Affiliations 

  • 1 Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan
  • 2 Institute for Research in Molecular Medicine, Universiti Sains Malaysia, Minden, Penang 11800, Malaysia
  • 3 ICLAS Monitoring Center, Central Institute for Experimental Animals, 3-25-12 Tonomachi, Kawasaki-ku, Kawasaki 210-0821, Japan
  • 4 Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
iScience, 2024 Feb 16;27(2):108853.
PMID: 38303707 DOI: 10.1016/j.isci.2024.108853

Abstract

Energy reserves, primarily stored in the insect's fat body, are essential for physiological processes such as reproduction and cocoon formation. However, whether these processes are mutually constraining is unknown. Here, we showed that cocoon-free silkworms accumulate amino acid constituents of silk proteins in the hemolymph and maintain lipid and sugar reserves in the pupal fat body by repressing the expression of sericin and fibroin genes in the middle and posterior silk glands, respectively, via butterfly pierisin-1A catalytic domain expression. This, in turn, upregulates insulin/insulin-like signaling and target of rapamycin (IIS/TOR) signaling, which enhances vitellogenesis and accelerates ovarian development, thus contributing to increased fecundity. The impacts of semi-starvation on fecundity and egg hatchability were also less pronounced in cocoon-free silkworms compared with wildtype silkworms. These data uncover the resource allocation trade-off between cocoon formation and fecundity and demonstrate that nutritional signaling plays a role in regulating silkworm reproduction.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.