Analysis of SKN-1 expression in vivo. (A) C. elegans life cycle stages. The hermaphrodite life cycle is shown [8]. The majority of C. elegans produced are hermaphrodites, which are typically studied in the laboratory. A small proportion of males are produced within each generation of approximately 300 animals. The pharynx, a pumping organ used for feeding, is shown in orange, the intestine in grey, the gonad in light blue, and embryos in dark blue. (B) SKN-1 protein expression. The expression pattern of a transgene that encodes the SKN-1b and SKN-1c isoforms is shown under stress conditions [7]. The SKN-1b isoform is expressed constitutively in the nuclei of the ASI neurons, and SKN-1c accumulates in intestinal nuclei in response to certain stresses [7,19].