Nejvíce citovaný článek - PubMed ID 15132645
Construction of silk fiber core in lepidoptera
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.
- Klíčová slova
- Limnephilus flavicornis, Plectrocnemia conspersa, Fibroin, Gene duplication, Hydrophobicity, Sericin,
- MeSH
- fibroiny genetika metabolismus chemie MeSH
- hedvábí * metabolismus chemie MeSH
- hmyz metabolismus genetika MeSH
- hmyzí proteiny genetika metabolismus MeSH
- proteom MeSH
- proteomika metody MeSH
- stanovení celkové genové exprese MeSH
- transkriptom MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Many lepidopteran species produce silk, cocoons, feeding tubes, or nests for protection from predators and parasites for caterpillars and pupae. Yet, the number of lepidopteran species whose silk composition has been studied in detail is very small, because the genes encoding the major structural silk proteins tend to be large and repetitive, making their assembly and sequence analysis difficult. Here we have analyzed the silk of Yponomeuta cagnagella, which represents one of the early diverging lineages of the ditrysian Lepidoptera thus improving the coverage of the order. To obtain a comprehensive list of the Y. cagnagella silk genes, we sequenced and assembled a draft genome using Oxford Nanopore and Illumina technologies. We used a silk-gland transcriptome and a silk proteome to identify major silk components and verified the tissue specificity of expression of individual genes. A detailed annotation of the major genes and their putative products, including their complete sequences and exon-intron structures is provided. The morphology of silk glands and fibers are also shown. This study fills an important gap in our growing understanding of the structure, evolution, and function of silk genes and provides genomic resources for future studies of the chemical ecology of Yponomeuta species.
Many lepidopteran larvae produce silk feeding shelters and cocoons to protect themselves and the developing pupa. As caterpillars evolved, the quality of the silk, shape of the cocoon, and techniques in forming and leaving the cocoon underwent a number of changes. The silk of Pseudoips prasinana has previously been studied using X-ray analysis and classified in the same category as that of Bombyx mori, suggesting that silks of both species have similar properties despite their considerable phylogenetic distance. In the present study, we examined P. prasinana silk using 'omics' technology, including silk gland RNA sequencing (RNA-seq) and a mass spectrometry-based proteomic analysis of cocoon proteins. We found that although the central repetitive amino acid sequences encoding crystalline domains of fibroin heavy chain molecules are almost identical in both species, the resulting fibers exhibit quite different mechanical properties. Our results suggest that these differences are most probably due to the higher content of fibrohexamerin and fibrohexamerin-like molecules in P. prasinana silk. Furthermore, we show that whilst P. prasinana cocoons are predominantly made of silk similar to that of other Lepidoptera, they also contain a second, minor silk type, which is present only at the escape valve.
- Klíčová slova
- Bena prasinana, Bombycidae, Nolidae, fibrohexamerins, phylogeny, transcriptomics,
- MeSH
- bourec klasifikace genetika metabolismus MeSH
- exokrinní žlázy metabolismus MeSH
- fibroiny chemie genetika MeSH
- fylogeneze MeSH
- molekulární evoluce * MeSH
- proteom genetika metabolismus MeSH
- transkriptom MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- fibroiny MeSH
- proteom MeSH
Insect silks are secreted from diverse gland types; this chapter deals with the silks produced by labial glands of Holometabola (insects with pupa in their life cycle). Labial silk glands are composed of a few tens or hundreds of large polyploid cells that secrete polymerizing proteins which are stored in the gland lumen as a semi-liquid gel. Polymerization is based on weak molecular interactions between repetitive amino acid motifs present in one or more silk proteins; cross-linking by disulfide bonds may be important in the silks spun under water. The mechanism of long-term storage of the silk dope inside the glands and its conversion into the silk fiber during spinning is not fully understood. The conversion occurs within seconds at ambient temperature and pressure, under minimal drawing force and in some cases under water. The silk filament is largely built of proteins called fibroins and in Lepidoptera and Trichoptera coated by glue-type proteins known as sericins. Silks often contain small amounts of additional proteins of poorly known function. The silk components controlling dope storage and filament formation seem to be conserved at the level of orders, while the nature of polymerizing motifs in the fibroins, which determine the physical properties of silk, differ at the level of family and even genus. Most silks are based on fibroin beta-sheets interrupted with other structures such as alpha-helices but the silk proteins of certain sawflies have predominantly a collagen-like or polyglycine II arrangement and the silks of social Hymenoptera are formed from proteins in a coiled coil arrangement.
- MeSH
- hedvábí chemie klasifikace metabolismus MeSH
- hmyz metabolismus MeSH
- molekulární sekvence - údaje MeSH
- sekvence aminokyselin MeSH
- slinné žlázy metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Názvy látek
- hedvábí MeSH
The silk of caterpillars is secreted in the labial glands, stored as a gel in their lumen, and converted into a solid filament during spinning. Heavy chain fibroin (H-fibroin), light chain fibroin (L-fibroin), and P25 protein constitute the filament core in a few species that have been analyzed. Identification of these proteins in Yponomeuta evonymella, a moth from a family which diverged from the rest of Lepidoptera about 150 million years ago, reveals that the mode of filament construction is highly conserved. It is proposed that association of the three proteins is suited for long storage of hydrated silk dope and its rapid conversion to filament. Interactions underlying these processes depend on conserved spacing of critical amino acid residues that are dispersed through the L-fibroin and P25 and assembled in the short ends of the H-fibroin molecule. Strength, elasticity, and other physical properties of the filament are determined by simple amino acid motifs arranged in repetitive modules that build up most of the H-fibroin. H-Fibroin synergy with L-fibroin and P25 does not interfere with motif diversification by which the filament acquires new properties. Several types of motifs in complex repeats occur in the silks used for larval cobwebs and pupal cocoons. Restriction of silk use to cocoon construction in some lepidopteran families has been accompanied by simplification of H-fibroin repeats. An extreme deviation of the silk structure occurs in the Saturniidae silkmoths, which possess modified H-fibroin and lack L-fibroin and P25.
- MeSH
- aminokyselinové motivy MeSH
- čas MeSH
- druhová specificita MeSH
- fibroiny biosyntéza chemie genetika MeSH
- glykoproteiny genetika MeSH
- hedvábí biosyntéza MeSH
- hmyzí proteiny genetika MeSH
- komplementární DNA izolace a purifikace MeSH
- konzervovaná sekvence * MeSH
- molekulární evoluce * MeSH
- molekulární sekvence - údaje MeSH
- můry genetika metabolismus MeSH
- sekvence aminokyselin MeSH
- sekvence nukleotidů MeSH
- sekvenční homologie aminokyselin MeSH
- sekvenční homologie nukleových kyselin MeSH
- strukturní homologie proteinů MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- fibroiny MeSH
- glykoproteiny MeSH
- hedvábí MeSH
- hmyzí proteiny MeSH
- komplementární DNA MeSH
- L-chain, fibroin protein, insect MeSH Prohlížeč
- P25 protein, Galleria mellonella MeSH Prohlížeč
