering procedure is to obtain a copy of the insulin gene. This copy can be obtained from a natural source

Phototake

(from the DNA in a pancreas, for example), or it can be manufactured in a laboratory.

The second step in the process is to insert the insulin gene into the vector. The term vector means any organism that will carry the gene from one place to another. The most common vector used in genetic engineering is a circular form of DNA known as a plasmid. Endonucleases are used to cut the plasmid molecule open at almost any point chosen by the scientist. Once the plasmid has been cut open, it is mixed with the insulin gene and a ligase enzyme. The goal is to make sure that the insulin gene attaches itself to the plasmid before the plasmid is reclosed.

The hybrid plasmid now contains the gene whose product (insulin) is desired. It can be inserted into the host cell, where it begins to function just like all the other genes that make up the cell. In this case, however, in addition to normal bacterial functions, the host cell also is producing insulin, as directed by the inserted gene.

Notice that the process described here involves nothing more in concept than taking DNA molecules apart and recombining them in a different arrangement. For that reason, the process also is referred to as recombinant DNA (rDNA) research.

The possible applications of genetic engineering are virtually limitless. For example, rDNA methods now enable scientists to produce a number of products that were previously available only in limited quantities. Until the 1980s, for example, the only source of insulin available to diabetics was from animals slaughtered for meat and other purposes. The supply was never large enough to provide a sufficient amount of affordable insulin for everyone who needed insulin. In 1982, however, the U.S. Food and Drug Administration approved insulin produced by genetically altered organisms, the first such product to become available.

Since 1982, the number of additional products produced by rDNA techniques has greatly expanded. Among these products are human growth hormone (for children whose growth is insufficient because of genetic problems), alpha interferon (for the treatment of diseases), interleukin-2 (for the treatment of cancer), factor VIII (needed by hemophiliacs for blood clotting), erythropoietin (for the treatment of anemia), tumor necrosis factor (for the treatment of tumors), and tissue plasminogen activator (used to dissolve blood clots).

Genetic engineering also promises a revolution in agriculture. Recombinant DNA techniques enable scientists to produce plants that are resistant to herbicides and freezing temperatures, that will take longer to ripen, and that will manufacture a resistance to pests, among other characteristics.

Today, scientists have tested more than two dozen kinds of plants engineered to have special properties such as these. As with other aspects of genetic engineering, however, these advances have been controversial. The development of herbicide-resistant plants, for example, means that farmers are likely to use still larger quantities of herbicides. This trend is not a particularly desirable one, according to some critics. How sure can we be, others ask, about the risk to the environment posed by the introduction of "unnatural," engineered plants?

The science and art of animal breeding also are likely to be revolutionized by genetic engineering. For example, scientists have discovered that a gene in domestic cows is responsible for the production of milk. Genetic engineering makes it possible to extract that gene from cows who produce large volumes of milk or to manufacture that gene in the laboratory. The gene can then be inserted into other cows whose milk production may increase by dramatic amounts because of the presence of the new gene.

One of the most exciting potential applications of genetic engineering involves the treatment of human genetic disorders. Medical scientists know of about 3,000 disorders that arise because of errors in an individual's DNA. Conditions such as sickle-cell anemia, Tay-Sachs disease, Duchenne muscular dystrophy, Huntington's chorea, cystic fibrosis, and Lesch-Nyhan syndrome result from the loss, mistaken insertion, or change of a single nitrogen base in a DNA molecule. Genetic engineering enables scientists to provide individuals lacking a particular gene with correct copies of that gene. If and when the correct gene begins functioning, the genetic disorder may be cured. This procedure is known as human gene therapy (HGT).

The first approved trials of HGT with human patients began in the 1980s. One of the most promising sets of experiments involved a condition known as severe combined immune deficiency (SCID). Individuals with SCID have no immune systems. Exposure to microorganisms that would be harmless to the vast majority of people will result in diseases that can cause death. Untreated infants born with SCID who are not kept in a sterile bubble become ill within months and die before their first birthday.

In 1990, a research team at the National Institutes of Health (NIH) attempted HGT on a four-year-old SCID patient. The patient received about one billion cells containing a genetically engineered copy of the gene that his body lacked. Another instance of HGT was a procedure, approved in 1993 by NIH, to introduce normal genes into the airways of cystic fibrosis patients. By the end of the 1990s, according to the NIH, more than 390 gene therapy studies had been initiated. These studies involved more than 4,000 people and more than a dozen medical conditions.

In 2000, doctors in France claimed they had used HGT to treat three babies who suffered from SCID. Just ten months after being treated, the babies exhibited normal immune systems. This marked the first time that HGT had unequivocally succeeded.

Controversy remains. Human gene therapy is the source of great controversy among scientists and nonscientists alike. Few individuals maintain that the HGT should not be used. If we could wipe out sickle cell anemia, most agree, we should certainly make the effort. But HGT raises other concerns. If scientists can cure genetic disorders, they can also design individuals in accordance with the cultural and intellectual fashions of the day. Will humans know when to say "enough" to the changes that can be made with HGT?

Photo Researchers, Inc.

Despite recent successes, most results in HGT since the first experiment was conducted in 1990 have been largely disappointing. And in 1999, research into HGT was dealt a blow when an eighteen-year-old from Tucson, Arizona, died in an experiment at the University of Pennsylvania. The young man, who suffered from a metabolic disorder, had volunteered for an experiment to test gene therapy for babies with a fatal form of that disease. Citing the spirit of this young man, researchers remain optimistic, vowing to continue work into the possible lifesaving opportunities offered by HGT.

The commercial potential of genetically engineered products was not lost on entrepreneurs in the 1970s. A few individuals believed that the impact of rDNA on American technology would be comparable to that of computers in the 1950s. In many cases, the first genetic engineering firms were founded by scientists involved in fundamental research. The American biologist Herbert Boyer, for example, teamed up with the venture capitalist Robert Swanson in 1976 to form Genentech (Genetic Engineering Technology). Other early firms like Cetus, Biogen, and Genex were formed similarly through the collaboration of scientists and businesspeople.

The structure of genetic engineering (biotechnology) firms has, in fact, long been a source of controversy. Many observers have questioned the right of a scientist to make a personal profit by running companies that benefit from research that had been carried out at publicly funded universities. The early 1990s saw the creation of formalized working relations between universities, individual researchers, and the corporations founded by these individuals. Despite these arrangements, however, many ethical issues remain unresolved.

Follow this link:

Genetic Engineering - humans, body, used, process, plants ...

Human genetic engineering is one of the most controversial aspects of a science, which is itself highly controversial, and it is still very much in its infancy. There have been a few isolated cases where an illness has been successfully cured by the use of genetic therapy, but there have also been other cases where patients have contracted diseases such as leukemia through experimentation with this type of therapy. At this stage it is impossible to say exactly what the future will hold, or exactly what the consequences of these developments will be.

So far, the only successes which the method has are in treating conditions relating to the human immune system. This is an obvious application of the technology, as the condition is caused purely by genetic factors. By replacing a gene which gives the patient a proclivity towards the disease with a healthy one a cure can be effected. This is more than just theory, as the numbers of cases where this has been successfully carried out is now into double figures, and is constantly increasing. The challenge lies in overcoming the potentially catastrophic side effects which can occur if the treatment does not work.

One of the most controversial of all applications of this technology is in allowing infertile mothers to conceive. This is done by using the eggs from a different mother, leaving the child with the genetic blueprint inherited from three people. This will then be passed on through future generations, leading to untold potential complications. It is still far too early to judge the potential consequences of the use of this type of genetic technology, but if there are any negative side effects they are likely to be far reaching and extremely damaging.

There have been many arguments put forward concerning human genetic engineering, some strongly in favor and some equally strongly against. The potential is there for diseases caused by genetics to be eliminated completely, and this is there area in which fewest dissenting voices will be heard. The use of genetics purely to overcome fertility is far more controversial, especially when you consider the permanent effect that this has on all future generations of that family. There are also many dissenters against the possibility of parents deciding features of their children using an advanced form of this technology, which cannot be used yet but which may be perfectly possible in the future.

If this technology is left unchecked it will definitely have far reaching consequences. There is no doubt that wealthy families would take advantage of such technology to try to give their children every advantage in their future life, and there could be several possible outcomes of this. One would be a rise in productivity and creativity which would penetrate through society, raising the standard of society for everyone and creating more opportunities. It is also possible that poor families who could not afford this technology would be left even further adrift, leading to sharp increases in crime rates, social disorder, and economic chaos.

Even though strong opinions are held on both sides of the argument, the truth is that it is far too early to know for sure exactly what is involved with human genetic engineering. There are some philosophical and moral arguments which will prove exceedingly difficult to resolve one way or another, but there are potential consequences which cannot possibly be known until more research has been carried out. The arguments over this technology are certain to rage for a great many years to come, and it is unlikely there will ever be universal agreement on human genetic engineering.

View original post here:

Genetic Engineering In Humans

Human Nature on Collision Course with Genetic Engineering

Human genetic engineering could be the next major battleground for the global conservation movement, according to a series of reports in the latest issue of World Watch magazine, published by the Worldwatch Institute, a Washington, D.C.-based research organization. While previous struggles have involved protecting ecosystems and human societies from the unpredicted consequences of new technologies, this fight over high-risk applications of human genetic engineering is a struggle over who will decide what it means to be human.

Many countries have already banned reproductive cloning, and the U.N. is working on a global treaty to ban it, but even more powerful and much more dangerous are the related technologies to modify the genes we pass on to our children, says Ed Ayres, Editor of World Watch magazine. The contributors to this special issue call on the U.N. and national governments to ban the technology known as inheritable genetic modification.

Many uses of human genetic technology could be beneficial to society, but as political scientist Francis Fukuyama writes in the magazine, our understanding of the relationship between our genes and whatever improvements we might seek for our children (and their descendants) is dangerously deficient. Fukuyama warns that the victim of a failed experiment will not be an ecosystem, but a human child whose parents, seeking to give her greater intelligence, will saddle her with a greater propensity for cancer, or prolonged debility in old age, or some other completely unanticipated side effect that may emerge only after the experimenters have passed from the scene.

Human genetic engineering has ramifications that reach far beyond the life of a single child. Several contributors highlight the disastrous results of the last serious effort to engineer genetic perfection. In the early part of the 20th century, scientists and politicians in the United States relied on the alleged science of eugenics to justify the forced sterilization of tens of thousands of people who were judged to be feebleminded, mentally defective, or epileptics. Hitler passed his own sterilization law soon after taking office in 1933, heading down the path toward the Holocaust. The U.S. biotechnology industry-which dominates the global industry-has become an increasingly powerful economic and political force, with revenues growing fivefold between 1989 ($5 billion) and 2000 ($25 billion). Aided by the equally rapid revolution in computing, laboratories that once took two months to sequence 150 nucleotides can now process over 30 million in a day, and at a small fraction of the earlier cost. The number of patents pending for human DNA sequences has gone from 4,000 in 1991, to 500,000 in 1998, to several million today.

We are publishing this special issue because we dont want to lose the opportunity to decide openly and democratically how this rapidly developing technology is used, says Ayres. This isnt a fight about saving whales, or the last rain forests, or even the health of people living today. The question is whether we can save ourselves from ourselves, to know and respect what we do not know, and to put the breaks on potentially dangerous forms of human genetic engineering.

Excerpts from the authors of the Beyond Cloning issue of World Watch

About World Watch magazine: This bimonthly magazine is published by the Worldwatch Institute, an independent research organization, based in Washington, DC. Launched in 1988, the magazine has won the Alternative Press Award for investigative journalism, the Project Censored Award, and a number of Utne Reader awards. Recent editions have featured articles on the imminent disappearance of more than half of the worlds languages, airport sprawl, and the rapid growth of organic farming. Please visit: http://www.worldwatch.org/mag/.

The Worldwatch Institute is an independent research organization that works for an environmentally sustainable and socially just society, in which the needs of all people are met without threatening the health of the natural environment or the well-being of future generations. By providing compelling, accessible, and fact-based analysis of critical global issues, Worldwatch informs people around the world about the complex interactions between people, nature, and economies. Worldwatch focuses on the underlying causes of and practical solutions to the worlds problems, in order to inspire people to demand new policies, investment patterns, and lifestyle choices. For more information, visit: http://www.worldwatch.org.

Disclaimer: Please note that the statement by eight leaders of environmental NGOs, which appears on page 25 of the magazine, represents the views of the individuals quoted, not necessarily of the organizations they lead.

Follow this link:

Human Nature on Collision Course with Genetic Engineering ...