Meeting Abstract

105-3  Saturday, Jan. 6 14:00 – 14:15  Regulation of intracellular Ca²⁺ signaling in molting glands of the blue crab, Callinectes sapidus. ROEGNER, ME*; CHEN, HY; WATSON, RD; ROEGNER, Megan; University of Alabama at Birmingham mzappe@uab.edu

In crustaceans, cycles of growth and molting are triggered by cholesterol-derived molting hormones (ecdysteroids) released from paired endocrine glands (the Y-organs) located in the anterior cephalothorax. During much of the molting cycle, the levels of ecdysteroids in hemolymph are kept low by the action of a peptide molt-inhibiting hormone (MIH), produced in the eyestalks. While the removal of MIH suppression during pre-molt coincides with increased ecdysteroidogenesis, there is evidence that an additional positive stimulus in the form of an intracellular Ca²⁺ signal also plays a significant role. To better understand Ca²⁺ signaling in Y-organs, our lab investigated the proteins involved in regulation of intracellular Ca²⁺. These include Ca²⁺ pumps, e.g., plasma membrane calcium ATPases (PMCAs) and sarco/endoplasmic reticulum calcium ATPases (SERCAs). We used a PCR-based cloning strategy (RT-PCR followed by 3′- and 5′-RACE) to clone a full-length cDNA encoding a putative SERCA protein from the Y-organs of the blue crab (Callinectes sapidus). SERCA transcript levels in Y-organs were then determined using quantitative PCR. Transcript abundance was assessed after Y-organs were activated by eyestalk ablation, and throughout a natural molting cycle. The results are consistent with the hypothesis that stage-specific changes in SERCA expression occur in response to increased intracellular Ca²⁺ and are not a causative factor in promoting ecdysteroidogenesis. Identification of the stimulus that drives the increase in intracellular Ca²⁺ is critical to an understanding of cellular mechanisms that regulate ecdysteroidogenesis in crustacean molting glands.