In an effort to determine which genes were involved with cancer, a gene was inserted into the mouse that made it susceptible to cancer. The protein, when missing in humans, can lead to a rare form of emphysema. Changes to the germ line are heritable from generation to generation within the herd, and this heritability has potential to facilitate long-term productivity gains. For example, fish can be bred for increased expression of a growth hormone, although the industries are currently wary of consumer preferences for gene-modified product. Due to the expense and difficulty in producing a transgenic animal, cloning is the method of choice to produce multiple transgenic animals without altering the animal s genes as traditional breeding would do.
Cloning is the process of replicating an identical gene, cell, or organism from a single ancestor.
Since Dolly the sheep was cloned by nuclear transfer in 1997, advances in cloning technology have made it easier to build a genetically tailored livestock herd. Concerns regarding transgenic animals have developed along with the new technologies. These concerns include safety of the food supply, safety of the pharmaceutical product, and keeping the transgenes out of non-transgenic animals. As of December 1999, no specific legislation had been enacted to direct federal oversight of transgenic animals. This report set guidelines for the development, maintenance and disposal of transgenic animals.