Health risks associated with sulfonamide and quinolone residues in cultured Chinese mitten crab (Eriocheir sinensis) in China

Preparation of a V-COF@SWCNTs-COOH/SPCE supported molecularly imprinted electrochemical sensor for real-time detection of trace sulfadimidine

To overcome the limitations of insufficient sensitivity and poor specificity of portable screen-printed carbon electrode-electrochemical sensors (SPCE-EC) in practical applications, we prepared carrier composites of carboxylic single-walled carbon nanotubes vertically grafted by covalent organic frameworks (v-COF@SWCNTs-COOH) and coated with a molecularly imprinted polymer (MIP) of sulfadimidine (SM2). 55 °C hot steam elution is more eco-friendly than traditional organic solvent elution. The results showed that when the mass ratio of DBA to DBA-SWCNTs was 1:1, the v-COF@SWCNTs-COOH obtained by the two-step synthesis method could increase the electrical signal up to 2.33-fold of the bare electrode. The bifunctional monomer MIP prepared on the above structure enhanced the signal response by 2.91-fold, with a high imprint factor of 20. The assembled MIP/v-COF@SWCNTs-COOH/SPCE were analyzed by differential pulse voltammetry (DPV) with a high sensitivity of 0.21 nM for LOD and 0.70 nM for LOQ. In milk and fish samples, the recovery rate was 95.0 %-104.8 %. The validation of authentic pork samples with the statutory LC-MS/MS method showed no significant difference (P > 0.05). The sensor's performance indicators remained robust after five repeated uses. Therefore, the MIP/v-COF@SWCNTs-COOH/SPCE combines the cheapness and portability of SPCE, while the sensitivity and specificity of small molecule detection were significantly improved.

Horizontal gene transfer plays a crucial role in the development of antibiotic resistance in an antibiotic-free shrimp farming system

Antibiotic selective pressure in aquaculture systems often results in the antibiotic resistance genes (ARGs) proliferation. Nonetheless, a paucity of data exists concerning the mechanisms of ARGs development in aquaculture systems without the influences of antibiotics. This study utilized metagenomic approaches to elucidate the dynamics and transfer mechanisms of ARGs throughout the aquaculture of Pacific white shrimp. A marked change in the resistome was observed throughout the aquaculture without antibiotics. The total ARGs relative abundance increased from 0.05 to 0.33 by day 90 of cultivation, with even higher in mixed wastewater (0.44). Both bacterial communities and mobile genetic elements play pivotal roles in the development of ARGs. Metagenome-assembled genomes showed enrichment of environmentally intrinsic ARGs on chromosomes including macB and mdtK. The plasmid-mediated horizontal transfer was recognized as a principal factor contributing to the rise of ARGs, particularly for tetG and floR, and this led to an escalation of resistance risk, peaking at a risks core of 35.43 on day 90. This study demonstrates that horizontal gene transfer plays a crucial role in ARGs development without antibiotic pressure, which can provide a theoretical foundation for controlling ARGs proliferation in aquaculture systems.

Environment consistently impact on aquaculture: The predominant source of residual pollutants in cultured Chinese mitten crab (Eriocheir sinensis) across China

Advancements in monitoring and operation of aquaculture environments has minimized the concentrations of some residual pollutants in cultured aquatic products. However, currently most aquatic products are "farmed", and relationships among residual pollutants in tissues of crabs were still unclear. In this study, 64 typical pollutants, including 25 antibiotics, 15 metal, 23 organochlorine pesticides, and one dioxin-like compound inducing hydrocarbon-receptor (AHR) activity were measured in Chinese mitten crab (Eriocheir Sinensis) risks of consumption assessed and ranked. The superposition of properties including severity and relative potency of effects and parameters describing persistence and exposure along with rates of usage and identification of groups most likely to be exposed were assessed in combination to rank likelihood of dietary exposure and probabilities of adverse effects for each contaminant. The results indicated that the total scores per pollutants found that Cadmium (Cd), Heptachlor epoxide (HEPE), dioxin TEQ exhibited the greatest scores and explained the severity of dietary risk, while source analysis found that the three main pollutants resulted from the ambient environment and are not due to specific aquaculture processes. In summary, environment is still the predominant source of residual pollutants in cultured Chinese mitten crab across China.

Microplastic aging alters the adsorption-desorption behaviors of sulfamethoxazole in marine animals: A study in simulated biological liquids

Antibiotics and microplastics (MPs) coexisting as unique environmental contaminants may cause unintended environmental issues. In this study, the adsorption-desorption behaviors of sulfamethoxazole (SMX) on both original and UV-aged MPs were examined. Polyhydroxyalkanoates (PHA) and polyethylene (PE), which represent degradable and refractory MPs, respectively, were chosen as two distinct types of MPs. Furthermore, simulated fish intestinal fluids (SFIF) and simulated mammalian stomach fluids (SMGF) were employed to evaluate the desorption behaviors of SMX from aged MPs. Our findings demonstrate that UV-aging altered the polarity, hydrophilicity, and structure of the MPs. Aged MPs showed a higher adsorption capacity than the original MPs and they have a higher desorption capacity than original MPs in simulated body fluids. PE has a higher SMX desorption capacity in SFIF and the opposite happened in SMGF. Our results highlight the importance of considering the different adsorption-desorption behaviors of antibiotics on MPs when evaluating their environmental impact.

Assessment of the benefits of essential fatty acids and risks associated with antimicrobial residues in aquatic products: A case study of Chinese mitten crab (Eriocheir sinensis)

Much attention has been given to the safety and quality of aquatic products, including consuming Chinese mitten crab (Eriocheir sinensis), which offers both nutritional benefits and toxicological risks. Eighteen sulfonamides, 9 quinolones and 37 fatty acids were analyzed in 92 crab samples from primary aquaculture provinces in China. Enrofloxacin and ciprofloxacin have been mentioned as typical antimicrobials occurring at the greatest concentrations (>100 μg/kg, wm). By use of an in vitro method, the proportions of enrofloxacin, ciprofloxacin and essential fatty acids (EFAs, DHA and EPA) in ingested nutrients were determined to be 12 %, none and 95 %, respectively. The risk-benefit quotient (HQ) between the adverse effects of antimicrobials and nutritional benefits of EFAs in crabs found that HQs based on data after digestion were significantly less (HQ = 0.0086) than that of the control group where no digestion occurred (HQ = 0.055). This result suggested that (1) there was less risk posed by antimicrobials due to the consumption of crab, and (2) ignoring the bioaccessible fraction of antimicrobials in crabs might overestimate risks to the health of humans due to dietary exposure. Meaning bioaccessibility can improve the accuracy of the risk assessment process. Realistic risk evaluation should be recommended to achieve a quantified assessment of the dietary risks and benefits of aquatic products.

Transcriptomics Analysis of the Toxicological Impact of Enrofloxacin in an Aquatic Environment on the Chinese Mitten Crab (Eriocheir sinensis)

Enrofloxacin is an important antimicrobial drug that is widely used in aquaculture. Enrofloxacin residues can have negative effects on aquatic environments and animals. The toxicological effects of different concentrations of enrofloxacin residues in cultured water on Chinese mitten crabs (Eriocheir sinensis) were compared. A histological analysis of the E. sinensis hepatopancreas demonstrated that the hepatopancreas was damaged by the different enrofloxacin residue concentrations. The hepatopancreas transcriptome results revealed that 1245 genes were upregulated and that 1298 genes were downregulated in the low-concentration enrofloxacin residue group. In the high-concentration enrofloxacin residue group, 380 genes were upregulated, and 529 genes were downregulated. The enrofloxacin residues led to differentially expressed genes related to the immune system and metabolic processes in the hepatopancreas of the Chinese mitten crab, such as the genes for alkaline phosphatase, NF-kappa B inhibitor alpha, alpha-amylase, and beta-galactosidase-like. The gene ontology terms "biological process" and "molecular function" were enriched in the carboxylic acid metabolic process, DNA replication, the synthesis of RNA primers, the transmembrane transporter activity, the hydrolase activity, and the oxidoreductase activity. A Kyoto Encyclopedia of Genes and Genomes pathway analysis determined that the immune and metabolic signal transduction pathways were significantly enriched. Furthermore, the nonspecific immune enzyme (alkaline phosphatase) and the metabolic enzyme system played a role in the enrofloxacin metabolism in the E. sinensis hepatopancreas. These findings helped us to further understand the basis of the toxicological effects of enrofloxacin residues on river crabs and provided valuable information for the better utilization of enrofloxacin in aquatic water environments.

Potential toxicity and dietary risk of tricyclazole to Chinese mitten crab (Eriocheir sinensis) in the rice-crab co-culture model

Tricyclazole is used as a common fungicide to control rice blast. However, studies on the toxicity of tricyclazole to crabs in the rice-crab co-culture system are still extremely rare. Here, the environmental dissipation of tricyclazole was monitored in this model, and the potential toxicity of tricyclazole to E. sinensis at environmental concentrations as well as the dietary risk was evaluated. The results showed that tricyclazole had no significant acute toxicity to E. sinensis (LC₅₀ > 100 mg/L), while it promoted body weight gain. Tricyclazole in the hepatopancreas had a higher persistent bioaccumulation risk than in the muscle. Tricyclazole suppressed the immune response of E. sinensis under prolonged exposure and there should be gender differences, with females being more sensitive. Lipid metabolism enzymes were also significantly inhibited. While tricyclazole stimulated males molting but prolonged molting duration, both molting and duration of females were also disturbed. The dietary risk assessment indicated that tricyclazole intake from current crab consumption was low risk. This evidence demonstrated that tricyclazole may have potential risks to individual development, nutritional quality, and economic value on E. sinensis and should be used with caution in rice-crab co-culture system whenever possible.

Occurrence and human health risk assessment of antibiotics in cultured fish from 19 provinces in China

The occurrence of antibiotics and potential health risk of 300 cultured fish samples from 19 provinces in China were investigated. The levels of 28 antibiotics (15 fluoroquinolones, 4 tetracyclines, 8 macrolides and rifampin) in 8 fish species were measured through liquid chromatography electrospray tandem mass spectrometry. As a result, 10 antibiotics were detected with an overall detection frequency of 24.3%, and the individual detection frequency of antibiotics ranged from 0.33 to 16.7%. The extremely high concentrations (above 100 µg/kg) of doxycycline and erythromycin were found in the samples. Antibiotics with high detection frequency was noticed in largemouth bass (41.2%), followed by snakehead (34.4%) and bream (31.2%). Specifically, Heilongjiang, Xinjiang, Qinghai and Gansu presented high detection frequency values of more than 60%. Moreover, the highest mean concentration was observed in Shandong, and the concentration covered from 34.8 µg/kg to 410 µg/kg. Despite the high detection frequency and levels of antibiotics were found in samples, ingestion of cultured fish was not significantly related to human health risks in China, according to the calculated estimated daily intakes and hazard quotients. These results provided us the actual levels of antibiotics in cultured fish and human health risk assessment of consuming fishery products.

Occurrence of quinolones in cultured fish from Shandong Province, China and their health risk assessment

The residue levels of 6 quinolones in 160 cultured fish samples from Shandong Province, China were investigated using UPLC-MS/MS. The detection rate was 43.1% and enrofloxacin had the highest detection rate as well as the highest residue concentration. The violation rates were 2.50% for the sum of enrofloxacin and ciprofloxacin and 1.25% for ofloxacin. Among the 9 fish species, quinolone contamination problems should receive more attention in Carp, Grass carp, Crucian and Catfish. The health risk assessment showed that when calculated by the maximum concentration, the estimated daily intakes (EDIs) of Carp, Grass carp and Crucian for the high consumption group accounted for more than 10% of the acceptable daily intakes (ADIs), indicating that a large intake of these fish species might pose a potential health risk and health risk monitoring of quinolones in cultured fish should be continually performed.

Effects of copper pyrithione (CuPT) on apoptosis, ROS production, and gene expression in hemocytes of white shrimp Litopenaeus vannamei

Copper pyrithione (CuPT) is used globally to prevent biofouling. However, it poses certain risks to aquatic ecosystems. To understand the effects of CuPT on Litopenaeus vannamei after exposure to different concentrations of CuPT (0, 64, and 128 μg/L), the apoptotic cell ratio, production of reactive oxygen species (ROS), and gene expression in the hemocytes were studied at 0, 3, 12, 24, and 48 h. The results revealed that ROS production was induced significantly at 3-48 h only in the 128 μg/L groups. The apoptotic cell ratio was increased significantly at 12 and 24 h in the 64 μg/L groups, and at 3-48 h in the 128 μg/L groups. Meanwhile, CuPT exposure changed gene expression in hemocytes at different levels. In the 64 μg/L groups, the expression of Mn-superoxide dismutase (MnSOD) was induced at 12 h, glutathione peroxidase (GPx) was induced at 24 and 48 h, caspase-3 induced at 24 h, metallothionein (MT) and HSP70 were increased at 3 h. In the 128 μg/L groups, MnSOD was increased at 3 h and then decreased at 12-48 h, GPx was up-regulated at 3, 24 h and then decreased at 48 h, caspase-3 was increased at 24 h, MT was increased at 3-48 h, HSP60 and HSP70 were up-regulated at 3-12 h. These results indicated that CuPT induced ROS production and the expression of caspase-3 in hemocytes, then caused hemocyte apoptosis. Expression levels of MnSOD, GPx, MT, HSP60, and HSP70 were up-regulated to protect the hemocyte against CuPT stress.

Occurrence of antibiotics and antibiotic resistance genes in cultured prawns from rice-prawn co-culture and prawn monoculture systems in China

Antibiotics and antibiotic resistance genes (ARGs) in the aquatic environment have raised great concerns, as the deleterious effects of residual antibiotics and the emergence of ARGs are challenges to aquaculture. This study analyzed feed, water, sediment and prawns' tissues from six culture ponds (integrated culture: rice-prawn pond; monoculture: prawn pond) in Tianjin, Northeast China. Eighteen types of antibiotics were detected in all ponds, which conferring to four classes of antibiotics including sulfonamides, tetracyclines, fluoroquinolones, macrolides. The mean log bioaccumulation factor (BAF) values for five antibiotics were analyzed in the hepatopancreas, muscle, and plasma, and we found the maximum Log BAF (1.45) for enrofloxacin in prawn plasma. Correlation analysis of antibiotic concentrations between the plasma and the other two tissues indicated that enrofloxacin, norfloxacin, and erythromycin levels in the hepatopancreas and muscle can be predicted by their plasma concentrations. We also conducted a hazard quotient analysis and found that the risk to human health of eating antibiotic-exposed prawns from the two types of aquaculture method was relatively low. Compared with monoculture, rice-prawn co-culture could significantly decrease the abundance of ARGs; additionally, significant correlations were detected among ARGs, antibiotics, and non-antibiotic environmental factors (e.g., total nitrogen, total ammonia nitrogen, and chemical oxygen demand) in prawn. The present study indicated that the rice-prawn co-culture system is more effective than monoculture for mitigating the bioaccumulation of antibiotics and the occurrence of ARGs in prawn.

Electrochemical activation of peroxymonosulfate (PMS) by carbon cloth anode for sulfamethoxazole degradation

Electrochemical activation of peroxymonosulfate (PMS) at carbon cloth anode (E (Carbon cloth Anode)/PMS system) was investigated for sulfamethoxazole (SMX) degradation. The results indicated that PMS could be activated at carbon cloth anode during electrolysis, resulting in the improvement of SMX degradation. The degradation efficiency of SMX was facilitated with the higher PMS concentration and current density, respectively. The degradation rate constant of SMX increased with the rising pH from 3.6 to 6.0, and reached the highest value at pH 6.0, and then decreased with further increasing pH to 8.0. The presence of chloride ion (Cl^-, 5-100 mM) significantly enhanced SMX degradation, while addition of humic acid (HA, 1-5 mgC L^-1) inhibited SMX degradation. Addition of carbonate (HCO₃^-, 5-20 mM) had a negligible impact on SMX degradation. Small amounts of phosphate (PO₄^3-, 0-5 mM) could promote degradation, while a large amount of PO₄^3- (10-20 mM) inhibited the degradation. Moreover, the quenching experiments demonstrated that sulfate radical (SO₄·^-), hydroxyl radical (·OH) and singlet oxygen (¹O₂) contributed to SMX degradation in E (Carbon cloth Anode)/PMS system. The degradation intermediates of SMX were identified by LC-MS/MS and the degradation pathways were deduced to be hydroxylation, the cleavage of S-N bond, and oxidation of aniline group. Moreover, the micronucleus test of Vicia faba root tips indicated that the E (Carbon Cloth Anode)/PMS system could reduce the genetic toxicity of SMX contaminated water to some extent.