Caddisfly larvae produce silk containing heavy and light fibroins, similar to the silk of Lepidoptera, for the construction of underwater structures. We analyzed the silk of Limnephilus lunatus belonging to the case-forming suborder Integripalpia. We analyzed the transcriptome, mapped the transcripts to a reference genome and identified over 80 proteins using proteomic methods, and checked the specificity of their expression. For comparison, we also analyzed the transcriptome and silk proteome of Limnephilus flavicornis. Our results show that fibroins and adhesives are produced together in the middle and posterior parts of the silk glands, while the anterior part produces enzymes and an unknown protein AT24. The number of silk proteins of L. lunatus far exceeds that of the web-spinning Plectrocnemia conspersa, a previously described species from the suborder Annulipalpia. Our results support the idea of increasing the structural complexity of silk in rigid case builders compared to trap web builders.

Biology Centre of the Czech Academy of Sciences Institute of Entomology Ceske Budejovice Czech Republic

Faculty of Science University of South Bohemia Ceske Budejovice Czech Republic

Institute of Molecular Genetics Academy of Sciences of the Czech Republic Prague Czech Republic

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Rouhová L, et al. Using the multi-omics approach to reveal the silk composition in Plectrocnemia conspersa. Front Mole Biosci. 2022;9:945239. doi: 10.3389/fmolb.2022.945239. PubMed DOI PMC

Wang YJ, et al. The silk gland proteome of Stenopsyche angustata provides insights into the underwater silk secretion. Insect Mol Biol. 2023 doi: 10.1111/imb.12874. PubMed DOI

Sehnal F, Zurovec M. Construction of silk fiber core in lepidoptera. Biomacromol. 2004;5:666–674. doi: 10.1021/bm0344046. PubMed DOI

Stewart RJ, Wang CS. Adaptation of caddisfly larval silks to aquatic habitats by phosphorylation of h-fibroin serines. Biomacromol. 2010;11:969–974. doi: 10.1021/bm901426d. PubMed DOI

Ashton NN, Taggart DS, Stewart RJ. Silk tape nanostructure and silk gland anatomy of trichoptera. Biopolymers. 2012;97:432–445. doi: 10.1002/bip.21720. PubMed DOI

Addison JB, et al. Reversible assembly of beta-sheet nanocrystals within caddisfly silk. Biomacromol. 2014;15:1269–1275. doi: 10.1021/bm401822p. PubMed DOI PMC

Ashton NN, Stewart RJ. Aquatic caddisworm silk is solidified by environmental metal ions during the natural fiber-spinning process. FASEB J. 2019;33:572–583. doi: 10.1096/fj.201801029R. PubMed DOI

Wang CS, Ashton NN, Weiss RB, Stewart RJ. Peroxinectin catalyzed dityrosine crosslinking in the adhesive underwater silk of a casemaker caddisfly larvae. Hysperophylax occidentalis Insect Biochem Mol Biol. 2014;54:69–79. doi: 10.1016/j.ibmb.2014.08.009. PubMed DOI

Engster M.S. Studies on silk secretion in the trichoptera (F. Limnephilidae), II. Structure and amino acid composition of the silk. Cell Tissue Res. 1976;169:77–92. doi: 10.1007/BF00219309. PubMed DOI

Kim HJ, Sun Y, Moon MJ. Fine structure of the silk spinning system in the caddisworm, Hydatophylax nigrovittatus (Trichoptera: Limnephilidae) Appl Microsc. 2020;50:16. doi: 10.1186/s42649-020-00036-5. PubMed DOI PMC

Cianficconi F, Bicchierai MC, Moretti G. in 7th Int. Symp. Trichoptera. 1993.

Frandsen P.B, et al. Exploring the underwater silken architectures of caddisworms: comparative silkomics across two caddisfly suborders. Philos Trans R Soc Lond B Biol Sci. 2019;374(1784):20190206. doi: 10.1098/rstb.2019.0206. PubMed DOI PMC

Yonemura N, Sehnal F. The design of silk fiber composition in moths has been conserved for more than 150 million years. J Mol Evol. 2006;63:42–53. doi: 10.1007/s00239-005-0119-y. PubMed DOI

Chao J, et al. MG2C: a user-friendly online tool for drawing genetic maps. Mol Hortic. 2021;1:16. doi: 10.1186/s43897-021-00020-x. PubMed DOI PMC

Kludkiewicz B, et al. Structure and expression of the silk adhesive protein Ser2 in Bombyx mori. Insect Biochem Molec. 2009;39:938–946. doi: 10.1016/j.ibmb.2009.11.005. PubMed DOI

Kludkiewicz B, et al. The expansion of genes encoding soluble silk components in the greater wax moth. Galleria mellonella Insect Biochem Mol Biol. 2019;106:28–38. doi: 10.1016/j.ibmb.2018.11.003. PubMed DOI

Hatano T, Nagashima T. The secretion process of liquid silk with nanopillar structures from Stenopsyche marmorata (Trichoptera: Stenopsychidae) Sci Rep. 2015;5:9237. doi: 10.1038/srep09237. PubMed DOI PMC

Heckenhauer J, et al. Characterization of the primary structure of the major silk gene, h-fibroin, across caddisfly (Trichoptera) suborders. iScience. 2023;26(8):107253. doi: 10.1016/j.isci.2023.107253. PubMed DOI PMC

Rouhova L, et al. Silk of the common clothes moth, Tineola bisselliella, a cosmopolitan pest belonging to the basal ditrysian moth line. Insect Biochem Mole Biol. 2021;130:103527. doi: 10.1016/j.ibmb.2021.103527. PubMed DOI

Thorvaldsdottir H, Robinson JT, Mesirov JP. Integrative Genomics Viewer (IGV): high-performance genomics data visualization and exploration. Brief Bioinform. 2013;14:178–192. doi: 10.1093/bib/bbs017. PubMed DOI PMC

Ponnuvel KM, et al. A lipase isolated from the silkworm Bombyx mori shows antiviral activity against nucleopolyhedrovirus. J Virol. 2003;77:10725–10729. doi: 10.1128/jvi.77.19.10725-10729.2003. PubMed DOI PMC

Levine JD, Sauman I, Imbalzano M, Reppert SM, Jackson FR. Period protein from the giant silkmoth Antheraea pernyi functions as a circadian clock element in Drosophila melanogaster. Neuron. 1995;15:147–157. doi: 10.1016/0896-6273(95)90072-1. PubMed DOI

Rindos M, et al. Comparison of Silks from Pseudoips prasinana and Bombyx mori Shows Molecular Convergence in Fibroin Heavy Chains but Large Differences in Other Silk Components. Int J Mol Sci. 2021;22(15):8246. doi: 10.3390/ijms22158246. PubMed DOI PMC

Afgan E, et al. The Galaxy platform for accessible, reproducible and collaborative biomedical analyses: 2018 update. Nucleic Acids Res. 2018;46:W537–W544. doi: 10.1093/nar/gky379. PubMed DOI PMC

Volenikova A, et al. Genome sequence and silkomics of the spindle ermine moth, Yponomeuta cagnagella, representing the early diverging lineage of the ditrysian Lepidoptera. Commun Biol. 2022;5(1):1281. doi: 10.1038/s42003-022-04240-9. PubMed DOI PMC

Seppey M, Manni M, Zdobnov EM. BUSCO: Assessing Genome Assembly and Annotation Completeness. Methods Mol Biol. 1962;227–245:2019. doi: 10.1007/978-1-4939-9173-0_14. PubMed DOI

Austin M, et al. The genome sequence of a caddisfly, Limnephilus lunatus (Curtis, 1834) Wellcome Open Res. 2023;8:25. doi: 10.12688/wellcomeopenres.18752.1. PubMed DOI PMC

Altschul SF, Gish W, Miller W, Myers EW, Lipman DJ. Basic local alignment search tool. J Mol Biol. 1990;215:403–410. doi: 10.1016/S0022-2836(05)80360-2. PubMed DOI

Tyanova S, Temu T, Cox J. The MaxQuant computational platform for mass spectrometry-based shotgun proteomics. Nat Protoc. 2016;11:2301–2319. doi: 10.1038/nprot.2016.136. PubMed DOI

R Studio Team. RStudio: Integrated development environment for R. Available at: https://www.rstudio.com/. 2015.

R Core Team. R: A language and environment for statistical computing. Available at: https://www.R-project.org/. 2017.

Trifinopoulos J, Nguyen LT, von Haeseler A, Minh BQ. W-IQ-TREE: a fast online phylogenetic tool for maximum likelihood analysis. Nucleic Acids Res. 2016;44:W232–235. doi: 10.1093/nar/gkw256. PubMed DOI PMC

Kalyaanamoorthy S, Minh BQ, Wong TKF, von Haeseler A, Jermiin LS. ModelFinder: fast model selection for accurate phylogenetic estimates. Nat Methods. 2017;14:587–589. doi: 10.1038/nmeth.4285. PubMed DOI PMC

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