Meeting Abstract
Molting in decapod crustaceans is controlled by ecdysteroid synthesis in the Y-organ (YO). Environmental stressors may inhibit molting by reducing YO ecdysteroidgenesis through altered expression of stress-response genes that maintain physiological stability. Stress response genes regulate the energy relocation in normal and extreme conditions. The purpose of this study was to quantify the effects of molt stage and elevated temperature on hemolymph ecdysteroid titer and AMPK, heat-shock protein (HSP), and Sirtuin (SIRT) gene expression in the YO of G. lateralis. Individuals were induced to molt by multiple leg autotomy. YO of animals at 27°C was harvested at intermolt; early, mid, and late premolt; and postmolt stages. Individuals at the five molt stages were exposed to 32 and 35°C for 1 hour. mRNA level was quantified by qPCR. Ecdysteroid was quantified by a competitive ELISA. In general, molt stage had no effect on gene expression at 27 and 32°C. Animals from intermolt through mid premolt and postmolt stages at 35°C showed lower mRNA levels of all genes. AMPK was significantly downregulated in intermolt, early and mid premolt, and postmolt individuals at 35°C. Late premolt crabs exposed to 35°C had higher HSP60, HSP70, and SIRT1 mRNA levels. At 35°C, altered gene expression in early and mid premolt may delay molting by reducing ecdysteroid synthesis in the YO. These data suggest that land crabs can tolerate 1-hour exposures at 32°C without eliciting a stress response at the transcriptional level. Future work will examine the effects of temperature on the phosphorylation of stress proteins. Supported by NSF (IOS-1257732).
