Pros, cons of genetic engineering

Biotechnology or genetic engineering has made tremendous advances during the last decade in the areas of agriculture and medicine. New disease-resistant and higher-yielding plants are increasing food production while diverse species from bacteria to pigs are churning out human medical products.

Controversy has increased along with each advance, however, and not everyone sees this new era of genetic tinkering as an unmitigated blessing. Nearly every journal one picks up today has at least one article arguing the pros and cons of genetic engineering. The following are excerpts from some of the more recent ones.

A race is currently under way in academic and industrial research centers to find ways of producing scarce human proteins outside of the body. The winners could realize astronomical rewards. For example, alpha-1-antitrypsin (AAT), a compound being investigated as a treatment for emphysema and other lung diseases, was quoted in a recent Science article as selling for $110 a gram. The same article lists the cost of erythropoietin, which offsets the bone-marrow destruction caused by drug therapies for AIDS, as an unbelievable $1.5 million a gram. This, in essence, means the drug is unavailable for significant research at the moment.

Currently, the only source of erythropietin is from human extracts but different groups are genetically altering both bacteria and animals such as sheep and goats in an effort to produce workable amounts of the precious compound.

Medical researchers have been trying to produce an acceptable synthetic blood substitute for the past 50 years. Last July, Science reported that DNX Inc., a biotechnology firm located in Princeton, N.J., had created a genetically altered pig that produces human hemoglobin, a breakthrough some reporters hailed as signaling the end of such worries as AIDS or hepatitis-tainted blood transfusions.

Unfortunately, the reality is not that simple. The pig does produce a hemoglobin identical to that manufactured in the human body, however, it has been known for some time that hemoglobin alone does not make a satisfactory blood substitute. Pure hemoglobin does bind oxygen so it may be transmitted to the cells but, once there, does not release it easily to the tissues. It also has a tendency to break down into two fragments that seriously damage the kidneys upon excretion. Once these problems have been solved, a virtually limitless source of disease-free hemoglobin has been made available but a lot of work remains to be done.

A major emphasis has been to create genetically altered animals that produce scarce human proteins in their milk. According to the September issue of Bio-Technology, Pharmaceutical Proteins Ltd. of Scotland has genetically engineered sheep to produce up to 35 grams per liter of human AAT. A cooperative effort between Tufts University School of Veterinary Medicine and Genzyme Corp., both based in Massachusetts, has led to a goat carrying the gene for human tissue plasminogen activator. This is a protein that aids in the prevention of blood clots with the top goat yielding 3 grams per liter of milk.

In an ironic twist, efforts to introduce the human lactoferrin gene, associated with milk production in nursing mothers, into cattle has proven successful but the recepient turned out to be a bull! He will be bred in the hopes that his daughters will acquire the gene and produce the protein in their milk.

Human proteins produced by genetically altered animals will be free of human pathogens but fears have been expressed that animal diseases could be transmitted too via this route. coursework.

Biotechnology will, without question, alter agriculture and medicine in ways that cannot even be guessed at today. It will happen but the road will not be smooth. Public concerns about safety, health, and economics will have to be addressed. Even more so will the fears that lie at the heart of most concerns: Should we be tampering with nature by the switching of genes between entirely unrelated species?

Clair Wood, a science instructor at Eastern Maine Technical College, is the NEWS science columnist.