STRUCTURE AND SEGREGATION OF ROBERTSONIAN TRANSLOCATIONS

罗伯逊易位构成了最常见的结构 普通人群中的染色体异常，发病率为 大约0.1%。染色体交换发生在着丝粒上， 在顶端着丝点的短臂、柄或卫星区域 染色体，导致单着丝粒或双着丝粒元件取决于 移位地点。 这项经过广泛修订的提案的目标是利用分子 用遗传学方法更好地理解细菌的形成和分离 平衡的染色体重排。罗伯逊易位涉及 14号和21号染色体将使用原位荧光技术进行研究。 与α-卫星、β-卫星、卫星I和 和核糖体DNA探针来确定它们的确切结构。 易位的结构差异将与 双着丝粒中的着丝粒区域是活跃的，以检验这一假设 着丝粒的功能状态取决于其邻近的结构。 此外，至少20名t(14q21q)男性携带者的精子将被 用FISH和单精子聚合酶链式反应进行了研究。出现异常的频率 分离物将由FSH决定，而交换的频率 在减数分裂中将通过单精子聚合酶链式反应确定。总而言之，这些 方法将允许直接评估以下各项之间的关系 着丝粒结构、减数分裂交叉和染色体分离。 这项修订后的申请中提出的研究将测试特定的 假设一类罗伯逊减数分裂行为 易位t(14q21q)可以用特殊的 每一次易位的着丝粒周围结构和功能。考查 这一假设不仅将提供对机制的洞察和 一类重要的人类染色体异常的后果，但 将能够分析该系统的结构和功能特点 影响基因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、项目三和项目四协同工作。

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.