Clonal Development and Organization of the Adult Drosophila Central Brain

Abstract

Summary Background The insect brain can be divided into neuropils that are formed by neurites of both local and remote origin. The complexity of the interconnections obscures how these neuropils are established and interconnected through development. The Drosophila central brain develops from a fixed number of neuroblasts (NBs) that deposit neurons in regional clusters. Results By determining individual NB clones and pursuing their projections into specific neuropils we unravel the regional development of the brain neural network. Exhaustive clonal analysis revealed 95 stereotyped neuronal lineages with characteristic cell body locations and neurite trajectories. Most clones show complex projection patterns, but despite the complexity, neighboring clones often co-innervate the same local neuropil(s) and further target a restricted set of distant neuropils. Conclusions These observations argue for regional clonal development of both neuropils and neuropil connectivity throughout the Drosophila central brain.

Drosophila intermediate neural progenitors produce lineage-dependent related series of diverse neurons

“…1W), reminiscent of some conventional type I lineages that exist as a lone hemilineage (Yu et al, 2010;Yu et al, 2013). Nonetheless, we could recover DL2 clones at comparable frequencies to the other type II NB clones with another type II NB-specific driver, giving us confidence in the identification of DL2 as the eighth type II NB lineage (data not shown).…”

“…1H-W). The complex yet stereotyped clone morphologies argue that each type II NB produces a characteristic set of diverse neuronal offspring in addition to glia (Izergina et al, 2009;Viktorin et al, 2011;Yu et al, 2013;Viktorin et al, 2013).…”

A Challenge of Numbers and Diversity: Neurogenesis in theDrosophilaOptic Lobe

“…Whereas the adult central brain of Drosophila is estimated to contain 11,000 neurons in each hemisphere (Ito et al, 2013;Yu et al, 2013), their optic lobes each consist of ∼60,000 neurons (Hofbauer & Campos-Ortega, 1990;. The eye constitutes a highly regular, almost crystalline array of ∼780 facets or ommatidia in female and ∼730 in male flies (Wolff & Ready, 1993), each containing the cell bodies of 8 photoreceptor subtypes (R cells, R1-R8).…”

Transcriptomes of lineage-specific Drosophila neuroblasts profiled via genetic targeting and robotic sorting

“…Approximately 100 cerebral NBs arise per hemisphere, with each expressing a unique combination of early patterning genes (Urbach and Technau, 2003). Labeling the offspring made by individual cerebral NBs has revealed the composition of ∼100 discrete NB clones per hemisphere with characteristic morphologies (Yu et al, 2013). Mapping individual neurons serially made by one NB provides a detailed description of the developmental fate of that NB.…”

“…A mouse brain consists of ∼75 million neurons (Oh et al, 2014) that arise from an undefined number of NSCs. Conserved neurogenic programs with stem celllike progenitors underlie the generation of ∼30,000 neurons from ∼200 neuroblasts (NBs) in the much smaller Drosophila cerebrum (Urbach and Technau, 2004;Yu et al, 2013). Moreover, Drosophila NBs, like mammalian NSCs, exhibit both basic and complex patterns of neurogenesis (Homem and Knoblich, 2012).…”