CUTICLE CHIRALITY AND BODY HANDEDNESS IN CAENORHABDITIS-ELEGANS

Caenorhabditis elegans adult animals exhibit an inherent chirality of fiber orientation in the basal layer of the cuticle, as well as a natu rally invariant but experimentally reversible handedness in the left-r ight (L-R) asymmetry of the body plan. We have examined the relationsh ip between cuticle chirality and body handedness in normal and L-R rev ersed animals, using Roller (Rol) mutants and transmission electron mi croscopy to monitor cuticle properties. Rot phenotypes, several of whi ch have been shown to result from mutations in cuticle collagen genes, are characterized by an invariant, allele-specific handedness in thei r direction of rolling. We show for several alleles that this directio n is not affected by L-R reversal of the body plan. We further show, b y electron microscopy, that the chiral orientation of cuticle Fibers i n animals with normal cuticle is not reversed by L-R body-plan reversa l. We conclude that cuticle chirality must be established independentl y of body-plan handedness. The cues that establish cuticle chirality a re still unknown, as are the causes for different rolling directions i n different Roller mutants. We discuss the question of how cuticle chi rality maintains its independence, and how the orientations of the fib er layers may be determined. (C) 1998 Wiley-Liss, Inc.