MOLECULAR BASIS FOR SELENIUM DIETARY REQUIREMENT

这项工作的广泛，长期目标是建立分子 硒（Se）营养需要量的基础。 硒是一种必需的 人类和动物饮食中的微量元素。 然而，机制 因为它的许多生物学效应仍然无法解释。 不幸 没有一个单一的、综合性的实验可以设计成 回答这个问题“还有哪些生理过程依赖于硒 摄入量？”或“还有哪些酶的活性依赖于Se？". 然而，在这方面， 利用现代生物学的技术， “硒调控哪些基因？他们怎么样 监管？". 通过识别这些基因，它们所产生的产物 代码，及其调节机制，额外的功能， 他会被发现的。 以前观察到的生物学机制 硒的影响将被提出。 硒营养状况的新标志物 可能会被发现。 此外，基金会将设立， 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cDNA中的基因， 表达随膳食硒摄入量的变化而变化。 具体目标2是 为了确定这些表达中的翻译前反应， 基因最依赖于膳食摄入的硒。 大鼠将被喂食饲料 硒不足、充足和高而无毒。 的技术 mRNA的差异显示将被用于鉴定和克隆cDNA， 基因在大鼠组织中表达水平不同， Se的水平。 这些差异表达克隆的序列 将与GenBank和其他数据库中的数据进行比较， 确定它们是先前表征的还是新表征的 发现了基因，其表达受硒摄入量的调节。 这些 实验将实现具体目标1。 对于这些基因中的每一个， 连续转录测定和北方印迹分析将显示 基因转录或mRNA稳定化是翻译前的步骤， 对硒摄入最敏感的基因表达。 序列之间的比较 在硒调节基因的cDNA的UTR中， 在这些不同的物种中，它们可以作为硒响应元件。 这些实验将实现具体目标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.