(PI is Nancy Moran, co-PI is Anthony Ives, co-PI is Katrina Mangin)
A grant has been awarded to Drs. Nancy Moran and Katrina Mangin of the University of Arizona, and Dr. Anthony Ives of the University of Wisconsin to address the role of symbiotic infections in determining tolerance of insects to heat stress, both at the molecular and ecological levels. The complete genome sequence of a facultative bacterial endosymbiont of aphids will be determined. Approaches exploiting this and other genomic data will be used, including measures of expression of heat stress genes of both hosts and symbionts under different thermal environments. These studies will reveal how heat sensitivity is affected by symbiont distributions among hosts as well as by genetic variation in stress responses. In addition, the ecological consequences of variation in thermal tolerances will be examined under field environments; these experiments will reveal how heat tolerance interacts with additional biological factors, such as predators and parasites, to determine population density and persistence.
Chronic infection is a normal part of the life cycle for most animals, including humans and insects, but it is not known how such infection affects tolerance to changing environmental conditions. At the same time, the forces that maintain symbiotic associations are dependent on the joint effects of genetic and environmental factors, but no studies have addressed these together. In this project, researchers with expertise in both ecology and molecular biology will apply methodologies from both fields to obtain answers to these issues. By illuminating the molecular and ecological mechanisms through which heat affects animal populations, the findings will demonstrate how geographic ranges and abundances of individual species are impacted by changes in climate over time. Results will be particularly relevant to insects that are agricultural pests and vectors of disease, a large proportion of which have symbiotic associations similar to those of aphids. In addition, a substantial educational program will introduce Arizona secondary school teachers to the use of state-of-the-art molecular tools for analyzing how organisms interact with environmental stress.
- Burke G, Fiehn O, Moran NA. "Effects of facultative symbionts and heat stress on the metabolome of pea aphids.," ISME Journal, v.4, 2009, p. 242.
- Burke GR, Normark BB, Favret C, Moran NA. "Evolution and Diversity of Facultative Symbionts from the Aphid Subfamily Lachninae," Applied and Environmental Microbiology, v.75, 2009, p. 5328-5335.
- Dale C, Moran NA. "Molecular mechanisms underlying symbiosis with heritable bacteria.," Cell, v.126, 2006, p. 453.
- Degnan PH, Moran NA. "Evolutionary genetics of a defensive facultative symbiont of insects: exchange of toxin-encoding bacteriophage," Molecular Ecology, v.17, 2008, p. 916.
- Degnan PH, Moran NA. "Diverse Phage-Encoded Toxins in a Protective Insect Endosymbiont," Applied and Environmental Microbiology, v.74, 2008, p. 6782-6791.
- Dunbar HE, Wilxon ACC, Ferguson NR, Moran NA. "Aphid thermal tolerance is governed by a point mutation in bacterial symbionts," PLoS Biology, v.5, 2007, p. e96.
- Harmon JP, Moran NA, Ives AR. "Species response to environmental change: impacts of food web interactions and evolution," Science, v.323, 2009, p. 1347.
- Moran NA. "Symbiosis as an adaptive process and source of phenotypic complexity.," Proceedings of the National Academy of Sciences USA, v.104, 2007, p. 8627.
- Moran NA, Plague GR. "Genomic changes following host restriction in bacteria," Current Opinions in Genetics and Development, v.14, 2004, p. 627.
- Moran NA, Dunbar HE. "Sexual acquisition of beneficial symbionts in aphids," Proceedings of the National Academy of Sciences USA, v.103, 2006, p. 12803.
- Moran NA, Degnan PH. "Functional genomics of Buchnera and the ecology of aphid hosts," Molecular Ecology, v.15, 2006, p. 1251.
- Moran NA, Dunbar HE, Wilcox JL. "Regulation of transcription in a reduced bacterial genome: nutrient-provisioning genes of the obligate symbiont," Journal of Bacteriology, v.187, 2005, p. 4229.
- Moran NA, Russell JA, Fukatsu T, Koga R. "Evolutionary relationships of three new species of Enterobacteriaceae living as symbionts of aphids and other insects," Applied and Environmental Microbioloy, v.71, 2005, p. 3302.
- Moran NA, Degnan PH, Santos SR, Dunbar HE, Ochman H. "The players in a mutualistic symbiosis: Insects, bacteria, viruses and virulence genes.," Proceedings of the National Academy of Sciences USA, v.102, 2005, p. 16919.
- Moran NA, Tran P, Gerardo NM. "Symbiosis and insect diversification: an ancient symbiont of sap-feeding insects from the bacterial phylum Bacteroidetes," Applied and Environmental Microbiology, v.71, 2005, p. 8802.
- Moran NA. "Symbiosis (A primer).," Current Biology, v.16, 2006, p. R866.
- Oliver KM, Degnan PH, Burke GR, Moran NA. "Facultative Symbionts in Aphids and the Horizontal Transfer of Ecologically Important Traits," Annual Review of Entomology, v.55, 2010, p. 247.
- Plague GR, Dunbar HE, Tran PL, Moran NA. "Extensive proliferation of transposable elements in heritable bacterial symbionts," Journal of Bacteriology, v.190, 2008, p. 777-779. Russell JA, Moran
- NA. "Horizontal transfer of bacterial symbionts: heritability and fitness effects in a novel aphid host," Applied and Environmental Microbiology, v.71, 2005, p. 7987.
- Russell JA, Moran NA. "Costs and benefits of symbiont infection in aphids: variation among symbionts and across temperatures," Proceedings of the Royal Society London Series B, v.273, 2005, p. 603.
- Takiya DM, Tran P, Dietrich CH, Moran NA. "Co-cladogenesis spanning three phyla: leafhoppers (Insecta: Hemiptera: Cicadellidae) and their dual bacterial symbionts.," Molecular Ecology, v.15, 2006, p. 4175.
- Wilson AC, Dunbar HE, Davis GK, Hunter WB, Stern DL, Moran NA. "A dual-genome microarray for the pea aphid, Acyrthosiphon pisum, and its obligate bacterial symbiont, Buchnera aphidicola.," BMC Genomics, v.7, 2006, p. 50.
- Wu D, Daugherty SC, Aken SE, Pai GH, Watkins KL, Khouri H, Tallon LJ, Zaborsky JM, Dunbar HE, Tran PL, Moran NA, Eisen JA. "Metabolic complementarity and genomics of the dual symbiosis of sharpshooters.," PloS-Biology, v.4, 2006, p. 188.