Effects of Chronic Hypoxic Exposure on Selected Temperature during Acute Normoxia, Hypoxia, and Inhibition of Oxidative Phosphorylation in the Protozoan Paramecium Caudatum
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Authors
Bencic, David C.
Issue Date
1993
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
Hypoxia (decreased availability of oxygen) elicits a variety of adaptive
physiological and behavioral responses in both endotherms and ectotherms
that either increase the supply of oxygen (02) or decrease the need for 02. An
important behavioral response that decreases 02 need is hypothermia.
Although hypoxia-induced hypothermia is important and widespread, little is
known of the factors that influence it. This study investigated effects of chronic
hypoxic exposure on this response in the protozoan Paramecium cauda tum.
Specific hypotheses tested were: 1) Paramecia grown in a hypoxic environment
would adapt and behaviorally maintain a higher mean selected temperature
(Ts) during acute hypoxia than normoxic-cultured paramecia. 2) Hypoxiaadapted
paramecia would have a higher Ts after addition of sodium azide
(NaN3) because adaptation to hypoxia involves an increase of capacity for
anaerobic respiration.
Paramecia were cultured in normoxic and hypoxic environments and
isolated during mid-log phase growth. The paramecia were placed in an aquatic
thermal gradient and recorded using video microscopy. The Ts was
determined after exposure to acute normoxia, hypoxia, and after addition of
NaN3, an inhibitor of oxidative phosphorylation. Under normoxic conditons,
no significant difference existed between the Ts of paramecia cultured in
normoxia and hypoxia, however; hypoxia-cultured paramecia were able to
successfully adapt to hypoxia and thus maintained a significantly higher Ts
during acute hypoxia than normoxic paramecia. Additionally, in the presence
of NaN3, hypoxia-adapted paramecia had a significantly higher Ts than the
normoxic paramecia, suggesting that the mechanism of adaptation may be an
increased ability for anaerobic respiration.
Description
v, 28 p.
Citation
Publisher
Kalamazoo College
License
U.S. copyright laws protect this material. Commercial use or distribution of this material is not permitted without prior written permission of the copyright holder.