碩士 / 國立臺灣大學 / 農業化學研究所 / 103 / Previous study indicates that nPbO2(s) causes inhibition of acetylcholinesterase (AChE) activity in larvae of medaka fish (Oryzias latipes). The bioavailability of nPbO2(s) is affected by particle aggregation and precipitation in water. However the uptake mechanism of nPbO2(s) in medaka fish and its bioaccessibility, bioaccumulation, and toxicity potency to aquatic organisms remain unclear. The objectives of this study is to understand the uptake mechanisms, bioaccumulation and toxic effects (on nervous system disruption) of 3 lead species [nPbO2(s), bulky lead dioxide bPbO2(s), and Pb2+(aq)] in medaka fish. Particle diameters of nPbO2(s) and bPbO2(s) measured with Transmission Electron Microscopy (TEM) were 34.5 ± 11.4 and 132.4 ± 54.2 nm respectively. The hydrodynamic diameters of nPbO2(s) and bPbO2(s) meausred with Dynamic light scattering (DLS) were 132.6 ± 36.9 and 217.3 ± 57.0 nm respectively. Results showed that both of nPbO2(s) and bPbO2(s) revealed low water solubility in dosing solutions, but nPbO2(s) had higher solubility than bPbO2(s). X-ray absorption near-edge structure (XANES) spectra also showed that both lead dioxide particles were stable in dosing solutions. However, XANES results and quantification of lead speciation showed that both nPbO2(s) and bPbO2(s) can be reductively dissolved into Pb(II) in gill and intestine with higher extend in gill tissues. As well, the nPbO2(s) has higher dissolution than bPbO2(s) in fish intestine. In addition, lead bioconcentration in liver of treated fish have no difference among lead groups; however, bPbO2(s) treatment appeared to result in higher lead bioaccumulation in fish brain, as compared with nPbO2(s) and Pb2+(aq) treatment. We observed dose-dependent inhibition of AChE activity in the brain of treated fish with 7-day exposures to three lead solutions; however, such inhibition appeared to be restored with 14-day exposure at higher concentrations. Both of nPbO2(s) and bPbO2(s) can increase the content of MDA in liver dose-dependently and the highest MDA content was found in Pb2+(aq) treated fish liver. Finally, the inhibition of NKA activity in gill was observed in nPbO2(s) and bPbO2(s) treated fish with 14-day exposure, and greatest inhibition was found in Pb2+(aq) treated fish with 14-day exposure.
| Identifer | oai:union.ndltd.org:TW/103NTU05406069 |
| Date | January 2015 |
| Creators | Yao Chu, 朱曜 |
| Contributors | Pei-Jen Chen, 陳佩貞 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 87 |
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