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An increased level of mutagenesis, partially caused by imbalanced activities of error prone DNA polymerases, is a key symptom of cell malignancy. To clarify the possible role of incorrect DNA polymerase iota (Pol iota) function in increased frequency of mutations in mammalian cells, the activity of this enzyme in extracts of cells of different mouse organs and human eye (melanoma) and eyelid (basal-cell skin carcinoma) tumor cells was studied. Both Mg2+, considered as the main activator of the enzyme reaction of in vivo DNA replication, and Mn2+, that activates homogeneous Pol iota preparations in experiments in vitro more efficiently compared to all other bivalent cations, were used as cofactors of the DNA polymerase reaction in these experiments. In the presence of Mg2+, the enzyme was active only in cell extracts of mouse testicles and brain, whereas in the presence of Mn2+ the activity of Pol iota was found in all studied normal mouse organs. It was found that in cell extracts of both types of malignant tumors (basal-cell carcinoma and melanoma) Pol iota activity was observed in the presence of either Mn2+ or Mg2+. Manganese ions activated Pol iota in both cases, though to a different extent. In the presence of Mn2+ the Pol iota activity in the basal-cell carcinoma exceeded 2.5-fold that in control cells (benign tumors from the same eyelid region). In extracts of melanoma cells in the presence of either cation, the level of the enzyme activity was approximately equal to that in extracts of cells of surrounding tumor-free tissues as well as in eyes removed after traumas. The distinctive feature of tissue malignancy (in basal-cell carcinoma and in melanoma) was the change in DNA synthesis revealed as Mn2+-activated continuation of DNA synthesis after incorrect incorporation of dG opposite dT in the template by Pol iota. Among cell extracts of different normal mouse organs, only those of testicles exhibited a similar feature. This similarity can be explained by cell division blocking that occurs in all normal cells except in testicles and in malignant cells.

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Human DNA polymerase iota (Pol ι) is a Y-family DNA polymerase with unusual biochemical properties and not fully understood functions. Pol ι preferentially incorporates dGTP opposite template thymine. This property can be used to monitor Pol ι activity in the presence of other DNA polymerases, e.g. in cell extracts of tissues and tumors. We have now confirmed the specificity and sensitivity of the method of Pol ι activity detection in cell extracts using an animal model of loach Misgurnus fossilis embryos transiently expressing human Pol ι. The overexpression of Pol ι was shown to be accompanied by an increase in abnormalities in development and the frequency of pycnotic nuclei in fish embryos. Further analysis of fish embryos with constitutive or regulated Pol ι expression may provide insights into Pol ι functions in vertebrate animals.

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A PCR assay has been developed to identify the DNA of the human herpes virus type 7. The search and selection of conserved regions was carried out by comparing the whole genome nucleotide sequences of HHV-7. A fragment duplicated in the HHV-7 genomes was chosen as a target for amplification. The performance of the assay was tested on a synthetic matrix and clinical samples. The developed assay has high sensitivity and specificity and showed good efficiency in detecting HHV-7 DNA in clinical samples.

BACKGROUND: In recent years, thanks to the development of methods of molecular genetic analysis, microRNA has become one of the promising markers for the diagnosis of many human diseases. AIMS: to study microRNA as a new method for the diagnosis of fungal mycosis. MATERIALS AND METHODS: The study included 30 patients with histologically confirmed diagnosis of T-cell lymphomas of the skin, 25 were diagnosed with fungal mycosis, 5 ― Cesari syndrome. The control group consisted of 10 patients with benign lymphoproliferative dermatoses. The patients underwent the determination of microRNA 223, 16, 326, 663, 423, 711 in blood plasma. MicroRNA was also detected in plasma in patients with T-cell lymphomas of the skin at early and late stages. RESULTS: Statistically significant difference of 223, 16, 326, 711 microRNAs in blood plasma was revealed in patients with fungal mycosis, compared with patients with benign lymphoproliferative dermatoses. Statistically significant difference of 663 microRNA in blood plasma was revealed in patients with T-cell lymphomas of the skin at early and late stages. A statistically significant difference of 223, 711 microRNAs in blood plasma was revealed in patients with fungal mycosis at an early stage compared with patients with benign lymphoproliferative dermatoses. CONCLUSION: The determination of microRNA 223, 16, 326, 711 in blood plasma can be used for early diagnosis of T-cell lymphomas of the skin.