MODEL RELEASED. DNA gun. Plant biologist using a particle gun apparatus to introduce DNA (deoxyribonucleic acid) into cultured plant cells (grown in petri dishes, lower left and upper centre). DNA-coated particles are fired into the plant cells, and DNA enters the nuclei. This method is commonly used to create transgenic plants, those carrying foreign DNA in addition to their own. The modification of a plant's genetic content can be used to introduce new characteristics such as increased yield. Photographed at Milan University, Italy.