Biochemical response to acute temperature change in Atlantic killifish, Fundulus heteroclitus (586.1)

Abstract

It is documented that after temperature acclimation, the killifish Fundulus heteroclitus shows differences in the activities of a number of enzymes including lactate dehydrogenase (LDH), an important catalyst in anaerobic respiration. Less well understood is the temporal pattern of change in activity from one temperature to another. We acclimated fish to 22°C, and shifted the temperature such that an equilibrium was reached at 4°C after 9 hours. During the shift, we collected liver and white muscle samples and assayed homogenates for the specific activity of LDH. After three hours, LDH activity in liver increased from 22.2 µmol·min‐1·mg protein‐1 to 75.1 µmol·min‐1·mg protein‐1 , but then dropped by nine hours to 25.4 µmol·min‐1·mg protein‐1. Conversely, LDH activity in muscle decreased from 154 µmol·min‐1·mg protein‐1 to 61.3 µmol·min‐1·mg protein‐1 and continued to decrease at a slowed rate. These data demonstrate that F. heteroclitus adjusts LDH activity extremely rapidly in response to temperature change. We are currently determining the response to the opposite temperature shift (4 to 22°C), and we plan to assess several enzymes associated with aerobic respiration and other aspects of metabolism. Together, these analyses will help us determine which major metabolic pathways are most critical to this species during rapid temperature change.Grant Funding Source: Supported by the Guerrieri Foundation and the Salisbury University Department of Biological Sciences