Original paper

Respiratory electron transport system (ETS) activity and respiration rate in cold-stenothermal and eurythermal chironomid larvae from highmountain lakes

Simčič, Tatjana

Abstract

Respiratory electron transport system (ETS) activity and respiration rate were measured in four genera (Paratanytarsus, Procladius, Macropelopia, Zavrelimyia) of chironomid larvae from high-mountain lakes. Thermal responses were measured in the laboratory as differences in ETS activity and respiration rate of field animals at experimental temperatures of 5, 10, 15 and 20 °C. ETS activity and respiration rate of all genera increased with increasing experimental temperature up to maximal values. However, genera differed in their actual and potential respiratory response to increasing temperature. Cold-stenothermal genera (Macropelopia, Zavrelimyia) had significantly lower Arrhenius activation energy (Ea) for ETS activity and respiration rate than eurythermal genera (Paratanytarsus, Procladius). Therefore, cold-stenothermal genera had a relatively more efficient respiratory system at the lowest experimental temperature than at the highest one when compared with genera less limited by temperature. This indicates that cold-stenothermal genera have respiratory enzyme systems well adapted to function at low environmental temperature, but less so at higher temperatures. Lower ETS/R ratios of Macropelopia than of Procladius, and of Zavrelimyia than of Paratanytarsus, are also consistent with their narrower ecological tolerance.

Keywords

ets activityoxygen consumptionchironomid larvaetemperaturethermal tolerancecold-stenothermseurythermsmetabolism