Biology and Life Sciences

Abstract: Fruits and vegetables constitute a significant component of the daily diet of the Kuwaiti population, and are among the most pesticide-intensive commodities in agriculture. The study assessed the level of pesticide residues in locally produced and imported fruits and vegetables, and the potential dietary health risks associated with their consumption among different age groups in Kuwait. A total of 505 foreign and 306 local fruit and vegetable samples were analyzed for the presence of 290 pesticides using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) multi-residue extraction, followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) or liquid chromatography-tandem mass spectrometry (LC-MS/MS). Pesticide residues above the maximum residue limits (MRL) were detected in 24% and 14% of the foreign and local vegetable samples, respectively. Residues above the MRL were detected in 31% of the foreign fruit samples and in 42% of the local samples. Fruit and vegetable samples with more than one residue were more frequently found in samples of foreign origin. Of the 290 pesticides investigated, 46 were detected, of which 74% were found to exceed the MRLs. The pesticide residues detected do not pose a risk to human health based on short-term (acute) exposures, but can pose long-term (chronic) health effects, at least for infants and children, following cumulative exposure. The estimated chronic hazard index (cHI) values were above 100% for infants and children, 144.85% and 107.48, respectively. These findings underscore the need for continuous pesticide residue monitoring, stricter enforcement of pesticide laws and regulations, and promoting alternatives to chemical pest control in agriculture to ensure food safety and protect consumer health.

Abstract: Background: Snakebite envenomation is a common and potentially life-threatening emergency in dogs, particularly in regions where elapid and viperid snakes are endemic. Secreted phospholipase A2 is a major toxic component of snake venom responsible for myotoxicity, neurotoxicity, hemolysis, and coagulopathy. Currently, no point-of-care tool exists to objectively quantify circulating venom burden at presentation, so clinicians rely on subjective assessment of clinical signs to guide antivenom dosing, often resulting in under- or over-treatment. Methods: We developed and analytically validated a lateral flow immunoassay strip for rapid, quantitative detection of serum snake venom (sv)PLA2 following envenomation by Micrurus fulvius (eastern coral snake). The assay employs a sandwich immunodetection strategy in which svPLA2 is captured between a FITC-labeled and a biotinylated anti-PLA2 polyclonal antibody, forming a gold nanoparticle-labeled complex that produces a visible test line at a streptavidin capture zone and a control line at an anti-FITC line. A standard curve was generated from serial dilutions of svPLA2 and fit to a log-linear regression model. The assay was then applied to serum samples from eight clinical canine patients. Results: The standard curve followed the equation y = 277,524·ln(x) − 571,808 (R² = 0.973), yielding a limit of detection of approximately 2.4 µg/mL and a limit of quantification of approximately 14.3 µg/mL. Among the eight patient samples, three showed no detectable svPLA2 (true negatives), while five showed clearly elevated signal consistent with envenomation, with intensity varying widely across positive samples, reflecting known variability in venom yield. One sample fell between the LOD and LOQ and was interpreted qualitatively as positive without quantitative estimation. Conclusions: This lateral flow strip assay reliably and rapidly distinguishes envenomated from non-envenomated dogs and stratifies relative svPLA2 burden. This platform offers a practical, equipment-light diagnostic tool to guide antivenom dosing decisions and may serve as a companion diagnostic for emerging PLA2-targeted therapies.

Abstract: Electronic cigarettes are widely promoted as a less harmful alternative to conventional cigarettes, but their cellular effects remain incompletely defined and may vary by flavouring composition. This study examined the effects of four flavoured e-cigarette aerosols, cigarette smoke, and nicotine on human THP-1 monocytic cells, focusing on cytotoxicity, oxidative stress, inflammatory activation, adhesion, and phagocytic function. Cells were exposed for 24 hours to conditioned media generated using a standardised puffing protocol and then analysed by microscopy, trypan blue exclusion, flow cytometry, and dual-fluorescence scatterplot analysis. Cigarette smoke-conditioned medium produced the greatest acute toxicity, significantly increasing cell death, membrane damage, and DNA fragmentation. In contrast, the tested e-cigarette aerosol-conditioned media and nicotine alone produced little overt cytotoxicity under the same experimental conditions. However, e-cigarette exposures increased cell adhesion and were associated with formulation- and cell subpopulation–dependent changes in CD11a, CD11b, and CD54 expression. E-cigarettes increased intracellular DCF-associated oxidative fluorescence and TNF expression, with the watermelon and strawberry formulations producing the strongest responses. Nicotine alone did not reproduce these pro inflammatory/pro oxidant effects to the same extent as the full aerosol. Instead, in non adherent cells, nicotine behaved more like an antioxidant/anti inflammatory agent, while in adherent cells, it showed a tendency toward pro oxidant/pro inflammatory behaviour, though generally weaker than cigarette smoke and e cigarette aerosols. These effects indicate that other aerosol components substantially contribute to biological activity, and the effect may be bimodal. Phagocytosis was reduced in selected groups, suggesting that some exposures may impair this cellular function. Bivariate fluorescence revealed exposure-dependent differences in the relationship between oxidative stress and TNF expression, with cigarette smoke producing the most pronounced disruption. Overall, these findings support the potential utility of bivariate fluorescence analysis as a complementary in vitro approach for detecting and comparing oxidative and inflammatory cellular responses to different e-cigarette aerosols.

Abstract: The widespread presence of nanoplastics (NPs) of different sizes and polymer compositions in aquatic ecosystems has raised increasing concern. Yet, their quantification remains difficult due to analytical limitations. Metal-doped model NPs offer a useful approach in toxicological studies enabling more quantitative assessment of NPs occurrence in organisms. This study provides a novel link between quantitative NP uptake and their transcriptomic effects in Acartia tonsa, highlighting the influence of polymer composition and exposure route. This study examined transcriptional responses in the marine copepod following both waterborne and foodborne exposure to NPs of varying sizes and polymer types, including polystyrene (PS) with and without a palladium tracer (Pd-doped PS and PS) as well as gold-doped polyvinyl chloride (Au-doped PVC), polypropylene (Au-doped PP) and polyethylene (Au-doped PE) NPs. Accumulation of Pd or Au was measured as a proxy of NPs in microalgae, copepods and their feces. All studied NPs were found in the feces. In exposed copepods, Pd-doped PS NPs showed the highest accumulation within organisms, followed by Au-doped PP NPs. These differences in accumulation may be influenced by the physicochemical properties of the NPs. The presence of Au/Pd-doped PS NPs in copepods and the routes of exposure were linked to alterations of transcription levels of general and oxidative stress genes. In contrast, non-doped PS NPs of different sizes did not affect the transcription levels of the selected genes. Overall, this study demonstrates that NP accumulation and excretion, as well as the molecular mechanisms regulated in A. tonsa, vary depending on NP polymer chemistry as well as on the exposure route.

Abstract: Electronic cigarette aerosols contain complex mixtures of flavoring chemicals and metals released from device components, yet the biological effects of these constituents in combination remain poorly understood. We examined the effects of vanillin, WS23, ethyl vanillin, p-anisaldehyde, and nickel oxide (NiO), alone and in selected mixtures at different ratios, in BEAS-2B human bronchial epithelial cells. Each flavoring chemical reduced metabolic activity and cellular ATP in a concentration-dependent manner. Chou–Talalay analysis showed synergistic interactions between vanillin and WS23 (combination index (CI) < 1) and antagonistic interactions between ethyl vanillin and p-anisaldehyde (CI > 1). Ethyl vanillin (100 µM), NiO (50 µg/cm²), and their combination did not significantly reduce cell viability but were associated with increased interleukin-6 (IL-6) and interleukin-8 (IL-8) in conditioned medium. Total H2AX abundance was unchanged by aldehyde-metal combinations. However, endonuclease VIII-like 2 (NEIL2) showed nonsignificant increases following NiO and combined exposure, whereas polynucleotide kinase 3′-phosphatase (PNKP) increased significantly following ethyl vanillin and combined ethyl vanillin–NiO exposure, suggesting the base-excision repair (BER) pathway mitigating oxidative damage. We show that e-cigarette constituents at relevant concentrations as a mixture may induce oxidative damage but can be repaired by BER. These findings demonstrate that e-cigarette constituents can produce mixture-dependent responses that are not predicted by individual exposures and the inflammatory and DNA-repair-associated responses observed under noncytotoxic conditions warrant further investigation.

Abstract: Background/Objectives: Ultraviolet C (UVC) disinfection devices have been widely adopted since the COVID-19 pandemic. Short UVC exposure reportedly exerts greater cytotoxicity against cancer cells than normal cells. This study examined whether this differential sensitivity is associated with rapid, cancer-cell-specific changes in intracellular metabolites. Methods: Two malignant/non-malignant cell pairs were examined: COLO 679 melanoma cells and human dermal fibroblasts (HDFa), and Ca9-22 gingival carcinoma cells and human gingival fibroblasts (HGF). Viability was assessed using the MTT assay, and metabolites extracted immediately after irradiation were quantified by capillary electrophoresis–time-of-flight mass spectrometry. Results: UVC caused a time-dependent reduction in viability that reached a plateau after 48 h. Sensitivity decreased in the following order: cancer cells, young normal cells, and normal cells at advanced population doubling levels. Baseline metabolic profiles differed markedly between malignant and non-malignant cells. UVC significantly altered 27 of 139 metabolites in Ca9-22 cells, 56 of 142 in HGF, 7 of 136 in COLO 679, and 18 of 129 in HDFa. All four cell types accumulated the pentose phosphate pathway intermediates 6-phosphogluconate and ribulose 5-phosphate, whereas the glycolytic intermediates fructose 6-phosphate, 3-phosphoglycerate, and phosphoenolpyruvate decreased. Succinate decreased in both gingiva-derived cell types. Glutathione, NAD-related metabolites, and ATP showed no marked immediate changes. Conclusions: No cancer-cell-specific metabolic response was identified. Instead, UVC induced a common pattern characterized by the accumulation of pentose phosphate pathway intermediates and the depletion of glycolytic intermediates. This pattern may reflect an early response supporting nucleotide synthesis for DNA repair that is subsequently disrupted, potentially in association with mitochondrial dysfunction.

Abstract: Microplastics (MP), including tire wear particles, are increasingly detected in aquatic environments where they may interact with co-occurring contaminants such as heavy metals (HM). However, the influence of metal loading on MP–plant interactions and subsequent biological responses remains poorly understood. This study investigated how heavy metal loading modifies the behavior of mixed MP and their effects on two aquatic macrophytes, Lemna minor L. and Spirodela polyrhiza (L.) Schleid. Mixtures of polyethylene, polypropylene, polystyrene, and tire rubber particles were tested in both virgin and HM-loaded forms, with the latter preincubated with Cu, Zn and Pb. Duckweed species were exposed to MP concentrations ranging from 20 to 10,000 particles/L for seven days. HM-loaded MP released Cu and Pb into the plant-free exposure medium, whereas Cu release was also detected from the nominally virgin MP mixture. Cu accumulation occurred in both duckweed species, indicating transfer of MP-associated metals to aquatic plants. MP adsorption increased with exposure concentration and was higher in L. minor than in S. polyrhiza, with polypropylene showing the strongest association with plant surfaces. Metal loading reduced MP adsorption at intermediate concentrations, indicating that adsorbed metals can influence MP–plant interactions in a polymer- and concentration-dependent manner. Although MP exposure did not significantly affect growth, chlorophyll a content and antioxidant/detoxification enzyme activities were altered, particularly in L. minor. Overall, the results demonstrate that heavy metal loading modifies microplastic behavior and influences metal availability and sublethal responses in aquatic plants.

Abstract: Microplastics (MPs) are ubiquitous marine pollutants that pose increasing ecological risks, yet their effects on intestinal physiology and gut microbial homeostasis during the juvenile developmental stages of Tachypleus tridentatus remain unclear. In this study, fifth- and sixth-instar juveniles of T. tridentatus were exposed to environmentally relevant concentrations of 6.0 μm polystyrene microplastics (PS-MPs; 0, 10², and 10⁴ particles/L) for 7 and 21 days to investigate intestinal toxicity and its underlying mechanisms. Intestinal accumulation, oxidative stress, innate immune responses, and gut microbiota were comprehensively evaluated. PS-MPs exposure induced dose- and time-dependent alterations in superoxide dismutase, catalase, malondialdehyde, and lysozyme, indicating excessive oxidative stress, impaired antioxidant defense, and compromised innate immunity. Fifth-instar juveniles exhibited stronger oxidative stress and immune responses than sixth-instar individuals, suggesting higher susceptibility during earlier developmental stages. Gut microbiota analysis revealed pronounced dysbiosis, characterized by a reduced relative abundance of Firmicutes, enrichment of Proteobacteria, depletion of beneficial taxa (e.g., Lactococcus), and increased abundance of opportunistic bacteria, including Pseudomonas and members of Enterobacteriaceae. These physiological and microbial alterations collectively suggest that environmentally relevant PS-MPs impair intestinal homeostasis in juvenile T. tridentatus by inducing oxidative imbalance, modifying innate immune responses, and reshaping gut microbial communities, with clear instar- and exposure time-dependent effects. These findings highlighting the importance of developmental stages in ecological risk assessment for benthic arthropods.

Abstract: Epidemiological studies have identified the developing brain as a target of concern for polychlorinated biphenyls (PCBs). In animal models, behavioral deficits caused by developmental exposure to PCBs have been associated with altered patterns of dendritic arborization in functionally relevant brain regions. In vitro studies revealed that PCB 95 promoted dendritic growth in primary rat hippocampal neuron-glia co-cultures via ryanodine receptor 1 (RYR1)-dependent Ca²⁺ signaling. However, it is not yet known whether RYR1 dysregulation contributes to disruption of dendritic morphogenesis in the intact developing brain, or whether PCB 95 affects translationally relevant behavioral endpoints in juvenile animals. To address these data gaps, we assessed Morris water maze (MWM) performance and dendritic arborization of hippocampal CA1 pyramidal neurons in C57BL/6 mice heterozygous for the human R163C-RYR1 gain-of-function mutation (HET) and congenic wild-type (WT) littermates exposed to vehicle or PCB 95 at 0.1, 1.0, or 6.0 mg/kg/d in the dam’s diet from conception through weaning. MWM performance was not altered in HET vehicle controls relative to WT vehicle controls; however, compared to genotype-matched vehicle controls, spatial learning was impaired in WT and HET male and female weanlings in the 1.0 mg/kg/d PCB 95 dose group and WT males in the 6.0 mg/kg/d PCB 95 dose group. Spatial memory was altered only in WT females exposed to 1.0 or 6.0 mg/kg/d PCB 95. Sholl analyses of Golgi-stained hippocampal neurons in male and female WT and HET weanling from the 1.0 mg/kg/d PCB 95 and vehicle groups indicated that relative to WT vehicle controls, basal dendritic arborization was significantly increased in in HET vehicle controls and in PCB 95-exposed WT weanlings; however, PCB 95 did not alter basal dendritic growth in HET weanlings relative to genotype-matched vehicle controls. PCB 95 significantly reduced training-induced dendritic arborization in WT but not HET weanlings. Measurement of tritiated ryanodine ([³H]Ry) binding in cortical tissue from these same animals revealed interactions between genotype, PCB 95 exposure and dose altered [³H]Ry binding relative to WT vehicle controls. Quantitative analyses confirmed a dose-dependent increase in PCB tissue burden that was not significantly altered by genotype, MWM training, or sex. Serum levels of progesterone, estradiol, cortisol and thyroid hormone (TH), and brain transcript levels of TH-responsive genes were not significantly altered by genotype or PCB 95 dose. These data demonstrate that PCB 95 caused behavioral deficits coincident with altered patterns of basal and training-induced dendritic arborization. Furthermore, behavioral and dendritic responses to PCB 95 were altered by expression of the human R163C-RYR1 gain-of-function mutation, supporting a role for RYR-dependent mechanisms in PCB 95 DNT in vivo.

Abstract: Chirantodendron pentadactylon L., known in Mexico City as “flor de manita”, is a plant native to Mexico that is used traditionally in gastrointestinal, cardiovascular, and neurological diseases. This study looked at its potential toxicity using computer models and animal testing. Many people believe that “natural” means “safe,” but this can lead to unregulated use and health risks because some compounds can be toxic. Using computer-based toxicology, researchers analyzed thirty-eight compounds from the flowers of Ch. pentadactylon. They found that 65.8% of the compounds were potentially harmful to the liver, 63.1% mutagenic, 63.5% carcinogenic, 7.8% posed risks to the heart, and 15.7% could affect reproduction. However, 84.2% of these compounds had predicted lethal doses (LD₅₀) greater than 1000 mg/kg. In tests on CD1 mice using water extracts, there were no signs of toxicity or death at doses up to 5000 mg/kg. The Integrative Toxicity Prediction Model suggests that the dried water extract (AEDF) is safe, with a protection value of 0.5332 compared to a toxicity value of 0.0395. This resulted in a safety-to-risk ratio of 13.5. A further analysis estimated a 38.45% chance of toxicity and a 61.55% chance of non-toxicity, placing the extract in a low-risk category for toxicity. These findings suggest that predicting toxicity from single ingredients might overstate the dangers of using combined plant materials. The safety of this plant appears to come from the high levels of beneficial compounds that protect against toxic effects. More long-term studies are needed to check for any cumulative risks.

Abstract: Background: Maternal smoking during pregnancy remains a significant public health concern. The molecular mechanisms underlying smoking-induced maternal-fetal impact remain incompletely understood. The objective of this study is to identify adductomic signatures of oxidant stress in cord blood associated with tobacco exposure during pregnancy. Methods: Through a prospective longitudinal cohort of mother-infant dyads enrolled at a single birth center (Chicago, IL) from 2008-2021, we linked prenatal maternal smoking status data to an existent database of 105 addition products (adducts) measured in cord blood plasma. Principal component analysis (PCA) and volcano plot analysis identified differential adduct profiles according to maternal smoking status using PERMANOVA (p≤0.05). Results: Among 158 births included in the analysis, 6 women reported currently smoking, 26 were former smokers, and 126 identified as never smokers. PCA revealed significant separation between current smokers and both other groups (p≤0.002), with R² effect sizes of 0.026 for current vs never smokers and 0.115 for current vs former smokers. Among 56 known (annotated) adducts of oxidant stress, 33 were significantly upregu-lated in current versus never smokers, and 34 were upregulated in current versus former smokers. Maternal chronic hypertension, but not preeclampsia or other covariates, was associated with current smoking status (P=0.001). Conclusions: Maternal smoking during pregnancy is associated with distinct cord blood adductomic signatures of oxidant stress. The persistence of these changes in current but not former smokers suggests potential reversibility upon smoking cessation.

Abstract:

The GARDskin DR assay is a non-animal method that predicts dermal sensitization potency of discrete compounds. This comparative analysis evaluates outputs from a component-based prediction model (CP), GARDskin DR, and historical local lymph node assays (LLNA) exploring the applicability of CP and GARDskin DR for evaluating the sensitization potencies of essential oils. Eight well-studied essential oils were selected including cedarwood, cinnamon bark, clove bud, geranium, lavender, lemongrass, spearmint, and tea tree oils. Each underwent GC-MS and GARDskin DR analysis. CP model outputs, GARDskin DR and reference LLNA data were compared using standard statistical methods. Spearman’s test shows significant correlation between NESIL_CP vs. NESIL_GARD (0.881, p = 0.007) and NESIL_LLNA (0.929, p = 0.007) but not between NESIL_GARD vs. NESIL_LLNA (0.607, p = 0.17). Friedman’s test detected a significant difference among methods (χ²(2) = 7.71, p = 0.021), with post hoc tests showing relatively greater NESIL_CP values. Kendall’s W shows overall strong statistical concordance between methods (0.857, p = 0.017). NESIL_GARD and NESIL_CP generally align with NESIL_LLNA for the essential oils tested, although the CP method yields greater values. With the limited number of materials tested, results should be interpreted descriptively but show promise for GARDskin DR and CP for evaluating dermal sensitization potency of essential oils.

Abstract: Natural products represent an important source of bioactive compounds with therapeutic potential in the fields of thrombotic and oxidative stress related disorders. The antiplatelet and hepatoprotective activity of ethanolic leaf extract of Ocimum sanctum L. was studied. Collagen-induced human platelet activation (CIHPA) and CCl₄-induced hepatotoxicity were used in rats as models to assess the (EEOSL) activity. EEOSL (1-10 mg/mL) showed to significantly and dose-dependently inhibit collagen-induced platelet aggregation. The extract also inhibited P-selectin expression, ATP release and intracellular Ca²⁺ mobilization, suggesting inhibition of major pathways in platelet activation. To understand the mechanisms, molecular docking was carried out with signaling molecules of platelets such as GPVI, SYK, PLCγ2, P2RY12, and PI3Kβ. Some phytoconstituents have good binding affinities, apigenin having the highest binding affinity to PI3Kβ (−8.01 kcal/mol), and binding was further validated by molecular dynamics simulations showing the formation of stable complexes. Intravenous injection of CCl₄ significantly increased the serum hepatic markers (SGOT, SGPT, LDH and SALP); the EEOSL treatment significantly reduced these increases in vivo. The extract normalized antioxidant enzyme activities (catalase, SOD and glutathione peroxidase) and antioxidant isozyme patterns. Histopathological results revealed a significant level of protection against liver damage. Overall, the results showed that EEOSL has strong antiplatelet and hepatoprotective properties, likely due to its ability to modulate platelet signaling pathways and increase antioxidant defense mechanisms.

Abstract: Animal models are standard for safety evaluation, yet physiological differences limit human translation. Doxorubicin (DOX), a chemotherapeutic, can cause off-target gastrointestinal (GI) toxicity and treatment discontinuation. This study evaluated human colonoids as a potential human-relevant epithelial model for DOX-induced GI toxicity by comparing transcriptomic responses across human colonoids, mouse colonoids, and male C57BL/6J mouse colon tissue. Within each dataset, DOX-treated conditions were pooled across model-specific exposure levels and time points to prioritize robust DOX-associated transcriptional signatures. Using a parallelogram approach, differential expression, co-expression, pathway mapping, and Comparative Toxicogenomics Database (CTD) benchmarking were applied to compare model concordance and identify DOX-responsive mechanisms. Shared responses converged on cell-cycle regulation, DNA damage response, DNA repair, and apoptosis. DEG-level concordance was highest between mouse colonoids and mouse colon, while pathway mapping showed similarities between colonoid systems. A core set of p53-associated genes, including BAX, INKA2, and ZMAT3, was shared across datasets, with additional apoptotic and DNA damage response features observed in colonoids. CTD benchmarking supported DOX biology and highlighted underrepresented GI-relevant signals, indicating gaps in intestinal toxicogenomic annotations. Colonoid-based transcriptomics supports human colonoids as controlled epithelial models for mechanistic GI toxicity assessment, although missing vascular, immune, and systemic context means clinical validation remains necessary.

Abstract: Background: VERO cells, derived from the kidney epithelium of the African green monkey, are widely used in virology, but their ability to metabolize xenobiotics is not fully understood. Since cytochrome P450 (CYP) enzymes participate in xenobiotic metabolism, we investigated which CYP genes are expressed in VERO-E6 cells. Methods: Reverse Transcription- quantitative Polymerase Chain Reaction (RT-qPCR) showed that VERO-E6 cells express CYP3A4, CYP3A5, and CYP3A7. In contrast, CYP1A1, CYP2E1, and CYP2D6 transcripts were at the low detection level. To determine whether the encoded enzymes have the potential to activate aflatoxin B1 (AFB1), we used artificial intelligence (AI) -based structural modeling along with molec-ular docking. Results: AI modeling indicated CYP3A enzymes position AFB1 in a manner that supports the formation of the reactive intermediate, and CYP3A4 showed the most favorable orientation. To demonstrate AFB1 bioactivation, we exposed VERO-E6 cells to 200 nmol/L AFB1. After 10 days, we observed about 40 % cell death. Liquid chromatography-tandem mass spectroscopy (LC–MS/MS) analysis confirmed the presence of AFB1-derived DNA adducts, indicating that metabolic activation occurred in these cells. Conclusion: These results suggest that VERO-E6 cells have functional CYP-mediated metabolic activi-ty. Thus, combining computational and experimental approaches elucidates xenobiotic metabolism in cells where biochemical data are limited.

Abstract: Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants with established carcinogenic properties traditionally linked to genotoxicity, oxidative stress, and DNA adduct formation. Emerging evidence, however, suggests that PAHs also function as chronotoxic agents capable of disrupting circadian homeostasis through transcriptional and epigenetic reprogramming of core clock genes. This review critically examines the molecular interplay between PAH exposure, circadian clock dysregulation, and the initiation and progression of lung and breast cancers. Central to this interaction is the activation of the aryl hydrocarbon receptor (AhR), which exhibits functional crosstalk with circadian regulators including CLOCK and BMAL1. Sustained AhR activation, coupled with oxidative stress, inflammatory signaling, and epigenetic modifications such as DNA methylation, histone remodeling, and non-coding RNA dysregulation, contributes to altered rhythmic expression of key circadian genes including PER, CRY, BMAL1, and CLOCK. These alterations impair DNA repair, cell-cycle regulation, apoptosis, and metabolic homeostasis, thereby creating a permissive environment for tumorigenesis. The review further highlights tissue-specific mechanisms underlying PAH-induced chronodisruption in lung and breast tissues and discusses the translational relevance of circadian biomarkers in cancer prognosis and therapy. Finally, emerging therapeutic strategies including chronotherapy, circadian-targeted interventions, and epigenetic modulation are explored as potential approaches for mitigating environmentally induced carcinogenesis. Collectively, this review positions environmental chronotoxicology as a critical framework for understanding the temporal dimension of cancer development associated with PAH exposure.

Abstract: DNA sequence context plays a critical role in modulating the mutational effects of DNA damage. Here, we investigated how base identity influences the replication bypass and mutagenicity of a site-specific dG-AAF (2-acetylaminofluorene) bulky adduct in the well-defined AG*N and TG*N sequence contexts. By selecting A (purine) and T (pyrimidine) as representative 5’-flanking bases and systematically varying the 3’-base, we established a controlled system to examine sequence-dependent lesion replication. We found that the 5’-flanking base strongly affects the bypass profile, with AG*N sequences exhibiting uniformly low bypass (≤ 9.7%) and TG*N sequences showing markedly elevated bypass (23.6 – 50.4%) with strong sequence dependence. These differences may arise from the structure of the dG-AAF, whose conformation heterogeneities are sensitive to the flanking sequence context. In contrast, mutagenicity remains consistently low across all sequences examined, with a low frequency of point mutations and no detectable frameshift events. These results reveal a clear decoupling between lesion bypass efficiency and replication fidelity, where sequence context strongly controls lesion tolerance but has limited impact on mutagenicity. In total, our findings demonstrate that DNA sequence affects lesion processing, providing insights into how local sequence context shapes genome stability and mutational processes.

Abstract: Cadmium (Cd) is a global toxic pollutant and a major foodborne hazard. Its widespread use in industrial processes, including its presence in fertilizers, combined with natural environmental occurrence, has led to persistent contamination of food and water supplies. Ingested Cd has been associated with visual impairments, but early predictors such as disruptions to nervous system function are elusive largely due to the reliance of in vitro and in vitro assays. Here, we examined the effects of human relevant dietary Cd concentrations (0, 30, and 600 µg/g Cd) on in vivo neuronal calcium (Ca²⁺) activity and visually-guided behavior, as assessed by the optomotor response, across multiple exposure windows. We found that human relevant dietary Cd exposure induced immediate deficits in whole brain neuronal activity that preceded impairments in the optomotor response. While Cd disrupted in vivo neuronal Ca²⁺ activity in zebrafish after a single day of exposure, these effects were transient, with differences across treatments diminishing after two weeks. In contrast, optomotor deficits emerged after two weeks of exposure and were concentration dependent. Notably, while alterations in neuronal Ca²⁺ activity occurred at Cd exposure levels comparable to those in human populations, early-life optomotor deficits were observed only at dietary Cd concentrations at the upper limit of human exposures. Overall, these findings demonstrate that ingested Cd poses significant risks to sensitive systems, including the nervous system, with downstream consequences for visually-guided behavior. This study provides insight into early neurophysiological predictors of dietary Cd–induced neurotoxicity and visual dysfunction.

Abstract: Perfluorohexanesulfonic acid (PFHxS) is a per- and polyfluoroalkyl substance (PFAS) frequently detected in aquatic environments, while chlorpyrifos (CPF) is a widely used organophosphate insecticide. Although their individual toxicity is well described, their combined effects remain poorly understood. Here, we evaluated the effects of CPF (0.7 to 700 µg/L), alone or in combination with PFHxS (10 µg/L), in zebrafish embryos. Survival, hatching, malformations, locomotor activity, oxidative stress, apoptosis, and gene expression were assessed after five days of exposure. CPF reduced survival in a concentration-dependent manner, with moderate enhancement under co-exposure, while hatching success was unaffected. Deformities increased with CPF concentration, which remained consistent with PFHxS co-exposure, suggesting toxicity was mediated by CPF. Locomotor activity was largely decreased in a concentration- and phase-dependent manner. No significant changes were observed in ROS levels nor apoptosis. Gene expression analysis revealed upregulation of neurotoxicity-related markers (ache, gfap, shha, syn2a), particularly at intermediate CPF concentrations and under co-exposure. Oxidative stress–related genes showed differential responses, with sod1 upregulated and cat downregulated only in the combined treatment. These findings highlight the importance of evaluating mixture toxicity to better understand the ecological risks of co-occurring contaminants.

Abstract: 2,2′,4,4′-Tetrabromodiphenyl ether (BDE-47) is a persistent organic pollutant detected in coastal environments. The effects of BDE-47 on mangrove plants at the molecular and histological levels remain elusive. In this study, seedlings of the man-grove species Avicennia marina were exposed to BDE-47 at concentrations of 0, 1 and 10 ng L-1 for 20 days under hydroponic conditions. Leaf growth parameters, anatomical structures, and transcriptomic profiles were examined. At 1 ng L-1 BDE-47, no signif-icant changes were observed in leaf growth or vascular tissue morphology. However, transcriptome analysis showed significant enrichment of differentially expressed genes in the linoleic acid metabolism pathway, indicating that A. marina initiates early stress perception via enhanced stress perception and signal transduction, trigger adaptive defense responses to low-level BDE-47 exposure, and circumvent growth inhibition. At 10 ng L-1 BDE-47, leaf area, width, length, and fresh weight were all reduced. In addi-tion, histological examination revealed vascular bundle sheath atrophy, impaired xy-lem and phloem development, reduced parenchyma cell diameter, and a decreased proportion of intercellular space. Transcriptomic analysis at 10 ng L^-1 exposure identi-fied significant enrichment of differentially expressed genes in the circadian rhythm and spliceosome pathways, indicating that the pollutant's toxicity has progressed from local metabolic disruption to perturbation of the plant's core regulatory network. Overall, our findings reveal distinct response patterns of A. marina leaves to BDE-47 exposure at environmentally relevant concentrations, initially elucidate the adaptive defense mechanism and underlying molecular basis of toxic effects in mangrove plants under low-concentration BDE-47 exposure, and provide critical scientific support for the ecological risk assessment and conservation of coastal mangrove wetlands.