Department of Biology, 112 Science Place, University of Saskatchewan, Saskatoon, Saskatchewan, Canada, S7N 5E2.
Comp Biochem Physiol C Toxicol Pharmacol. 2012 May;155(4):560-5. doi: 10.1016/j.cbpc.2012.01.005. Epub 2012 Jan 12.
The toxicity of selenium in fish is influenced by its chemical speciation and the exposure route. In the natural environment, selenium exposure to fish occurs primarily in the form of selenomethionine in diet. Thus, the main objective of this study was to examine the tissue-specific selenium burden and speciation in fish exposed to elevated dietary selenomethionine. Rainbow trout (Oncorhynchus mykiss) were treated with dietary selenomethionine (40 μg g(-1) dry mass) for 2 weeks, and at the end of the exposure different tissue samples were collected to assess the tissue-specific distribution and speciation of selenium. We used synchrotron-based X-ray absorption near edge spectroscopy (XANES) to determine the selenium speciation profile. Selenomethionine, selenocysteine and selenocystine were found to be the predominant form of selenium in all of the tissues; however their relative proportion varied across different tissues. In general, the organs primarily involved in selenium handling in fish (e.g., liver, kidney) accumulated a higher percentage of selenocystine. We also found that dietary selenomethionine exposure resulted into a marked increase in selenium burden of all major tissues in fish including the brain. Collectively, our findings provide new insights into the tissue-specific distribution and speciation of selenium in fish exposed to selenomethionine via diet.
鱼类中硒的毒性受其化学形态和暴露途径的影响。在自然环境中，鱼类主要通过饮食中的硒代蛋氨酸形式暴露于硒。因此，本研究的主要目的是研究暴露于高膳食硒代蛋氨酸的鱼类中组织特异性的硒负担和形态。虹鳟（Oncorhynchus mykiss）用膳食硒代蛋氨酸（40μg g(-1)干重）处理 2 周，在暴露结束时收集不同的组织样本，以评估硒在组织中的分布和形态。我们使用基于同步加速器的 X 射线吸收近边缘光谱（XANES）来确定硒的形态分布。发现硒代蛋氨酸、硒代半胱氨酸和硒代胱氨酸是所有组织中硒的主要形态，但它们在不同组织中的相对比例不同。一般来说，鱼类中主要参与硒处理的器官（如肝脏、肾脏）积累了更高比例的硒代胱氨酸。我们还发现，膳食硒代蛋氨酸暴露导致鱼类包括大脑在内的所有主要组织的硒负担显著增加。总之，我们的研究结果为通过饮食暴露于硒代蛋氨酸的鱼类中硒的组织特异性分布和形态提供了新的见解。
