Meeting Abstract
Cyclic nucleotides mediate the repression of the crustacean molting gland (Y-organ or YO) by molt-inhibiting hormone (MIH). When MIH levels decline, 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 therefore can modify the response of the YO to MIH. In some species, PDE inhibitors decrease molting hormone (ecdysteroid) biosynthesis in the YO in vitro , indicating that PDE activity maintains low cyclic nucleotide levels in the activated YO. Increased PDE activity is correlated with a reduced sensitivity of the committed YO to MIH. Contigs encoding nine PDEs (1, 2, 3, 4, 5, 7, 8, 9, &11) were identified in the Gecarcinus lateralis YO transcriptome. General and selective inhibitors were used to characterize the PDEs regulating ecdysteroid secretion in the Carcinus maenas YO. IBMX, vinpocetine, and zaprinast ± rMIH significantly inhibited ecdysteroid secretion, while EHNA, rolipram, dipyridamole, and BC11-38 did not. This suggests that PDE1 and PDE5/11 are primarily responsible for regulating cAMP and cGMP levels. Analysis of RNA-Seq data using eXpress showed that all nine PDEs were expressed at their highest levels in YO from intermolt G. lateralis . mRNA levels decreased during premolt and reached their lowest levels in postmolt. These data suggest that PDEs are regulated posttranscriptionally. qPCR and RNA-Seq will be used to quantify the effects of eyestalk ablation on the mRNA levels of the nine PDEs. Supported by NSF (IOS-1257732).
