MOLECULAR-CLONING OF A CDNA-ENCODING MOLT-INHIBITING HORMONE OF THE CRAB, CANCER-MAGISTER

A neuropeptide molt-inhibiting hormone (MIH) negatively regulates crus tacean molting glands (Y-organs). We report here the molecular cloning of a cDNA encoding putative MIH of the Dungeness crab, Cancer magiste r. A cDNA library was commercially prepared using poly (A(+)) RNA isol ated from C. magister eyestalk neural ganglia. The library was screene d using as probe a previously cloned portion of a cDNA encoding MIH of the blue crab, Callinectes sapidus. DNA sequence analysis of one posi tive clone revealed a 339 base pair open reading frame encoding a 78 a mino acid putative MIH and a 35 amino acid signal peptide. The deduced amino acid sequence of C. magister MIH shows high sequence identity ( 80-98%) with MIH of three other brachyuran crabs, but lower identity ( 26-45%) with MIH and MIH-like peptides from astacurans and shrimp. Stu dies using reverse transcription-polymerase chain reaction (RT-PCR) in dicate the MIH gene is expressed in eyestalk but not control (muscle, gill, gonad, hepatopancreas) tissue. (C) 1998 Elsevier Science Ireland Ltd.