The next time you see a fruit fly buzzing around your kitchen, take a beat before you smack it with a swatter and remind yourself of the amazing discoveries due to organisms like the (not so) lowly fruit fly. Maybe you’ll offer a thank-you glass of grape juice instead and show the intruder back outside. Today’s image is from a paper describing a fly model of a serious human disease, and serves as a great example of the power in a model organism.
Spinal muscular atrophy (SMA) is a heritable disease that results in infant mortality due motor neuron dysfunction and rapid degeneration of muscle. SMA is caused by the depletion of the SMN (survival motor neuron) protein. A recent paper describes the use of fruit flies in studying SMA, and shows that flies lacking SMN have reduced muscle size and defective motor neuron neurotransmission similar to SMA patients. Imlach and colleagues found that replenishing SMN levels in motor neurons and muscles did not reverse the defects of SMN depletion, yet increasing SMN levels in partner cells (proprioceptive neurons and interneurons) can reverse the defects. These results suggest that SMN depletion primarily affects the sensory-motor network, with secondary effects seen in the motor circuit. In addition, Imlach and colleagues found that increasing motor neural circuit excitability, either genetically or with drugs, could relieve SMN-depletion defects. Using this fly model of SMA, these results suggest that SMA patients may improve by enhancing motor neural network activity. The images above show the differences in muscle size in wild-type (left) and SMN-depleted (right) flies.
Imlach WL, Beck ES, Choi BJ, Lotti F, Pellizzoni L, & McCabe BD (2012). SMN Is Required for Sensory-Motor Circuit Function in Drosophila. Cell, 151 (2), 427-39 PMID: 23063130
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