Cloning and sequence analysis of a cDNA encoding a crustacean hyperglycemic hormone from the Kuruma prawn Penaeus japonicus

The crustacean hyperglycemic hormones (CHHs) are released from the X-organ sinus gland complex and regulate the glucose level in the hemolymph. In the present study, we have isolated a complementary DNA that encodes a CHI-I (Pej-SGP-III) of the Kuruma prawn Penaeus japonicus to study its expression and the structure of its precursor. In a cDNA clone of 774 base pairs (bp), an open reading frame of 345 bp was found. The conceptually translated protein consists of a signal peptide (24 residues), a CHH-precursor-related peptide (CPRP, 17 residues), and Pej-SGP-III (72 residues). This CPRP in P. japonicus was homologous to, but significantly shorter than, those in other crustacean species. In a Northern blot analysis, the cDNA specifically hybridized to a seemingly single mRNA species (approximately 0.8 kb) in the eyestalk. This mRNA was not detected in the hepatopancreas or abdominal muscle.