New Zealand Engineering 1997 April

Features

Genetic Engineering

Howard Bezar is communication manager with Crop & Food Research, Christchurch

Human insulin produced by bacteria, soybeans resistant to `Roundup', tobacco plants that produce haemoglobin _ hardly a week goes by without the media announcing a new application of genetic engineering.

And then of course came `Dolly', the Scottish cloned sheep, prompting new debate about the ethics of the technology.

What is genetic engineering? Simply defined, it is the transfer of genes from one species to another. Thus we have transgenic tomatoes or soybeans. Biotechnology is a wider term for the use of living organisms or their products to modify the environment and molecular biology is another term often used by scientists to describe research at the molecular level. Molecular biology advances our knowledge of living systems and provides the information underpinning the development of transgenic plants and animals.

Essentially genetic engineering is a new, high-tech tool in a process that is at least 10,000 years old. The maize we know today is a result of Native Americans crossing two species of a wild plant called teosinte about 8,000 years ago. Similarly, the origin of modern bread wheats involved combining genetic material from three grass species. Prehistoric biotechnologists used yeast cells to raise bread dough and to ferment alcoholic beverages, and bacterial cells to make cheeses and yogurt. They also practised selective breeding to strengthen desirable characteristics in animals.

A great deal has been learnt about the different organisms that our ancestors used so effectively. We can control many of the functions of various cells and organisms because of the marked increase in our understanding of these organisms, their cells, molecular structure and their chemical products. Using the techniques of cutting and re-splicing genes (called recombinant DNA), we can now actually combine the genetic elements of two or more living cells. Functioning lengths of DNA can be taken from one organism and placed into the cells of another organism. Both DNA and videotapes are linear informational tapes that carry encoded information which can be decoded, expressed, copied, spliced, edited, and you can make copies of the edits. As a result, for example, we can use bacterial cells with a human gene which is responsible for the production of insulin, to produce human protein instead of using animal insulin.

Genetic engineering has quickly become a very precise technology, much more so than traditional breeding techniques. The sequence of every base pair that makes up the DNA of the gene can be easily determined. The site of integration into the new chromosome can be determined. The degree of impact of the transferred gene can be determined. While it is not possible to eliminate completely the risk of a genetic engineering accident, the experience of the last ten or so years of research has indicated that the chances of constructing a disease-producing organism, a weed or a `triffid' by accident are very remote. This is because such organisms require an extremely complex set of distinct characteristics, and are effective only when all are present.

Control and containment of experiments is the key to safety. Scientists have their own codes of practice and ethics committees. In New Zealand, contained experiments and field testing are currently controlled by two interim authorities but will be controlled under the new Environmental Risk Management Authority (ERMA) from 1998. The release and sale of genetically modified foods is controlled in Australia and New Zealand by the Australia New Zealand Food Authority (ANZFA).

In the 1920s people were concerned about using electricity to cook food _ in the 1990s some are voicing concern about genetic engineering. Having considered the safety issues over several years the American National Academy of Sciences concluded that "there is no evidence that unique hazards exist either in the use of R-DNA technique or in the transfer of genes between unrelated organisms," and that "the risks ... are the same kind as those associated with the introduction of unmodified organisms."

Why all the investment?

There is huge international investment in biotechnology. Potential benefits include solving world food shortages, and improvements in medicine, agriculture and food production, manufacturing, electronics and the environment.

In the medical field, considerable efforts are being devoted to developing vaccines for diseases such as AIDS. Monoclonal antibodies are being developed to boost the body's defences, guide anti-cancer drugs to their target sites, and control particular parasites. Synthesis of drugs, hormones, and animal health products, are all advancing rapidly. Enzyme replacement and gene replacement therapy for diseases such as cystic fibrosis are other areas where progress can be expected.

In mining and waste management, the new technology may enable the use of genetically engineered microbes to extract oil from the ground and valuable metals from factory wastes. Already we have bacteria that can clear up oil spills.

The bio-revolution resulting from advances in biotechnology is likely to outstrip the advances of the "Green Revolution." In the early 1960s, the pioneering studies of Nobel prize winner, Norman Borlaug, used conventional cross-breeding techniques to produce new wheat hybrids that dramatically increased yield in third world countries. Recently, an American seed company announced the release for trial of 35 new genetically engineered maize, soybean and squash varieties. It does not require a crystal ball to imagine the potential of likely developments based on research now in progress. The `Flavr Savr' tomato with increased shelf life, marketed in the USA since 1995, is likely to be the first of many fruits and vegetables with improved storage quality and flavour. There is a big thrust in New Zealand's research on pest and disease resistance to reduce chemical usage and also animal vaccines to control a wide range of diseases. Continued improvement and diversity in breeding agricultural livestock is well underway; eg. pigs with less fat, and animals with improved feed conversion ratios. Breeding plants and animals to produce medicinal compounds for human use, dyes, flavourings, and chemicals is also well advanced. We are likely to be growing crops such as potatoes for harvesting for the extraction of saccharin-type sweeteners or human growth hormones.

Biosensors with unparalleled chemical recognition properties can be coupled to the unique ability of microelectronic circuits to amplify and process minute electronic signals. Biosensors will assist doctors in making rapid diagnoses. They are finding applications in industry, where they permit rapid detection and measurement of acids, alcohols, and phenols. Diagnostic kits to detect drugs, and alarm systems warning workers of dangers before they reach critical levels are amongst the benefits in health and safety. DNA technology is also leading to the development of biochips _potentially enormously faster than the silicon chip.

The contribution of bioreactors to fuel needs is at present very low but if that process can be improved and modified the potential is huge. By developing enzymes, like cellulase, which break down cellulose, enormous amounts of cellulose could be converted into chemical energy, eventually transforming biofuel production. In another area, bacteria and algae have been discovered that produce the enzyme, hydrogenase, which is necessary to make hydrogen. Such a system could supply the world's current energy needs using 500,000 thousand square kilometres ( about the size of France).

Undoubtedly genetic engineering has the potential to enormously accelerate the biological processes that have been going on throughout the millennia. However, the technology may be slowed or even halted if the public are unconvinced of the benefits and fearful of the risks. Clearly, the level of risk in the technology is low and can be contained, but will the public accept technical assurances on issues that impinge on long held moral and religious beliefs? In further articles we will explore these issues.