The Journal of Neuroscience, June 15, 2002, 22(12):4906-4917
Dendritic Remodeling and Growth of Motoneurons during
Metamorphosis of Drosophila melanogaster
Christos
Consoulas,
Linda L.
Restifo, and
Richard B.
Levine
Arizona Research Laboratories, Division of Neurobiology, University
of Arizona, Tucson, Arizona 85721
Insect motoneurons display dramatic dendritic plasticity during
metamorphosis. Many larval motoneurons survive to adulthood but undergo
dendritic regression and outgrowth as they are incorporated into
developing circuits. This study explores the dendritic remodeling and
development of Drosophila motoneurons MN1-MN5, which
innervate indirect flight muscles of the adult. MN1-MN5 are persistent
larval neurons exhibiting two distinct metamorphic histories. MN1-MN4 are born in the embryo, innervate larval muscles, and undergo dendritic
regression and regrowth during metamorphosis. MN5, which was identified
through a combination of intracellular dye injection and retrograde
staining at all stages, is also born embryonically but remains
developmentally arrested until the onset of metamorphosis. In the
larva, MN5 lacks dendrites, and its axon stops in the mesothoracic nerve without innervating a target muscle. It is dye coupled to the
peripherally synapsing interneuron, which will become part of the giant
fiber escape circuit of the adult fly. During pupal development, MN5
undergoes de novo dendritic growth and extension of its
axon to innervate the developing target muscle. Its unique developmental history and identifiability make MN5 well suited for the
study of dendritic growth using genetic and neurophysiological approaches.
Key words:
insect; motor neuron; dendrite; dendritic plasticity; CNS; spine; indirect flight muscles
Copyright © 2002 Society for Neuroscience 0270-6474/02/22124906-12$05.00/0