Figure 1. CUT genes are expressed pan-neuronally.

(A) Schematic illustration of two main components of neuronal gene batteries, pan-neuronally expressed genes, for which no current regulator is known, and neuron type-specific gene batteries that are controlled by terminal selector-type transcription factors ¹. Examples for genes in each category are provided.

(B-E) Schematic representation of ceh-48 (B), ceh-44 (C), ceh-41, ceh-21 and ceh-39 (D), and ceh-38 (E), gene loci showing mutant alleles, GFP tags, and CUT and Homeodomain motifs location. Reporter expression at the comma embryonic stage (bottom left, lateral view), L1 larval stage (top, full worm lateral views) and young adult stage (bottom right, lateral view of the head) showing ceh-48 (ceh-48fosmid::GFP[wgIs631]). (B) and ceh-44 (ceh-44(ot1015[ceh-44::GFP])) (C) pan-neuronal expression, and ceh-41, ceh-21 and ceh-39 (D), ceh-38 (ceh-38fosmid::GFP[wgIs241]) (E) ubiquitous expression. We use a fosmid reporter for ceh-41 (ceh-41fosmid::GFP[wgIs759]), the last gene in the operon of three ONECUT genes, which provides a read-out for expression of all genes in the operon. The embryonic comma stage is the stage when neurons are born. Head ganglia, ventral nerve cord, and tail ganglia outlined in L1 images, and head ganglia outlined in young adult images for ceh-48 and ceh-44 reporters. Asterisks (*) indicate autofluorescence in L1 (ceh-48 and ceh-44) and Comma (ceh-44) images. See Figure S1 for a comparison between CRISPR reporters expression for the different CUT genes. Note that the ceh-44(ot1028) allele was design to introduce a frameshift in the CUT homeobox isoform of the Y54F10AM.4 locus (isoform a) and does not affect the b isoform of this locus, which generates a different, non-homeodomain containing isoform, homologous to CASP protein ¹⁵.

YA, young adult; Scale bars 15 μm.