Fengling Li

In this study, a robust UHPLC-MS/MS method was developed for simultaneously determining 14 organophosphate ester flame retardants (OPEs) in aquatic products. Sample extraction and clean-up procedures were optimized, and matrix effects were corrected using matrix-matched calibration with internal standards. The validated method exhibited good linearity (R² > 0.991), low detection limits (0.015–0.180 ng g⁻¹ wet weight, ww), low quantification limits (0.050–0.600 ng g⁻¹ ww), high recoveries of 70.6–119%, and good precision (relative standard deviations < 15%). Application to fish, sea cucumber, shrimp, and mussel samples confirmed the method’s high sensitivity and accuracy. Analysis of 200 aquatic product samples revealed widespread yet species- and compound-specific OPE contamination, with total concentrations up to 1429.4 ng g⁻¹ ww. Chlorinated OPEs predominated, particularly tris(2-chloroethyl) phosphate (TCEP) and tris(1-chloro-2-propyl) phosphate (TCIPP). TMCP, TOCP, and TMPP were reported as a combined concentration (ΣTCP) in real samples, expressed as TMCP equivalents. These findings suggest that further investigations are required to assess OPE distributions, accumulation patterns, and dietary exposure risks in aquatic products.

Co-contamination risks of Per- and polyfluoroalkyl substances (PFASs) and brominated flame retardants (BFRs) to marine ecosystems remain poorly understood. This study investigated the mechanisms of co-exposure to perfluorooctane sulfonate (PFOS) and tetrabromobisphenol A (TBBPA) in the thick-shell mussel Mytilus coruscus. Tissue-specific bioaccumulation, histopathological damage, and time-dependent transcriptional and metabolic reprogramming were observed in the digestive gland over a 28-day exposure and depuration period. Integrated multi-omics analysis revealed a coordinated disruption of the detoxification-antioxidant network, encompassing phase I-III metabolic genes and Nrf2-mediated responses, with pollutant levels positively correlated with oxidative stress markers. Molecular docking further revealed the affinity differences between PFOS, TBBPA and detoxification, metabolism and transport-related proteins, suggesting possible reasons for distinct interference mechanisms and differential accumulation. These findings highlight that PFOS-TBBPA mixtures impaired the detoxification system, leading to incomplete metabolic recovery and persistent oxidative stress, thereby offering mechanistic insights for the management and remediation of emerging pollutant mixtures in marine ecosystems.

Listeria monocytogenes is a high-risk pathogenic bacterium associated with ready-to-eat foods and poses a potential threat to consumer health. This study aimed to investigate the prevalence, characterization and genetic diversity of L. monocytogenes in ready-to-eat raw salmon and trout products obtained from physical stores and online stores in China. Out of 150 samples analyzed, 23 (15.3%) were positive for L. monocytogenes. Among these positive samples, three (12%) were from Japanese restaurants, four (16%) from farmers markets, one (2.9%) from large supermarkets and fifteen (30%) from e-commerce platforms, and only one sample showed a contamination level exceeding 100 most probable number (MPN)/g. The isolates from positive samples demonstrated a concrete public health risk through several findings: twenty-three L. monocytogenes exhibited varying degrees of cytotoxicity, ranging from 7.6% to 71.8%. Compared with the reference strain ATCC 19115, five of these isolates were highly cytotoxic, a result that was validated by mouse survival rate experiment, which also confirmed their high virulence at tested dose. All isolates were resistant to cefuroxime sodium, ceftriaxone, cefepime and nalidixic acid, and 13% showed resistance to sulphamethoxazole-trimethoprim. Three serogroups were identified, with serogroup Ⅰ.1 (1/2a, 3a) being the most prevalent (65.2%). These isolates were grouped into eight sequence types, with ST8 (34.8%) and ST87 (30.4%) dominating. All isolates carried virulence genes associated with LIPI-1 andmultiple internalin genes (inlA, inlB, inlJ and inlK), confirming their potential pathogenicity. Additionally, the isolates harbored antimicrobial resistance genes lin and FosX. The five highly virulent isolates exhibited the highest genetic similarity to J2-031 (GCA_000438645.1) and C1-387 (GCA_000438605.1). The results provided valuable information for Chinese regulatory authorities to strengthen the risk monitoring of L. monocytogenes in ready-to-eat raw salmon and trout products.

SARS-CoV-2 non-structural protein 13 (nsp13) is a highly conserved helicase and RNA 5'-triphosphatase. It uses the energy derived from the hydrolysis of nucleoside triphosphates for directional movement along the nucleic acids and promotes the unwinding of double-stranded nucleic acids. Nsp13 is essential for replication and propagation of all human and non-human coronaviruses. Combined with its defined nucleotide binding site and druggability, nsp13 is one of the most promising candidates for the development of pan-coronavirus therapeutics. Here, we report the development and optimization of bioluminescence assays for kinetic characterization of nsp13 ATPase activity in the presence and absence of single-stranded DNA. Screening of a library of 5000 small molecules in the presence of single-stranded DNA resulted in the discovery of six nsp13 small-molecule inhibitors with IC₅₀ values ranging from 6 ± 0.5 to 50 ± 6 μM. In addition to providing validated methods for high-throughput screening of nsp13 in drug discovery campaigns, the reproducible screening hits we present here could potentially be chemistry starting points toward the development of more potent and selective nsp13 inhibitors, enabling the discovery of antiviral therapeutics.

Polyfluorinated alkylated substances are recognized as an important class of pollutants in marine environments. Bivalves are good model organisms for evaluating the toxicity of pollutants and monitoring marine environments. Here, immunotoxicity of perfluorooctanoate acid (PFOA) was investigated by measuring biomarkers of the immune profile of Ruditapes philippinarum. In bivalves, hemocytes are an important component of the immune system. Thus, the hemocyte proliferation, phagocytosis, cell viability, and immune enzyme activities, which have been applied as marine pollution bio-indicators, were identified and observed for changes after exposure to PFOA in R. philippinarum. Based on the integrated biomarker responses method, we selected five biomarkers to evaluate PFOA risk at multi-biomarker level. In addition, the histopathological alterations of hemocytes in bivalves were used as indexes of the response to environmental stress. The sub-cellular structure of the hemocytes in R. philippinarum changed significantly with PFOA exposure, including hemocyte and nucleus morphological changes, organelle dissolution, cytomembrane and karyotheca swelling, and cytoplasm vacuolization. The present work verifies PFOA immunotoxicity to R. philippinarum at different levels and the integerated assessment of stress level caused by PFOA in marine environment. Our results will provide new insights into evaluating adverse effects of PFOA and monitoring marine ecosystem.

In order to understand pharmacokinetics in vivo and tissue residues of florfenicol in Hybrid sturgeon cultured in cold water, changes in concentration of florfenicol in plasma, muscle, liver and kidney of sturgeon after administration were measured by high performance liquid chromatography mass spectrometry. The results show that after 15.0 mg/kg dose administration, the concentration change in plasma and liver, kidney and muscle of sturgeon are suitable for the one compartment open model. Florfenicol pharmacokinetic parameters in plasma, liver, kidney and sturgeon muscle showed that the peak concentration (C_max) were 549.7, 551.8, 958.2 and 405.4 μg/kg, respectively. The peak time (T_max) was 17.5, 14.2, 14.0 and 20.8 hr, respectively. The elimination half‐life (T_1/2) was 75.1, 99.8, 68.8 and 75.5 hr, respectively. Area under the curve were 70,048.9, 63,850.6, 109,579.9 and 53,437.3 μg/kg hr, respectively. Mean residence time was 100.6, 96.4, 96.5 and 104.6 hr, respectively. The absorption speed and elimination of florfenicol in cold water cultured sturgeon is slow, and the peak concentration is low, but the florfenicol was widely distributed in the body of sturgeon. The results provide a theoretical basis for formulation of medication and withdrawal period of florfenicol used in sturgeon cultured in cold water.