Abstract
Bombyx mori cocoon has a multi-layer structure that provides optimal protection for silkworm pupa. Research on the mechanical properties of the multi-layer structure revealed structure-property relationships of the cocoon. Here, we investigated the protein components of the B. mori cocoon in terms of its multi-layer structure. Liquid chromatography-tandem mass spectrometry identified 286 proteins from the multiple cocoon layers. In addition to fibroins and sericins, we identified abundant protease inhibitors, seroins and proteins of unknown function. By comparing protein abundance across layers, we found that the outermost layer contained more sericin1 and protease inhibitors and the innermost layer had more seroin1. As many as 36 protease inhibitors were identified in cocoons, showing efficient inhibitory activities against a fungal protease. Thus, we propose that more abundant protease inhibitors in the outer cocoon layers may provide better protection for the cocoon. This study increases our understanding of the multi-layer mechanism of cocoons, and helps clarify the biological characteristics of cocoons. The data have been deposited to the ProteomeXchange with identifier PXD001469.
Highlights
Many insect larvae spin silky cocoons for pupation
Cocoons were split into five layers after removing amorphous scaffold silk from the surface
Twenty proteins were identified by only one peptide, and for these we have provided the annotated MS/MS spectrum (S1 Fig)
Summary
Many insect larvae spin silky cocoons for pupation. Cocoons protect pupae from predation and microbial degradation and prevent dehydration during metamorphosis [1,2,3,4,5]. The most well-characterized cocoon is from the domestic silkworm, Bombyx mori. The cocoon has been used for textile material for around 5000 years. Silkworms spin cocoons at the final larval stage. After finding a suitable place, silkworm larvae construct a loose scaffold silk and spin cocoons that are firmly attached to a substrate by scaffold silk [6, 7]
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.