After material is taken into a cell, it is transported in vesicles to different destinations. These vesicles are very dynamic—they frequently fuse together to form larger vesicles, or undergo fission to form smaller vesicles. A recent paper shows that the fusion of late endosomes and lysosomes is regulated by ARL-8 GTPase. Image above shows labeled ARL-8 (red) and RME-8 (green) in a scavenger cell in the worm C. elegans. In the merged image (left), ARL-8 is not found on vesicles with RME-8, which labels early and late endosomes.
Reference: Isei Nakae, Tomoko Fujino, Tetsuo Kobayashi, Ayaka Sasaki, Yorifumi Kikko, Masamitsu Fukuyama, Keiko Gengyo-Ando, Shohei Mitani, Kenji Kontani, and Toshiaki Katada. Authors’ Molecular Biology of the Cell paper can be found here.