Previous studies using reporters driven by the
ins-9 promoter suggested that
ins-9 is expressed in the ASI and ASJ amphid neurons as well as in additional tissues (Chen and Baugh, 2014; Pierce et al., 2001; Ritter et al., 2013). In contrast, in transgenic L2 larvae expressing
ins-9::SL2::mNG, we consistently observed green fluorescence solely in one pair of sensory neurons. In animals in which neuronal morphology was discernable, we identified the fluorescent cells as the ASI amphid neurons. We did not observe fluorescence in more than one pair of amphid neurons in any animal, nor did we detect fluorescence in other neurons or tissues. Since
ins-9::SL2::mNG contains genomic elements from the
ins-9 locus that are missing from other reporters in the literature (Chen and Baugh, 2014; Pierce et al., 2001; Ritter et al., 2013), these observed patterns of expression are likely to be physiologically relevant.