Meeting Abstract
We hypothesize that the mTOR pathway and AMP-dependent protein kinase (AMPK) are involved in the regulation of the molt cycle in response to temperature in juvenile Dungeness crabs Metacarcinus magister. We used PCR cloning to obtain partial cDNA sequences of mTOR, Rheb, AKT, S6K and AMPK. We incubated crabs at 12 d, 18 d and 26 d postmolt at 5, 10, 15, 20, 25 and 30°C for up to 14 d to study survival and progression of the molt cycle. We quantified gene expression in the molting gland of AKT, upstream of mTOR, and S6K, downstream of mTOR, of the possible housekeeping gene RbS3, and of Na+/K+-ATPase in crabs that had been held at 10, 15 or 20°C. Survival was 97-100% at temperatures from 5-20°C, and was time-dependent, but 0% after 14 d at 25°C. All animals had died after 24 h at 30°C. Significant progression of the molt cycle was observed at 15 and 20°C, but not at 5 and 10°C. An overall two-way ANOVA indicated an effect of temperature on expression of all four genes, whereas only AKT, RbS3 and Na+/K+-ATPase were significantly affected by molt stage. The post hoc Tukey multiple comparisons test revealed significant effects of temperature at either 26 d, 32 d or at both time points, gene expression being significantly lower at 20°C compared to 10°C. Molt-stage specific effects were prominent at 20°C, with increased gene expression in premolt. We conclude that AKT, an activator of mTOR, may be involved in the regulation of the molt cycle in a temperature-dependent manner. Funding: EU FP7 Marie Sklodovska Curie International Outgoing Fellowship PIOF-GA-2012-326483 to ACW, NSF grant IOS-1257732 to DLM.
