Zhongxiang Chen

This study systematically analyzed the pollution levels, distribution characteristics, and associated health risks of 17 organochlorine pesticides (OCPs) and 9 polychlorinated biphenyls (PCBs) in Oviductus Ranae (Rana dybowskii) from major production areas in Heilongjiang Province, China. OCPs and PCBs were detected in all samples. The total concentration of OCPs ranged from 11.7 to 67.9 ng/g (dry weight), while that of total PCBs ranged from 4.43 to 8.06 ng/g. Endosulfans constituted the predominant OCP group, accounting for 54.5% of ∑OCPs, with an α/β-endosulfan ratio (~2:1) indicative of recent agricultural input. Among DDTs, the dominance of p,p′-DDE and the absence of parent DDT suggested aerobic degradation of historical residues. For HCHs, the isomer profile (β-HCH predominance, α/γ-HCH = 0.27) pointed to weathered lindane sources. The PCB profile was uniquely dominated by lower-chlorinated congeners (PCB1 and PCB29), implying influences from atmospheric transport and/or in situ microbial dechlorination of legacy PCBs. The persistent organic pollutants (POPs) contamination profile in Oviductus Ranae reflects a combined influence of recent pesticide application, weathered historical residues, and long-range transport. Although the concentrations are below current regulatory limits, the cumulative and persistent nature of these POPs, coupled with the product’s medicinal use, justifies a precautionary stance regarding long-term consumption. The distinct congener patterns underscore the necessity for future research to prioritize the environmental behavior and toxicology of dominant transformation products within such specific agro-ecosystems.

This study investigated the accumulation characteristics and associated health risks of 11 trace elements (Al, Rb, Cr, Ni, Mo, Sr, Pb, Ba, Ag, As, and Ga) in four crucian carp varieties: gene-edited intermuscular bone-free crucian carp (Carassius auratus, WUCI) and its sibling wild-type (Carassius auratus, WT), Fangzheng silver crucian carp (Carassius gibelio var Fangzheng, FZYJ), and Songpu silver crucian carp (Carassius gibelio var Songpu, SPYJ). Results showed that Al and Rb were the most abundant elements across all groups. WUCI exhibited distinct accumulation patterns, including significantly higher hepatic Mo concentrations (0.265 ± 0.032 mg/kg) and muscle/liver Rb levels (muscle: 8.74 ± 1.21 mg/kg; liver: 12.56 ± 2.05 mg/kg) compared to other varieties (p < 0.05), which supports the hypothesis of genotype-specific differences in heavy metal accumulation. Correlation analysis revealed that WUCI exhibited similar elemental interactions with WT and SPYJ (e.g., Al-Ni positive correlation, |rs| ≥ 0.8), while SPYJ displayed distinct patterns with fifteen negative correlations compared to three to five in others varieties, suggesting a potential alteration in elemental homeostasis. Pollution index (P_i) assessments indicated mild contamination for Pb in SPYJ liver (P_i = 0.265) and Cr/As in WUCI muscle (P_i = 0.247/0.218). Despite these values, all hazard indices remained below the established safety thresholds (THQ < 0.1, HI < 0.25, TCR < 10⁻⁶), reinforcing the overall safety of the tested fish. Notably, muscle As levels (0.86 ± 0.15 mg/kg) exceeded hepatic concentrations (0.52 ± 0.09 mg/kg), potentially due to differential detoxification mechanisms. These findings demonstrate the food safety of all tested varieties, while highlighting genotype-specific metabolic adaptations, providing critical data for evaluating gene edited aquatic products.

Common carp (Cyprinus carpio) is extensively cultured and widely consumed in Heilongjiang Province, China. Due to the proximity of freshwater ponds to agricultural cultivated areas, these aquatic systems are inevitably influenced by the historical application of organochlorine pesticides (OCPs), due to their prolonged half-life and resistance to degradation. Gas chromatography-tandem mass spectrometry (GC-MS/MS) was utilized to quantify the levels of hexachlorocyclohexane (HCHs) and dichlorodiphenyltrichloroethane (DDTs) in the muscle tissue of cultured common carp. This study examined the enrichment characteristics of HCHs and DDTs in fish muscle, as well as their correlation with sediment and associated risk assessments. The results showed that the residual levels of HCHs and DDTs in fish muscle ranged from 0.387 μg·kg⁻¹ to 3.418 μg·kg⁻¹ and from 0.114 μg·kg⁻¹ to 0.420 μg·kg⁻¹, respectively. They were all below the maximum residue limits specified in GB 2763-2021 (HCHs: 100 μg·kg⁻¹, DDTs: 500 μg·kg⁻¹). The concentrations of HCHs and DDTs in sediment were found to be lower than those in muscle tissue. Notably, the concentrations of HCHs were higher than those of DDTs in both muscle and sediment. Among the HCHs, γ-HCH was the predominant residual substance, contributing a significant proportion of 42.16% to 86.47%. No significant residues of DDT derivatives were detected. A significant correlation was observed between the concentrations of HCHs and DDTs in the muscle tissue and those present in the sediment (p < 0.01). The health risk assessment indicated that both the carcinogenic and non-carcinogenic risks associated with OCPs from common carp muscle and sediment were within acceptable limits. Therefore, it was recommended to regulate fish consumption during the breeding period.

The aquatic products of grazing ecological culture exhibit a strong reliance on the production environment system, which may result in heavy metal contamination. In this study, 24 elements (Ag, Al, As, Ba, Cd, Co, Cr, Cs, Cu, Fe, Ga, K, Mg, Mn, Na, Ni, Pb, Rb, Se, Sr, Tl, U, V, Zn) were determined for Oviductus Ranae (OR) from more than 1,000 individuals of Rana dybowskii produced by pond culture–forest grazing relay mode from six major production areas in Heilongjiang Province, China. Furthermore, we assessed the associated health risks. Our findings indicate that most of these 24 metal elements were detected in OR at a detection rate of 100%, with the exceptions being As (98.0%), Ga (98.0%), Co (98.0%), V (94.0%), Cd (89.0%), Pb (76.0%), Cs (74.0%), Tl (35.0%), and U (not detectable). Variations in element concentrations were significant across the six sampling sites, with characteristic elements identified to account for spatial differences. The total target hazard quotient was determined to be 0.152 in Heilongjiang Province, thereby suggesting a relatively low health risk associated with consuming OR from this region’s production systems according to existing standards and guidelines. Nevertheless, special attention is needed for monitoring the habitat environments of R. dybowskii from two sampling locations showing heightened pollution levels.

In this study, a carbon nanotube (CNTs)—supported dummy template molecularly imprinted polymer (DMIPs) material was synthesized and utilized for the detection of amide herbicides in aquatic products via matrix solid-phase dispersion technology (MSPD). The DMIPs material was characterized, and its adsorption kinetics and isotherm were determined, the adsorption model was established, and the selective adsorption coefficient was calculated. The extract parameters of the method were optimized and successfully employed for the separation, analysis and detection of real samples, with satisfactory detection limits and linear ranges obtained. By comparing with other methods, the CNTs@DMIPs combined with MSPD technology established in our study can effectively solve false negative problems caused by insufficient destructive force, using dummy template molecules can also address the issue of false positives caused by template molecule leakage in molecular imprinting. Overall, the method is appropriate for the separation and detection of endogenous substances from highly viscous and poorly dispersed samples and is used as a routine detection tool in the aquaculture industry.

Multiple freeze-thaw cycles due to temperature fluctuations irreversibly damage the muscle tissue of fish, thereby reducing their edibility. The aim of this study was to determine the effects of the number of freeze-thaw (F–T) cycles on protein and lipid oxidation, microstructure, physical index, and nutritional quality of rainbow trout muscle. The results showed that F–T cycles accelerated protein carbonyl formation and thiobarbituric acid reactive substances (TBARS) generation (p < 0.05), as well as increased the loss of total sulfhydryl (SH) groups (p < 0.05). Moreover, transmission electron microscope (TEM) images illustrated that the microstructure of muscle fibers was loosed and disintegrated after the third F–T cycle, causing a reduction in water holding capacity (WHC). In addition, muscles lost the intrinsic color of fresh meat after the fifth cycle, with lightness L* and yellowness b* increasing, while redness a* declined (p < 0.05). The hardness, springiness, and chewiness of muscles decreased, and the shear force first increased and then decreased after the third cycle. Furthermore, the proximate components, essential amino acids (EAAs), and total amino acids (TAAs), decreased significantly after the third cycle (p < 0.05) due to the decrease of WHC as well as protein and lipid oxidation. The results indicated that the quality of rainbow trout muscle changed after the third cycle, deteriorated seriously after the fifth cycle, and was unacceptable after the seventh cycle. Therefore, it is necessary to reduce the temperature fluctuation to less than three times during freezing. The results provided a reference for the identification and classification of frozen aquatic products.

Elimination of intermuscular bones (IMBs) is vital to the aquaculture industry of cyprinids. In our previous study, we characterized bmp6 as essential in the development of IMBs in zebrafish. Knockout of bmp6 results in the absence of IMBs in zebrafish without affecting growth and reproduction. Therefore, we hypothesized that bmp6 could be used to generate new cyprinid strains without IMBs by gene editing. In this study, we established a gene editing strategy for knocking out the two orthologs of bmp6 in diploid crucian carp ( Carassius auratus ). We obtained an F ₃ population with both orthologs knocked out, in which no IMBs were detected by bone staining and X-ray, indicating that the new strain without IMBs (named WUCI strain) was successfully generated. Furthermore, we extensively evaluated the performance of the new strain in growth, reproduction, nutrient components, muscle texture and structure, and metabolites in muscle. The results showed that the WUCI strain grew faster than the wild-type crucian carp at 4-month-age. The reproductive performance and flesh quality did not show significant differences between the WUCI strain and wild-type crucian carp. Moreover, the metabolomics analysis suggested that the muscle tissues of the WUCI strain significantly enriched some metabolites belonging to the Thiamine metabolism, Nicotinate and Nicotinamide Metabolism pathway, which plays beneficial effects in anti-aging, anti-oxidant, and anti-radiation damage. In conclusion, we established a strategy to eliminate IMBs in crucian carp and obtain a WUCI strain whose performance was expected compared to the wild-type crucian carp; meanwhile, the WUCI strain enriched some beneficial metabolites to human health in muscle tissue. This study is the first report that a farmed cyprinid strain without IMBs, which could be stably inherited, was obtained worldwide; it provided excellent germplasm for the cyprinids aquaculture industry and a useful molecular tool for eliminating IMBs in other cyprinids.