Spindles and Microtubules

In the late-1960s and early-1970s, biochemists had identified that the polymers that Shinya had found were in a state of dynamic equilibrium (growing or shrinking depending on the chemical and physical environment they finds themselves in), and were made up of subunits of different types of a molecule called tubulin. The polymers were named microtubules. Together with microfilaments made from actin, microtubules form part of the cytoskeleton found in all cells, which is responsible for maintaining or changing the structure and shape of the cell, processes such as cell division, and transport throughout the cell. In the late-1960s, Inoué demonstrated that the changes to the birefringence that resulted from changes to the spindle was related to changes in microtubules, which provided key evidence for the microtubular nature of spindles. In the mid-1970s, he collaborated with others to elaborate on his idea that the microtubules are in dynamic equilibrium.

In the early-1970s, Shinya began to work with George M. Langford at the University of Pennsylvania and the MBL. They worked on a species of protozoan, Pyrsonympha vertens, which lives in the gut of termites. Decades earlier, Inoué had demonstrated that what was supposed to be a rigid rod running through the protozoan was in fact not static at all, but “a birefringent whip, which churned inside the cell.” [p. 94] Once again, Inoué’s techniques to examine live cells had shown him something that had been previously unknown. With Langford, two decades later, Inoué was able to deepen our understanding of the activity and role of the axostyle. They analyzed the beating patterns, and the fine structure of the axostyle, which were made from microtubules. Like many who have worked with Shinya, George M. Langford went on to have a distinguished career in research.