Developmental regulation of mitochondrial biogenesis in Trypanosoma brucei

Mitochondrial genome repositioning during the differentiation of the African trypanosome between life cycle forms is microtubule mediated

The cell cycle of the African trypanosome requires a precise orchestration of nuclear and mitochondrial genome (kinetoplast) positioning to ensure faithful segregation during division. The controls underlying these events must be subject to modulation, however, as the respective positioning of these organelles changes during the parasite's complex life cycle. We have studied mitochondrial DNA repositioning during differentiation between the trypanosome's bloodstream and procyclic form. We have found that repositioning occurs simultaneously with the DNA replication phase of the cell cycle of the differentiating parasite. Furthermore, we demonstrate, at the cell and individual microtubule level, that this organelle repositioning is achieved via microtubule-dependent processes. Our results have implications for the control of cell differentiation and division in African trypanosomes.

Mechanisms of stage-regulated gene expression in kinetoplastida

During their life cycle, trypanosomatid parasites of mammals encounter substantially different environments in their hosts and insect vectors, to which they must adapt by undergoing a series of differentiation processes. At the molecular level, these processes must be the direct result of an elaborate series of changes in stage-regulated expression of a wide range of gene products. How are these changes accomplished? In this review, Sheila Graham discusses some recent advances in understanding the mechanisms of gene expression in trypanosomatids, and examines some clues to some intriguingly complex means of regulating life cycle stage-specific gene expression.