Nuclear and nucleolar ultrastructural lesions induced by 1-nitro-9-aminoacridine (C-283) in human ovarian carcinoma cells

Interchromatin granules during phytohemagglutinin stimulation of human lymphocytes. A cytochemical study

We studied the formation of interchromatin granules (IGs) in phytohemagglutinin (PHA)-stimulated lymphocytes. The bismuth staining method was used for the visualization of IGs, and we also applied high-resolution autoradiography after incubating cells in the presence of 3H-leucine during different stages of lymphocyte activation. The disaggregation of chromatin and the enlargement of interchromatinic areas in stimulated lymphocytes were found to be accompanied by an increase in the number of IGs, and it was shown that IGs were formed during all of the investigated stages of lymphocyte stimulation.

Distribution of interchromatin granules in nuclear matrices obtained from nuclei exhibiting different degree of chromatin condensation

Female Wistar rats were injected intraperitoneally with thioacetamide or Ledakrin (1-nitro-9/3'-dimethylpropyloamine/acridine . 2 HCl) to provoke chromatin decondensation or condensation, respectively. Liver nuclei of each experimental group were used to isolate nuclear matrices. The results provide evidence that interchromatin granules are components of the nuclear matrix obtained by the procedure used in these experiments. They also reveal that the general ultrastructural pattern of the nuclear matrix is related to the degree of chromatin condensation in the nuclei used for its isolation. The distribution of interchromatin granules characteristic for the source nuclei is maintained in the nuclear matrices.

High-resolution autoradiographic study on the presence of chromatin structures within interchromatin granule conglomerations

In Ehrlich ascites tumour cell nuclei ledakrin (1-nitro-9/3'-dimethylpropyloamine/acridine-2 HCl) induces condensation and margination of chromatin, compaction and segregation of nucleolar components and conglomeration of chromatin granule clusters. Localization of DNA in nuclei of the cells labelled with 3H-thymidine and subsequently treated with ledakrin is studied using high-resolution autoradiography. Besides strong labelling of condensed chromatin some radioactivity is associated with IG conglomerations. Possible role of chromatin fibrils in the formation of conglomerations of IG is discussed.

Genetic effects of acridine compounds

Acridines and a very large number of acridine derivatives are used in enormous quantities both in medicine and industry. The mutagenic action of these compounds has been demonstrated in a wide variety of organisms and is known to occur both in the dark as well as in the presence of light (photodynamic action). At the molecular level, acridines have been shown to cause frameshift mutations of both the addition and deletion types, a characteristic which has been of tremendous help in elucidating the nature of the genetic code. These and various other biological effects of acridines, such as inhibition of DNA repair, curing of plasmids and cell-growth inhibition, are examined in this review.

Interactions of some nitro-derivatives of substituted 9-aminoacridine with DNA

The mechanism of the biological activity of the 1-nitro and 2-nitro aminoacridine derivatives containing the dimethylaminopropyl side chain was studied. RNA synthesis in the isolated rat liver nuclei was only slightly influenced by both compounds. They do not differ in their ability to form an intercalative complex with DNA. Only the 1-nitro derivative exhibited strong inhibitory effect on RNA biosynthesis and caused distinct ultrastructural changes (nucleolar segregation, chromatine margination etc.) in a living cell. The 1-nitro derivative binds covalently to DNA in vivo resulting in crosslink formation. It is concluded that the biological activity of 1-nitro acridine derivatives depends more on their crosslinking activity than on their ability to intercalate into DNA.