In the absence of any metal,
numr-1 and
numr-2 showed identical patterns of transcription. Both genes showed developmental patterns of expression, where maximal levels of constitutive expression were observed throughout the intestine of L1 nematodes. This expression decreased as the nematodes developed into adults, at which point it was minimal. qRT-PCR analysis confirmed that the steady-state level of
numr-1/-2 mRNA was highest in L1 C. elegans and that it gradually decreased as nematodes developed into adults. In addition to developmentally regulated intestinal cell expression,
numr-1 and
numr-2 were constitutively expressed at all developmental stages in a few cells in the posterior of the nematode and in a pair of sensory neurons in the head. They were also constitutively expressed in egg-laying muscles of the adult vulva. To distinguish which sensory neurons expressed
numr-1, JF85(mtEx60) nematodes were treated with DiI.
numr-1 expression was detected in a pair of sensory neurons with processes extending towards the external environment, but the expression did not overlap with cells stained by DiI. This suggested that
numr-1 was expressed in AW sensory neurons.