Comparative mRNA and LncRNA Analysis of the Molecular Mechanisms Associated With Low Silk Production in Bombyx mori

Abstract

Naked pupa sericin and Naked pupa are two mutant strains of Bombyx mori with extremely low or no fibroin production compared to the Qiufeng and Baiyu strains, both of which exhibit very high silk fibroin production. However, the molecular mechanisms by which long non-coding RNAs regulate fibroin synthesis need further study. In this study, we performed high-throughput RNA-seq to investigate lncRNA and mRNA expression profiles in the posterior silk gland of Qiufeng, Baiyu, Nd-sD, and Nd silkworms at the third day of the 5th instar. Our efforts yielded 26,767 novel lncRNAs and 6,009 novel mRNAs, the expression levels of silk protein genes and silk gland transcription factors were decreased in Qiufeng vs. Nd-sD and Qiufeng vs. Nd, while those of many genes related to autophagy, apoptosis, RNA degradation, ubiquitin-mediated proteolysis and heat shock proteins were increased. Moreover, the expression of a large number of genes responsible for protein synthesis and secretion was significantly decreased in Nd. GO and KEGG analysis results showed that nucleotide excision repair, mRNA surveillance pathways, amino acid degradation, protein digestion and absorption, ER-associated degradation and proteasome pathways were significantly enriched for the Qiufeng vs. Nd-sD and Qiufeng vs. Nd comparisons. In conclusion, our findings contribute to the lncRNA and mRNA database of Bombyx mori, and the identified differentially expressed mRNAs and lncRNAs help to reveal the molecular mechanisms of low silk production in Nd-sD and Nd, providing new insights for improvement of silk yield and elucidation of silk mechanical properties.

The Synergistic Effect of Honey and Lemon Juice-Enriched Mulberry Diets on the Silk Gland Growth and Sericultural Productivity of Bombyx mori

“…In B. mori, the silk gland is a paired tubular exocrine gland, which is located at the two lateral sides under the gut and it is functionally distinguishable into three parts; the anterior (ASG), middle (PSG) and posterior (PSG) glandular regions [37] . The silk gland synthesizes and stores two categories of proteins, namely the silk-constituent and silk-associated proteins that constitutes 25% of its weight [38,39] . The former includes two major silk proteins; fibroin and sericin, while the latter comprises other 91 different proteins that are implicated in larval growth, metabolism and metamorphosis [40,41] .…”

K64 acetylation of heat shock protein 90 suppresses nucleopolyhedrovirus replication in Bombyx mori

“…Bombyx mori is the moth whose larvae produce silk, which gives it great value as an important agricultural and economic insect in China (Xia et al, 2004). Moreover, its short generation time, clear genetic background, rich genetic toolbox, and a considerable number of genes homologous to humans, have made the silkworm into a widely used model in life science research (Ruan et al, 2020; Xia et al, 2009).…”

The Spatio-Temporal Expression Profiles of Silkworm Pseudogenes Provide Valuable Insights into Their Biological Roles

“…The silkworm pangenome project have provided a large-scale genetic resource (such as genome assemblies, genomic variations and traits) for research communities, therefore, laid a foundation to study the relationships between traits and genomes. 15 However, most genomic variations are located outside of protein-coding genic regions, therefore, it’s urgent to obtain more comprehensive genome annotations, such as miRNA, 22 , 23 lncRNA, 24 smORF, 25 and pseudogenes. Researches involves in pseudogenes silkworms are limited.…”