Abstract
The sev-Gal4 driver is widely used in Drosophila to express the target gene in specific subsets of cells in ommatidial units of the developing eye. A 2015 report (Ray and Lakhotia, J. Genet. 94, 407-416) from our laboratory claimed that besides the eye disc cells, the sev-Gal4 (Bloomington stock 5793) also expresses in eight pairs of dorsomedial neurons and some other cells in larval and early pupal ventral ganglia. The current study reveals that this claim was incorrect since the UAS-GFP transgene in Bloomington stock 1521 used as a reporter in the 2015 study expresses in the eight pairs of dorsomedial neurons and some other cells in larval and early pupal ventral ganglia even in undriven condition. The UAS-eGFP reporter in the BL-5431 stock, however, does not express in these ganglia, neither in undriven nor in sev-Gal4 driven condition. This was also confirmed by the G-TRACE cell lineage study. Present results suggest that only four dorsalmidline cells in the ventral ganglia and a cluster of cells in the central region of the brain hemisphere, besides the earlier known cells in the eye disc and optic lobe of the brain, express the sev-Gal4 transgene in the stock 5793. The essentiality of examining the undriven expression of a transgene cannot be over-emphasized.
