Amyloids protect the silkmoth oocyte and embryo

Chorion is the major component of silkmoth eggshell. More than 95%, of its dry mass consists of proteins that have remarkable mechanical and chemical properties protecting the oocyte and the developing embryo from a wide rang e of environmental hazards. We present data from electron microscopy (negat ive staining and shadowing), X-ray diffraction and modeling studies of synt hetic peptide analogues of silkmoth chorion proteins indicating that chorio n is a natural amyloid, The folding and self-assembly models of chorion pep tides strongly support the beta-sheet helix model of amyloid fibrils propos ed recently by Blake and Serpell [Structure 4 (1996) 989-998], (C) 2000 Fed eration of European Biochemical Societies. Published by Elsevier Science B. V. All rights reserved.