We tested the hypotheses that hypoxic toads (Bufo marinus) in a thermal gradient would select a lower than normal temperature and that this behavioral response would be beneficial. Under normoxic conditions, selected body temperature was 24.2 +/− 3.6 degrees C. When inspired O2 was 10% or less, mean selected temperature decreased to 15.3 +/− 2.4 degrees C. The theoretical advantages of hypoxia-induced hypothermia we tested include (1) a reduction of oxygen uptake (VO2) by a Q10 effect; (2) increased arterial saturation (SaO2), (3) a decreased ventilatory response, and (4) a decreased stress response. Gas exchange, hematocrit, hemoglobin, SaO2, PaO2 and pH were measured at 25 degrees C (normal preferred temperature) and 15 degrees C (hypoxia preferred temperature) in toads breathing normoxic or hypoxic gas mixtures. During graded hypoxia at 15 degrees C, SaO2 was significantly increased and VO2 was significantly reduced compared with 25 degrees C. Graded hypoxia did not significantly affect VO2 at 25 degrees C, despite evidence for increased ventilation at that temperature (increased pH and respiratory exchange ratio, RE). At 15 degrees C, graded hypoxia had a significant effect on VO2 only at an inspired O2 of 4%. Increased RE with hypoxia was significant at 25 degrees C but not at 15 degrees C. Hematocrit and [hemoglobin] rose significantly during graded hypoxia at 25 degrees C but did not change at 15 degrees C. Toads exposed to 10% O2 (the value that elicits behavioral hypothermia) showed a significant respiratory alkalosis at 25 degrees C but not at 15 degrees C. Likewise, hypoxia caused a significant drop in SaO2 and PO2 at 25 degrees C. Cooling to 15 degrees C during hypoxia caused a significant rise in SaO2 but no change in PaO2. In conclusion, behavioral hypothermia is a beneficial response to hypoxia in Bufo marinus.
Announcing the 2024 JEB Outstanding Paper Prize shortlist and winner
Every year JEB celebrates early-career researchers through the Outstanding Paper Prize. We recognise the shortlisted ECRS that contributed to 11 remarkable studies published in 2024 and congratulate the winner, Elise Laetz, from University of Groningen. See how else JEB supports and promotes ECRs.
Inside the Intergovernmental Panel on Climate Change with Hans-Otto Pörtner
During the past two decades, Hans-Otto Pörtner has steered climate change policy as a co-Chair of IPCC Working Group II. He tells us about the experience in this Perspective.
Photosynthesis turns symbiotic sea anemone's tentacles toward sun
Snakelocks sea anemones point their tentacles, packed with symbiotic algae, toward the sun so their lodgers can photosynthesize, and now Vengamanaidu Modepalli & colleagues have discovered that photosynthesis by the algae guides their host's tentacles towards the sun.
History of our journals
As our publisher, The Company of Biologists, turns 100 years old, read about JEB’s history and explore the journey of each of our sister journals: Development, Journal of Cell Science, Disease Models & Mechanisms and Biology Open.
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