Role of Meiotic Genes in the Basal Eukaryote Giadia lambia

减数分裂基因在基础真核生物贾迪亚兰比亚中的作用

• 批准号: 7329321
• 负责人: MARIANNE K POXLEITNER
• 金额: $ 4.79万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-15 至 2008-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7329321
• 关键词: Animal Model; Arabidopsis; Arizona; Behavior; Bioinformatics; Biological; Biological Models; Biological Process; Cell Nucleus; Cells; Chromosomes; Condition; Cyst; DNA; DNA Damage; DNA Repair; DNA Repair Pathway; Data; Depth; Dominant-Negative Mutation; Double Strand Break Repair; Episome; Eukaryota; Eukaryotic Cell; Event; Evolution; Feces; Fluorescent in Situ Hybridization; Genes; Genetic Materials; Genome; Genome Stability; Genomic Instability; Giardia; Giardia lamblia; Goals; Green Fluorescent Proteins; Homologous Gene; In Vitro; Intestines; Knowledge; Laboratories; Lead; Light Microscope; Maize; Malignant Neoplasms; Meiosis; Microscopy; Microtubules; Modification; Molecular; Monitor; Morphology; Mus; Mutation; Nuclear; Nuclear Envelope; Nuclear Fusion; Oncogenic; Organism; Parasites; Partner in relationship; Pathway interactions; Pattern; Plasmids; Population; Process; Processed Genes; Puromycin; Research; Resistance; Role; Somatic Cell; Staging; Standards of Weights and Measures; Synaptonemal Complex; Universities; Yeasts; asexual; cell transformation; excystation; homologous recombination; in vivo; interest; man; mouse model; protein expression; repaired

DESCRIPTION (provided by applicant): The goal of this proposed research is to study the evolution of meiosis using the intestinal parasite Giardia lamblia as a model organism. Evolutionary, Giardia is the most basal eukaryote available for study having last shared a common ancestor with man or the yeasts over 1.5 billion years ago; thus it is an ideal model organism for this project. Giardia is believed to be an asexual organism, but the recent discovery of meiotic gene homologs in its genome raises the possibility that Giardia either undergoes meiosis or a process that is evolutionary related to meiosis. It has been proposed that the genes and processes involved in meiotic double stranded break repair (DSBR) and homologous recombination (HR) between homologous chromosomes evolved from processes used by somatic cells to repair DNA damage. Therefore, the presence of these candidate meiotic genes (CMGs) in Giardia allows the study of the mechanisms involved in repairing DNA damage in an evolutionary context. Understanding these mechanisms is important because mutations in many genes normally involved in DNA damage repair and meiosis lead to genome instability and cancer. The specific aims of this research are: (1) To discover molecular evidence for meiotic-like processes in Giardia. (2) To discover cytological evidence for meiotic- like processes in Giardia. (3) To search for evidence of Giardia mating both in vitro and in vivo. GFP expression data reveal that six CMGs show temporal and spatial expression patterns consistent with a meiotic-like function. The biological functions of selected CMGs involved in DNA damage/repair and nuclear fusion will be investigated by creating dominant/negative mutants. Preliminary fluorescent in situ hybridization (FISH) data support a nuclear fusion event in cysts. Additional evidence of nuclear fusion and exchange of nuclear material between nuclei will be accomplished by performing FISH on excyzoites, as well as monitoring nuclear behavior during the encystation process using both immunofluorescent microscopy and TEM. In vivo evidence of a meiotic event in Giardia will be sought with the use of a mouse model system. Because DNA damage is induced in cells undergoing meiosis, modifications of these processes can be oncogenic. If DNA repair mechanisms fail, the induction of DSBs can be deleterious to the cell and could result in genome alterations. This project will greatly enhance knowledge in the field of DNA damage repair as it relates to genome stability. Overall, this project will lead to a deeper understanding of the evolution of meiotic processes involved in DNA damage repair pathways.

描述（由申请人提供）：本研究的目的是使用肠道寄生虫蓝氏贾第鞭毛虫作为模式生物研究减数分裂的进化。在进化上，贾第鞭毛虫是可用于研究的最基本的真核生物，最后一次与人类或酵母共享共同祖先超过15亿年;因此它是该项目的理想模式生物。贾第虫被认为是一种无性生物，但最近在其基因组中发现的减数分裂基因同源物提出了贾第虫要么经历减数分裂，要么经历与减数分裂相关的进化过程的可能性。已经提出，参与减数分裂双链断裂修复（DSBR）和同源染色体之间的同源重组（HR）的基因和过程是从体细胞用于修复DNA损伤的过程进化而来的。因此，这些候选减数分裂基因（CMG）在贾第鞭毛虫的存在允许参与修复DNA损伤的进化背景下的机制的研究。理解这些机制是很重要的，因为通常参与DNA损伤修复和减数分裂的许多基因的突变会导致基因组不稳定和癌症。本研究的具体目的是：（1）发现贾第虫类减数分裂过程的分子证据。(2)发现贾第鞭毛虫类减数分裂过程的细胞学证据。(3)寻找贾第虫体内外交配的证据。GFP表达数据显示，6个CMG显示与减数分裂样功能一致的时间和空间表达模式。选择CMG参与DNA损伤/修复和核融合的生物学功能将通过创建显性/阴性突变体进行研究。初步的荧光原位杂交（FISH）数据支持囊肿核融合事件。核融合和核之间的核物质交换的其他证据将通过在外孢子上进行FISH来完成，以及使用免疫荧光显微镜和TEM来监测成囊过程中的核行为。将使用小鼠模型系统寻找贾第虫减数分裂事件的体内证据。由于DNA损伤是在减数分裂的细胞中诱导的，因此这些过程的改变可能是致癌的。如果DNA修复机制失败，DSB的诱导可能对细胞有害，并可能导致基因组改变。该项目将大大提高DNA损伤修复领域的知识，因为它涉及到基因组的稳定性。总的来说，该项目将导致对DNA损伤修复途径所涉及的减数分裂过程的进化有更深入的了解。