2011-present: Postdoc, University of Georgia, Athens, GA, USA

2005-2010 Ph.D. University of Arizona, Tucson, AZ, USA
Dissertation: "Evolution and function of an aphid facultative symbiont"

2002-2004: B. S. University of Queensland, Brisbane, QLD, Australia

Hereditary symbiosis is a common mechanism by which eukaryotic hosts can acquire traits beneficial for their fitness. Many insects have symbiotic associations with bacteria that trace back millions of years, whose function and evolution are well characterized. Insects can also possess more recently derived symbionts that are closely related to free-living bacteria, and often play a role in host defense. My dissertation focused upon Serratia symbiotica, a recently derived symbiont that infects aphids and provides protection against heat stress, and possibly also plays a nutritional role. I studied several aspects of the biology of recent symbionts, including the diversity of functional roles and evolution among hosts for single lineages of symbionts, the molecular mechanisms that contribute to defense, the early stages of symbiont genome evolution, and interactions with hosts.

While bacteria are well recognized to form beneficial symbiotic associations with metazoans, viruses are usually viewed as non-living, parasitic entities that interact with hosts in ways that only benefit their own transmission and persistence. Parasitoid wasps have viruses that have been associated with their hosts for 100 million years, and have evolved to be beneficial symbionts. These polydnaviruses (PDVs) are essential to the survival of the wasp’s offspring, which depend upon PDV gene products that suppress host immune defenses.

PDV persists as an integrated provirus in wasps, and is transmitted through the germ line, while replication to form virus particles only occurs in the reproductive tract of female wasps. Little is currently known about how virus- and wasp-derived genes interact to regulate viral replication and maintain the symbiotic association. My research in Dr. Strand’s group will focus on the wasp Microplitis demolitor and its associated polydnavirus named M. demolitor bracovirus (MdBV).

Burke GR and Moran NA (2011) Massive genomic decay in Serratia symbiotica, a recently evolved symbiont of aphids. Genome Biology and Evolution. Epub Jan 25.

Burke GR and Moran NA (2011) Responses of the pea aphid transcriptome to infection by facultative symbionts. Insect Molecular Biology. In press.

Burke GR, McLaughlin HJ, Simon J-C, Moran NA (2010) Dynamics of a recurrent mutation in Buchnera symbionts affecting thermal tolerance of pea aphid hosts. Genetics. 186 (1): 367-72.

The International Aphid Genomics Consortium (2010) Genome sequence of the pea aphid Acyrthosiphon pisum. PLoS Biology, 8(2): e1000313.

Burke GR, Fiehn O, Moran NA (2009) Effects of facultative symbionts and heat stress on the metabolome of pea aphids. ISME Journal, 4 (2): 242-52.

Oliver KM, Degnan PH, Burke GR, Moran NA. 2009. Facultative symbionts of aphids and the horizontal transfer of ecologically important traits. Annual Reviews of Entomology. 55: 247-66.

Burke GR, Normark BB, Favret C, Moran NA. 2009. Evolution and diversity of facultative symbionts from the aphid subfamily Lachninae. Applied and Environmental Microbiology. 75 (16): 5328-35.

Iturbe-Ormaetxe I, Burke GR, Riegler M, O'Neill SL. 2005. Distribution, expression, and motif variability of ankyrin domain genes in Wolbachia pipientis. Journal of Bacteriology. 187 (15): 5136-45.