 I'd like to start by asking you all to take a deep breath. Go on, humor me. Inhale all the way. Now exhale. You just exercised my favorite organ, the lungs. You contracted your diaphragm, which increased the volume of your chest cavity. It decreased the pressure within and allowed up to three liters of air to enter, depending on how deep of a breath you took. Now, the lung is my favorite organ, both because it's beautiful, as well as an amazing feat of engineering. The human lung contains 8 million tubes that deliver oxygen to a gas exchange surface, approximately 100 square meters in area, or about the size of a tennis court. That surface is less than the thickness of a sheet of paper, and the entire organ has to function immediately after you're born. One third of all babies admitted to the neonatal intensive care unit arrive there because of breathing problems. And in adults, by the year 2030, it's projected that chronic lung disorders will be the third leading cause of death worldwide. Now, despite the fact that the human lung is my favorite organ, it's not the most efficient gas exchanger. That distinction belongs to the birds. There is an amazing diversity of lung structures that have evolved to enable the breathing of air, and all of them are comprised of space-filling branching trees. My lab has been inspired by this evolutionary diversity to start to try to uncover new ways to engineer lungs, to serve as replacements for those diseases I mentioned. And what we're doing is combining techniques from biology, computational sciences, and engineering to uncover how lungs build themselves in reptiles, birds, and mammals. When we entered this field 10 years ago, it was thought that all branched organs build themselves the same way, whether it's a human kidney, a mouse lung, or a fruit fly trachea. So we decided to take a step back and just watch how lungs build themselves. And what we've figured out, what we've learned, is that just as there is an incredible diversity of structures, there's also a huge diversity of mechanisms that have evolved to build them. The bird lung begins as a simple tube that splits in half to form two primary bronchi, one for the left lung and one for the right lung. New branches form in the bird lung because the cells within those tubes undergo a change in shape. They turn from being rectangular in geometry to trapezoidal in geometry when one side pinches its surface. And that change in shape is sufficient to generate a force to bend the tissue and form a branch. In the mouse, the lung also begins as a simple tube. But in this case, those 8 million branches that form do so by bifurcating branching, where the tip of a parent branch splits in half to form two daughter branches. Using time-lapse imaging, we've found that the cells that line the airways do not undergo a change in shape in mice. Instead, we've uncovered an important role for smooth muscle. At the same time as the airways are bending and branching to form the tubes, airway smooth muscle wraps circumferentially around them, from the trachea to the terminal ends. Using time-lapse imaging of fluorescent reporter animals, we've found that that airway smooth muscle cinches the epithelium, the airway, into a branched structure, much like a corset or a girdle. And so plays an instructive role in the formation of the branches. So we found, looking at these two different species, two different ways in which simple tissues form branch structures. In the bird, the cells actively change shape to form a branch, whereas in the mouse, smooth muscle sculpts the surrounding tissue. What we're excited to do now is to combine these two separate mechanisms from two separate species in the lab to build entirely new organs. What this will require us to do, obviously, is to be able to change cell shape and cause smooth muscle contraction at will, which could be realized with advances in optogenetics and CRISPR-Cas9-mediated gene editing. We're also incredibly excited to start to uncover the rich and vast diversity of mechanisms that have evolved to build lungs across the animal kingdom, specifically by examining how lungs are sculpted in reptiles, including the American alligator and the green anole lizard. And our hope is that by doing so, we'll increase the depth of the toolbox that we have available to us to engineer tissues, so that now by combining approaches from different species, we'll be able to engineer more efficient lungs so that future generations can breathe more easily. Thank you.