Professor Elizabeth Marin makes discovery from fruit fly research

Gillian Feehan, writer

Assistant Professor of Biology Elizabeth Marin recently discovered evidence that failing to provide a fruit fly with proper nutrition during development increases growth in brain structures, the structures that help the fly learn and remember food sources.

Marin and several other researchers from Suewei Lin’s group at the Janelia Farm Research Campus in Ashburn, Va. have been studying a brain structure in the fruit fly called the mushroom body for years.

“[The mushroom body] consists of thousands of neurons that all work together in order to control olfactory associative memory, which allows the flies to associate particular odors with a bad stimulus, like electric shock in laboratory tests, or a positive stimulus, for example, feeding them a sucrose reward,” Marin said.

Marin wanted to look at how nutrition affects the size and structure of the mushroom body, and she wanted to see how many neurons were made in order to test the plasticity of the structure.

For her experiment, Marin fed the fruit flies only sucrose water during their early larval development. This sucrose water starves the fruit flies of important nutrients, such as fats and proteins, that they get from normal food. Marin found that the larval tissues stopped developing, but the stem cells that make the mushroom body continued to divide despite the lack of adequate nourishment.

“We think that the [fruit flies] are cannibalizing the rest of the animal in order to keep making these particular types of cells,” Marin said.

Marin’s fellow researchers also investigated a second structure that is involved in olfaction, called the antenna lobe, which is similar to a human’s olfactory bulb. The researchers found no change in the number of neurons in the antenna lobe when the fruit flies were starved.

Unlike the mushroom body, the antenna lobe is very resistant to change. In their paper published in Current Biology, Marin and researchers hypothesized that the differences in plasticity between the mushroom body and the antenna lobe are linked to adaptation.

Marin chose this field of research based on her interest in genetics and development. Also, insects and fruit flies are relatively inexpensive and allow for fairly quick experiments. More importantly, fruit flies and humans share some genetic similarities.

“We share about 50 percent of our genes with fruit flies; we have more genes, but not that many more. Lots of genes that have been identified to be important in human disorders were originally found in fruit flies,” Marin said.

Through her research, Marin is able to educate students and give them the opportunity to participate in hands-on research.

“I’ve learned a lot about experiments and research with Professor Marin. I look forward to taking what I’ve learned into my summer project and adding to the knowledge we have on neurological development in the mushroom body,” Andreas Bub ’15 said.

“I can train the students to do everything, so they aren’t just assisting in a small way. They are actually doing the research and are able to create and analyze the data while they’re here, which is really great. That’s probably my favorite part of being at Bucknell,” Marin said.

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