Institut National de la Recherche Agronomique, Unité Mixte de Recherche 0320/Unité Mixte de Recherche 8120 Génétique Végétale, F-91190 Gif-sur-Yvette, France.
Plant Cell. 2009 Dec;21(12):3915-25. doi: 10.1105/tpc.109.071514. Epub 2009 Dec 29.
We apply modeling approaches to investigate the distribution of late recombination nodules in maize (Zea mays). Such nodules indicate crossover positions along the synaptonemal complex. High-quality nodule data were analyzed using two different interference models: the "statistical" gamma model and the "mechanical" beam film model. For each chromosome, we exclude at a 98% significance level the hypothesis that a single pathway underlies the formation of all crossovers, pointing to the coexistence of two types of crossing-over in maize, as was previously demonstrated in other organisms. We estimate the proportion of crossovers coming from the noninterfering pathway to range from 6 to 23% depending on the chromosome, with a cell average of approximately 15%. The mean number of noninterfering crossovers per chromosome is significantly correlated with the length of the synaptonemal complex. We also quantify the intensity of interference. Finally, we develop inference tools that allow one to tackle, without much loss of power, complex crossover interference models such as the beam film. The lack of a likelihood function in such models had prevented their use for parameter estimation. This advance will allow more realistic mechanisms of crossover formation to be modeled in the future.
我们应用建模方法研究玉米（Zea mays）中晚期重组结的分布。这些结表明在联会复合体上的交叉位置。使用两种不同的干涉模型（“统计”伽马模型和“力学”梁膜模型）分析了高质量的结数据。对于每条染色体，我们在 98%的置信水平上排除了单个途径是所有交叉形成基础的假设，这表明玉米中存在两种类型的交叉，这在其他生物体中已经得到了证明。我们估计非干涉途径产生的交叉比例在 6%到 23%之间，具体取决于染色体，细胞平均值约为 15%。每条染色体上非干涉交叉的平均数量与联会复合体的长度显著相关。我们还量化了干涉的强度。最后，我们开发了推断工具，允许在不损失太多功率的情况下处理梁膜等复杂的交叉干涉模型。由于缺乏似然函数，这些模型无法用于参数估计。这一进展将允许未来对更现实的交叉形成机制进行建模。
