All science writers are familiar with O-rings because they were the culprit behind the 1986 Challenger disaster, the investigation of which was the subject of what in my opinion is one of the greatest popular science books ever written: the classic, What do You Care What Other People Think? But while I know all about O-rings, thanks to the eloquence of Richard Feynman, I knew almost nothing of Z-rings before this past Sunday.
In the New and Notable Symposium, Suliana Manley of the Swiss Federal Institute of Technology in Lausanne, Switzerland introduced me to the term in describing a protein involved in the strange, asymmetric cell division of the bacterium Caulobacter crescentus. The protein, called FtsZ, is initially localized to one end of the bacteria and then migrates to the middle where a “Z-ring” structure it forms pinches off the bug in the middle.
There were some earlier cryo EM and superresolution microscopy studies of FtsZ, but Manley and her colleagues went a step further by using automated contrast imaging to obtain the outlines of hundreds of these cells and then combining that with 3D PALM to image the localization of the Z-rings throughout the cell cycle as they migrate and ultimately pinch off the cell. Find a little more information on her EPFL Web page.
In the same symposium, Elizabeth Chen of Johns Hopkins University was looking at what you might think of as the opposite of division (or… sort of): cell-cell fusion, a physiological phenomenon important during conception, development and many other processes in mammals and other multicelled organisms.
Her talk focused on myoblast fusion in Drosophila — an asymmetric process involving an invasive “podosome-like” structure. You can find some nice pictures and links on her Web site.