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; this transition requires mTOR. During mid-premolt, the YO transitions to the committed state, in which the YO becomes insensitive to MIH. Cyclic nucleotide phosphodiesterases (PDEs) convert cAMP and cGMP to AMP and GMP, respectively, and therefore can modify the response of the YO to MIH. Transcriptomics was used to quantify the effects of molt induction by multiple limb autotomy (MLA) or eyestalk ablation (ESA) ± mTOR inhibitor rapamycin on expression of PDE 1, 2, 4, 5, 7, 9, and 11 in Gecarcinus lateralis YO. In response to MLA, all seven PDEs were expressed at their highest levels in the intermolt YO. mRNA levels declined during premolt and reached their lowest levels in postmolt. In response to ESA, the mRNA levels of PDE 1, 4, 5, 7, 9, and 11 showed no significant change by 7 days post-ESA. Rapamycin had no significant effect, as PDE mRNA levels were similar to those of controls at all time points, indicating that PDE expression is not regulated by mTOR. The data suggest that transcriptional regulation does not contribute the reduced sensitivity of the committed YO to MIH; the increased PDE activity during mid and late premolt is likely regulated post-transcriptionally. Supported by NSF (IOS-1257732).
