Putting new genes into cells

The usual reason for making recombinant DNA is to introduce a new sequence into a species where it doesn't normally occur. The added sequence includes a gene that modifies the host cell in some way. For example, scientists may want to introduce a gene for producing an antiviral compound into bacteria, so the bacteria will manufacture this compound for medical use. The challenge is to get the recombinant DNA into the host cells without seriously disrupting their normal functioning. This is where...

A copy in every cell

All the cells in your body have essentially identical copies of the unique DNA sequences that were put together at the moment of your conception. To get copies from that original single cell into every cell of the body, DNA molecules must faithfully duplicate themselves each time a cell divides in two. What makes this possible is the way the bases on the two strands of the double helix complement one another. If you take another look at the double helix in Figure 1.4, you'll see that the four...

Let there be DNA

In 1869, a young Swiss chemist named Johann Miescher wanted to know what chemicals occur in cell nuclei. He analyzed the material he extracted from white blood cells found in pus and named the substance nuclein. A few years later, he separated a phosphorus-containing acid from his cell substance, and renamed the chemical nucleic acid. Miescher had discovered DNA (deoxyribonucelic acid), the material from which genes are made, but the significance of this molecule wasn't recognized until 75...

Glossary

Alkaptonuria a genetic disease in which the urine turns black when exposed to air, due to homogentistic acid in the urine. amino acids naturally occurring biological molecules with a variety of functions. Among the amino acids, there are 20 that are used as building blocks for making proteins. antisense therapy administration of a drug consisting of short pieces of artificially produced, single-stranded DNA (about 15 to 25 nucleotides). The DNA is complementary to a section of an RNA molecule....

Pros and cons of gene therapy

Should we be altering something as fundamental as people's genes The issue still causes dispute 16 years after the first attempts were made on human patients. There are important distinctions to be made between altering the somatic genes found in most body cells (which affects only the person concerned) and altering germ-line genes found in sperm and egg cells (which affects descendants of the patient). A study published by the U.S. Congress Office of Technology Assessment in 1984 reported a...

Closing thoughts

A cleaner environment, like better health and nutritious food, is something everybody wants. And we want to achieve it cheaply and easily. Environmental biotechnology makes such promises, with its tremendous potential to find better ways to dispose of waste, convert by-prod-ucts to energy and new materials, and clean up polluted areas. But it sometimes sounds too good to be true. A 1993 statement from the U.S. National Research Council Committee on In Situ Bioremediation said that this field is...

A new angle to landscaping

It's not only microbes and people that collect gold plants can also accumulate it from either water or soil. In the early 1900s, in fact, some scientists speculated that plants had played an important part in forming certain gold deposits in rock over geological time. For generations, knowledgeable prospectors have used differences in plant distribution to guide them to buried gold and other metals. But exactly how certain organisms dissolve and concentrate metals has been poorly understood...

Genes and vaccines

A big advantage of using genetic engineering to produce drugs is that it's possible to mass-produce chemicals that might otherwise be difficult and costly to extract, or simply unavailable by conventional means. Another important advantage is that drugs produced in this way are pure and, if made using human genes, fully compatible with use in people. For example, before engineered bacteria were cloned to manufacture human insulin, the main source of this hormone (used to treat diabetes) was the...

Golden harvest

There may be gold in them thar hills, but its shine quickly grows dimmer when you add up the cost of labor and equipment needed to extract it, and the pollution created in the process. While Hollywood movie heroes may turn up gold nuggets with only a little light panning, a typical gold mining operation must go through a ton of rock, sand, or gravel to end up with about l 50th of an ounce of gold. And digging or dredging out the ore is only the beginning. As well as being one of earth's...

Pests and diseases

Take a field of rye and watch what happens when the plants are infected with a fungus. The fungus sweeps through the field and plants die. But not all of them. The question is why does one plant succumb to a fungal disease while a second plant growing near it resists Researchers have found that, in many cases, the difference between resistance and susceptibility is simply the rate of the plant's response. If a plant can respond to the first attack of fungi rapidly, then it can resist further...

Frozen fish

Since North Atlantic fish stocks fell so dramatically in the 1990s, many fishing communities scattered along Canada's eastern shoreline turned to aquaculture of salmon and other fish. But the more northerly communities face the challenge of protecting their captive fish stocks (especially young ones) from the cold. During the Canadian winters, much of the east coast has sub-zero seawater temperatures. These conditions would freeze halibut and Atlantic salmon raised on fish farms, making the use...

Unzipped

JOSEPH HENRY PRESS Washington, D.C. 1997 2101 Constitution Avenue, NW Washington, DC 20418 The JOSEPH HENRY PRESS, an imprint of the NATIONAL ACADEMY PRESS, was created by the National Academy of Sciences and its affiliated institutions with the goal of making books on science, technology, and health more widely available to professionals and the public. Joseph Henry was one of the founders of the National Academy of Sciences and a leader of early American science. Any opinions, findings,...

How does DNA store information

The key to DNA's astonishing power to store information lies in the four different bases (G, C, T, and A). They form the letters of the genetic alphabet. Imagine yourself walking up a DNA molecule on one side of the steps, reading off the bases as you go. Your journey might read AGGTCTATCAGC, and so on. Another section of steps further along will give you a completely different sequence of letters. In fact, the four bases can be arranged along the DNA molecule in a practically infinite variety...

A quick reading

On the slimy underwater surfaces of rocks, stems, and leaves in streams and lakes is a thin layer of microscopic life. This ubiquitous submerged film of algae, bacteria, fungi, and protozoans is called periphyton. It can be used like a book to read the health of its aquatic world. Monitoring environmental quality is a key task of biotechnology, and what better way to do it than to use organisms themselves as sensitive, built-in record-keepers. The advantage of periphyton as an environmental...

Why bacteria

Anyone who wants to study bacteria needs only a small spoonful of garden soil or a scraping from inside somebody's mouth to get about 10 million subjects for investigation. The most numerous of single-celled organisms on earth, bacteria are easy to house, cheap to feed, and multiply rapidly to say the least. Given the right conditions, a bacterial culture may double in weight in as little as 20 minutes. On a commercial scale, this growth rate lets managers quickly clone genetically altered...

How genes make proteins

It becomes difficult at this point in the story to avoid a textbook-like complexity, with descriptions of sections of genes that don't code for amino acids, sections that carry instructions for starting and stopping protein building, sections that overlap with each other, and so on. But although there's much more that can be said about the action of genes, you don't need these additional details in order to make sense of biotechnology. The table below summarizes the history outlined so far....

Colored bodies

The way in which organisms reproduce themselves demonstrates the primacy of cells, for every living individual starts life as just a single cell. All the information needed to build the organism must reside in that cell, information given to it by the reproductive cells of its parents, as they were given it by their parents, and so on. The most likely carriers of information seen inside animal and plant cells were chromosomes, threadlike bodies that make a distinctive appearance in the nucleus...

Contents

Preface How Biotechnology Came About What is biotechnology In the beginning The voyager and the monk A striking coincidence Colored bodies Fruit flies in the lab Let there be DNA Unraveling the double helix How does DNA store information A copy in every cell What do genes Protein primer Examples of proteins Proteins are us The amino acids Genes, proteins, and your eyes The genetic code Nature, the expert packer How genes make proteins Daring nucleotide adventures Tools in the Genetic...

Protein primer

We return now to the idea I began with at the start of this chapter the notion that people and all other organisms are built and run by molecules. It isn't a metaphorical or a metaphysical idea it's literally true. To convince you of this, I'll introduce you to protein molecules. Protein is one of the things listed on my boxes of breakfast cereal, but to a molecular biologist, proteins are the very foundation of living systems. Virtually every process and product in living cells depends on...

Underwater drugs

Drugs both legal and illegal are simply chemicals that affect how living things function, by interacting with particular parts of particular cells to change the way they work. They are no different in principle from some of the chemicals our own bodies produce, such as hormones and enzymes. Every living thing makes its own set of drug-like chemicals for its own purposes, and the only sources of drugs before the establishment of large-scale drug manufacturing in the 19th century were plants, ani...

The genetic code

A strand of DNA is a polynucleotide a long chain of nucleotides, connected to one another by chemical bonds. The question is, how do four different nucleotides translate into 20 amino acids and thousands of different proteins It's not a big problem, really, just a matter of coding. Think of the dots and dashes of the Morse Code giving alphabetic instructions for writing out King Lear and you'll have an idea of how it can be done. Like the dot-dot-dot and dash-dash-dash signifying S and O in...

Prometheus revisited

Prometheus was the Greek demi-god who stole a spark of fire and was punished by Zeus for his presumption. In the minds of many people, the enterprise of biotechnology is a Promethean risk, another example of humanity's self-destructive aspirations to play god. But it's rather late in the game to object to human nature. We have benefited and suffered from our curiosity since the days when we discovered that rocks have better uses than to be left lying on the ground. Powerful though our species...

A cornucopia of chemicals

Forty seven billion dollars' worth of pesticides are sold each year in the United States alone, and the search for new and more effective chemicals to control pests is nev-erending. As with germs and antibiotics, the living targets of pesticides eventually evolve resistance to particular toxins, and their populations begin to climb again. To keep control, pesticides themselves have evolved over the years, from the synthetic, widely toxic sprays and powders of the 1950s and '60s to chemicals...

What is biotechnology

The molecular waltzes of life take place largely inside cells, and one simple definition of biotechnology is the commercialization of cell biology. More generally, biotechnology is an umbrella term that covers various techniques for using the properties of living things to make products or provide services. The term was first used before the 20th century for such traditional activities as making dairy products, bread, or wine, but none of these would be considered biotechnology in the modern...

Problems with patents

In order to get a patent, an invention must be novel, useful, and not obvious. The purpose of a patent is to give whoever holds it a number of years (usually 15 to 20) to have exclusive control over what they claim to have invented. Patent holders can then either monopolize production of their invention or license it to others. The dilemma faced by biotechnologists is to know exactly what to claim from the results of their work, and at what stage in their research to file for a patent. In rare...

Medicines from plants

Another fruitful source of natural medicines is plants. Many have already proved their value and there is a huge untapped potential for further discoveries, since more than 90 percent of the world's half million plant species have never been tested for their pharmaceutical value. Only 120 prescription drugs worldwide are based on extracted plant products. Taxol, an anticancer drug made from the bark of the Pacific yew tree, is a recent and much-publicized example of a valuable plant-derived...

Microbes in medicine

The pharmaceutical business was using the products of cells long before genetic engineering developed in the 1970s. Interest in the potential use of microbes in medicine was stimulated in 1928 by the discovery of penicillin the first of four major classes of antibiotics now in common use (the others being tetracyclines, cephalosporins, and erythromycins). The original fuzzy mold that settled on some untidy dishes in Alexander Fleming's London lab, however, was very different from the organisms...

Gene therapy revisited

CLAIM 1 A process for providing a human with a therapeutic protein comprising introducing human cells into a human, said human cells having been treated in vitro to insert therein a DNA segment encoding a therapeutic protein, said cells expressing in vivo in said human a therapeutically effective amount of said therapeutic protein. That piece of legalese above is part of the patent for gene therapy issued in March 1995 to William French Anderson, Michael Blaese, and Steven Rosenberg scientists...

Monoclonal antibodies

Probably the most important products now derived from hybridoma technology are monoclonal antibodies, whose development won George Koehler and Cesar Milstein a Nobel prize in 1984. Antibodies are proteins produced by certain white blood cells to fight infection. Each antibody is specific to a particular foreign particle invading the body, such as a bacteria or virus. They inactivate the invaders by attaching themselves to them. Obviously it would be of great value to medicine if antibodies...

How Biotechnology Came About

If you want a quick insight into what modern biotechnology is all about, start thinking of yourself as being built and run by molecules. It's thanks to the cooperation of these small chemical units that you and I can blink, breathe, and read. Thanks to molecules, we once grew from microscopic fertilized eggs into functioning human beings. The amazing thing is that these molecules are nothing special in and of themselves. They are combinations of only half a dozen common elements carbon,...

Designer drugs

The close connection between antibody and antigen is a model for understanding how the body's biochemical systems in general work. One molecule aligns with another and something happens in the body an infection is blocked, a nerve impulse is sent, a building block of tissue is formed, a cell starts to die. This model is what modern pharmaceutical companies use to design new drugs, custom-made for specific purposes. Design is the right word here, because researchers can now develop drugs on...

Making opinions

The average person gets news of biotechnology mainly through the media. Who provides this information Does it present a balanced perspective Does it deal with the various concerns people have about biotechnology To answer these questions, researchers at the Center for Biotechnology Policy and Ethics at Texas A & M University analyzed 132 newspaper articles about biotechnology, collected from a variety of newspapers throughout the United States during 1991 and 1992. The bulk of information...

Unraveling the double helix

There was great excitement among molecular biologists during the 1930s and '40s. The physical basis of heredity was rapidly becoming better understood, and scientists felt they were close to peering inside the hidden machinery of the cells, into the little black box that directs what each living thing is to become. They knew that heredity is controlled by discrete factors called genes genes are located on threadlike chromosomes found Clearly this DNA molecule needed looking into. Investigators...

Its all in the genes

A length of DNA that's all it takes to make one individual different from another. One person may be born to live a robust life into healthy old age, while another suffers a crippling disability leading to an early grave. According to this view of things, our state of health is already circumscribed by genetic lottery months before we even began to draw breath, primed by an inheritance that will eventually give us one disease or another. Biotechnology's big promise is to subvert genetic destiny...

Chapter

Tools in the Genetic Engineering Workshop I asked the woman at the biotech trade display what the little microwave-size machine did. It's a PCR machine, she said, beginning to demonstrate. She opened a lid to expose a grid of small wells in the heart of the machine. Put your samples in there, close the lid, punch in the numbers, and wait. So simple even a child could do it, provided the child has the 7,000 currently needed to buy the machine. This is now all it takes to clone DNA. (Cloning...

What do genes do

To say that a gene consists of a particular sequence of bases in a DNA molecule isn't a very satisfying description. It doesn't tell us anything about what bases actually do, or how they do it. To the average person, a gene is something that gives you, say, blue eyes or brown eyes. So how does a sequence of bases in a DNA molecule do that To get a clue, let's turn to British physician Archibald Garrod and a few of his patients. In 1902, Garrod was examining a disorder named alkaptonuria, in...

Great expectations

Between 1950 and 1984, world grain output rose an astonishing 260 percent, thanks to a combination of improved varieties, irrigation, artificial fertilizers, and chemical pest control. During the same period, the number of people on the planet almost doubled. Today, world population growth adds about 90 million new mouths to feed every year, while land degradation, pest resistance, pollution, and climate changes have slowed or leveled growth in crop production. In the early 1990s, world grain...

Biotechnology on the Farm

Is biotechnology the answer to a hungry world's food supply, or is that only self-serving rhetoric from a profit-hungry agribusiness You hear both sides in the talk over biotech on the farm and it's not always easy to sort out the facts from the propaganda. Where food is concerned, people are especially wary. Will genetically engineered foods cause health problems How does changing technology affect farmers What impacts will it have on the environment As the first products of agricultural...

Finding the right microbes for the job

A great deal of research in environmental biotechnology is devoted simply to finding better ways of measuring and sampling the activities of microbes that might be potentially useful. It can take a lot of time and a lot of highly trained microbiologists to find the right microbes needed, for example, to degrade a particular pollutant. Only after the microbes are found can the task of genetic improvement proceed. To speed things up, many biotech companies are racing to develop more...

Hijackers and molecule snippers

Enigmatic entities occupying the borderlines between living and non-living things, viruses are little more than maverick molecules of DNA or RNA housed in protective protein coats. They resemble cells in having genetic instructions for making new versions of themselves, but differ from living organisms in lacking the biochemical machinery needed for their own multiplication. Left to themselves, viruses do nothing. They can remain unchanging for years, inert as a jar full of pebbles. To...

An ocean of opportunity

A chart of evolution on my wall shows the major groups of animals rising and branching from a submarine stem of single-celled ancestors, growing upward through a deep blue sea to thrust their topmost twigs above the surface and into the air. It's a vivid reminder that not only did life begin in the water but that the great majority of organisms today remain aquatic. Only reptiles, birds, mammals, insects, and plants have truly conquered dry land. By far the bigger share of earth's living...

Ethical Issues

hould we, or shouldn't we Ethical questions deal with the effects our actions (or inactions) have on the world around us. If something is harmful, we shouldn't do it. A simple enough guideline in theory, but one that's not very useful when the consequences of an activity aren't yet clear, or when its effects can be both harmful and helpful. Biotechnology falls into this ambiguous camp. Most differences of opinion between supporters and opponents of genetic manipulation come down to different...

Microbes clean up

Broadly speaking, environmental biotechnology includes any applications that reduce pollution. Methods might use organisms to break down or sequester pollutants (sometimes making useful products on the way), or replace existing activities that pollute with ones that don't. The concept isn't totally new. A traditional example is the septic field, sewage so that only harmless breakdown products are released into waterways. Microbes were first used to treat industrial wastewater as early as the...

A harvest of wood

To sustain a tree harvest into the future, forest managers need to replace what they cut an obvious if late-acknowledged truth. Where forests have grown undisturbed for centuries, they are impossible to replace, but the next best thing is to substitute tree plantations, in which the focus is on planting improved varieties of trees. Trees are a crop that can outlive their growers, and people in past generations planted trees that their children would harvest. With such a long growth period, it...

W

Who would have thought that healing the sick was so fraught with controversy When less was known about how the body works, and what causes diseases, people had little choice but to accept illness and disability as part of their fate. Depending on a person s philosophy of life, good health was a question of good luck or good morals, disease a misfortune or a punishment for wrongdoing. Today, we are not inclined to accept fate. Our bodies are less like reflections of our souls, more like...

The Human Genome Project

The Human Genome Project is an ambitious plan to map and sequence all 100,000 or so genes found in human DNA. It is a task that has occupied hundreds of scientists in labs around the world since about 1986. The first human genes to be identified, back in the 1970s, were those connected with diseases such as cystic fibrosis. Part of the motivation to sequence the entire genome (that is, all the genes present in a complete set of chromosomes) was the desire to learn more about the genetic roots...

The interferon story

The first big success story in the commercial production of drugs by genetic engineering was interferon, another naturally occurring compound connected with the immune system. Discovered in 1957, interferon is produced by cells in the human body in response to viral attack. It promotes production of a protein that stimulates the immune system, interfering with the spread of infection. Although the usefulness of interferon was recognized at once, it could not be marketed for widespread medical...

Further Reading

If you'd like to read more about topics covered in this book, check out the following recommended books. Chapter 1. How Biotechnology Came About Levine, Joseph and David Suzuki. The Secret of Life Redesigning the Living World. Toronto Stoddart Publishing Co. Ltd., 1993. Prentis, Steve. Biotechnology A New Industrial Revolution. New York George Braziller, 1984. Watson, James D. et al. Recombinant DNA A Short Course. New York Scientific American Books, 1983. Chapter 2. Tools in the Genetic...

Postscript

I have tried to put my finger on what it is about biotechnology that causes some people to hold it out as a great hope for the future and others to reject it as a dangerous and unwise application of science. How is it that adversaries can look at the same evidence and come up with opposite interpretations Is the evidence too inadequate to be conclusive Or is something else going on One answer to the dilemma is another apparent paradox both sides are right, and neither side is right. Like many...

Making recombinant DNA

The snips made by restriction enzymes at a given nucleotide sequence are usually offset on the two strands of DNA rather than directly opposite each other (see Figure 2.3). This leaves both cut fragments of DNA with dangling, single-stranded tails of unpaired bases, which are used to bond them to other fragments. Any two fragments of DNA sheared by the same restriction enzyme can be joined together, since they will have complementary sequences on their dangling strands (often called sticky...

Biotechnology in Seas and Trees

The ability of biotechnology to develop new cures, design better crops, and reduce pollution ultimately depends on the properties of living things. It is on our planet's variety of organisms, and their multitude of chemical and genetic resources, that the future of biotechnology rests. Although the applications of biotechnology today use mainly familiar organisms from labs and farms, there is a vast untapped well of life around the world from which tomorrow's successes may flow. Serendipitous...

Polymerase chain reaction

How does it work I asked the woman, nodding at the small black machine. It uses a heating-cooling cycle, she began. It heats up the DNA and melts it so the two strands come apart. Then it cools down and lets each strand build a complementary strand. Then it heats up again and splits them, and so on. It doubles your DNA each time. Of course, there's more to it than that simple version allows (see Figure 2.8), but there's the gist of it enough to give an insight into the remarkable extent to...

Fighting chemicals with chemicals

Among the most widespread pollutants in much of the world today are chemicals known as halogenated aromatic compounds. They are commonly found in such products as flame retardants, hydraulic fluids, pharmaceuticals, pesticides, and electrical equipment. Typically, these compounds are chemically inert, water-repelling, toxic and extremely difficult to get rid of. An important subgroup of the halogenated aromat-ics includes pentachlorophenol (PCP), a chlorine-containing chemical commonly used by...

Weather and soil

Everything that biotechnology can do to increase yields and decrease weeds, animal pests, and diseases can quickly be undone by the farmer's enduring nemesis bad weather. Although better forecasts help farmers plan for minor problems (such as unseasonable frosts or rain), a major flood, snowstorm, drought, or high winds can knock billions of dollars off the potential value of a year's planting. Today's farmer isn't quite as much at the mercy of the weather as yesterday's, however. Large,...

Cloning plants animals and cells

Take a cutting from a plant, put it in a pot of soil, and you have cloned an organism. The plant that grows from the cutting will be genetically identical to the one from which you took the cutting. Its development is made possible because each cell at the cut edge has the genetic potential to develop into any type of plant tissue needed to form a whole new plant. While whole plants have been regenerated from cuttings for centuries, biologists in the late 1950s discovered that whole plants can...

Developing regulations

Since 1986 there have been over 2,000 field trials of transgenic crops around the world, exposing natural ecosystems to the introduction of engineered genes. But while genetically novel organisms establish their place in agriculture, regulations governing their use are inconsistent. Proponents of biotechnology support deregulation, a trend being followed by the United States. Others are concerned about the dangers of releasing genetically engineered organisms before their safety has been...

Let us spray

To increase the world's food supply, farmers must not only grow more food but also reduce food losses. As much as a third of the world's crops are lost to pests and diseases, so protecting plants from these hazards is one of agriculture's biggest challenges. The word pests typically conjures up images of insects nibbling holes in fruits and vegetables however, farmers face another problem that's less obvious but just as troublesome. About 60 percent of the chemicals used to control pests in the...

DNA fingerprinting

Also known as DNA profiling, this is the technique you most often read about in connection with criminal cases. Developed by Alec Jeffreys in England in the early 1970s, the process is based on the fact that the distance between restriction cleavage sites on DNA strands (that is, the sites at which restriction enzymes make their cuts) differs from person to person. If you cut up DNA samples from any two people using the same restriction enzymes, you end up with two different assortments of DNA...

Farmerceuticals

On tomorrow's farm, the seeds being gathered by a harvester, and the eggs being collected from hens, may not be on their way to the mouths of people or livestock. Genetic engineering is also turning plants and animals into bioreactors living factories for making drugs, industrial chemicals, fuels, plastics, medical products, and other materials. It's an enterprise some call molecular farming. Plants are already a vast source of natural chemicals and materials such as medicines, solvents,...

Microbes as monitors

Using microbes to carry out tasks in the great outdoors poses a practical difficulty How on earth do you keep track of what they're doing It's especially challenging when the microbes are working below the surface of the soil for example, when they are breaking down underground contaminants. One method of monitoring that has been widely tested involves linking the genes that cause bacteria to degrade contaminants with genes for producing bioluminescence. Bioluminescence is biologically produced...

Research and development

While investigators strive to apply the properties of marine molecules, a huge amount of research is aimed at finding those useful molecules in the first place. New methods of analyzing molecular properties on a large scale have stimulated the booming biotechnology industry as much as actual product development itself. In the not-too-distant past, testing new chemicals for their biological effects was a long, laborious, and labor-intensive process. It required multiple, separate measurements,...

The continuing story of gene therapy

The first actual use of gene therapy began in September 1990, with the treatment of a child suffering from a rare genetic immunodeficiency disease caused by the lack of the enzyme adenosine deaminase (ADA). ADA-deficient people have persistent infections and high risk of early cancer, and many die in their first months of life. The much-publicized bubble boy, David, had this disease. David lived for nine years in a plastic chamber to prevent contact with viruses, which his immune system could...

The beginnings of gene therapy

The story of the race to carry out gene therapy is engagingly told in the book Altered Fates, written by two prizewinning journalists, Jeff Lyon and Peter Gorner. Like James Watson's 1968 book, The Double Helix, the account makes interesting reading not only for its descriptions of important scientific discoveries, but also for its portaits of the personalities involved, and its revelations about the behind-the-scenes politics of high-profile scientific research. The steps leading to the first...