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This study investigated elimination of the herbicide pendimethalin using an integrated rice and Procambarus clarkii breeding model of indoor and outdoor (pond culture) exposure tests. The pendimethalin levels in 484 samples from the primary rice and P. clarkii integrated breeding areas in Hubei province were monitored, and dietary risk assessments of pendimethalin were calculated. Pendimethalin was quantified using high-performance liquid chromatography tandem mass spectrometry, and detection levels were linear in the range of 1.0 to 10.0 μg/L, and peak areas were positively correlated with concentration, with a correlation coefficient of 0.9996. Recoveries ranged from 86.9 to 103.5%, and the limit of quantitation was 2.5 × 10−4 μg/L in water, and 1 × 10−2 μg/kg in tissues, sediments, and waterweeds. The dissipation rate of pendimethalin in tissues and water followed first-order kinetics, with half-lives of 0.51–5.64 d. In 484 samples taken from aquaculture farms, pendimethalin was detected in 8.67% of the samples at levels in the range of 1.95 to 8.26 μg/kg in Hubei province from 2018 to 2020. The maximum residue limit of pendimethalin in P. clarkii has not been established in China, but our dietary risk assessments indicated that consumption of P. clarkii from integrated rice farms was acceptable. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the plasma protein binding rates (PPBRs) of doxycycline (DC) in the plasma of grass carp (Ctenopharyngodon idella), yellow catfish (Pelteobagrus fulvidraco) and crayfish (Procambarus clarkii) at different temperatures (4, 18 and 25℃) with different concentrations (1, 5, 10 and 20 μg/ml). A rapid and simple method of ultrafiltration (UF) was employed to determine the PPBR of DC in the plasma. The results showed that PPBRs were increased with the rise of the concentration of DC at the same temperature. At 4 ℃, PPBRs were increased from 90.00% to 99.51%, 89.81% to 98.71% and 84.08% to 99.21% in the plasma of grass carp, yellow catfish and crayfish respectively. At 18℃ and 25℃, the same trend was also presented in the three species. Meanwhile, PPBRs of DC might have the atypical nonlinear phenomenon. Otherwise, the temperature could affect the PPBR of DC at a certain degree in the plasma of grass carp and yellow catfish at the same concentration of DC. However, no regularity was presented in the plasma of crayfish. Overall, the increased concentration of DC significantly affected the PPBR in the plasma of grass carp, yellow catfish and crayfish at the same temperature, but the temperature only had a certain influence on the PPBR of grass carp and yellow catfish. Hence, this study is beneficial to design suitable therapeutic regimens and formulations of DC in grass carp, yellow catfish and crayfish at different temperatures. [ABSTRACT FROM AUTHOR]

We established a high-performance liquid chromatography-triple quadrupole mass spectrometry method for the analysis of pendimethalin residues in water, sediments, and Procambarus clarkii (Louisiana crayfish) tissues. Water samples were concentrated on a HLB solid-phase extraction column and eluted with dichloromethane and acetone (1:1). After drying under a stream of nitrogen gas, the sample volume was adjusted to 1 mL with the mobile phase solvent methanol/water/acetic acid (8:20:0.1). Pendimethalin was extracted with ethyl acetate containing 0.1% acetic acid, after rotary evaporation to dryness at 35 °C, the residue was dissolved in mobile phase solvent, purified by a neutral alumina column and graphitized carbon black powder (0.1 g). The mass characterization was conducted in positive ion mode, and the corresponding ions were detected in multi-reaction monitoring mode. The linear equations were y = 1 × 106x + 14275, at pendimethalin levels of 0.05–20 μg L−1 and y = 691029 × − 414368 for 20–200 μg L−1. The detection limits of pendimethalin in water, sediments, and P. clarkii tissues were 1.0 × 10−4μg L−1 , 5.0 × 10−3μg kg −1 and 5.0 × 10−3 μg kg −1, respectively. The spiked recoveries ranged from 81.6 to 106.3%, and the relative standard deviations ranged from 4.58 to 13.6% (n = 6). The method provided an efficient and low-cost extraction and purification procedure that enabled a sensitive determination of pendimethalin in water as well as complex matrices. [ABSTRACT FROM AUTHOR]

Crayfish is a very popular aquatic food in many countries, and enrofloxacin (ENR) and ciprofloxacin (CIP) was the most frequently detected in aquatic products. However, limited information is available on the residue characterization, biotransformation rate and withdrawal period (WT) of ENR and CIP in crayfish and health risk via consumption of ENR and CIP remained crayfish. Herein, a comprehensive investigation was conducted to study residue depletion, biotransformation, ingestion risk, and WT of ENR and its predominate metabolite CIP in crayfish following different routes with repeated doses. The results showed that the elimination half-life (T 1/2) of target compounds in crayfish were all in order of hepatopancreas > muscle > gill, and the order of T 1/2 in different crayfish tissues were intramuscular (IM) route > oral (PO) treatment > immersion (IMMR) administration. The biotransformation rates from ENR to CIP varied from 0.75% to 3.45% in crayfish tissues following different exposure routes. The high dietary risk (RQ > 1) consuming muscle and hepatopancreas of ENR and CIP remained crayfish occurred at early after different administrations. WT is the key to control the drug residue risk, and the longest WT of marker residue of ENR in crayfish was calculated to be 51 d (1275 °C-day). [Display omitted] • Residue elimination characteristics of ENR and CIP in crayfish were revealed following three administration routes. • Low biotransformation ratios from ENR to CIP were found in crayfish tissues. • Dietary risk (RQ > 1) consuming crayfish occurred at early after multiple-dose administration of ENR. • WT were suggested to prevent the risk from ENR and CIP remained crayfish consumption. [ABSTRACT FROM AUTHOR]

We developed a method for determination of imidacloprid and its metabolites 5-hydroxy imidacloprid, olefin imidacloprid, imidacloprid urea and 6-chloronicotinic acid in Procambarus clarkii (crayfish) tissues using quick, easy, cheap, effective, rugged, and safe (QuEChERS) and high-performance liquid chromatography-triple quadrupole mass spectrometry. Samples (plasma, cephalothorax, hepatopancrea, gill, intestine, and muscle) were extracted with acetonitrile containing 0.1% acetic acid and cleaned up using a neutral alumina column containing a primary secondary amine. The prepared samples were separated using reverse phase chromatography and scanned in the positive and negative ion multiple reaction-monitoring modes. Under the optimum experimental conditions, spiked recoveries for these compounds in P. clarkii samples ranged from 80.6 to 112.7% with relative standard deviations of 4.2 to 12.6%. The limits of detection were 0.02–0.5 μg·L−1, the limits of quantification were 0.05–2.0 μg·L−1 and the method of quantification was 0.05–2.0 μg·kg−1. The method is rapid, simple, sensitive and suitable for rapid determination and analysis of imidacloprid and its metabolites in P. clarkii tissues. [ABSTRACT FROM AUTHOR]

In this study, the characteristics of a dominant strain wx3 isolated from the tissues of several sick red swamp crayfish were studied, and the immune response of the red swamp crayfish under stress was analyzed. The whole genome analysis of wx3 identified it as Aeromonas salmonicida subsp. Masoucida , which was confirmed using the bacterial challenge test, and is the pathogen that causes red swamp crayfish head rot. The sensitivity of wx3 to a variety of antibiotics was found that wx3 was highly sensitive to 13 antibiotics, but was not sensitive to 4 antibiotics. Comparative transcriptome analysis showed that 811 differentially expressed genes (DEGs) were enriched in the hepatopancreas 48 h after wx3 infection. The KEGG pathway analysis and GO analysis detected differentially expressed immune related genes, including C-type lectin 3 and Hsp22, which were upregulated, and also enriched in immune related pathways, such as the C-type lectin receptor signaling pathway, etc. In conclusion, by analyzing transcriptome, we found that red swamp crayfish infected with wx3 can exert a strong immune response. • It was found for the first time that Aeromonas salmonicida subsp. Masoucida caused the disease of red swamp crayfish. • Aeromonas salmonicida subsp. Masoucida can induce the expression of C-type lectin 3 and Hsp22 in red swamp crayfish. • wx3 showed severe drug resistance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Residue accumulation and risk assessment of doxycycline was studied in crayfish in the natural environment. • Statistical approaches were used to evaluate the homogeneity, linearity, and normality of errors for obtained data. • The dairy assessment indicated that hazard quotients were far less than 1 after post-doses for 5 days. • Reliable withdrawal times were determined in muscle (43 d) and hepatopancreas (89 d) of crayfish. Doxycycline is an important medicine in aquaculture for treating fish diseases. However, its excess use causes residue exceeding to threaten human health. So, this study aimed to estimate a reliable withdrawal time (WT) of doxycycline (DC) in crayfish (Procambarus clarkii) based on statistical approaches and conduct a risk assessment for human health in the natural environment. Samples were collected at predetermined time points and determined by high-performance liquid chromatography. A novel statistical method was used to process the data of residue concentration. The homogeneity and linearity of the regressed line of data were evaluated by Bartlett's, Cochran's, and F tests. Outliers were excluded by establishing the standardized residual versus their cumulative frequency distribution on a normal probability scale. The calculated WT was 43 days in muscle of crayfish based on China and European stipulations. After 43 days, estimated daily intakes of DC were ranged from 0.022 to 0.052 µg/kg/d. Hazard Quotients were ranged from 0.007 to 0.014, which were far less than 1. These results indicated that established WT could avoid health risks for humans resulting from DC's residue in crayfish. [ABSTRACT FROM AUTHOR]

The objective of the present study was to investigate the pharmacokinetic (PK) properties of doxycycline (DC) in crayfish after three different drug administrations of oral (per os , P.O.) gavage, intramuscular (IM) injection, and intrasinus (IS) injection at a dose of 20 mg/kg at 24.0 °C. Samples of hepatopancreas, muscle, gill, and hemolymph were collected at pre-determined time points after cessation of drug treatment (n = 5 for per time point). DC concentrations were determined by high-performance liquid chromatography with an ultraviolet detector. Results demonstrated that the multiple-peak phenomenon occurred in hemolymph and tissues irrespective of using any drug administration. With the changing of drug administration, the PK parameters were correspondingly altered. The elimination rate constant (t 1/2λ) were 28.90, 32.99, and 31.70 h; 42.00, 60.21, and 25.28 h; 32.17, 26.00, and 21.15 h; 69.53, 23.25, and 31.20 h in hepatopancreas, muscle, gill, and hemolymph after P.O., IM, and IS dosing, respectively. The values of the area under the concentration-time curve (AUC last) after IM and IS treatment were comparable in hepatopancreas, muscle, gill, and hemolymph, respectively, but the value following P.O. treatment was less than the values after IM and IS treatment except for hepatopancreas that presented an opposite trend. The volume of distribution (V z _F) was estimated to be 2625.30 mL/kg, and the systemic total body (Cl_F) was 58.30 mL/h/kg. Finally, the P.O. and IM bioavailability were calculated to be 19.58% and 104.76%. This study will provide the useful PK information of DC after different administrations, and is beneficial for a specific dosage regime in line with the drug given route. • Doxycycline's PKs were investigated in crayfish after P.O., IM, and IS administrations. • The changing of drug administration considerably affected t 1/2λz , T max , C max , and AUC last. • Bioavailability values were 19.58% and 104.76% after oral and intramuscular dosing. • The results provide useful information for the effective use of doxycycline in crayfish. [ABSTRACT FROM AUTHOR]