Emmerich P, Loos P, Jauch A, Hopman A H, Wiegant J, Higgins M J, White B N, van der Ploeg M, Cremer C, Cremer T
Institute of Anthropology and Human Genetics, University of Heidelberg, Federal Republic of Germany.
Exp Cell Res. 1989 Mar;181(1):126-40. doi: 10.1016/0014-4827(89)90188-2.
Double in situ hybridization with mercurated and biotinylated chromosome specific DNA probes in combination with digital image analysis provides a new approach to compare the distribution of homologous and nonhomologous chromosome targets within individual interphase nuclei. Here we have used two DNA probes representing tandemly repeated sequences specific for the constitutive heterochromatin of the human chromosomes 1 and 15, respectively, and studied the relative arrangements of these chromosome targets in interphase nuclei of human lymphocytes, amniotic fluid cells, and fibroblasts, cultivated in vitro. We have developed a 2D-image analysis approach which allows the rapid evaluation of large numbers of interphase nuclei. Models to test for a random versus nonrandom distribution of chromosome segments are discussed taking into account the three-dimensional origin of the evaluated 2D-distribution. In all three human diploid cell types the measurements of target-target and target-center distances in the 2D-nuclear image revealed that the labeled segments of the two chromosomes 15 were distributed both significantly closer to each other and closer to the center of the nuclear image than the labeled chromosome 1 segments. This result can be explained by the association of nucleolus organizer regions on the short arm of chromosome 15 with nucleoli located more centrally in these nuclei and does not provide evidence for a homologous association per se. In contrast, evaluation of the interphase positioning of the two chromosome 1 segments fits the random expectation in amniotic fluid and fibroblast cells, while in experiments using lymphocytes a slight excess of larger distances between these homologous targets was occasionally observed. 2D-distances between the labeled chromosome 1 and 15 segments showed a large variability in their relative positioning. In conclusion our data do not support the idea of a strict and permanent association of these homologous and nonhomologous targets in the cell types studied so far.
将汞化和生物素化的染色体特异性DNA探针进行双重原位杂交，并结合数字图像分析，提供了一种新方法，可用于比较单个间期核内同源和非同源染色体靶标的分布。在此，我们使用了两种分别代表人类染色体1和15组成型异染色质特异性串联重复序列的DNA探针，并研究了这些染色体靶标在体外培养的人淋巴细胞、羊水细胞和成纤维细胞间期核中的相对排列。我们开发了一种二维图像分析方法，可快速评估大量间期核。讨论了用于测试染色体片段随机分布与非随机分布的模型，同时考虑了所评估的二维分布的三维起源。在所有三种人类二倍体细胞类型中，二维核图像中靶标-靶标和靶标-中心距离的测量结果表明，两条15号染色体的标记片段彼此之间的分布以及与核图像中心的距离均明显比标记的1号染色体片段更近。这一结果可以通过15号染色体短臂上的核仁组织区与这些核中更位于中心位置的核仁的关联来解释，本身并不能为同源关联提供证据。相比之下，对两条1号染色体片段间期定位的评估符合羊水细胞和成纤维细胞中的随机预期，而在使用淋巴细胞的实验中，偶尔会观察到这些同源靶标之间较大距离略有增加。标记的1号和15号染色体片段之间的二维距离在其相对定位上表现出很大的变异性。总之，我们的数据不支持在目前所研究的细胞类型中，这些同源和非同源靶标存在严格且永久关联的观点。
