Meeting Abstract
P2.186 Monday, Jan. 5 A novel cellular marker for temperature stress in marine invertebrates JOST, JA*; O’ROURKE, M; FUREY, N; DIONNE, M; FREDERICH, M; University of New England; University of New England; University of New England; University of New England; University of New England jjost@une.edu
In the context of global climate change the need to assess the effects of heat stress in marine organisms is increasing. Heat shock proteins (HSP) are frequently used as an indicator for heat stress, but there is often a time lag of several hours between the actual heat stress and detectable up-regulation of HSPs. For identifying an earlier stress indicator, we investigated whether AMP-activated protein kinase (AMPK), a regulator of cellular energy, is activated by temperature in the rock crab, Cancer irroratus. Crabs were exposed to a fast temperature increase (6°C/hour) and heart tissue was sampled every 2°C between 12 and 30°C. Righting reaction times, AMPK activity, total AMPK protein and mRNA, HSP70 protein and mRNA, and lactate accumulation were measured. There was no detectable change in righting response up to 18°C. Above 18°C, reaction time slowed, and AMPK activity increased. At 28°C, there was a loss of righting response, an onset of anaerobiosis, indicated by lactate accumulation, a peak in AMPK activity, and a slight increase in HSP70 mRNA expression. The combination of reduced motor activity, biochemical and molecular markers can be used to characterize temperature thresholds in the context of Shelfords law of tolerance. We propose that the onset of AMPK activity and reduced motor activity at 18°C, coinciding with the average maximum temperature where the animals were collected, indicates the transition from the optimum range, into a range between optimum and pessimum, defined as the pejus range. Therefore, AMPK activity is a cellular marker that can detect temperature stress in a marine invertebrate earlier than HSP70, and may serve as a tool for detecting temperature stress in other invertebrate species as well.
