MOLECULAR BASIS FOR SELENIUM DIETARY REQUIREMENT

这项工作的广泛、长期的目标是建立分子 根据硒(Se)营养需求。硒是一种必需的 人和动物饮食中的微量元素。然而，这些机制 因为它的许多生物学效应仍未得到解释。不幸的是 没有一个单一的、综合性的实验可以设计成 回答问题“还有哪些其他生理过程依赖于硒？ 摄入量？“或”还有什么酶依赖于硒的活性？“ 利用现代生物学的技术，问和答是可能的 问题是“哪些基因受Se调控？”和“他们怎么样？ 通过识别这些基因，它们所针对的产品 代码及其调节机制，附加功能用于 Se将会被揭晓。先前观察到的生物学机制 将提出Se的影响。硒营养状况的新标记物 可能会被发现。此外，该基金会将成立，以 探讨硒营养需求变异的遗传基础。 本项目的具体目标1是分离大鼠的cDNA，以寻找其基因 随着饮食中硒摄入量的变化，表达也会发生变化。具体目标2是 确定这些基因表达中的翻译前反应(S) 基因最依赖于膳食中的硒摄入量。老鼠将被喂食食物 硒含量不足、充足、含量高，但无毒。技术和技术 将使用mRNA差异显示来鉴定和克隆cDNA 不同饮食习惯大鼠组织中不同水平的基因表达 硒的水平。这些差异表达克隆的序列 将与GenBank和其他数据库中输入的数据进行比较 确定它们代表的是以前的特征还是新的 发现了基因，其表达受硒摄入量的调节。这些 实验将实现特定的目标1.对于这些基因中的每一个， 连续转录分析和Northern印迹分析将显示 基因转录或mRNA稳定是翻译前的步骤 对Se摄入量最敏感的基因表达。序列间的比较 在cDNA的UTRs中，受Se调节的基因将显示保守的序列 在这些不同的物种中，可能作为对Se的响应元素。 这些实验将实现特定的目标2。

The broad, long-term objective of this work is to establish the molecular basis for selenium (Se) nutrient requirement. Selenium is an essential trace element in the diets of man and animals. However, the mechanisms for many of its biological effects remain unexplained. Unfortunately there is no single, comprehensive experiment that can be designed to answer the question "What other physiological processes depend on Se intake?" or "What other enzymes depend on Se for activity?". However, using the techniques of modern biology, it is possible to ask and answer the questions "What genes are regulated by Se?" and "How are they regulated?". By identifying such genes, the products for which they code, and the mechanisms of their regulation, additional functions for Se will be revealed. Mechanisms for previously observed biological effects of Se will be suggested. New markers for Se nutritional status may be discovered. In addition, the foundation will be established to explore the genetic basis for variability in Se nutrient requirement. Specific Aim 1 in this project is to isolate rat cDNAs for genes whose expression is varied by changes in dietary Se intake. Specific Aim 2 is to determine the pretranslational reaction(s) in the expression of these genes most dependent on dietary intake of Se. Rats will be fed diets inadequate, adequate and high but nontoxic in Se. The techniques of differential display of mRNA will be used to identify and clone cDNAs for genes expressed at different levels in tissues of rat consuming different levels of Se. The sequences of these differentially expressed clones will be compared to those entered into GenBank and other data bases to determine if they represented previously characterized or newly discovered genes, whose expression is regulated by Se intake. These experiments will accomplish Specific Aim 1. For each of these genes, run-on transcription assays and Northern blot analyses will show whether gene transcription or mRNA stabilization is the step in pretranslational gene expression most sensitive to Se intake. Comparison among sequences in the UTRs of cDNAs for Se-regulated genes will show sequences conserved among these different species which may serve as Se-responsive elements. These experiments will accomplish Specific Aim 2.