Chromosome segregation

When a trypanosome cell divides, all of the ~120 chromosomes has to equally partitioned into the two daughter cells. All 3 chromosomal classes are segregated through interactions with the mitotic spindle and all with great fidelity (an individual chromosome will be lost only once in more than 1000 cell divisions).

Division of the minichromosomes by interaction with the mitotic spindle. The small chromosomes have been stained by in situ hybridisation to a 177 bp repeat probe (red) and the microtubules by a monoclonal antibody (KMX; green).

However, in trypanosomes the number of chromosomes far out-numbers the number of spindle microtubules and the molecular details of this segregation mechanism are almost entirely unknown. The lab is currently working to discover the components of the mitotic machinery in trypanosomes and what features of the small chromosomes enable them to interact with the spindle. This will reveal how an essential part of the trypanosome cell functions and will also tell us about the evolution of mitosis in other organisms.

A molecular motor on the trypanosome spindle. Signal from kinesin TbKIN13-1 tagged with GFP is shown (green) as well as a stain for tubulin (red) for cytoskeletons made by extracting cells with non-ionic detergent in microtubule-stabilising buffer. Overlays of DAPI-stained DNA (blue) and phase-contrast images are also shown (right panel). Extract from Wickstead et al. (2010) PLoS One 5:e15020.