Identification and functional characterization of molt-inhibiting hormone in Neocaridina denticulata.

Abstract

Molting is an essential physiological process in crustaceans and is tightly regulated by neuroendocrine signaling. Molt-inhibiting hormone (MIH) is a key neuropeptide that suppresses ecdysteroid synthesis and orchestrates molting in decapods, yet the tissue-specific transcriptional consequences of MIH signaling reduction remain poorly characterized. Here, we identified and functionally characterized a MIH gene in the freshwater shrimp Neocaridina denticulata. Its 333 bp open reading frame encodes a 110 amino acids precursor with a typical N-terminal signal peptide and six conserved cysteine residues. Phylogenetic analysis showed that NdMIH clusters with MIH homologs from other decapod crustaceans. Spatiotemporal expression profiling revealed predominant eyestalk localization and a developmental peak at the zoeal stage. In vivo knockdown significantly reduced NdMIH transcript abundance and whole-body MIH content, leading to accelerated molting. Comparative transcriptomic analysis identified 138 and 456 differentially expressed genes (DEGs) in the eyestalk and hepatopancreas, respectively. These DEGs were functionally associated with neuroendocrine signaling, extracellular processes, metabolism, nutrient transport, steroid responsiveness, and molting-related pathways. Overall, these findings provide functional evidence for the conserved inhibitory role of NdMIH in molting and reveal tissue-specific transcriptional responses associated with reduced MIH signaling in N. denticulata.