CORRELATIONS BETWEEN ISOCHORES AND CHROMOSOMAL BANDS IN THE HUMAN GENOME
CORRELATIONS BETWEEN ISOCHORES AND CHROMOSOMAL BANDS IN THE HUMAN GENOME
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DOI：
10.1073/pnas.90.24.11929
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发表时间：
1993-12-15
影响因子：
11.1
通讯作者：
BERNARDI, G
中科院分区：
文献类型：
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作者：
SACCONE, S;DESARIO, A;BERNARDI, G
人类基因组由较长的DNA片段组成，这些片段在组成上是均匀的，可以细分为具有不同G+C水平的少数家族。染色体原位抑制杂交（加入多余的未标记的人类DNA来抑制探针中重复序列的杂交，从而增强对单拷贝序列的观察）以G+C水平增加为特征的DNA片段在中期染色体上的分布，以确定L1 + L2， H1， H2和H3等染色质家族对应的“单拷贝”序列。这产生了条带模式，从相对弥漫性染色到r -带，再到t -带。更具体地说，我们的结果表明(i) t波段是由H3家族的G+ c富同工和H1和H2家族的部分G+ c富同工组成的（以后者为主）；（ii） H1家族富含G+ c的同工（H2和H3家族的贡献较小）和L1 + L2家族缺乏G+ c的同工形成的R′带（即不含t′带的R′带）几乎相同；（iii） G波段主要由L1 + L2家族的G+ c差等杂项组成，H1家族的等杂项贡献较小。这些结果不仅阐明了DNA碱基组成与染色体带之间的相关性，而且提供了基因在染色体中的分布信息，基因浓度随着G+C水平的增加而增加。
The human genome is made up of long DNA segments, the isochores, which are compositionally homogeneous and can be subdivided into a small number of families characterized by different G+C levels. Chromosome in situ suppression hybridization (in which excess unlabeled human DNA is added to suppress hybridization of repeated sequences present in the probe, enabling enhanced observation of single-copy sequences) of DNA fractions characterized by an increasing G+C level was carried out to determine the distribution of ''single-copy'' sequences corresponding to isochore families L1 + L2, H1, H2, and H3 on metaphase chromosomes. This produced a banding pattern progressing from a relatively diffuse staining to an R-banding, to a T-banding. More specifically, our results showed that (i) T-bands are formed by the G+C-richest isochores of the H3 family and by part of the G+C-rich isochores of the H1 and H2 families (with a predominance of the latter); (ii) R'-bands (namely, R-bands exclusive of T-bands) are formed to almost equal extents by G+C-rich isochores of the H1 families (with a minor contribution of the H2 and H3 families) and by G+C-poor isochores of the L1 + L2 families; (iii) G-bands essentially consist of G+C-poor isochores from the L1 + L2 families, with a minor contribution of isochores from the H1 family. These results not only clarify the correlations between DNA base composition and chromosomal bands but also provide information on the distribution of genes in chromosomes, gene concentration increasing with the G+C levels of isochores.