The purpose of this study was to investigate the effects of Pb and hypoxia co-exposure on Pb toxicity and Ca homeostasis in early life stage (ELS) zebrafish (Danio rerio). Previous evidence indicates that exposure of ELS zebrafish to hypoxia (~20% air saturation) reduces Ca uptake, likely through down-regulation of the apical epithelial Ca channel (ECaC). Considering that Pb and Ca are known antagonists and compete for uptake pathways, it was hypothesized that co-exposure of Pb with hypoxia would decrease Pb toxicity by reducing Pb uptake (likely mediated through a reduced number of ECaCs). However, it was shown that at 96 hpf, whole body accumulation of both Pb and Ca was lower at 40% air saturation compared to 100% and 20% air saturation. This result closely aligned with the 96h LC50 results which showed the highest mortality of zebrafish at 40% compared to the other air saturation levels. This suggests that toxicity is likely the result of exacerbated hypocalcemia at 40% air saturation due to both Pb competition for Ca binding to Ca uptake channels/transporters, such as ECaC, and potentially reduced expression of such channels/transporters in response to this level of hypoxia. Overall, it appears that ELS zebrafish respond differentially to the 40% and 20% hypoxia levels when co-exposed with Pb. Further investigation is needed to illustrate the physiological and molecular mechanisms underlying this response.
| Identifer | oai:union.ndltd.org:unt.edu/info:ark/67531/metadc1873844 |
| Date | 12 1900 |
| Creators | Moghimi, Mehrnaz |
| Contributors | Mager, Edward M., Roberts, Aaron P., Burggren, Warren W. |
| Publisher | University of North Texas |
| Source Sets | University of North Texas |
| Language | English |
| Detected Language | English |
| Type | Thesis or Dissertation |
| Format | v, 35 pages : color illustrations, Text |
| Rights | Public, Moghimi, Mehrnaz, Copyright, Copyright is held by the author, unless otherwise noted. All rights Reserved. |
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