Nancy A. Moran


Research Projects in the moran lab

Glassy Winged Sharpshooter drawing by JAson Z. Zhu

Molecular mechanisms of endosymbiont evolution

(PI is Jeffrey Barrick)
(Co-Principal Investigators are Nancy MoraN, BRYAN DAVIES, STEPHEN TRENT, & CHARLEs Schroeder)

drawing of brochosome

Many animals and plants have symbiotic bacteria that live inside their cells, organs, or tissues. These bacteria range from recently acquired symbionts that can still replicate outside of their hosts to obligate endosymbionts that have essentially evolved into new types of intracellular organelles. Many questions remain about the mechanisms by which novel symbiotic associations originate and how bacterial and eukaryotic cells in symbioses exchange molecules that allow them to coordinate their functions in ways that benefit one or both partners. Better understanding of these mechanisms would broadly impact future applications of symbionts in microbiome engineering, as living therapeutics, and for biological control.

Insects are an incredibly diverse group of animals that fulfill critical roles in natural ecosystems.

In accordance with the variety of their lifestyles, insects display a similarly wide range of associations with symbiotic microbes. For example, aphids, leafhoppers, and other sap-sucking insects have bacterial endosymbionts that live inside of specialized cells in their bodies and are inherited across generations. Honey bees, on the other hand, have a conserved gut microbiome consisting of coevolved bacteria that contributes to their nutrition and health. Fruit flies have a gut microbiome that also impacts their fitness, but its composition is more heavily influenced by which microbes they encounter in their food and environment. The diversity of insect symbionts and the ease with which bacteria can be removed from and transplanted among insects in the laboratory makes them powerful model systems for studying the molecular mechanisms of symbioses and for understanding how and why symbionts originate from certain free-living bacteria that insects encounter in their environments.

Our project concentrates on two overall categories of basic research questions:

  1. By what molecular mechanisms—other than basic metabolism and nutritional cross-feeding —do symbionts communicate with and benefit eukaryotic cells and animal hosts? What functional and informational biopolymers are exchanged between symbionts and hosts?
  2. Why do some types of bacteria more commonly evolve into host-restricted symbionts? What latent capacities need to be already present in a protosymbiont? What barriers

Selected publications

  • Li Z, Xue AZ, Maeda GP, Li Y, Nabity PD, Moran NA. 2023. Phylloxera and aphids show distinct features of genome evolution despite similar reproductive modes. Mol Biol Evol. 2023 Dec 9:msad271. doi: 10.1093/molbev/msad271. [Online ahead of print.]
  • Li Z, Li Y, Xue AZ, Dang V, Renee Holmes V, Spencer Johnston J, Barrick JE, Moran NA. 2022. The genomic basis of evolutionary novelties in a leafhopper. Mol Biol Evol. 39(9):msac184. doi: 10.1093/molbev/msac184.