The sev-GAL4 driver in Drosophila melanogaster does not express in the eight pairs of dorso-medial and some other neurons in larval ventral ganglia: A correction

The sev-Gal4 driver is widely used in Drosophila to express the target gene in specific subsets of cells in ommatidial units of developing eye. A 2015 report (Ray & 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 8 pairs of dorso-medial 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 reporter in the 2015 study expresses in the 8 pairs of dorso-medial 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 dorsal-midline cells in ventral ganglia and a cluster of cells in central region of brain hemisphere, besides the earlier known cells in eye disc and optic lobe of brain, express the sev-Gal4 transgene in the stock 5793. The essentiality of examining undriven expression of a transgene cannot be under-emphasized.