STRUCTURE AND SEGREGATION OF ROBERTSONIAN TRANSLOCATIONS

罗伯逊易位构成了最常见的结构 一般人群中的染色体异常， 约0.1%。 染色体交换发生在着丝粒， 在短臂，柄，或卫星区的近端着丝粒 染色体，导致单或双着丝粒元件取决于 易位位点。 这一广泛修订的提案的目的是利用分子 遗传学的方法，以更好地了解形成和分离， 染色体平衡重排 罗伯逊易位 14号和21号染色体将使用荧光原位研究 用α-卫星、β-卫星、卫星I和 III，和核糖体DNA探针，以确定其确切的结构。 易位中的结构差异将与 双着丝粒体中的着丝粒区域是活跃的，以检验以下假设： 着丝粒的功能状态取决于其相邻结构。 此外，至少20名t（14 q21 q）男性携带者的精子将被 使用FISH和单精子PCR进行研究。 异常的频率 分离子将由FSH决定，而交换频率 将通过单精子PCR测定减数分裂中的精子数。 结合起来，这些 方法将允许直接评估 着丝粒结构、减数分裂交换和染色体分离。 本修订申请中提出的研究将测试特定的 一个假设，一类罗伯逊的减数分裂行为 易位，t（14 q21 q），可以解释为特定的 每个易位的着丝粒周围结构和功能。 考试 这一假说不仅将提供深入了解的机制， 人类染色体异常的一个重要类别的后果，但 将允许分析的结构和功能特点， 影响遗传重组和染色体分离的着丝粒。 因此，该项目的具体目标是补充和 与项目一、三和四的活动具有协同作用。

Robertsonian translocations constitute the most common structural chromosomal abnormalities in the general population, with an incidence of approximately 0.1%. The chromosome exchange takes place at the centromere, in the short arms, stalks, or satellite regions of the acrocentric chromosomes, resulting in either mono- or dicentric elements depending on the translocation site. The objective of this extensively revised proposal is to utilize molecular genetic approaches to better understand the formation and segregation of balanced chromosome rearrangements. Robertsonian translocations involving chromosomes 14 and 21 will be studied using fluorescence in situ hybridization (FISH) with alpha-satellite, beta-satellite, satellite I and III, and ribosomal DNA probes to determine their exact structure. Structural differences in the translocations will be compared to which centromere region in dicentrics is active to test the hypothesis that the functional status of a centromere is dependent on its adjacent structure. In addition, sperm from at least 20 male carriers of t(14q21q) will be studied both using FISH and single sperm PCR. The frequency of abnormal segregants will be determined by FSH, while the frequency of crossing over in meioses will be determined by single sperm PCR. In combination, these approaches will allow direct assessment of the relationships among centromere structure, meiotic crossing over and chromosome segregation. The studies proposed in this revised application will test the specific hypothesis that the meiotic behavior of one class of Robertsonian translocation, t(14q21q), can be explained by the particular pericentromeric structure and function of each translocation. Examination of this hypothesis will not only provide insight into the mechanisms and consequences of an important class of human chromosome abnormality, but will permit analysis of structural and functional features of the centromere that influence genetic recombination and chromosome segregation. As such, the specific goals of this project are complementary to and synergistic with those of Projects I, III, and IV.