AIC Alumni Profile: Brian Stramer

Watching Immune Cells Build a Developing Fruit Fly

Macrophages are immune cells known to respond to infections and wounds. But in flies macrophages also play an essential role in shaping the developing embryo, where they produce most of the extracellular matrix (ECM). Composed largely of collagen, the ECM provides a structure around which cells organize themselves to form the developing body.

Brian Stramer and his team from Kings College London are interested in understanding why and how the ECM is produced from fly immune cells, which – unlike skin, muscle, nerve, or other cells – are highly mobile. “We hypothesize that some of these matrix components don’t diffuse very well, and as a result you need a moving source of matrix to evenly distribute ECM within the embryo,” explained Stramer.

At the AIC, Stramer and his team of two students and a postdoc used the lattice light sheet microscope to visualize the immune cells in developing embryos. “On the lattice, we could watch the macrophages, at the earliest stages of development, producing matrix locally as they moved,” said Stramer. “We could see the fine structure and reorganization of the matrix as they were migrating, which was not possible with conventional microscopy.” Two weeks of imaging produced 30 terabytes of data, which the team is currently analyzing.

Stramer noted the extensive support his team received during the visit. “The AIC staff is amazing,” Stramer said.“They helped with every stage of the project, from its initial planning to data acquisition and analysis.” The project received other essential support as well, he said.  “Todd [Laverty], the manager of the Janelia Drosophila Resources, and his team helped maintain and amplify our fly stocks prior to our visit so that we could begin experiments on day one of our arrival.”

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