RADIATION-INDUCED PLASMID DNA DAMAGE: EFFECT OF CONCENTRATION AND LENGTH

Integration of RNA-seq and ATAC-seq analyzes the effect of low dose neutron-γ radiation on gene expression of lymphocytes from oilfield logging workers

Objective: Although radiation workers are exposed to much lower doses of neutron-γ rays than those suffered in nuclear explosions and accidents, it does not mean that their health is not affected by radiation. Lower doses of radiation do not always cause morphological aberrations in chromosomes, so more sophisticated tests must be sought to specific alterations in the exposed cells. Our goal was to characterize the specific gene expression in lymphocytes from logging workers who were continuously exposed to low doses of neutron-γ radiation. We hypothesized that the combination of cell type-specific transcriptomes and open chromatin profiles would identify lymphocyte-specific gene alterations induced by long-term radiation with low-dose neutron-γ-rays and discover new regulatory pathways and transcriptional regulatory elements. Methods: Lymphocytes were extracted from workers who have been occupationally exposed to neutron-γ and workers unexposed to radiation in the same company. mRNA-seq and ATAC-seq (Assay for Transposase-Accessible Chromatin with high-throughput sequencing) were performed, followed integrative analysis to identify specific gene regulatory regions induced by neutron-γ radiation. A qPCR assay was then performed to verify the downregulation of RNA coding for ribosomal proteins and flow cytometry was used to detect ribosomal protein expression and cell cycle alterations. Results: We identified transcripts that were specifically induced by neutron-γ radiation and discovered differential open chromatin regions that correlated with these gene activation patterns. Notably, we observed a downward trend in the expression of both differentially expressed genes and open chromatin peaks. Our most significant finding was that the differential peak upregulated in ATAC-seq, while the differential gene was downregulated in the ribosome pathway. We confirmed that neutron-γ radiation leads to transcriptional inhibition by analyzing the most enriched promoters, examining RPS18 and RPS27A expression by qPCR, and analyzing protein-protein interactions of the differential genes. Ribosomal protein expression and cell cycle were also affected by neutron-γ as detected by flow cytometry. Conclusion: We have comprehensively analyzed the genetic landscape of human lymphocytes based on chromatin accessibility and transcript levels, enabling the identification of novel neutron-γ induced signature genes not previously known. By comparing fine-mapping of open chromatin and RNA reads, we have determined that neutron-γ specifically leads to downregulation of genes in the ribosome pathway, with pseudogenes potentially playing a crucial role.

Nanoscopic biodosimetry using plasmid DNA in radiotherapy with metallic nanoparticles

Nanoscopic lesions (complex damages), are the most lethal lesions for the cells. As nanoparticles have become increasingly popular in radiation therapy and the importance of analyzing nanoscopic dose enhancement has increased, a reliable tool for nanodosimetry has become indispensable. In this regard, the DNA plasmid is a widely used tool as a nanodosimetry probe in radiobiology and nano-radiosensitization studies. This approach is helpful for unraveling the radiosensitization role of nanoparticles in terms of physical and physicochemical effects and for quantifying radiation-induced biological damage. This review discusses the potential of using plasmid DNA assays for assessing the relative effects of nano-radiosensitizers, which can provide a theoretical basis for the development of nanoscopic biodosimetry and nanoparticle-based radiotherapy.

Plasma Damage Control: From Biomolecules to Cells and Skin

The antibacterial and cell-proliferative character of atmospheric pressure plasma jets (APPJs) helps in the healing process of chronic wounds. However, control of the plasma-biological target interface remains an open issue. High vacuum ultraviolet/ultraviolet (VUV/UV) radiation and RONS flux from plasma may cause damage of a treated tissue; therefore, controlled interaction is essential. VUV/UV emission from argon APPJs and radiation control with aerosol injection in plasma effluent is the focus of this research. The aerosol effect on radiation is studied by a fluorescent target capable of resolving the plasma oxidation footprint. In addition, DNA damage is evaluated by plasmid DNA radiation assay and cell proliferation assay to assess safety aspects of the plasma jet, the effect of VUV/UV radiation, and its control with aerosol injection. Inevitable emission of VUV/UV radiation from plasmas during treatment is demonstrated in this work. Plasma has no antiproliferative effect on fibroblasts in short treatments (t < 60 s), while long exposure has a cytotoxic effect, resulting in decreased cell survival. Radiation has no effect on cell survival in the medium due to absorption. However, a strong cytotoxic effect on the attached fibroblasts without the medium is apparent. VUV/UV radiation contributes 70% of the integral plasma effect in induction of single- and double-strand DNA breaks and cytotoxicity of the attached cells without the medium. Survival of the attached cells increases by 10% when aerosol is introduced between plasma and the cells. Injection of aerosol in the plasma effluent can help to control the plasma-cell/tissue interaction. Aerosol droplets in the effluent partially absorb UV emission from the plasma, limiting photon flux in the direction of the biological target. Herein, cold and safe plasma-aerosol treatment and a safe operational mode of treatment are demonstrated in a murine model.