hda-1 is broadly expressed throughout development. The earliest expression was detected in gastrulating embryos. The larvae exhibited GFP expression in several neuronal and epidermal cells, primarily in the anterior ganglion and ventral hypodermal regions. Expression persisted in many cells in later larval and adult stages (data not shown). In the vulva,
hda-1::gfp expression was first detected in the progeny of P(5-7).p in mid-L3 animals. At this stage, GFP fluorescence was absent in other VPC lineages (P3.p, P4.p and P8.p) (data not shown). By the L4 stage, almost all vulval cell types were observed fluorescing, with presumptive vulA, vulB1, vulB2, and vulD cells being the brightest. GFP fluorescence in vulval cells was mostly absent beyond the late-L4 stage, suggesting that
hda-1 may not be needed in vulval cells at later stages of development. The broad expression of
hda-1 is in consistent with the involvement of the gene in multiple developmental processes. This multifaceted role for
hda-1in C. elegans appears to be conserved in C. briggsae, because
Cbr-hda-1::gfp is expressed in a similar manner.
hda-1::gfp expression was also observed in the AC in L3 animals that persisted until the early L4 stage (data not shown). No expression was observed in pi cells or their progeny at any developmental stage.