Meeting Abstract
P3.26 Monday, Jan. 6 15:30 Myostatin and mTOR expression in the blackback land crab (Gecarcinus lateralis) Y-organ after molt cycle manipulation MUDRON, M. R.*; CHANG, E. S.; MYKLES, D. L.; Colorado State University, Fort Collins ; UC Davis Bodega Marine Lab, Bodega Bay; Colorado State University, Fort Collins megan.mudron@gmail.com
Ecdysteroids produced from the molting gland (Y-organ or YO) induce molting in decapod crustaceans. Reduction in molt-inhibiting hormone (MIH) activates the YO and animals enter premolt. At mid-premolt, YOs transition to the committed state, during which ecdysteroid production increases further. In blackback land crab (Gecarcinus lateralis), SB1431542, an inhibitor of Activin receptors, decreases hemolymph ecdysteroid titers in premolt animals and delays the activation of the molt cycle. This may suggest that an Activin-like transforming-growth factor (TGF-β) is produced by the activated YO and drives the transition of the YO to the committed state. Rapamycin (Sirolimus) blocks mechanistic Target of Rapamycin (mTOR) and thus prevents early premolt from occurring. Myostatin (Gl-Mstn) is an Activin-like factor that is highly expressed in skeletal muscle. As Gl-Mstn is expressed in the YO of intermolt animals, the effects of molting on the Gl-Mstn expression in the YO were determined. The expression of mTOR signaling genes (Gl-mTOR, Gl-S6 kinase, Gl-Akt, and Gl-Rheb) were also quantified using qPCR. Intermolt animals were eyestalk ablated (ESA) and injected with vehicle (DMSO), rapamycin, or SB1431542 at Day 0. YOs were harvested from intact (intermolt) animals and from animals at 1, 3, 5, 7, and 14 days post-ESA. ESA-dependent increases in expression of mTOR signaling genes and Gl-elongation factor-2 (Gl-EF2) was blocked by SB1431542. Gl-Mstn mRNA level peaked at 3 days post-ESA, which is before the transition to the committed state at 7 days post-ESA. Expression of Gl-EF-2 was increased 7 days post-ESA, indicating an increase in protein synthetic capacity in the YO. Gl-mTOR and other genes will be quantified. Supported by NSF (IOS-1257732).
