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Vol. 53, 2014
Short-term
effects of thermal stress on the responses of branchial protein quality
control and osmoregulation in a reef-associated fish, Chromis viridis
Cheng-Hao Tang1,2*, Ming-Yih Leu2,3, Katrina Shao4, Lie-Yueh Hwang5 and Wen-Been Chang2,3
1Institute of Marine Biotechnology, National Dong Hwa University, 2 Houwan Road, Checheng, Pingtung 944, Taiwan
2National Museum of Marine Biology and Aquarium, Pingtung 944, Taiwan
3Institute of Marine Biodiversity and Evolutionary Biology, National Dong Hwa University, Pingtung 944, Taiwan
4Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106-9610, USA
5Taishi Station, Mariculture Research Center, Fisheries Research Institute, Council of Agriculture, Taishi, Yulin 636, Taiwan
Abstract
Background: Changes
in ambient temperature seriously affect physiological regulation and
biochemical reactions in ectotherms. However, transient elevation in
oceanic temperature occurs naturally during the day. Short-term
elevation in the ambient temperature affects different physiological
responses in marine fish, including cellular protein stability and
osmotic balance of the internal environment. Since fish gills are vital
osmoregulatory organ which directly contacts external environment,
activation of cytoprotective responses to maintain gill cell viability
and biological function is essential for fish survival under
challenging environmental conditions. The purpose of this study was to
investigate the short-term effects of elevated temperature on
physiological regulation in the gills of a marine teleost, blue green
damselfish (Chromis viridis).
Results: As
part of the stress response, plasma glucose levels were induced by
short-term hyperthermic exposure (12 h). Furthermore, upregulation of
the levels of gill heat shock proteins (HSPs) and ubiquitinated
proteins was essential for preventing the accumulation of protein
aggregations in branchial cells of C. viridis under hyperthermic stress. The specific activity of branchial Na+/K+-ATPase (NKA), however, significantly reduced while the amount of protein was similar between normal and high-temperature groups.
Conclusions: The
present study provided the evidence to illustrate that activation of
the branchial protein quality control mechanism to carry out
cytoprotective response was involved in coping with thermal stress.
However, plasma osmolality and muscle water content, respectively, that
slightly but evidently increased and decreased might result from
impaired osmoregulatory ability due to hyperthermia-decreased gill NKA
activity.
Key words: Thermal stress; Blue-green damselfish; Protein quality control; Osmoregulation.
*Correspondence: E-mail: ce: wtang@mail.ndhu.edu.tw
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