1. Inhibition of calcium uptake during hypoxia in developing zebrafish is mediated by hypoxia-inducible factor.
- Author
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Kwong, Raymond W. M., Kumai, Yusuke, Tzaneva, Velislava, Azzi, Estelle, Hochhold, Nina, Robertson, Cayleih, Pelster, Bernd, and Perry, Steve F.
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LOGPERCH ,ANIMAL behavior ,CALCIUM ,HYPOXEMIA ,HYPOXIA-inducible factors - Abstract
The present study investigated the potential role of hypoxia-inducible factor (HIF) in calcium homeostasis in developing zebrafish (Danio rerio). It was demonstrated that zebrafish raised in hypoxic water (30 mmHg; control, 155 mmHg P
O ) until 4 days post-fertilization exhibited a substantial reduction in whole-body Ca2 2+ levels and Ca2+ uptake. Ca2+ uptake in hypoxia-treated fish did not return to prehypoxia (control) levels within 2 h of transfer back to normoxic water. Results from real-time PCR showed that hypoxia decreased the whole-body mRNA expression levels of the epithelial Ca2+ channel (ecac), but not plasma membrane Ca2+ -ATPase (pmca2) or Na+/ Ca2+ -exchanger (ncx1b). Whole-mount in situ hybridization revealed that the number of ecac-expressing ionocytes was reduced in fish raised in hypoxic water. These findings suggested that hypoxic treatment suppressed the expression of ecac, thereby reducing Ca2+ influx. To further evaluate the potential mechanisms for the effects of hypoxia on Ca2+ regulation, a functional gene knockdown approach was employed to prevent the expression of HIF-1αb during hypoxic treatment. Consistent with a role for HIF-1αb in regulating Ca2+ balance during hypoxia, the results demonstrated that the reduction of Ca2+ uptake associated with hypoxic exposurewas not observed in fish experiencing HIF-1αb knockdown. Additionally, the effects of hypoxia on reducing the number of ecac-expressing ionocytes was less pronounced in HIF-1αb-deficient fish. Overall, the current study revealed that hypoxic exposure inhibited Ca2+ uptake in developing zebrafish, probably owing to HIF-1αb-mediated suppression of ecac expression. [ABSTRACT FROM AUTHOR]- Published
- 2016
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