Isolation and characterization of the cuticle from the free-living nematode Panagrellus silusiae

Abstract

The cuticle (0.15 to 0.5 μm thick) of the microscopic free-living nematode Panagrellus silusiae was isolated intact by incubating worms with 1% sodium dodecyl sulfate at 37°C overnight. After shearing and further treatment with detergent, electron microscopy revealed that the cuticular pieces were free of contaminating material and retained their characteristic in situ ultrastructure. From amino acid determinations, the cuticle is collagen-like with high levels of glycine (≈31 residue %), proline (≈20 residue %) and alanine (≈21 residue %) although the hydroxyproline (2.6 residue %) content is low. Half-cystine (≈1 residue %) is present in purified cuticles. Treatment with 8 M guanidine hydrochloride-2% β-mercaptoethanol can solubilize more than 85% of the cuticular preparation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the solubilized cuticles from juvenile, adult and old dead worms revealed, at least, 18 discrete components. Estimated molecular weights ranged from about 26 000 (peak 1) to 250 000 (peak 18).