b'Genetics/Developmental BiologyContinued30 Hijacking Jumping Genes CauseThejumping genes use Disease, Drive Evolution nurse cellsto produce Almost half of our DNA sequences are made up ofinvasive material . . . that moves jumping genes called transposons. They jump aroundinto a nearby egg and then the genome in developing sperm and egg cells and are important to evolution. But their movement caninto the eggs DNA.also cause mutations that lead to diseases, such as hemophilia and cancer. Since Carnegies Nobel Laureate Barbara McClintock discovered jumpingmovement. They found that during a particular genes more than six decades ago, scientists have notperiod of egg development, a group of jumping understood how they mobilize and prepare for theirgenes called retrotransposons hijacks special cells next generation, until now.called nurse cells that nurture the developing eggs. The jumping genes use nurse cells to produce The Carnegie team, led by Zhao Zhang with Luinvasive material, copies of themselves called virus-Wang, Kun Dou, Sungjin Moon, and Frederick Tan,like particles, that moves into a nearby egg and then developed new techniques to track jumping geneinto the eggs DNA.Animals developed a powerful system to suppress jumping gene activity that uses small, noncoding RNAs called piRNAs which recognize and suppress jumping gene activity. Occasionally, jumping genes still manage to move, suggesting that they employ special tactics to escape piRNA control. Tracking the movement of jumping genes to understand their tactics has been daunting.The Carnegie team tracked jumping gene movements using the fruit fly Drosophila melanogaster. They disrupted piRNA suppression to increase the activity of the jumping genes, then monitored their movement during egg development, which led to their discovery on the tactic that allows jumping genes to move.The blue spheres in this image are nurse cells. The red is the developing egg lighting up from the invading material from the jumping genes.Image courtesy Zhao Zhang'