Grant: Discovery Grants Program - Individual

Model organisms have been the mainstay of research for much of the 20th century. In part, model organisms have been selected for their straightforward development and constant morphology. However, the advent of rapid genome sequencing and the ready transfer of molecular tools to non-traditional model organisms have blurred the lines between model, emerging and non-traditional model organisms. The more complex life histories of non-traditional model organisms provide a unique opportunity to expand our understanding of biology. *My proposed research program will explore the epigenetic foundation of the biology of non-traditional model organisms. For example, Drosophila like mice and humans, responds to modest nutrient deprivation in development by nothing more exciting than developing as smaller adults. In contrast, Daphnia responds to adverse environmental circumstances by producing an additional sex - males. Similarly, in the presence of predators, the morphology of Daphnia is grossly remodeled and the animals can produce massive helmets, tail spines, clubs, neck teeth and other morphological elaborations that completely change their appearance. These exuberant morphological changes are necessarily epigenetic, as they occur in clones with identical genomes. These dramatic and biologically essential epigenetic responses demonstrates the advantages of non-traditional model organisms. *The epigenome reflects the suite of epigenetic changes in gene expression; that is, changes in gene expression not due to altered DNA sequence. The epigenome is responsive to external environmental factors such as nutrition, toxin exposure, hormonal milieu, social interactions, and possibly even the weather. Less well documented is the effect of the internal environment of cells, in particular the effect of endobacteria. Among the endobacteria, bacteria with obligate intracellular reproduction, a-proteobacteria is arguably the most famous, as an ancient member of this group gave rise to our mitochondria. However, this ubiquitous group of bacteria also includes less domesticated extant relatives, Wolbachia and Rickettsia, obligate endobacteria of inverterbrates and vertebrates, respectively. *I will extend our work on the epigenetic effects of endobacteria in Drosophila by exploring their control of their host's genome in the non-traditional model systems, Daphnia, ticks and mammalian cell culture. The manifold ways in which ubiquitous endobacteria control their host, and so influence host phenotype and biology, are the questions that will be tackled in this research programme. *