SYMBIONTS, WITHIN SYMBIONTS, WITHIN PARASITES: A KEY TO THRIVE IN SUBOXIC CONDITIONS?

摘要

Midichloria mitochondrii is an intracellular bacterium (order Rickettsiales), found in ticks of different species. In the females of the sheep tick Ixodes ricinus the prevalence of M. mitochondrii is 100%, while prevalence in males is lower (40-50 %) (Sassera et al., 2006). Available information suggests that M. mitochondrii might play a beneficial role in female ticks (Lo et al., 2006). A unique characteristic of this bacterium is that it is able to grow and replicate both in the cytoplasm and in the intramembrane space between the outer and inner mitochondrial membranes in tick oocytes. Another important characteristic of this bacterium is that it seems to be able to reach its intramitochondrial localization without damaging the external mitochondrial membrane (Beninati et al., 2004; Sacchi et al., 2004).