Regulating neuronal composition in the Drosophila mushroom body through hormonal extrinsic cues. Daniel I Fritz, Abigail Lubin, Alper Dincer, Jaspinder Kanwal, Elizabeth Marin. Biology, Bucknell University, Lewisburg, PA.
The Drosophila mushroom body is composed of thousands of intrinsic neurons, which are generated by only four original neuroblasts. At least three major neuronal subtypes (, /, and /) are born sequentially during development, but the mechanism that regulates fate switching in these cells at the appropriate time is unclear. Through the use of sucrose starvation to uncouple mushroom body neuroblast divisions from organismal growth in newly hatched larvae excess neurons can be generated. This result strongly suggests that neuronal composition is plastic and can be regulated by an extrinsic developmental cue.
Ecdysone, insulin, and juvenile hormone (JH) would appear to be the most logical candidates for this extrinsic cue. In prior experiments, the corpora allata (CA), the source for JH, was ablated in males resulting in total and non- class neurons being reduced in count. Conversely, dietary pyriproxifen, a JH mimic, increased number of non- and total neurons in males. In females, CA ablation alone did not affect total or non- neuron numbers, however the introduction of pyriproxifen with or without the CA ablation increased total and non- neuron numbers. We are currently performing additional genetic experiments to further explore the regulatory effects JH has on mushroom body neuronal fate determination.
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