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First published online June 29, 2007
Journal of Experimental Biology 210, 2540-2547 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.005322

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Prolonged deprivation of sleep-like rest raises metabolic rate in the Pacific beetle cockroach, Diploptera punctata (Eschscholtz)

Richard Stephenson^*, Karen M. Chu and James Lee

Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, M5S 3G5, Canada

View larger version (16K): [in this window] [in a new window]   Fig. 1. Schematic diagram of the apparatus (not drawn to scale). (A) The chamber used for repetitive stimulation of the cockroaches. Stimuli consisted of 2 s rotation (1 cm motion) of the chamber and simultaneous pulse of CO2 (peak concentration <1%). One chamber was scheduled to present stimuli continuously at the rate of 1 min–1 (SD group) and another chamber ran with a schedule of 6 h cycles with 3 h of stimuli at 2 min–1 and 3 h without stimuli (SC group). The study started with 15 animals per chamber. (B) Closed respirometry was used to measure oxygen consumption of individual cockroaches. Respiratory CO2 was absorbed by AscariteTM, and the change in chamber gas volume due to consumption of O2 was recorded every 10–20 min by measuring the position of a fluid indicator in the side arm. Ten animal chambers and four thermobarometers were all submerged to the level of the side arm in a constant-temperature water bath and studied simultaneously.

View larger version (7K): [in this window] [in a new window]   Fig. 2. Rate of oxygen consumption (A) and body mass (B) of two groups of cockroaches measured weekly during prolonged deprivation of sleep-like rest (SD; filled circles) or control protocol (SC; open circles). Symbols indicate means ± s.e.m., sample size=10, except where indicated by numbers in parentheses. Asterisks indicate values significantly different from baseline (day 0) and significantly different from corresponding values in SC group.

View larger version (4K): [in this window] [in a new window]   Fig. 3. Kaplan-Meier survival curves for SC (control, dotted line) and SD (deprived, solid line) cockroaches over the 44-day study.