Many lepidopteran larvae produce silk secretions to build feeding tubes and cocoons that play important protective roles in their lives. Recent research on the silk of bombycoid and pyralid moths has shown that it contains several highly abundant silk components with remarkable mechanical properties. It was also found to contain a number of other proteins of which the functions have yet to be identified. To gain an overview of the silk composition in more primitive lepidopteran species and to identify the core silk components common to most species, we analyzed the cocoon proteins of Tineola bisselliella, which belongs to the basal ditrysian moth line. Using de novo transcriptome sequencing combined with mass spectrometry (MS)-based proteomics, we detected more than 100 secretory proteins in the silk cocoons. Fibroin, sericins, and protease inhibitors were found to be the most abundant proteins, along with several novel candidate silk components. We also verified the tissue and developmental stage specificity of the silk protein expression and characterized the morphology of both the silk glands and silk in T. bisselliella. Our study provides a detailed analysis of silk in the primitive moth, expands the known set of silk-specific genes in Lepidoptera, and helps to elucidate their evolutionary relationships.

Biology Centre of the Czech Academy of Sciences Institute of Entomology Branisovska 31 370 05 Ceske Budejovice Czech Republic

Biology Centre of the Czech Academy of Sciences Institute of Entomology Branisovska 31 370 05 Ceske Budejovice Czech Republic; Faculty of Sciences University of South Bohemia Branisovska 31 370 05 Ceske Budejovice Czech Republic

Faculty of Sciences University of South Bohemia Branisovska 31 370 05 Ceske Budejovice Czech Republic

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Absence of fibroin H sequences and a significant divergence in the putative fibroin L homolog in Neomicropteryx cornuta (Micropterigidae) silk

Characterization and comparative analysis of sericin protein 150 in Bombyx mori

Comprehensive analysis of silk proteins and gland compartments in Limnephilus lunatus, a case-making trichopteran

Characterization of silk genes in Ephestia kuehniella and Galleria mellonella revealed duplication of sericin genes and highly divergent sequences encoding fibroin heavy chains

Genome sequence and silkomics of the spindle ermine moth, Yponomeuta cagnagella, representing the early diverging lineage of the ditrysian Lepidoptera

Using the multi-omics approach to reveal the silk composition in Plectrocnemia conspersa

The Role of Filippi's Glands in the Silk Moths Cocoon Construction

Comparison of Silks from Pseudoips prasinana and Bombyx mori Shows Molecular Convergence in Fibroin Heavy Chains but Large Differences in Other Silk Components