Exploring Bioethics - NIH Office of Science Education - National ...

Spider-Silk GoatsSpider silk is stronger and more flexible than any other knownfiber. Five times stronger for its weight than steel, it can be usedin many products. Medical uses could include making artificialtendons and ligaments, bandages, sutures, and artificial limbs.Because it can be woven into fiber, it can be used to make protectiveclothing, bulletproof vests, and body armor. Its flexibilitymakes it valuable as paper. Other products could include ropes,nets, parachutes, seatbelts, and airbags. In addition to being oneof the toughest materials on Earth, spider silk is also environmentallyfriendly; no toxic substances are used to make it and itis biodegradable.Genetically engineered goats withspider-silk-making genes.Photo: Courtesy Nexia Biotechnologies Ltd.To date, no one has successfully farmed spiders for silk, nor has anyone been able to produce spidersilk artificially on a large scale. However, researchers have been able to create goats that produce spidersilk, by inserting spider genes into goat eggs. In these genetically engineered goats, the gene is expressedin the mammary glands, and the transgenic goats secrete silk fibers in their milk. The fibersare removed from the milk and spun into thread. These transgenic goats have since been bred, andtheir offspring pass on their silk-producing genes to their offspring. In this way, thousands of goatscapable of producing the silk-fiber-containing milk can be generated.Copyright © 2009 Education Development Center, Inc. Exploring Bioethics.Permission granted for classroom use.Cloning is not a perfect science and often produces many animals with deformities and conditionsthat are fatal. Because this is a relatively new science, there are uncertainties about the long-termhealth of the resulting cloned goats. Issues such as accelerated aging, compromised immune systems,and premature death have arisen. The risks of genetic engineering may include disrupting certaingenes of the goat so they no longer function and allowing the introduced gene to enter the wild populationthrough unregulated breeding.In addition to the environmental concerns of farming animals discussed in other cases, raising dairyanimals requires techniques that some consider problematic. Females produce milk (lactate) whenthey are nursing their young. Female goats that are already lactating can be bred while they are nursingand will produce milk for over a year. They are bred again about every 12 months and are given a2-month dry interval when they are not milked. Some people believe that goats need more time torest between breeding cycles.There is no alternative to creating transgenic goats as a profitable source of spider silk.Is it ethically acceptable to genetically engineer goats to produce spider silk? Why or why not?Master 6.2 (Page 10 of 12)