Schmidt E R
Differentiation. 1977 Jan 14;7(2):107-12. doi: 10.1111/j.1432-0436.1977.tb01503.x.
The behaviour of isolated cell nuclei of different tissues in the mediterranean meal moth has been studied in metrizamide density gradients to find whether differences exist in the bouyant density between nuclei derived from different specialized tissues. The different nuclei studied have buoyant densities ranging form 1.228-1.295 g/cm3 in metrizamide density gradients and clear differences exist between different populations of nuclei. The different buoyant densities make it possible to separate isolated nuclei from a heterogeneous population of nuclei according to their characteristic densities. This has been tested by the separation of silk gland nuclei from follicle cell nuclei by the density centrifugation method. The degree of polyploidy of the nuclei is not correlated to a decrease or increase of the buoyant density, which suggests that different amounts of nuclear proteins, ribonucleoproteins or RNA are responsible for the differences determined. These tissue-specific differences of the nuclear densities might be correlated to different transcriptional activities. In addition to this, the isopycnic sedimentation technique in metrizamide density gradient provides a method to purify nuclei very carefully without any visible alteration of their morphology and integrity.
在地中海粉螟中，已在甲泛葡胺密度梯度中研究了不同组织的分离细胞核的行为，以确定源自不同特化组织的细胞核在浮力密度上是否存在差异。在所研究的不同细胞核中，其在甲泛葡胺密度梯度中的浮力密度范围为1.228 - 1.295 g/cm³，不同细胞核群体之间存在明显差异。不同的浮力密度使得能够根据其特征密度从异质细胞核群体中分离出分离的细胞核。这已通过密度离心法从卵泡细胞核中分离丝腺细胞核进行了测试。细胞核的多倍体程度与浮力密度的降低或增加无关，这表明不同量的核蛋白、核糖核蛋白或RNA是造成所确定差异的原因。核密度的这些组织特异性差异可能与不同的转录活性相关。除此之外，甲泛葡胺密度梯度中的等密度沉降技术提供了一种非常小心地纯化细胞核的方法，而不会对其形态和完整性造成任何可见的改变。
