MOLECULAR-BIOLOGY OF NEUROHORMONE PRECURSORS IN THE EYESTALK OF CRUSTACEA

Our knowledge concerning the primary structures of crustacean neuropep tides has been broadened considerably during the last few years and ha s greatly contributed to the successful application of molecular biolo gical techniques to crustacean neuroendocrine research, In this review , we compare and discuss the preprohormones of the Red Pigment Concent rating Hormone (RPCH), the Pigment-Dispersing Hormone (PDH) and the di fferent members of the Crustacean Hyperglycemic Hormone, Molt-Inhibiti ng and Gonad-Inhibiting Hormone family (CHH/MIH/GIH peptide family), r ecently elucidated by cloning and sequencing of the respective cDNAs. Expression studies, using in situ hybridization, Northern blots and RN ase. protection assays, have demonstrated that the mRNAs encoding some of the aforementioned preprohormones (for example, preproPDH and prep roCHH) are not only expressed in the eyestalk but also in other parts of the central nervous system, The combination of molecular biological techniques with (bio)chemical and immunochemical methods provides ele gant tools to study neuropeptides at the level of mRNA and peptide in individual animals during different physiological conditions, The fund amental knowledge obtained by such a combined approach will give detai led insight into how neuropeptides are involved in the adaptation of C rustacea to a broad spectrum of natural and aquacultural conditions.