The
daf-2 gene acts as a developmental switch. High
daf-2 activity leads to normal development, whereas low
daf-2 activity leads to the formation of an alternative larval stage, the dauer larva. Multiple signals such as food availability, dauer pheromone concentration, and temperature can induce dauer formation (1). Sensory neurons and a genetic patway have been demonstrated to control dauer formation (2-4).
daf-2 functions at a downstream position in this genetic pathway. Dauers have many specialized cells and tissues, including the hypodermis, the pharynx, and the intestine. Is
daf-2 function required in each of these tissues to promote their normal development? Or does absence or presence of
daf-2 function in some cells control the development of other cells? We are particularly interested in these questions since
daf-2 has been implicated in lifespan regulation (5). To answer these questions we are analyzing daf! -2 genetic mosaic worms. We find that the
daf-2 state (wild type or mutant) of some cells can control the dauer phenotype of other cells. Genetic mosaics are isolated from
daf-2(
e1370)
dpy-17(
e164)
ncl-1(
e1865)
unc-36(
e251)III; sDp3. Animals carrying sDp3 form non-dauers that are non-Dpy, non-Ncl, and non-Unc, while worms lacking sDp3 form dauers that are Dpy, Ncl, and Unc. We find that mosaic worms form both dauers and non-dauers. We distinguish full dauers from non-dauers by the following strict criteria: * full dauers are thinner than comparable L3 larvae, * they have specialized cuticular alae which are absent in L3 larvae, * they have a structurally remodeled pharynx that does not pump, is slimmer and has a more dorsal posterior bulb than that of L3 larvae, * they have highly refractile intestinal cells instead of the light intestinal cells of L3 larvae, * they are resistant to 1% SDS. Some mosaics have a partial dauer phenotype: they express some, but not all, features of a full dauer. The partial dauer mosaics stay in this state only transiently. All partial dauer mosaics are SDS resistant and have continuous dauer alae which sometimes is less refractile than that of a full dauer. Other aspects of the full dauer phenotype are variable or incomplete in the partial dauer mosaics: some partial dauers mosaics have light intestinal coloration, pharyngeal pumping, or an incompletely remodeled dauer pharynx.