Nancy A. Moran


PAST Research Projects

<A. pisum

En-Gen: Mutation in Genomes of Obligate Symbionts and Impacts on the Ecological Tolerances and Distributions of Hosts: Buchnera and Pea Aphids

(PI is Nancy Moran)

pea aphids in perti dishesThe health and survival of most animals and plants depends on specialized symbiotic microorganisms, mostly bacteria. Symbionts can affect the tolerances of hosts to environmental factors such as heat, parasites or nutritional stress. In many cases, symbionts are transferred from mother to offspring before birth, with maternal transmission especially common in insects. This project focuses on mutations affecting symbiont genomes and on how these mutations impact the functioning and environmental tolerances of hosts. Full genome resequencing will be carried out for Buchnera, the bacterial symbionts of aphids and one of the best studied examples of symbiosis. These data will reveal the overall frequency of mutations in the symbiont genome and the frequency of mutations that affect functions important to hosts, such as production of essential nutrients or tolerance to heat. To quantify the effects of these mutations on hosts, lab experiments with live insects containing different symbiont genotypes will be conducted. Preliminary evidence indicates that even a single change in the symbiont DNA sequence can have a massive effect on the aphid's ability to survive heat exposure. The new results will show the extent of such mutations across the entire symbiont genome.

The results will add to understanding of fundamental processes determining the distribution of a major group of crop pests (aphids) and will have implications for similar symbiotic systems found in many other insect pests. The study has direct implications for predicting how organisms respond to climate change. Educational components, from the high school to graduate level, are integrated into the research. Graduate and undergraduate students will conduct significant portions of the primary research. In addition, high school students will participate through a sustained collaboration between the main investigator and a biology teacher at a large urban high school with a majority of students from groups underrepresented in science and in the university.

Selected publications

  • Hansen AK, Moran NA. 2014. The impact of microbial symbionts on host plant utilization by herbivorous insects. Mol Ecol. 23: 1473-1496.
  • Vogel KJ, Moran NA. 2013. Functional and evolutionary analysis of the genome of an obligate fungal symbiont. Genome Biol Evol. 5: 891-904.
  • Nováková E, Hypša V, Klein J, Foottit RG, Dohlen CD, Moran NA. 2013. Reconstructing the phylogeny of aphids (Hemiptera: Aphididae) using DNA of the obligate symbiont Buchnera aphidicola. Mol Phylogenet Evol. 68: 42-54.
  • Hansen AK, Moran NA. 2012. Altered tRNA characteristics and 3' maturation in bacterial symbionts with reduced genomes. Nucleic Acids Res. 40: 7870–7884.
  • Hansen AK, Vorburger C, Moran NA. 2012. Genomic basis of endosymbiont-conferred protection against an insect parasitoid. Genome Res. 22: 106-114.
  • Nováková E, Moran NA. 2011. Diversification of genes for carotenoid biosynthesis in aphids following an ancient transfer from a fungus. Mol Bio Evol. 1: 313-323.
  • Burke GR, Moran NA. 2011. Massive genomic decay in Serratia symbiotica, a recently evolved symbiont of aphids. Genome Biol Evol. 3: 195-208.
  • Burke GR, Moran NA. 2011. Responses of the pea aphid transcriptome to infection by facultative symbionts. Insect Mol Biol. 20: 357-365.
  • Hansen AK, Moran NA. 2011. Aphid genome expression reveals host-symbiont cooperation in the production of amino acids. Proceedings of the National Academy of Sciences USA. 108: 2849-2854.
  • Moran NA, Jarvik T. 2010. Lateral transfer of genes from fungi underlies carotenoid production in aphids. Science 328: 624-627.
  • Harmon JP, Moran NA, Ives AR. 2009. Species response to environmental change: Experimental evidence of food-web interactions and evolution. Science 323: 1347-1350.
  • Moran NA, McLaughlin HJ, Sorek R. 2009. The dynamics and timescale of ongoing genomic erosion in symbiotic bacteria. Science 323: 379-382.
  • Degnan PH, Leonardo TE, Cass B, Hurwitz B, Stern D, Gibbs RA, Richards S, Moran NA. 2010. Dynamics of genome evolution in facultative symbionts of aphids. Environmental Microbiology 12:2060-2069.
  • Degnan PH, Yu Y, Sisneros N, Wing RA, Moran NA. 2009. Hamiltonella defensa, genome evolution of a protective bacterial endosymbiont from pathogenic ancestors. Proceedings of the National Academy of Sciences USA 106: 9063-9068.
  • 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: 5328-5335.
  • Peccoud J, Simon JC, McLaughlin HJ, Moran NA. 2009. Recent adaptive radiation of pea aphids revealed by their rapidly evolving symbionts. Proceedings of the National Academy of Sciences USA 106: 16315-16320.
  • Oliver KM, Degnan PH, Burke GR, Moran NA. 2009. Facultative symbionts of aphids and the horizontal transfer of ecologically important traits. Annual Review of Entomology 55: 247-266.
  • Oliver KM, Degnan PH, Hunter MS, Moran NA. 2009. Bacteriophage encode factors required for protection in a symbiotic mutualism. Science 325: 992-994.
  • Burke G, Fiehn O, Moran N. 2009. Effects of facultative symbionts and heat stress on the metabolome of pea aphids. ISME Journal 4: 242-252.
  • Degnan PH, Moran NA. 2008. Diverse phage-encoded toxins in a protective insect endosymbiont. Applied and Environmental Microbiology 74: 6782-6791.
  • Oliver KM, Campos J, Moran NA, Hunter MS. 2008. Population dynamics of defensive symbionts in aphids. Proceedings of the Royal Society of London Series B 275: 293-299.
  • Degnan PH, Moran NA. 2008. Evolutionary genetics of a defensive facultative symbiont of insects: exchange of toxin-encoding bacteriophage. Molecular Ecology 17: 916-929.
  • Dunbar HE, Wilson ACC, Ferguson NR, Moran NA. 2007. Aphid thermal tolerance is governed by a point mutation in bacterial symbionts. PLoS Biology 5: e96.
  • Moran NA, Degnan PH. 2006. Functional genomics of Buchnera and the ecology of aphid hosts. Molecular Ecology 15: 1251-1261.