Down Syndrome Cell Adhesion Molecule, Dscam Molecular Diversity Crucial for Survival in Drosophila Melanogaster

Abstract

There are 250,000 neurons and millions of synaptic connections in the fruit fly Drosophila Melanogaster. The molecular mechanism behind the precision and timing of these neural connections during development still eludes us. The Drosophila Down syndrome cell adhesion molecule or Dscam encodes 152,064 isoforms that are believed to be significant in regulating branching and targeting of neurites and, consequently in neuronal wiring and the viability of the organism. This study presents evidence that distinct set of Dscam isoform diversity is paramount to the survival of the organism. Single domain specific isoforms have been shown to rescue lethality caused by Dscam mutations up to the third instar larval stage (Wang, 2004). This study demonstrates that isoform specific single and multiple transgenes can rescue lethality caused by Dscam mutations up to the stage of adulthood with varying degrees of efficiency. The differences in rescuing abilities were found not only between isoforms belonging to different domains but also within the same domain. These individual differences reflect distinct functions for distinct isoforms in contributing to Dscam's overall function.