Study On Toxicity Assessment Of Polycyclic Aromatic Hydrocarbons And Antibiotics On Litopenaeus Vannamei

In this paper, according to the present situation of offshore PAHs pollution andfishing with the use of antibiotics. We used the white shrimp Litopenaeus vannamei(Boone), which is a commercially important shrimp species currently being cultured inmany parts of the world as the research object, the most toxic to polycyclic aromatichydrocarbons (PAHs)–benzo (a) pyrene (BaP) as the representative of PAHS, and thecommonly used antibiotics in the shrimp farming–florfenicol (FLR) represents theantibiotics used as fishing, research on PAHs (BaP) content distribution in L. vannameigills and hepatopancreas, metabolic enzyme activities in the two tissues and relatednuclear receptors to regulate gene expression in the determination of macromoleculardamage, and preliminary study on the effects of BaP on L. vannamei immune andantioxidant system of fishing with antibiotics. The distribution and elimination of FLRin L. vannamei gills, hepatopancreas and muscle tissues, the expression of metabolicenzymes in hepatopancreas of FLR and related genes was determined, oxidativedamage, and a preliminary study on the effect of FLR on L.vannamei gills andhepatopancreas antioxidative capacity and immune parameters activities, the resultsobtained are as follows1. Study on toxicity assessment of BaPon L. vannameiWe adopted laboratory study, shrimps were exposed to0.03μg/L,0.3μg/L and3μg/L of BaP for21days, and sampled at1d,3d,6d,10d,15d,20d. BaPconcentration in gills and hepatopancreas were analysed using liquid-liquid extractionand HPLC. There’s very little BaP accumulation in control group. BaP accumulationin hepatopancreas of0.03μg/L BaP treatment group became significantly higher thancontrol group at day1, and became stable from day3to day20. BaP accumulation inhepatopancreas of0.3μg/L and3μg/L of BaP treatment group and in gill of0.5μg/L, 3μg/L and10μg/L of BaP treatment group became markedly higher than controlgroup at day1, and gradully increased from day15to day21, tissue dose of BaP atday10is significantly higher than in day3. The tissue dose of BaP became stablefrom day10to day20. BaP concentration in hepatopancreas is higher than in gill. BaPcan be quickly accumulated from environment to shrimp tissues. According to theNation Standard of Peoples Republic of China GB7104-84, BaP concentration in foodshould be less than5μg/kg. In our results, tissue dose of BaP in every treatmentgroup are all excessed the standard.The purpose of this study was to investigate the impact of benzo[a]pyrene（BaP）on metabolic detoxification system and bioaccumulation of white shrimp Litopenaeusvannamei. In this study, juvenile white shrimp L. vannamei were exposed for21daysat four different concentrations as0,0.03,0.3and3μg/L. Detoxification enzymeactivities of phase I（aryl hydrocarbon hydroxylase（AHH）,7-ethoxyresorufinO-deethylase （EROD）, epoxide hydrolase （EH）） and phase II（glutathione-S-transferase（GST）, sulfotransferase（SULT）, uridine diphosphateglucuronyl transferase（UGT）） were determined, and results showed that all thedetoxification enzyme activities increased in a dose-dependent manner except for thelow BaP exposure. Transcription of genes were detected and measured by real-timeRT-PCR. It showed that at day6BaP increased cytochrome P450（CYP）1A1, GST,SULT visa aryl hydrocarbon receptor（AhR） mRNAexpression in a dose-dependentmanner, which suggests that they could be potential targets of BaP that disruptdetoxification system. The consistency of their responses to BaP exposure implies thatAhR action may be involved in invertebrate CYP regulation. Additionally, BaPbioaccumulation increased rapidly first and showed an incoming plateau. Besides, theenzyme activities and bioaccumulation in the hepatopancreas were higher than thosein the gills. These results will not only provide information on BaP metabolicmechanism for this species, but also scientific data for pollution monitoring.The effects of benzo(a）pyrene（Bap）（0.03,0.3and3μg/L） on the function ofthe immune system including total hemocyte count（THC） in the hemolymph, phagocytic activity and pro-phenoloxidase（pro-PO）activity of the hemocyte,phenoloxidas（ePO）activity, α2-macroglobulin（α2-M）activity, bacteriolytic activityand antibacterial activity in the hemolymph of juvenile white shrimp Litopenaeusvannamei were determined under laboratory conditions. The results showed that BaPcould inhibit the immune function of L. vannamei significantly under highconcentration BaP exposure. Moreover, the results indicated the THC in hemolymph,pro-PO activity and phagocytic activity of hemocyte, and bacteriolytic activity inhemolymph could be used as potentially suitable biomarkers for early warningindication of PAHs toxicity, this could provide useful information for toxic riskassessment of environmental pollutants.2. Study on toxicity assessment of FLR on L. vannameiFlorfenicol（FLR） is a commonly used antibiotic for the treatment of bacterialdiseases in white shrimp Litopenaeus vannamei. In this study, we evaluated the tissuedistribution and elimination, changes in selected metabolism enzymes andtranscriptional activity of metabolism-related genes following oral administration ofFLR. Juvenile shrimps（9.5±0.5cm） were fed coated with FLR100mg kg1and200mg kg1body weight for6days followed by a period of feeding without antibiotic for10days to evaluate the elimination pattern. Gill, hepatopancreas and muscle tissueswere collected on the3rd,6th day of feeding the antibiotics and at3,5and10daysafter FLR withdrawal. The concentration of FLR residue in hepatopancreas wassignificantly higher than that in other tissue. Ethoxyresorufin-O-deethylase（EROD）and glutathione-S-transferas（eGST）activities were significantly increased in gill andhepatopancreas of FLR-fed shrimps until the6th day post-withdrawal. Furthermore,transcriptional profiles of selected genes（CYP1A1, CYP3, CYP4, GST） weredependent on the dosage of antibiotics that was administered and the time of sampling.Results in the present study were expected to provide additional contribution to theemerging field of crustaceans in understanding the pharmacodynamics and the metabolic progress of L. vannamei following oral administration.Florfenicol（FLR） is a commonly used antibiotic for the treatment of bacterialdiseases in white shrimp Litopenaeus vannamei. The aim of this study was toinvestigate the effects of FLR on immune response, antioxidant status andbiomolecule damage of L. vannamei juveniles. In this study, juvenile shrimps（9.5±0.5cm） were fed coated with FLR100mg kg1and200mg kg1body weightfor6days followed by a period of feeding without antibiotic for10days. Hemolymphand hepatopancreas were collected on the3rd,6th day of feeding the antibiotics andat1,3,6and10days after FLR withdrawal. Results showed phenol oxidase（PO）activity in both FLR treatments had no significantly change compared to controlduring the experiment. There were also no significant differences in proPO activity inhemocytes, bacteriolytic and antibacterial activities in plasma between100mg kg1FLR treatment and control group, while200mg kg1FLR suppressed all of them（P<0.05）. It showed that following6days FLR-medicated feed, FLR affectedimmune parameters of total hemeocyte count（THC） and phagocytic activity inhemocytes, antioxidant status of T-AOC and GSH/GSSG ratio in plasma andhepatopancreasas well as biomolecule damage of lipid peroxidation（LPO）and DNAdamage in both tissues in a time-dose dependent manner, which suggests theseparameters are potential biomarkers for evaluating the physiological health of FLR inL. vannamei. To understand the mechanisms by which the drugs affect the immuneand antioxidant systems as well as the damage indexes, we need much more detailedinformation on the penetration, distribution and metabolism of the drugs on thecellular level.