Mesostoma ehrenbergii spermatocytes provide an unusual and exciting model to investigate chromosome movement, cleavage furrows and tethers during cell division

For my PhD thesis I studied and tracked chromosome movement in primary spermatocytes from a species of aquatic flatworm, the Mesostoma ehrenbergii, with the hope to better understand what determines the force behind these intricate and highly co-ordinated movements during meiosis. Canonical theories of chromosome movement state that microtubules are the main producers of force for chromosome movement in the meiotic spindle, however my research has shown chromosomes can not only move but can move even faster in the absence of microtubules. I also tracked the cleavage furrow and showed it was able to simultaneously move and ingress in the absence of microtubules. I worked on determining how the force is produced by using a laser microbeam to sever various components in the cell and by adding various myosin and actin inhibiting and enhancing drugs to see how chromosome movement may be altered. In addition, I discovered elastic tethers are present in Mesostoma during metaphase and anaphase and my research on functionally disabling tethers suggests they play a role in coordinating or maintaining non-random chromosome movement in these cells. In sum, my PhD research has added evidence to the non-microtubule model of chromosome movement by showing actin and myosin is involved in movement and that tethers may play a role in coordinating or maintaining non-random chromosome movement in these cells.