Referee 1's review (Wolfgang Blenau):

This is an excellent concise paper on the distribution of putative aminergic neurons in the thoracic and abdominal neuromeres of the Drosophila larval ventral ganglion relying on Fasciclin2-immunoreactive tracts as 3-dimensional landmarks. For TH- and TDC2-specific gal4-drivers the authors also analysed the distribution of ectopically expressed compartment markers (synaptobrevin, synaptotagmin, Down syndrome adhesion molecule) in putative DA and TA/OA containing neurons, respectively. This paper is a logical follow-up of an earlier paper of the authors on the neuroarchitecture of peptidergic systems in the ventral ganglion which was also published in PloS ONE (Santos JG et al., 2007, PLoS ONE 2: e695). In the current analysis, all experimental assays were performed accurately. The subject is put into the context of similar studies and is discussed appropriately. The manuscript is well written. I have discovered no problems with this paper.

Minor issues:

p9, line 6 from below: Instead of "TDC catalyzes the first step in the synthesis of TA from tyrosine" it should be "TDC catalyzes the synthesis of TA from tyrosine" because there is only one step.

P16, line 7 from below: Instead of "dopaminergig" it should be "dopaminergic".

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N.B. These are the comments made by the referee when reviewing an earlier version of this paper. Prior to publication the manuscript has been revised in light of these comments and to address other editorial requirements.