One man’s trash is another man’s treasure. Photobleaching is an unavoidable side effect of imaging that leads to weakened fluorescent signals. Most of us pooh-pooh photobleaching, but some clever cell biologists use photobleaching as a fantastic tool instead. Today’s image is my new favorite use of photobleaching.
Glial cells function in the nervous system to support neurons and their signal transmission. Schwann cells are glial cells found at the neuromuscular junction (where neurons signal to muscles), and monitor the neurotransmission exchanged. Schwann cells can even function to form and regenerate the neuromuscular junction. A recent paper describes how Schwann cells establish their arrangement around the neuromuscular junction. In this paper, Brill and colleagues labeled individual Schwann cells and used live imaging to monitor their positioning. Schwann cells are dynamic during development, finding their appropriate position by competing for space with other Schwann cells. Schwann cells in adult animals, however, are much more static. In the images above, individual Schwann cells (pseudo-colored yellow, blue, white, and purple) were labeled by sequentially photobleaching one cell at a time, leading to distinct levels of fluorescence in each cell. The axon of the neuromuscular junction is in green. The Schwann cells are very dynamic in young mice (left) compared with adult mice (right), seen as the frequent formation and retraction of cell protrusions (arrowheads in the images of the boxed regions).
Brill, M., Lichtman, J., Thompson, W., Zuo, Y., & Misgeld, T. (2011). Spatial constraints dictate glial territories at murine neuromuscular junctions originally published in The Journal of Cell Biology, 195 (2), 293-305 DOI: 10.1083/jcb.201108005