Arabidopsis 2010: Defining the Role of Nurse Cells in the Propagation of Transposable Element Epigenetic Silencing

多细胞生物中的DNA并不只编码基因。更确切地说，包括人类在内的大多数生物体的基因组也是由被称为“跳跃基因”或转座因子（te）的古老病毒和其他寄生虫组成的。te是能够在基因组中从一个位置移动到另一个位置的DNA片段。当te活跃时，它有可能进入基因并产生突变、染色体断裂和基因组不稳定。为了抑制与活性TE相关的新突变的形成，植物、动物和真菌都具有抑制和沉默TE活性的机制。这一机制是基于TE RNA转录物降解为TE小RNA。这些TE小rna用分子标记（如DNA甲基化或翻译后组蛋白修饰）标记TE DNA，告诉细胞沉默TE。这个标志?或者DNA上的基因调控信息可以通过细胞分裂而不被重置，这一事件被称为表观遗传。在植物（在某些情况下动物）中，这些信息也可以代代相传，帮助后代确定DNA中哪些蛋白质编码区是基因，应该表达，哪些是te，应该沉默。这个项目旨在确定表观遗传信息是如何从一代传递到下一代的。在开花植物中，每个花粉粒由精细胞和一个称为花粉营养细胞的非生发哺乳细胞组成。精子细胞依靠花粉营养细胞将其传递给雌卵，但只有精子细胞的DNA才能传递给下一代。花粉营养细胞的细胞核经历了TE的表观遗传沉默缺失，导致TE RNA和一些新的TE小RNA的增加。在模式开花植物拟南芥中，研究将集中在1)花粉营养细胞TE的再激活是否影响精子细胞TE的沉默状态，2)花粉粒中TE小rna的增加是否有助于下一代TE沉默的增强。3)研究重点是遗传信息如何从非萌发花粉营养细胞传递到萌发精子细胞。这项研究有可能改变对亲代营养的理解，以及多细胞生物如何将遗传信息传递给后代。更广泛的影响该项目将影响从中学到博士后各个学术水平的学生的教育、培训和丰富。每年为俄亥俄州立大学青年学者项目（Ohio State Young Scholars Program）的中学生开设一门教育拓展课程，该项目专门为STEM领域中代表性不足的少数族裔提供学术丰富和职业探索经验。高中生将在与俄亥俄州立大学STEM学习网络的一部分Metro学校合作的实验室中进行高级研究项目。本科生将通过俄亥俄州立大学本科生研究经验获得暑期教育丰富和接触科学作为职业选择。通过与中学和高中外展组织的合作，以及本科生、研究生和博士后的多元化项目，该项目将成为培养新科学家的教育工具。

The DNA in multicellular organisms does not exclusively code for genes. Rather, most organisms' genome, including humans, is also composed of ancient viruses and other parasites call 'jumping genes' or transposable elements (TEs). TEs are fragments of DNA that have the ability to move from one location to another in the genome. When active, TEs have the potential to jump into genes and generate mutations, chromosome breakage and genomic instability. To inhibit the formation of new mutations associated with active TEs, plants, animals and fungi possess a mechanism to suppress and silence TE activity. This mechanism is based on degradation of TE RNA transcripts into TE small RNAs. These TE small RNAs result in the marking of the TE DNA with a molecular flag (such as DNA methylation or post-translational histone modification) that tells the cell to silence the TE. This ?flag? or gene regulatory information on the DNA can be passed through cell division without being reset in an event termed epigenetic inheritance. In plants (and in some cases animals), this information can also be inherited from one generation to the next, helping offspring determine what protein coding regions of DNA are genes and should be expressed, and which are TEs and should be silenced. This project aims to determine how epigenetic information is passed from one generation to the next.In flowering plants, each pollen grain consists of sperm cells and a non-germinal nurse cell termed the pollen vegetative cell. The sperm cells depend on the pollen vegetative cell for delivery to the female egg, but only the DNA of the sperm cells is passed on to the next generation. The nucleus of the pollen vegetative cell undergoes a loss of epigenetic silencing of TEs, resulting in an increase in TE RNA and some new TE small RNAs. In the model flowering plant Arabidopsis thaliana, investigation will focus on 1) whether TE reactivation in the pollen vegetative cell influences the silenced state of sperm cell TEs, and 2) if the increased TE small RNAs in the pollen grain help to reinforce TE silencing in the next generation. 3) Research will focus on how heritable information is physically passed from the non-germinal pollen vegetative cell to the germinal sperm cells. This research has the potential to shift the understanding of parental nourishment, and how multicellular organisms pass heritable information to their offspring. Broader ImpactsThis project will impact the education, training and enrichment of students at each academic level from middle school to post-doctoral. An educational outreach course is taught annually to middle school students from The Ohio State Young Scholars Program, which specializes in providing academic enrichment and career exploration experiences to racial and ethic minorities under represented in STEM fields. High school students will perform senior research projects in the laboratory in collaboration with The Metro School, part of The Ohio State University STEM Learning Network. Undergraduate students will gain summer educational enrichment and exposure to science as a career option through The Ohio State Research Experience for Undergraduates. Through collaborations with outreach organizations at the middle school and high school levels, as well as diversity programs for undergraduate, graduate and post-doctoral students, this project will serve as an educational tool for the development of new scientists.