Eliminating 'junk' genes.

Scientists at Purdue University, West Lafayette, Ind., have found a way to reduce the guesswork and errors in genetic engineering. It could speed the delivery of biotech-derived crops and possibly even benefit human gene therapy.

Thomas K. Hodges, the Joseph C. Arthur Distinguished Professor of Botany and Plant Physiology; Leszek Lyznik, a post-doctoral researcher; and colleagues have developed a two-step process that can insert desired genes on a specific place on a plant chromosome, then excise other unwanted or "junk" genes that were already on the plant's chromosomes.

Before, when scientists used a variety of methods to insert new genes into a plant's chromosomes, the insertions were random, with genes landing anywhere on the chromosomes, possibly interrupting other gene sequences that coded for vital proteins. In creating crop plants, the result was that often as few as one in 1,000 transformed plants might germinate. Even if the plant survived, these random insertions have been a large concern to governmental regulators because they allowed the possibility that the genetic transformation would have unforeseen consequences.

As frustrating and potentially harmful as random insertions are in plant science, the ramifications of similar problems virtually have stymied animal and human gene transformations. With the new technique, the gene can be placed on the recipient chromosome exactly where the scientist desires, eliminating these difficulties. For example, a scientist might want to move a gene for drought resistance from sorghum to corn. The new method allows the plant breeder to place the gene exactly on the corn chromosome where it will be most effective and gives the breeder the opportunity to remove any corn genes that may be in conflict with the new gene. It also will allow scientists...