Miklos G L, John B
Am J Hum Genet. 1979 May;31(3):264-80.
In reviewing the properties of heterochromatin and satellite DNA in man, it is clear that the human genome does not readily lend itself to experimental tests of the postulated functions for satellite DNA. Since the spectrum of known structural properties of vertebrate and invertebrate satellite DNAs are broadly overlapping, an alternative avenue is to experimentally manipulate the heterochromatin of an organism, and then evaluate the generality of the results. When this is done in Drosophila melanogaster, the one organism where such an experimental approach is indeed possible, the results provide no support for most of the popular hypotheses concerning satellite DNA function. They do, however, reveal an important effect on the meiotic system, namely that the position of crossover events can be markedly altered in the presence of heterochromatin known to be rich in satellite DNAs. This effect is not peculiar to Drosophila, since supporting data are readily available from natural situations in both mammals and grasshoppers. In all such cases, the effects are most easily discernible where the heterochromatic blocks are substantial in size, and non-centric in location, situations which do not apply in man. The human system, however, offers other potentials. The ubiquity of naturally occurring heterochromatic polymorphisms, coupled with the extreme sensitivity of the human genome to perturbation, offers some scope for assessing the possible somatic effects of alterations in the amount of satellite DNA.
在回顾人类异染色质和卫星DNA的特性时，很明显人类基因组并不容易用于对卫星DNA假定功能的实验测试。由于脊椎动物和无脊椎动物卫星DNA已知结构特性的范围广泛重叠，另一条途径是通过实验操纵生物体的异染色质，然后评估结果的普遍性。当在黑腹果蝇中进行此操作时（在这种生物体中这种实验方法确实可行），结果并不支持大多数关于卫星DNA功能的流行假设。然而，它们确实揭示了对减数分裂系统的一个重要影响，即已知富含卫星DNA的异染色质存在时，交叉事件的位置会明显改变。这种影响并非果蝇所特有，因为在哺乳动物和蚱蜢的自然情况下都很容易获得支持数据。在所有这些情况下，当异染色质块尺寸较大且位置非中心时，这种影响最容易辨别，而人类并不适用这些情况。然而，人类系统提供了其他潜力。自然存在的异染色质多态性的普遍性，再加上人类基因组对扰动的极端敏感性，为评估卫星DNA数量改变可能产生的体细胞效应提供了一些空间。
