A Male-Biased Ion Transport Peptide-Like Gene Regulates Sex Dimorphic Growth in Litopenaeus vannamei.

The crustacean hyperglycemic hormone (CHH) family is a group of key neuroendocrine regulators of molting, metabolism, and reproduction in crustaceans. Litopenaeus vannamei, the most widely farmed shrimp, exhibits pronounced sexual growth dimorphism, yet the role of CHH family genes in this process remains poorly understood. Here, we identified an ion transport peptide-like (ITP-like) gene in L. vannamei, and demonstrated its male-biased expression and sexually dimorphic functions. The ITP-like gene was predominantly expressed in eyestalks, with significantly higher levels in males than females, suggesting its role in sex-specific physiological regulation. Functional experiments using RNA interference (RNAi) and recombinant protein injection revealed its divergent and sex-dependent roles: ITP-like knockdown enhanced male growth but reduced female growth, while recombinant ITP-like protein showed opposing effects. Transcriptomic analysis of eyestalks identified differentially expressed genes linked to digestive enzymes, cuticle formation, lipid metabolism, and phototransduction, revealing a complex regulatory network underpinning the sexually dimorphic effects of ITP-like. Our findings demonstrate that ITP-like influences shrimp growth by modulating metabolic pathways, molting processes and photoreceptive responses, providing new insights into crustacean endocrine regulation. This study advances understanding of the mechanisms underlying sex-biased growth in L. vannamei and highlights potential targets for aquaculture improvement.