James Gahan

Dr James Gahan
Senior Lecturer
ERC Starting Grant Awardee
james.gahan@universityofgalway.ie
Gahan Lab Website

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Research interests

• Animal Evolution
• Differentiation and Development
• Gene Regulation and chromatin

Research overview

The group is broadly interested in how changes in genome regulation contributed to animal evolution. To fill this fundamental gap, the group focuses on two distinct model systems.

Investigating the role of chromatin during cell differentiation in choanoflagellates, the closest relatives of animals

In the first project, funded by an ERC starting grant, we aim to reconstruct the origin and evolution of cell-type-specific gene expression by investigating the gene-regulatory mechanisms that drive life history transitions in choanoflagellates. Choanoflagellates are the closest living unicellular relatives of animals. They are thus extremely informative for dissecting the earliest stages of animal evolution. The primary species utilized in the lab in Salpingoeca rosetta. S. rosetta is a very useful and informative model for several reasons. Firstly, it has a complex life cycle with many different life stages which allow us to compare gene expression and chromatin in different cell types. S. rosetta also has a small genome (~55 Mb) and a chromosome level assembly is available. In addition, work in recent years has led to the development of transgenesis and genome editing in S. rosetta allowing us to perform functional experiments. Although S. rosetta is our primary model we are also interested in expanding our models to include new choanoflagellates and beyond

Dissecting gene regulation in the sea anemone Nematostella vectensis

In a second project we use the sea anemone Nematostella to investigate chromatin function during development and differentiation. Nematostella is part of the phylum cnidaria, the sister group to the majority of animals and thus in a pivotal phylogenetic position for understanding early animal evolution. We work to dissect chromatin regulation during development and also in differentiation, using the nervous system as a model. In doing so we aim to understand how the processes underlying developmental gene regulation in more “complex” animals first evolved while simultaneously addressing more general questions about the role of chromatin in development and differentiation.

Keywords

Evolution, development, chromatin, histone modifications, differentiation, cnidarians, choanoflagellates, Salpingoeca rosetta, gene regulation, genome engineering.

Selected publications

• The genetic basis for PRC1 complex diversity emerged early in animal evolution
• Histone demethylase Lsd1 is required for the differentiation of neural cells in Nematostella vectensis
• A developmental role for the chromatin-regulating CoREST complex in Nematostella vectensis 

Most Recent Publications

• Chromatin profiling identifies putative dual roles for H3K27me3 in regulating transposons and cell type-specific genes in choanoflagellates
• The genome of the colonial hydroid <em>Hydractinia</em> reveals that their stem cells use a toolkit of evolutionarily shared genes with all animals
• Fluorescence In Situ Hybridization as a Tool for Studying the Specification and Differentiation of Cell Types in Nematostella vectensis

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Get in Touch!

james.gahan@universityofgalway.ie