Would you rather solve a 302-piece or a 100 billion-piece puzzle? This is a question I like to throw out when I explain the power of model organisms at family gatherings. Worms have 302 neurons, while the human brain has about 100 billion (give or take a few). Today’s image is from a great example of how informative model organisms can be in understanding key processes in our bodies.
Neurons are made of axons and dendrites – axons transmit information, while dendrites receive it. While both processes are key to the formation of a healthy nervous system, very little is known about dendrite formation. A recent paper describes dendrite development, using an oxygen-sensing neuron in the worm C. elegans. Kirszenblat and colleagues showed that dendrite formation in the oxygen sensory neuron is dependent on Wnt signaling, which is frequently used throughout development. Specifically, the LIN-44/Wnt signal and its associated LIN-17/Frizzled receptor trigger the initiation and guidance of the dendrite independently of axon development. Images and cartoons above show the oxygen sensory neuron (green) in normal worms (top left) and Wnt mutants (all others). Arrows point to axons while the arrowheads point to dendrites, which are either absent or incorrectly formed in the mutants.
Kirszenblat, L., Pattabiraman, D., & Hilliard, M. (2011). LIN-44/Wnt Directs Dendrite Outgrowth through LIN-17/Frizzled in C. elegans Neurons PLoS Biology, 9 (9) DOI: 10.1371/journal.pbio.1001157