Research

 

Associate Professor Patrick Ferree publishes a study in the journal Current Biology
Patrick Ferree
9/21/2016
 
 
Male killing bacteria are widespread in nature, especially among arthropod species. These pathogens live symbiotically within their hosts’ cells and are transmitted to new progeny through the egg cytoplasm, similarly to mitochondria. It is believed that because the male sex is a ‘dead end’ regarding bacterial transmission, males are killed in order to provide more resources for females, which can lead to higher bacterial transmission. A longstanding mystery is how these bacteria selectively kill males while sparing females. The Ferree group published findings showing that a male killing bacterium known as Spiroplasma kills males in its natural host, Drosophila melanogaster, by disrupting a male-specific process known as dosage compensation, which is responsible for up-regulating genes present on the male’s single X chromosomes to normal that match gene expression levels found in females, which have two X chromosomes (and thus two copies of each X-linked gene). Specifically, the Ferree group found that Spiroplasma causes an enzymatic complex called the dosage compensation complex (DCC), which normally associates with the male’s single X chromosome, to abnormally bind to other chromosomes. This effect, in turn, causes gene mis-expression across the genome, and effect that leads to early death. The Ferree group further tested this idea by artificially expressing the DCC in females, which normally do not have this complex. The outcome was that females expressing the DCC died due to the Spiroplasma infection for the same reasons. The findings of this study have broad implications for how other pathogens might interact with their hosts at the molecular level, as well as how symbionts can be used as agents to manipulate insect pests. Most of this work was performed by two CMC students, Becky Cheng (’16) and Nitin Kuppanda (’16). Becky Cheng, Nitin Kuppanda, John C. Aldrich, Omar S. Akbari, and Patrick M. Ferree (2016). Male-Killing Spiroplasma Alters Behavior of the Dosage Compensation Complex During Drosophila melanogaster Embryogenesis. Current Biology 26, 1339-1345  
 

 

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