Transcriptional Response of Silkworm (Bombyx mori) Eggs to O2 or HCl Treatment

Diapause is a common biological phenomenon that occurs in many organisms, including fish, insects, and nematodes. In the silkworm (Bombyx mori), diapause generally occurs in the egg stage. Treatment with O2, HCl, or other compounds can prevent egg diapause. Here, we characterized the transcriptomic responses of newly laid eggs treated with O2 or HCl. Digital gene expression analysis showed that 610 genes in O2-treated eggs and 656 in HCl-treated eggs were differentially expressed. Of these, 343 genes were differentially expressed in both treatments. In addition to trehalases, sorbic acid dehydrogenases, and some enzymes involved in the carbohydrate metabolism, we also identified heat shock proteins, cytochrome P450, and GADD45, which are related to stress tolerance. Gene ontology enrichment analysis showed differentially expressed genes in O2-treated eggs were involved in oxidoreductase activity as well as in binding, catalytic, and metabolic processes. The Kyoto Encyclopedia of Genes and Genomes analysis showed that the pathways for ribosome biogenesis, spliceosome, and circadian rhythm were significantly enriched in HCl-treated eggs. The reliability of the data was confirmed by qRT-PCR analysis. Our results improved the understanding of the mechanism of diapause blocking in silkworm eggs treated with O2 or HCl and identified novel molecular targets for future studies.