A tale of two motilities: adaptive locomotion in complex, changing environments
Motile organisms have developed strategies to move through natural environments, which are spatially complex and can fluctuate with time. I will discuss two (quite different!) broadly successful locomotive modes: flagellated motility in bacteria and interfacial locomotion in geckos. (1) A bacterium’s life is complicated: it interacts with different fluids, and may need to switch between swimming and surface attachment. We used magnetic tweezers to manipulate the flagellar apparatus and characterized the dynamics of mechanosensitive adaptation in the bacterial flagellar motor (BFM). Our model for the dynamics of environmentally-regulated assembly in the BFM illustrates how bacteria sense and adapt to changes in their surroundings. (2) Animals in areas that periodically flood must deal with seasonal fluctuations in their habitat. We showed that tropical geckos can run across the water’s surface as fast as they can on land using both surface slapping and surface tension. Taking advantage of these multiple modalities allows geckos to transition between terrestrial and semi-aquatic locomotion.