DNA uptake stimulating protein from Neurospora crassa enhances DNA and oligonucleotide uptake also in mammalian cells.

The presence of the DNA uptake stimulating protein (designated earlier as DUSF by Schablik and Szabó (1981) FEMS Microbiol. Lett. 10, 395-397) was demonstrated on the surface of Neurospora crassa (FGSC 1118, slime) fungal cells as well as on HEp-2 and K562 human and F4N mouse tumor cells by immunofluorescence microscopy. DUSF markedly enhanced the uptake of both macromolecular [3H]DNA and of [3H]oligonucleotides by K562, HL-60 and also by DD human leukemia cells. Polyclonal anti-DUSF antibodies inhibited both the basal and stimulated [3H]oligonucleotide uptake by K562 cells. DNA-DNA hybridization has shown that the uptake of linearized pBR322 plasmid DNA into N. crassa and K562 cells was stimulated by DUSF, increasing proportionally with the length of incubation time. Unfragmented plasmid molecules were recovered from the cells. It is assumed that DUSF (or related proteins) may play a role in the physiological uptake of oligonucleotides and DNA not only in N. crassa but also in--at least some--mammalian cells.

Different effects of an oligonucleotide uptake stimulating protein on leukemic cells in their primitive and differentiated state.

The single stranded [3H]oligonucleotide uptake by HL-60 human promyelocyte and K562 human erythroleukemia cells was stimulated 20-45-fold by DUSF (DNA uptake stimulating protein), and this effect was drastically reduced (to 1.6-13x) if the cells were induced to differentiate. The oligonucleotide uptake stimulating effect of DUSF was not altered in HL-60 and K562 cells, if the proliferation of the cells was inhibited by hydroxyurea (HU) treatment. The oligonucleotide uptake by separated granulocytes and mononuclear cells from healthy donors was not stimulated by DUSF, while the uptake of oligonucleotides by myeloid and lymphoid leukemic cells was greatly stimulated (10-15x). The uptake of oligonucleotides by differentiated mononuclear cells of healthy donors could not be stimulated by DUSF, but the oligonucleotide uptake was greatly increased (11x) by DUSF if the cells were subjected to blast transformation.

Protease-elicited TUNEL positivity of non-apoptotic fixed cells.

The appearance of free DNA ends in the chromatin is usually considered an indication of advanced apoptosis. Unexpectedly, the nuclei of non-apoptotic cells derived from mouse thymuses could be specifically labeled by terminal transferase after proteinase K treatment of the fixed, cytocentrifuged samples. Artifactual mechanical or contaminating nucleolytic factors have been ruled out as players in the generation of free DNA ends. The phenomenon was detected in both formaldehyde- and ethanol-fixed specimens, in agarose-embedded fixed cells, and in chromatin spreads. By urea-agarose gel electrophoresis, the average single-strand size of the DNA molecules carrying the free ends was found between 50 and 250 kb. We suggest that ss discontinuities preexisting in the fixed normal cells are unmasked by protease treatment eliciting TUNEL (terminal transferase-mediated nick end-labeling) positivity.

Inhibition of the development of Q-bands on human chromosomes by netropsin.

Netropsin, an oligopeptide-type basic antibiotic, having exclusively A-T-specific DNA-binding affinity and situating itself into the minor groove of the double helix, represses the development of Q-bands if human chromosome preparations are treated with it before quinacrine mustard staining. The most probable interpretation of this effect is that netropsin interferes with the intercalation of the dye molecules. It is assumed this phenomenon supports the hypothesis that quinacrine mustard binds preferentially to A-T-rich sequences of DNA in the metaphase chromosomes.

X-linked recessive ichthyosis. Reinvestigation of a family first described in 1928.

Recent findings in a family with X-linked recessive ichthyosis are presented. The first description of this family in the literature was given and correctly diagnosed by Csörsz in 1928. His paper can be considered one of the most widely cited proofs of the existence of X-linked ichthyosis. The extended pedigree as well as data of steroid sulfatase and arylsulfatase C determinations presented in this paper verify the diagnosis of the X-linked mode of inheritance of ichthyosis in this family. The biochemical investigations carried out on leukocytes of family members resulted not only in a confirmation of the clinico-genetic diagnosis, but they also helped to establish the heterozygous genotype of a female mentioned previously as an affected person.

Progressive systemic sclerosis occurring in patients exposed to chemicals.

Eight patients with systemic sclerosis previously exposed to organic chemical agents were investigated. Laboratory and clinical data of these patients were evaluated. The interval between the beginning of exposition and symptoms was 6.1 +/- 4.9 years. Considering the laboratory findings, a slight decrease in OKT4 positive T cell number was found. The antinucleolar and fine speckled antinuclear antibody pattern was found simultaneously in five cases. The possible role of chemical agents in the development of sclerodermic changes is discussed.