Tracking Proteins in Recombination Nodules During Synapsis

研究计划是利用保守重组蛋白的光镜和电子显微镜免疫定位，将遗传重组的分子方面与早期重组结节(ENS)、晚期重组结节(LNS)和联会复合体的细胞学结构更全面地整合在一起。番茄是这项研究的最佳选择，原因有很多，包括其出色的细胞学，关于番茄ENS和LNS的广泛信息，以及一些番茄重组蛋白的抗体已经可用。这项研究的三个具体目标是：1)利用光学和电子显微镜确定整个突触中重组结节中重组蛋白的免疫标记模式。这方面的研究将包括对标记的和未标记的EN进行详细的EM观察，包括它们之间的关系，与突触起始点和突触分叉的关系，以及与LNS的关系。2)验证ENS在突触过程中蛋白质组成和功能不同的假说。这可能与当前证据表明EN的一个子集成为LN和/或存在不止一条基因重组途径有关。3)检验在LN(交叉)之间存在一定数量的EN(基因转换)的假设。这一假说被认为是解释遗传干扰的一种可能机制。这项研究将为我们理解RN成分与突触、交换和遗传干扰的关系提供重要的一步。此外，这项工作将帮助我们评估减数分裂途径的保守方面，以及识别可能是植物特有的特征。更广泛地说，阐明作物番茄的这些特性可能有助于解决实际问题，如改变重组率和/或在植物育种计划中帮助将理想的“野生”等位基因转移到驯化物种。由于减数分裂重组是高度保守的，本研究的结果将普遍适用于其他具有重要经济意义的植物，如玉米和水稻。这项工作的一个重要内容将是对几名本科生和一名研究生进行培训和教育。

The research plan is to use light and electron microscopic immunolocalization of conserved recombination proteins to integrate more fully the molecular aspects of genetic recombination with the cytological structures of early recombination nodules (ENs), late recombination nodules (LNs) and synaptonemal complexes. Tomato is the optimum choice for this study for a number of reasons, including its excellent cytology, the extensive information available on tomato ENs and LNs, and the fact that antibodies are already available for a number of tomato recombination proteins. The three specific objectives for this research are: 1) To determine the pattern of immunolabeling of recombination proteins in recombination nodules throughout synapsis using both light and electron microscopy. This aspect of the research will include detailed EM observations of labeled and unlabeled ENs including their relationship to each other, to synaptic initiation sites and synaptic forks, and to LNs. 2) To test the hypothesis that ENs differ in protein composition and function during synapsis. This may be related to current evidence that a subset of ENs become LNs and/or that there is more than one pathway for genetic recombination. And 3) to test the hypothesis that there are a defined number of ENs (gene conversions) between LNs (crossovers). This hypothesis has been proposed as a possible mechanism to account for genetic interference. This research will provide an important step in our understanding of RN components in relation to synapsis, crossing over, and genetic interference. In addition, this work will help us evaluate conserved aspects of the meiotic pathway as well as identify features that may be specific to plants. More broadly, elucidating these features in tomato, a crop plant, may help with practical issues such as changing recombination rates and/or aiding transfer of desirable "wild" alleles to domesticated species in plant breeding programs. Because meiotic recombination is highly conserved, the results of this study will be generally applicable to other plants of economic importance, such as maize and rice. An important element of this work will be the training and education of several undergraduate students as well as a graduate student.