Mutation research. Genetic toxicology and environmental mutagenesis最新文献

There has been a shift from traditional animal models towards alternative methods. While 2D cell culture has a decade long tradition, more advances methods like 3D cultures, organoids, and co-culture techniques, which better mimic in vivo conditions, are not yet well established in every research area. Genotoxicity assessment is an integral part of toxicological testing or regulatory approval of pharmaceuticals and chemicals. The micronucleus assay is now a standard method in this context. In this systematic literature review, we aim to describe the state of the art of the application of co-cultures of two mammalian cell lines for micronucleus assessment. We summarized the cell types used, methods for co-culture, disease models and agents, as well as the application of additional genotoxicity endpoints and viability tests. Airway system cells were the most frequent, followed by macrophage-like cells, liver cells, and various others. Co-culture techniques involve either direct physical contact or separation by porous membranes. Within a limited number of investigations using other genotoxicity assays like the comet and γH2AX assays in parallel, the micronucleus assay performed well. Overall, the micronucleus test demonstrating its suitability in disease models and for a more complex substance testing beyond simple 2D cultures, encouraging a more widespread use in co-culture systems in the future.

Zinc oxide nanoparticles (ZnO-NPs) are of interest in biomedical applications, environmental remediation, and agriculture. ZnO-NPs inhibit the growth of phytopathogenic fungi and bacteria. We have evaluated their effects on mitochondrial function and the induction of membrane damage, apoptosis, and DNA damage in human peripheral blood mononuclear cells (PBMC) in vitro. ZnO-NPs caused significant reduction in cell viability and LDH release, indicating damage to cell membranes. Late apoptosis was significant and necrosis was significant at higher concentrations tested. ZnO-NPs did not induce micronucleus formation.

We have studied the presence and frequency of micronuclei in exfoliated oral mucosa cells of full-term newborns and their association with maternal prenatal factors. We report an analytical, observational, cross-sectional, prospective study that includes 97 preterm infants (<37 weeks), 37 newborns from mothers with comorbidities, and 60 newborns from mothers without comorbidities, in a tertiary public hospital. Oral mucosa cells were collected within 24 h after birth. The frequency of cells with micronuclei and karyolytic cells was significantly higher in the group whose mothers had some form of comorbidity. Mothers with comorbidities had a shorter gestational age; the number of cells with micronuclei was higher in mothers with preterm premature rupture of membranes; and there were fewer karyolytic cells.

Mutagenicity testing is a component of the hazard assessment of industrial chemicals, biocides, and pesticides. Mutations induced by test substances can be detected by in vitro and in vivo methods that have been adopted as OECD Test Guidelines. One of these in vivo methods is the Transgenic Rodent Assay (TGRA), OECD test guideline no. 488. An analogous in vitro TGRA has been described, but experience with this test method is limited. In this study, six in vivo TGRA positive mutagens were tested in the in vitro TGRA based on primary MutaMouse hepatocytes. In addition to the functional read-out of the lacZ reporter gene, induced mutations were analysed by next-generation sequencing (NGS). Five of the six in vivo TGRA positive mutagens (N-ethyl-N-nitrosourea (ENU), ethyl methanesulfonate (EMS), mitomycin C (MMC), benzo[a]pyrene (B[a]P), and azathioprine (AZA), but not cyproterone acetate) mutated the lacZ gene in vitro. NGS identified mutations which matched the mutagenic mechanisms described in the literature. The alkylating agent ENU induced a greater proportion of A:T to T:A transversions than did the other alkylating agent, EMS, whereas EMS increased smaller deletions (1-4 bp). G:C to T:A transversions accounted for the majority of mutations identified after treatments with MMC and B[a]P, both of which form monoadducts at the guanine N2 position. AZA induced mainly G:C to A:T transitions, explained by the structural similarity of one of its metabolites to guanine. An increased proportion of mid-size changes (0.3-2.5 kb) was detected only for the crosslinking mutagen MMC. The in vitro TGRA based on primary MutaMouse hepatocytes is a promising in vitro assay for the assessment of mutation induction, reflecting many aspects of the corresponding in vivo TGRA and allowing for mutation spectra analysis to evaluate the induced mutations.

Photodegradation of azilsartan yields a phenanthridine derivative (APP). We suspected that APP could be a DNA-reactive substance, since many phenanthridine derivatives are mutagenic. In silico quantitative structure-activity relationship analysis indicated potential mutagenicity of APP, due to DNA reactivity at the 6-aminophenanthridine moiety. However, APP was not mutagenic in the Ames test. Density functional theory (DFT) calculations showed that APP cannot intercalate into DNA, due to its nonplanar structure, resulting from steric hindrance of its phenanthridine and benzimidazole moieties.