UNIPARENTAL INHERITANCE OF CHLOROPLAST DNA

真核生物已经进化出几种策略来确保单亲 细胞器DNA的遗传。 拟议工作的目标是 用实验方法阐明单亲遗传的机制， 易处理的生物，单细胞藻类，莱茵衣藻。 叶绿体遗传受两个交配型等位基因控制， 衣原体，mt+和mt-。 在单倍体细胞交配并进行减数分裂后， 后代仅保留mt+叶绿体DNA。 的策略 衣原体用于维持单亲遗传似乎 包括从合子中选择性保护mt+叶绿体DNA 在mt-和mt+叶绿体中都有活性的核酸酶。 拟议 实验的目的是隔离这个系统的关键组成部分， 核酸酶和保护因子。 第一种是有序列的菌株 将构建特异性叶绿体标签， 可以定量监测叶绿体DNA。 第二，这些标记 菌株将用于开发MT特异性的体外测定。 叶绿体DNA降解和mt+特异性保护。 本试验将 用于纯化核酸酶和保护活性。 最后， 核酸酶和保护活性缺陷的突变体将 分离和克隆。 的生化和遗传特性 这一系统将允许解剖的分子机制， 单亲遗传 除了深入了解一个基本的 真核细胞器生物学的属性，这项工作也可能有 对衰老和癌症的影响 删除和调换 线粒体DNA和线粒体代谢的改变， 与癌症和衰老过程有关。 了解细胞如何 例如Chalmyeloid消除了不需要的细胞器基因组， 提供了细胞如何识别和调节 它们细胞器DNA的命运

Eukaryotes have evolved several strategies to ensure uniparental inheritance of organellar DNA. The goal of the proposed work is to elucidate the mechanism of uniparental inheritance using an experimentally tractable organism, the unicellular algae, Chlamydomonas reinhardtii. Chloroplast inheritance is controlled by the two mating type alleles in Chlamydomonas, mt+ and mt-. After haploid cells mate and undergo meiosis, the progeny retain only mt+ chloroplast DNA. The strategy that Chlamydomonas utilizes for maintaining uniparental inheritance appears to involve selective protection of mt+ chloroplast DNA from a zygotic nuclease that is active in both mt- and mt+ chloroplasts. The proposed experiments are designed to isolate the key components of this system, the nuclease and the protection factor(s). First, strains with sequence specific chloroplast tags will be constructed so that degradation of mt- chloroplast DNA can be quantitatively monitored. Second, these tagged strains will be used to develop an in vitro assay for mt- specific chloroplast DNA degradation, and mt+ specific protection. This assay will be used to purify the nuclease and protection activities. Finally, mutants that are defective for the nuclease and protection activities will be isolated and cloned. The biochemical and genetic characterization of this system will allow a dissection of the molecular mechanisms underlying uniparental inheritance. Besides gaining insight into a fundamental property of eukaryotic organellar biology, this work may also have implications for aging and cancer. Deletions and transpositions of mitochondrial DNA and alterations in mitochondrial metabolism are associated with cancer and the aging process. Understanding how a cell such as Chalmydomonas eliminates undesirable organellar genomes will provide important basic information on how cells recognize and regulate the fate of their organellar DNA.