Mutation research. Genetic toxicology and environmental mutagenesis最新文献

Persons living in industrial environments are exposed to levels of air pollution that can affect their health and fertility. The Czech capital city, Prague, and the Ostrava industrial agglomeration differ in their major sources of air pollution. In Prague, heavy traffic produces high levels of nitrogen oxides throughout the year. In the Ostrava region, an iron industry and local heating are sources of particulate matter (PM) and benzo[a]pyrene (B[a]P), especially in the winter. We evaluated the effects of air pollution on human sperm mitochondrial DNA (mtDNA). Using real-time PCR, we analysed sperm mtDNA copy number and deletion rate in Prague city policemen in two seasons (spring and autumn) and compared the results with those from Ostrava. In Prague, the sperm mtDNA deletion rate was significantly higher in autumn than in spring, which is the opposite of the results from Ostrava. The sperm mtDNA copy number did not show any seasonal differences in either of the cities; it was correlated negatively with sperm concentration, motility, and viability, and with sperm chromatin integrity (assessed with the Sperm Chromatin Structure Assay). The comparison between the two cities showed that the sperm mtDNA deletion rate in spring and the sperm mtDNA copy number in autumn were significantly lower in Prague vs. Ostrava. Our study supports the hypothesis that sperm mtDNA deletion rate is affected by the composition of air pollution. Sperm mtDNA abundance is closely associated with chromatin damage and standard semen characteristics.

We have evaluated the induction of complete (i.e., without open ends) and incomplete (i.e., with non-rejoined or open ends) chromosomal aberrations by the radiomimetic antibiotic bleomycin (BLM) in human lymphoblastoid cells immortalized with the Epstein-Barr virus (EBV). An EBV-induced lymphoblastoid cell line (T-37) was exposed to BLM (10–200 µg/mL) for 2 h at 37ºC, and chromosomal aberrations were analyzed 24 h after treatment, using PNA-FISH with pan-telomeric and pan-centromeric probes. Both complete (multicentrics, rings, compound acentric fragments, and interstitial deletions) and incomplete (incomplete chromosomes or IC, and terminal acentric fragments or TAF) chromosomal aberrations increased significantly in BLM-exposed cells, although the concentration-response relationship was non-linear. Of the acentric fragments (ace) induced by BLM, 40 % were compound fragments (CF, ace +/+). TAF (ace, +/-) and interstitial fragments (IAF, ace -/-) were induced at similar frequencies (30 %). 230 ICE were induced by BLM, of which 52 % were IC and 48 % TAF. The average ratio between total incomplete chromosome elements (ICE) and multicentrics was 1.52. These findings suggest that human lymphoblastoid cells exhibit less repair capacity than human lymphocytes, with respect to BLM-induced ICE, and that chromosomal incompleteness is a common event following exposure of these cells to BLM.

Environmental pollution can affect immune health and genome stability. We have studied the immunological and cytogenetic status of healthy urban (Almaty City, which has high levels of air pollution) and rural residents of southern Kazakhstan, over the past 15 years. Differences between the groups in plasma immunoglobulin levels and chromosomal aberration frequencies were noted. Over the 15-year study period, decreases of immunoglobulin levels and increases of chromosomal aberration frequencies were observed and correlated with place of residence and ecological status of the region of residence; both ecological deterioration and the coronavirus pandemic are likely to have had negative effects.

Diabetes mellitus is known as the “epidemic of the century” due to its global prevalence. Several pre-clinical and clinical studies have shown that male germ cell toxicity is one of the major consequences of diabetes mellitus. Although β-aminoisobutyric acid (BAIBA) has been shown to be advantageous in the diabetic nephropathy and cardiomyopathy, its specific role in the diabetes-induced testicular toxicity remains unknown. In this study, an attempt was made to elucidate the molecular mechanisms of BAIBA-mediated germ cell protection in diabetic rats. Adult male Sprague-dawley rats were subjected to either no treatment (control) or BAIBA (100 mg/kg; BAIBA control) or Streptozotocin (50 mg/kg; diabetic control) or low (25 mg/kg), medium (50 mg/kg) and high (100 mg/kg) doses of BAIBA in diabetic conditions. Significant alterations in sperm related parameters, oxidative stress and apoptotic biomarkers, pancreatic and testicular histology, DNA damage and changes in expression of proteins in testes were found in the diabetic rats. 100 mg/kg of BAIBA significantly reduced the elevated blood glucose levels (P ≤ 0.05), increased body weight (P ≤ 0.01 in the 4th week), lowered malondialdehyde (P ≤ 0.05) and nitrite levels (P ≤ 0.01), elevated testosterone (P ≤ 0.05) and FSH levels (P ≤ 0.05), increased sperm count and motility (P ≤ 0.01), decreased testicular DNA damage (P ≤ 0.001), improved histological features of pancreas and testes, decreased TUNEL positive cells (P ≤ 0.01), decreased RAGE (P ≤ 0.01) and Bax (P ≤ 0.05) expressions and increased SIRT1 (P ≤ 0.05) and Atg 12 (P ≤ 0.05) expressions in the testes. 50 mg/kg of BAIBA partially restored the above-mentioned parameters whereas 25 mg/kg of BAIBA was found to be insignificant in counteracting the toxicity. It is interesting to note that BAIBA protects male germ cell damage in diabetic rats by regulating the IGF-1/AMPK/SIRT-1 signaling pathway.

Safety evaluation is essential for the development of chemical substances. Since in vivo safety evaluation tests, such as carcinogenesis tests, require long-term observation using large numbers of experimental animals, it is necessary to develop alternative methods that can predict genotoxicity/carcinogenicity in the short term, taking into account the 3Rs (replacement, reduction, and refinement). We established a prediction model of the hepatotoxicity of chemicals using a DNA adductome, which is a comprehensive analysis of DNA adducts that may be used as an indicator of DNA damage in the liver. An adductome was generated with LC-high-resolution accurate mass spectrometer (HRAM) on liver of rats exposed to various chemicals for 24 h, based on two independent experimental protocols. The resulting adductome dataset obtained from each independent experiment (experiments 1 and 2) and integrated dataset were analyzed by linear discriminant analysis (LDA) and found to correctly classify the chemicals into the following four categories: non-genotoxic/non-hepatocarcinogens (−/−), genotoxic/non-hepatocarcinogens (+/−), non-genotoxic/hepatocarcinogens (−/+), and genotoxic/hepatocarcinogens (+/+), based on their genotoxicity/carcinogenicity properties. A prototype model for predicting the genotoxicity/carcinogenicity of the chemicals was established using machine learning methods (using random forest algorithm). When the prototype genotoxicity/carcinogenicity prediction model was used to make predictions for experiments 1 and 2 as well as the integrated dataset, the correct response rates were 89 % (genotoxicity), 94 % (carcinogenicity) and 87 % (genotoxicity/carcinogenicity) for experiment 1, 47 % (genotoxicity), 62 % (carcinogenicity) and 42 % (genotoxicity/carcinogenicity) for experiment 2, and 52 % (genotoxicity), 62 % (carcinogenicity), and 48 % (genotoxicity/carcinogenicity) for the integrated dataset. To improve the accuracy of the toxicity prediction model, the toxicity label was reconstructed as follows; Pattern 1: when +/+ and −/− chemicals were used from the toxicity labels +/+, +/−, −/+ and −/−; and Pattern 2: when +/+, +/−, and −/+ other than −/− were replaced with the label "Others". As a result, chemicals with only +/+ and −/− toxicity labels were used and the correct response rates were approximately 100 % for the measured data in experiment 1, 53 %–66 % for the data in experiment 2, and 59–73 % for the integrated data, all of which were 10 %–30 % higher compared with the data before the label change. In contrast, when the toxicity labels were replaced with −/− and “Others”, they reached nearly 100 % in the measured data from experiment 1, 65 %–75 % in the data from experiment 2, and 70 %–78 % in the integrated data, all of which were 10 %–50 % higher compared with the data before the label change.

The aim of this study was to evaluate the in vitro cytotoxic, genotoxic, and mutagenic potential and to determine the in silico ADME parameters of two synthetic β-carboline alkaloids developed as prototypes of antitumor agents (NQBio-06 and NQBio-21). Additionally, acute toxicity of the compounds was evaluated in mice. The results from the MTT assay showed that NQBio-06 presented higher cytotoxicity in the ovarian cancer cell line TOV-21 G (IC₅₀ = 2.5 µM, selectivity index = 23.7). NQBio-21 presented an IC₅₀ of 6.9 µM and a selectivity index of 14.5 against MDA-MB-231 breast cancer cells. Comet assay results showed that NQBio-06 did not induce chromosomal breaks in vitro, but NQBio-21 was genotoxic with and without metabolic activation (S9 fraction). Micronucleus assay showed that both compounds were mutagenic. In addition, metabolic activation enhanced this effect in vitro. The in silico predictions showed that the compounds met the criteria set by Lipinski's rules, had strong prediction for intestinal absorption, and were possible substrates for P-glycoprotein. The in vivo results demonstrated that both the compounds exhibited low acute toxicity. These results suggest that the mechanisms underlying the cytotoxicity of NQBio-06 and NQBio-21 are related to DNA damage induction and that the use of S9 enhanced these effects. In vivo analysis showed signs of toxicity after a single administration of the compounds in mice. These findings highlight the potential of β-carboline compounds as sources for the development of new anticancer chemotherapeutic agents.

These days, exposure to electromagnetic fields has become omnipresent in modern society. Not only the extremely-low frequency and radiofrequency, but also intermediate frequency (IF) magnetic field (MF) might be absorbed in the human body resulting in an ever-growing concern about their possible health effects. Devices, such as induction cooktops, chargers, compact fluorescent lamps, touchscreens and electric vehicles emit a wide range of intermediate frequency fields. We investigated the effects of 22 kHz or 250 kHz intermediate frequency magnetic field exposure on the human skin cells. We also examined the adaptive response phenomenon; whether IF MF exposure could possibly reduce the harmful genotoxic effects of ionizing radiation. To get answers to these questions, in vitro studies were carried out on fibroblast cells to investigate the effects on oxidative stress, DNA damage and micronucleus formation. We found a decreased micronucleus formation due to the 22 kHz IF MF exposure and significantly increased oxidative stress in fibroblast cells, which were exposed only to 250 kHz IF MF. We were unable to detect the protective or co-genotoxic effects of intermediate frequency magnetic field exposure combined with ionizing radiation, thus we found no evidence for the adaptive response phenomena.

Long-term exposure to fine particulate matter (PM_2.5) can lead to chronic lung injury, including inflammation, idiopathic pulmonary fibrosis, and cancer. Mesenchymal cells, such as fibroblasts, myeloid-derived suppressor cells (MDSCs), and interstitial macrophages (IMs), contribute to immune regulation in lung, yet their diversity and functions upon long-term exposure to particulate matter (PM) remain inadequately characterized. In this study, we conducted a 16-week real-ambient PM exposure experiment on C57BL/6 J male mice in Shijiazhuang, China. We used single-cell RNA sequencing to analyze the cellular and molecular changes in lung tissues. Notably, we revealed a significant increase in specific fibroblast (ATX⁺, Col5a1⁺Meg3⁺, universal fibroblasts) and monocyte-derived cell subpopulations (monocytic-MDSCs (M-MDSCs), Lyve1^loMHC-Ⅱ^hi IMs, Lyve1^hiMHC-Ⅱ^lo IMs) that exhibited pro-inflammatory and pro-fibrotic functions. These cell subpopulations engaged in immunosuppressive signaling pathways and interactions with various cytokines, shaping a pulmonary microenvironment similar to those associated with cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs). This altered immune environment may promote the development of pulmonary fibrosis caused by PM exposure, underscoring the intricate roles of mesenchymal cells in chronic lung injury and highlighting the cancer-causing potential of PM_2.5 exposure.

Heavy metals like arsenic is ubiquitously present in the environment. Geologic and anthropogenic activities are the root cause behind high concentration of arsenic in natural water bodies demanding strict monitoring of water quality prior to human consumption and utilization. In the present study, we have employed Daphnia magna for studying the biological effects of environmentally relevant high concentration of arsenic in water. In acute toxicity study, the LC₅₀ value for 24hr exposure was found to be 2.504 mg/L, which gradually decreased with increase in time period (24hr- 96hr) to 2.011 mg/ L at 96hr. Sub-chronic toxicity was evaluated over 12 days using sub-lethal concentrations (5 %, 10 %, 15 %, and 20 % of the 24-hr LC₅₀). Survivability in Daphnia showed a decreasing trend from 96 % to 91 % with increase in arsenic concentrations from 5 % of LC₅₀ 24 hr value to 20 % of LC ₅₀ 24hr value respectively. Alongside decreased survivability, there was a significant reduction in body size, with organisms exposed to the highest concentration of arsenic measuring 0.87±0.01 mm compared to 1.51±0.10 mm in the control group. Reproductive potential declined concentration dependently with exposure, with the highest reduction observed at 20 % of LC₅₀ 24hr value, where offspring numbers decreased to 7±1 from 23±5 in the control. Heart rate decreased in concentration and time-dependent manners, with the lowest rates observed at the highest arsenic concentration (279±16 bpm after 24hr and 277±27 bpm after 48hr). Comet assay and micronucleus assay conducted after 48 hrs of exposure revealed concentration-dependent genotoxic effects in Daphnia magna. Our results indicate negative impact on physiology and reproduction of Daphnia magna at environmentally existent concentration of arsenic. Also Daphnia magna could serve as a sensitive test system for investigating arsenic contamination in water bodies.

Papillary thyroid carcinoma (PTC) is a common endocrine cancer with a good prognosis. Radioactive iodine is thought to be useful for individuals who have had a total or almost total thyroidectomy, but its effects are still controversial. The effects of radioactive iodine-131 (I-131) treatment on oxidative and chromosomal damage in PTC patients were examined in this study, which was carried out with 16 patients newly diagnosed with PTC and 20 healthy control subjects with similar age and gender. Blood samples were taken from patients with PTC at five sampling times (before total thyroidectomy, after total thyroidectomy, and seven days, six months, and one year after treatment) and from control subjects. The cytokinesis block micronucleus cytome (CBMN-cyt) assay parameters in peripheral blood lymphocytes of patients with PTC and controls were evaluated and plasma 8-hydroxydeoxyguanosine (8-OHdG) levels were measured. Furthermore, genome instability and oxidative DNA damage in peripheral blood lymphocytes and plasma of patients with PTC were evaluated before total thyroidectomy (n=16), after total thyroidectomy (before I-131 treatment) (n=16), seven days (n=10), six months (n=5), and one year after treatment (n=5). The numbers of CBMN-cyt assay parameters (micronucleus; MN and nucleoplasmic bridges; NPB) and 8-OHdG levels in patients with PTC were determined to be significantly higher than in those of the control subjects and these values significantly decreased after total thyroidectomy (before I-131 treatment). While the number of MN, apoptotic, and necrotic cells increased after I-131 treatment, it significantly decreased after six months and one year after treatment. The results achieved in this study suggest that I-131 treatment may pose a threat to cells and that radioactive iodine therapy should be avoided (if possible) for patients with PTC after total thyroidectomy.