Analyses of the\nMolecular Mechanisms Associated with\nSilk Production in Silkworm by iTRAQ-Based Proteomics and RNA-Sequencing-Based\nTranscriptomics

Abstract

Silkworm\nis used as a model organism to analyze two standard complex\ntraits, which are high and low silk yields. To understand the molecular\nmechanisms of silk production, the posterior silk glands aged to the\nthird day of the fifth instar were analyzed from the ZB strain with\nlow silk production and from the control strain Lan10. Using isobaric\ntags for relative and absolute quantification (iTRAQ) quantitative\nshotgun proteomics and RNA-sequencing-based transcriptomics, 139 proteins\nand 630 transcripts were identified as novel in the ZB strain compared\nwith the Lan10 strain, indicating that these results significantly\nexpand the coverage of proteins and transcripts of the posterior silk\nglands in the silkworm. Of the 89 differently changed proteins, 23\nwere increased, and 66 were decreased. Of the 788 transcripts, 779\nwere upregulated, and 9 were downregulated. These results confirm\nthat decreased energy utilization/protein translation and enhanced\nprotein degradation are the key factors in lower silk production.\nMoreover, this study provides novel insight into the molecular changes\nthat may result in lower silk production, namely, a combination of\nimpaired transcription activity, missed protein folding/transport,\nand lowered yields of the main components of fibroin, along with weakened\ngrowth/development of the posterior silk gland.