Dorsal Dauers and Directionally Dysfunctional dex-1 Dumpies

Science Center, Bent Corridor

The dauer life stage in wild-type C. elegans exhibits morphological and behavioral characteristics that differentiate it from non-dauers. In addition to the commonly observed radial shrinkage, quiescence and lack of pharyngeal pumping, we noted a tendency of wild-type dauers to lie dorsoventrally when mounted on agarose slides, as opposed to laterally like adults. To quantify this observation, we mounted wild-type dauers and L3s on increasing concentrations of agarose with 0.1 M levamisole. We found that 75-90% of wild-type dauers mounted with levamisole lie dorsoventrally regardless of agarose concentration. Very few (2.5-5%) non-dauer animals were positioned dorsoventrally. There was no significant difference in positioning between dauers that still retained their L2d cuticle and those that were completely molted. We then utilized a non-anesthetic method of immobilization by mounting dauers on 10% agarose with 10 micron polystyrene microbeads. Interestingly, only 15% of wild type dauers lie dorsoventrally when mounted using microbeads. We hypothesized that the radial shrinkage and the presence of lateral alae in wild-type dauer cuticles may cause anesthetized dauers to roll to a dorsoventral position, but that “conscious” dauers immobilized with microbeads would remain lateral, despite the presence of alae. To test this, we examined dex-1 mutant dauers. We recently found that dex-1(ns42) dauers are defective for dauer alae formation and radial constriction leading to a “dumpy” dauer phenotype. We found that dex-1 dauers are significantly more likely to lay laterally than wild-type dauers (p=0.0013) suggesting that dauer alae or overall body dimensions regulate the anesthetized “sleeping” position.