Characterization of the IGFBP-rP cDNA and its associations with growth traits in Macrobrachium rosenbergii

Insulin-like growth factor binding proteins (IGFBPs) are key regulators of insulin-like growth factors (IGFs), which play essential roles in growth and development. In this study, a IGFBP related protein cDNA from Macrobrachium rosenbergii (designated Mr-IGFBP-rP) was identified. The full-length cDNA of Mr-IGFBP-rP is 1494 base pairs (bp) including a 22 bp 5'-untranslated region (UTR), a 707 bp 3'-UTR, and a 765 bp open reading frame (ORF) encoding a 254-amino acid protein. The Mr-IGFBP-rP protein contains three conserved domains: an IGF-binding domain (amino acids 34-89), a Kazal-type serine protease inhibitor domain (102-125), and an immunoglobulin-like C2-type domain (147-245). Sequence analysis revealed that Mr-IGFBP-rP shares 75.74 % identity with the IGFBP-rP1 of Palaemon carinicauda and 63.26 % with that of Penaeus chinensis. Expression analysis showed that Mr-IGFBP-rP is most highly expressed in the abdominal ganglia, followed by gill, heart, and brain. Eleven single nucleotide polymorphisms (SNPs) were identified within Mr-IGFBP-rP. Of these, three SNPs showed significant associations with growth traits in M. rosenbergii. Specifically, individuals with the AA genotype at the 5263-G/A locus exhibited greater body weight. Those with the TT genotype at the 5302-G/T locus showed increased body weight, cephalothorax height, and abdominal segment 1 height. In contrast, the CC genotype at the 5743-G/C locus was associated with reduced cephalothorax length, cephalothorax height, abdominal segment 1 height, and abdominal length. This study lays a foundation for understanding the role of Mr-IGFBP-rP in growth regulation in M. rosenbergii. The identified SNPs hold potential as candidate markers for marker-assisted selection in this species.