Immunocytochemical and freeze-fracture characterization of the Caenorhabditis elegans DR 847 bli-1(n361) mutant which produces abnormal cuticle blisters

Abstract.

The bli-1 gene of Caenorhabditis elegans has previously been described as a mutation which disrupts the structure of the adult-stage cuticle, causing the formation of fluid-filled blisters. We investigated the blistering phenotype exhibited of n361 allele through immunocytochemical and freeze-fracture techniques. In the course of the blistering process several fine changes occurred, including a high-electron-density granulous material filling the intermediate layer, alterations in strut structure, and finally the total disappearance of the fibrous and basal layers. A polyclonal antibody against a synthetic 18-amino-acid peptide of the 3A3-collagen sequence labeled all the cuticular regions of the N₂ strain of the nematode C. elegans except for the intermediate layer. Similarly, no reaction was observed in the intermediate layer of the mutant strain DR 847 bli-1 (n361), which was filled by the granulous and electron-dense material. Replicas of quick-frozen, freeze-fracture, deep-etched, and rotatory-shadowed adult forms of the mutant DR 847 bli-1 (n361) of C. elegans revealed an increased number of the filamentous structures filling the intermediate layer in older nematodes, and also a gradual destruction and disappearance of the fibrous and basal layers. Based on these results, we postulated that the blistering phenotype is due to an altered function of bli-1 gene, which is probably enzymatic.