Meeting Abstract
Cyclic nucleotide signaling mediates the suppression of the crustacean molting gland (Y-organ or YO) by molt-inhibiting hormone (MIH). When MIH level drops the YO transitions from the basal to the activated state and the animal enters premolt. During mid-premolt, the YO transitions to the committed state, in which the YO becomes insensitive to MIH. Phosphodiesterases (PDEs) hydrolyze the phosphodiester bond in cAMP and cGMP to AMP and GMP, respectively, and thus can modulate the response of the YO to MIH. In some species, PDE inhibitors decrease molting hormone (ecdysteroid) biosynthesis by the YO in vitro, indicating that PDE activity can keep cyclic nucleotide levels low. Increased PDE activity in the YO is correlated with a reduced sensitivity to MIH when the animal becomes committed to molt. In mammals, 21 PDE genes are organized into 11 families, designated PDE1 to PDE11. Each PDE family has specific catalytic and biochemical properties and tissue distributions. The number and types of PDE genes in crustaceans is unknown. A reference YO transcriptome from the blackback land crab (Gecarcinus lateralis), consisting of 3 biological replicates of intermolt animals, was analyzed for PDE sequences. Six different contigs encoding full-length PDE sequences were identified. Protein alignments and ClustalX analysis of the Gl-PDE sequences with orthogs from other species in the GenBank database showed that the sequences corresponded to PDE1, 2, 4, 6, 9, and 11. The next phase is to use transcriptomics and qPCR to quantify the expression of the 6 PDEs in the YO over the molt cycle with the goal of identifying the PDEs that modulate the response of the YO to MIH. Supported by NSF (IOS1257732).
