Molecular cloning and sequence analysis of a cDNA encoding a molt-inhibiting hormone-like neuropeptide from the white shrimp Penaeus vannamei.

The X-organ of the eyestalk in crustaceans is a source of neurosecretory peptides. Total RNA was isolated from X-organs of the white shrimp Penaeus vannamei and used to clone a cDNA encoding a molt-inhibiting hormone-like (MIH-like) neuropeptide by the 3' and 5' rapid amplification of cDNA ends (RACE) method. Sequence analysis of the 470-bp cDNA reveals a 306-bp open reading frame and a 164-bp 3' untranslated region. The deduced polypeptide consists of a 72-amino acid mature peptide and a 30-amino acid region of propeptide. The mature peptide shares 49 and 29% amino acid identity to the MIH from the lobster Homarus americanus and the crab Carcinus maenas, respectively. Northern hybridization shows that the MIH-like mRNA has a molecular size of 2.0 kb and is present in the eyestalk.