Concordantly, a higher dose of DBL-1 pathway signaling increases barrier exclusion of higher molecular weight molecules, but does not further decrease access of smaller 4EGI-1 molecules to their targets. To quantify these differences in drug responsiveness, we determined the dose response of DBL-1 variant animals compared to wild type using a range of levamisole concentrations. Because our results indicate permeability of the cuticle and ionic surface properties are altered in DBL-1 variant strains, we asked if specific cuticular properties are altered in animals with decreased or increased DBL-1 signaling. The C. elegans cuticle is composed of different layers that entirely cover the animal��s external surface in a flexible, resilient exoskeleton. This exoskeleton protects the animal from environmental insults and infection. A surface coat of charged glycoproteins, the glycocalyx, covers the epicuticle, a lipid-rich cuticular layer. Under the epicuticle are the cortical, medial, and basal cuticular layers. Wheat germ agglutinin binds glycoproteins and stains the C. elegans cuticular surface when surface antigenicity is altered, as in srf mutant animals, while the red fluorescent lipophilic dye DiI stains phospholipids. We then asked if DBL-1 pathway signaling affected external cuticle morphology. A previous report that analyzed DBL-1 pathway genes sma-2, a Smad transcriptional CH5132799 regulator, and lon-2 showed a relationship between body length and distance between annuli, ridges patterning the cortical layer that ring the animal from nose to tail. Mild perturbations of annuli and longitudinal ridges called alae in lon-2 mutant animals were noted. Other mutations that affect cuticle and body length show differences in annular ridge width. Using DiI, a vital lipophilic dye that binds to lipids in the cuticular surface, to highlight annular furrows, we also found a direct correlation between annular width and body length in DBL-1 signaling variants. We did not discern noticeable aberrations in annuli or alae in animals with decreased or increased DBL-1 signaling.