Meeting Abstract

1.1  Monday, Jan. 4  A comparison in cellular stress response between subtidal and intertidal crustacean species JOST, JA*; PODOLSKI, S; WILLARD, K; FREDERICH, M; University of New England; University of New England; University of New England; University of New England jjost@une.edu

We investigated the mechanisms involved in cellular stress using AMP-activated protein kinase (AMPK) as an indicator of high temperature stress in invertebrates. AMPK acts as a “fuel gauge” for the cell and is activated in mammals by hypoxia, exercise, osmotic shock and cold stress. While AMPK activity has not been thoroughly investigated in invertebrates, we previously identified AMPK in the subtidal rock crab, Cancer irroratus, and measured an increase in AMPK activity due to high temperature stress, which occurred earlier than heat shock protein (HSP70) up-regulation. We conducted similar experiments on the intertidal green crab, Carcinus maenas. Crabs were exposed to a fast temperature increase (6°C/hour) and heart tissue was sampled every 2°C between 12 and 35°C. Righting reaction times, heart rate, AMPK activity, HSP70 protein, and lactate accumulation were measured. Above 35°C, there was a loss of righting response, an onset of anaerobiosis and an increased heart rate. At 36°C, there was 100% mortality. HSPs and AMPK activity did not significantly increase. Therefore, the green crab switches from maximum performance to heat coma within a very narrow temperature range. In contrast, previous data show a slow decline in fitness, well before the lethal temperature, in the rock crab. These data can be interpreted in the context of Shelford’s law of tolerance: the subtidal rock crab shows an early transition from the optimum range to a range with declining fitness (pejus range), while the subtidal green crab demonstrated almost no pejus range and a sharp transition directly from optimum to pessimum. The differential response of AMPK activation by heat stress indicates habitat specific adaptations of the cellular energy metabolism.