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Diversifying selection and host adaptation in two endosymbiont genomes
Jeremy C Brownlie1, Marcin Adamski, Barton Slatko
1School of Integrative Biology, University of Queensland, Brisbane, QLD, Australia. j.brownlie@uq.edu.au <j.brownlie@uq.edu.au>
BMC Evolutionary Biology
|May 2, 2007
Summary
Wolbachia bacteria show diverse adaptations to insect and nematode hosts. Comparative genomics reveals selection on genes involved in host interaction and metabolism, explaining varied symbiotic relationships.
Area of Science:
- Microbiology
- Evolutionary Biology
- Genomics
Background:
- Wolbachia pipientis is an endosymbiont in arthropods and nematodes, crucial for studying host-symbiont coevolution.
- Its ability to alter host reproduction is key for pest control and disease vector management.
- Nematode-infecting Wolbachia are distinct, vertically transmitted, and essential for host development, unlike more fluid insect associations.
Purpose of the Study:
- To identify molecular mechanisms mediating diverse Wolbachia-host interactions.
- To understand the nature of varied symbiotic associations across different hosts.
- To identify genes under diversifying selection in Wolbachia lineages.
Main Methods:
- Comparative genome analysis of Wolbachia from Drosophila melanogaster (wMel) and Brugia malayi (wBm).
- Utilized Anaplasma marginale as an outgroup for phylogenetic comparison.
- Identified genes experiencing diversifying selection in Wolbachia lineages.
Main Results:
- Selection was more prevalent in wMel (insect) than wBm (nematode).
- Genes for DNA metabolism, cofactor biosynthesis, and secretion were positively selected in both.
- wMel showed increased selection on DNA repair, cell division, protein stability, and cell envelope synthesis.
Conclusions:
- Selection on secretion pathways and outer surface proteins aligns with host:parasite theory.
- Evidence suggests both insect and nematode Wolbachia may provision hosts with substances.
- Selection on cell envelope synthesis, DNA replication/repair, and heat shock indicates insect Wolbachia strategies for diverse environments.
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