TESTS OF THE UNINEME MODEL FOR MAMMALIAN CHROMOSOME

这个项目将检验染色体结构的一元性假设 通过直接测量哺乳动物细胞的分子量(MR) 几种哺乳动物的染色体DNA分子。初步数据， 几种啮齿动物细胞(V79)的粘弹性测量(VE) 中国仓鼠肺、L5178Y小鼠淋巴细胞性白血病和9L大鼠脑 肿瘤)表明哺乳动物(或至少是啮齿动物)DNA分子具有MR 仅相当于平均染色单体DNA含量的1/4至1/8。这意味着一个 多分子DNA染色体结构。第二场预赛 与一元假说不一致的观察是，啮齿动物的DNA 分子在辐照时增加其流体动力学(不包括)体积 电离辐射剂量预计会产生一个平均值 每个分子有一个双链断裂(DSB)。这样的行为是意料之中的 对于环状分子。目前尚无数据可供人类细胞确定它们是否 在这方面是相同的还是不同的。然而，不同的剂量 早熟浓缩染色体(PCC)产生的依赖性 这些碎片表明，人类细胞可能含有线形DNA。因此，数据 将被用来确定啮齿动物和人类染色体DNA分子 是线性的还是圆形的及其大小(S)。将使用两种方法。 首先，DNA的大小和形状将在细胞裂解物上确定；这将 产生最大的DNA分子的大小和形状。研究将会是 执行以确定VE检测大小异质性的灵敏度 这样我们就可以确定一个核中的所有DNA分子是否都是相同的 大小或不同。第二种方法是对特定的大型和 用流式细胞术测量小染色体的大小(和形状) 他们的DNA由VE提供。将进行附属研究，以增加 高离子强度溶液中DNA大小测定的准确性 用于脱蛋白DNA，并控制染料的任何影响 用于染色体的流动分选。因此，这些研究将：1) 确定一元模型对啮齿动物和人类细胞的有效性，2) 测定啮齿动物和人类DNA分子的大小和形状 染色体，以及3)确定特定DNA分子的大小 人类和啮齿动物的染色体。

This project will test the unineme hypothesis of chromosome structure in mammalian cells by a direct measurement of the molecular weight (Mr) of chromosomal DNA molecules in several mammalian species. Preliminary data, obtained by viscoelastometry (VE), for several species of rodent cells (V79 Chinese hamster lung, L5178Y mouse lymphoblastic leukemia and 9L rat brain tumor) show that mammalian (or at least rodent) DNA molecules have an Mr equal to only 1/4 to 1/8 the average chromatid DNA content. This implies a multimolecular DNA chromosomal architecture. A second preliminary observation in disagreement with the unineme hypothesis is that rodent DNA molecules increase their hydrodynamic (excluded) volume when irradiated with ionizing radiation doses which would be expected to create an average of one double-strand break (DSB) per molecule. Such behavior is expected for circular molecules. No data exist for human cells to determine if they are the sam or different in this regard. However, the different dose dependence for the creation of prematurely condensed chromosome (PCC) fragments suggests that human cells may have linear DNAs. Therefore, data will be obtained to determine if rodent and human chromosomal DNA molecules are linear or circular and their size(s). Two approaches will be used. First, DNA size and shape will be determined on cell lysates; this will yield the size and shape of the largest DNA molecules. Studies will be performed to determine the sensitivity of VE to detect size heterogeneity so that we can determine if all DNA molecules in a nucleus are the same size or different. The second approach will be to sort specific large and small chromosomes by flow cytometry and measure the size (and shape) of their DNAs by VE. Subsidiary studies will be performed to increase the accuracy of DNA size determination in the high ionic strength solutions used to deproteinize the DNA, and to control for any effects of the dyes used for flow sorting of the chromosomes. Thus, these studies will: 1) determine the validity of the unineme model for rodent and human cells, 2) determine the size and shape of the DNA molecules of rodent and human chromosomes, and 3) determine the size of the DNA molecules of specific human and rodent chromosomes.