eQTL analysis of Toxoplasma development

弓形虫发育的 eQTL 分析

• 批准号: 7844438
• 负责人: Michael W White
• 金额: $ 18.03万
• 依托单位: UNIVERSITY OF SOUTH FLORIDA
• 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 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7844438
• 关键词: Acquired Immunodeficiency Syndrome; American; Animals; Apicomplexa; Appendix; Blood; Brain; Chromosome Mapping; Chromosomes; Chronic; Condition; Cyst; Data; Data Set; Depth; Development; Equilibrium; Europe; Expressed Sequence Tags; Family; Family Felidae; Gene Expression; Gene Expression Profile; Gene Expression Regulation; Genes; Genetic; Genetic Crosses; Genetic Markers; Genetic Transcription; Genome; Glass; Global Change; Grant; In Vitro; Internet; Investigation; Kinetics; Lead; Letters; Life Cycle Stages; Link; Manuscripts; Maps; Messenger RNA; Methods; Microarray Analysis; Mutation; Numbers; Oocysts; Parasite Control; Parasites; Parents; Phenotype; Population; Quantitative Genetics; Quantitative Trait Loci; RNA; Range; Recombinants; Research Personnel; Resolution; Scanning; Series; Slide; Solid; Staging; Standards of Weights and Measures; Time; Tissues; Toxoplasma; Toxoplasma gondii; Toxoplasmosis; Variant; Virulence; Work; base; burden of illness; cell type; clinically relevant; cost effective; genetic analysis; genetic profiling; improved; mRNA Expression; member; migration; mutant; novel; pathogen; research study; trait; transcription factor

DESCRIPTION (provided by applicant): Recent genetic analysis of parasite virulence confirms that there is an important link between increased parasite burden and disease caused by the AIDS pathogen, Toxoplasma gondii. The factors that control parasite burden are not understood, but it is clear that the balance between tachyzoite replication and switching to the persistence tissue cyst is critical to parasite numbers in the host. Gene transcription is an important mechanism in the control of Toxoplasma gondii development as evidenced by the large coordinate changes in transcription associated with parasite stage transitions that lead to the tissue cyst. We estimate that the number of genes under developmental control in the intermediate life cycle is ~20% of total gene expression detected in this parasite. Gene expression also varies between genetically diverse strains and these differences underlie phenotypic differences in parasite intracellular replication, tissue migration and invasion, virulence, and the establishment of long-term persistence. In this proposal, we will investigate the genetic basis for differences in the switching mechanism that accompanies formation of the bradyzoite stage found in the tissue cyst. In Aim 1, we will construct a comprehensive profile of tachyzoite- to-bradyzoite mRNA expression in early passage lines representing the three canonical lineages (Type I- GT-1, Type II-Me49B7, and Type III-CTG). Microarray data from a detailed kinetic series of all three strains induced to differentiate in vitro will be compared to profiles of brain cyst-derived bradyzoites in order to construct a high quality profile of tachyzoite-to-bradyzoite regulated mRNAs. These RNA profiles will also be compared with data from several bradyzoite mutants and from alternate methods of induction and host cell types in order to improve the overall resolution of these data. All hybridization results generated by this project will be downloaded onto ToxoDB in a format accessible to other investigators. In Aim 2, we will examine the genetic basis of developmental variation in a set of independent progeny obtained from a genetic cross between Type I-GT-1 and Type III-CTG. We will utilize microarray data to generate global mRNA profiles for genetic progeny under conditions that induce bradyzoite-specific gene expression. Differentially expressed mRNAs will be identified by standard methods, and then quantitative expression values and ratios from these analyses will be utilized as traits in QTL analysis to define chromosome regions and their interactions that control the expression of specific genes. These studies have the potential to identify genes that reduce developmental efficiency in Type I strains, while at the same time revealing groups of genes that positively regulate bradyzoite switching in more developmentally active strains. Recent genetic analysis of parasite virulence confirms that there is an important link between increased parasite burden and disease caused by the AIDS pathogen, Toxoplasma gondii. The factors that control parasite burden are not understood, but it is clear that the balance between tachyzoite replication and switching to the persistence tissue cyst is critical to parasite numbers in the host. In this proposal, we will investigate the genetic basis for differences in the switching mechanism that accompanies formation of the bradyzoite stage found in the tissue cyst, which is responsible for chronic toxoplasmosis.

描述（由申请人提供）：最近对寄生虫毒力的遗传分析证实，寄生虫负担增加与艾滋病病原体弓形虫引起的疾病之间存在重要联系。控制寄生虫负荷的因素尚不清楚，但很明显，速殖子复制和转变为持久性组织包囊之间的平衡对于宿主体内的寄生虫数量至关重要。基因转录是控制弓形虫发育的重要机制，与导致组织囊肿的寄生虫阶段转变相关的转录的巨大坐标变化就证明了这一点。我们估计，在中期生命周期中受发育控制的基因数量约占该寄生虫中检测到的总基因表达的 20%。遗传多样性菌株之间的基因表达也存在差异，这些差异是寄生虫细胞内复制、组织迁移和侵袭、毒力以及长期持久性建立方面表型差异的基础。在本提案中，我们将研究伴随组织囊肿中发现的缓殖子阶段形成的转换机制差异的遗传基础。在目标 1 中，我们将构建代表三个典型谱系（I 型-GT-1、II 型-Me49B7 和 III 型-CTG）的早期传代系中速殖子到缓殖子 mRNA 表达的综合谱。将体外诱导分化的所有三种菌株的详细动力学系列的微阵列数据与脑囊肿衍生的缓殖子的概况进行比较，以构建速殖子到缓殖子调节的 mRNA 的高质量概况。这些 RNA 谱还将与来自几种缓殖子突变体以及来自替代诱导方法和宿主细胞类型的数据进行比较，以提高这些数据的整体分辨率。该项目生成的所有杂交结果都将以其他研究人员可以访问的格式下载到 ToxoDB 上。在目标 2 中，我们将检查从 I 型-GT-1 型和 III 型-CTG 遗传杂交获得的一组独立后代中发育变异的遗传基础。我们将利用微阵列数据在诱导缓殖子特异性基因表达的条件下生成遗传后代的全局 mRNA 图谱。将通过标准方法鉴定差异表达的 mRNA，然后将这些分析中的定量表达值和比率用作 QTL 分析中的性状，以定义控制特定基因表达的染色体区域及其相互作用。这些研究有可能识别出降低 I 型菌株发育效率的基因，同时揭示在发育更活跃的菌株中积极调节缓殖子转换的基因组。最近对寄生虫毒力的遗传分析证实，寄生虫负担增加与艾滋病病原体弓形虫引起的疾病之间存在重要联系。控制寄生虫负荷的因素尚不清楚，但很明显，速殖子复制和转变为持久性组织包囊之间的平衡对于宿主体内的寄生虫数量至关重要。在本提案中，我们将研究伴随组织囊肿中发现的缓殖子阶段形成的转换机制差异的遗传基础，组织囊肿是导致慢性弓形虫病的原因。