Study Of Bioaccumulation And Toxicity Effects Of Scallop Chlamys Farreri Exposed To Polycyclic Aromatic Hydrocarbons (PAHs)

Polycyclic aromatic hydrocarbons (PAHs) are mainly produced from incompletecombustion of fossil fuels and organic materials as well as petroleum. As a kind ofglobal persistent organic pollutant (POPs), PAHs have also been included in the groupof persistent toxic substances (PTS), due to their well-known carcinogenic andmutagenic properties. In2008, the European Food Safety Authority (EFSA) hasintroduced a system of four specific PAHs, namely benzo[a]anthracene (BaA),benzo[a]pyrene (BaP), benzo[b]fluoranthene (BbF) and chrysene (CHR), assessingthat the sum of the four PAH compounds would be the most suitable indicator forPAHs in food. The main objective of this study was two-fold: to investigate theaccumulation rules of selected PAHs and to select useful biochemical biomarkers forPAHs pollution monitoring. This study may provide scientific data for development ofthe contaminant monitoring strategy, and the bioaccumulation results of juvenilescallops may make sense for resource protection as C. Farreri is a commercialspecies.1. Study of bioaccumulation and toxicity effects of juvenile scallop Chlamysfarreri exposed to three PAHsIn the present study, we use juvenile scallop, C. Farreri, as a model organism,and studied PAH concentrations, LPO levels, protein carbonyl (PC) contents andDNA strand breakage in soft parts of scallops, with exposure to selectedconcentrations of individual PAHs. All the results indicated that a clear time effectwith exposure concentration was established for PAHs. At0.2μg/L levels, the scallops accumulated CHR almost twice as many as BaP and BbF, while thebioaccumulation of BaP in the tissues was close to that of BbF. During the BaPexposure time, MDA and PC contents in tissues showed positive significantcorrelations with BaP concentrations in tissues, while DNA damage index (F value) atday15and day21showed no significant correlation. Among the studied indices, PCcontents may be a reliable biomarker to evaluate the toxicity of PAHs, as theyconsistently increase with the concentration of the analyzed contaminants. Thesequence of toxicity for juvenile scallops C. ferrari is BaP> BbF> CHR. Besides, C.ferrari is a suitable sentinel species for PAHs pollution monitoring.2. Study of bioaccumulation and toxicity effects of mature scallop Chlamysfarreri exposed to CHRThis chapter aimed to study CHR accumulation, detoxification and antioxidantenzymes (AHH, EROD, GST, SOD) and related key genes (AhR, ARNT, CYP1A1,GST-pi, Cu/Zn-SOD) and damage effects of biological macromolecules (LPO level,PC content and DNA strand breaks) of both male and female scallops (C. farreri)exposed to chrysene during the maturation of gonads. Experimental exposureconcentration is set to the control group,0.2,0.8,3.2μg/L, while at1,3,6,10,11,15and21d (10d after which sampling method to stimulate the use of dried scallopsspawn/ejaculation, respectively take male and female individuals gill, digestive gland,adductor muscle, hemolymph, gonads and software unit measures the cumulativecontent CHR,digestive blind sac and gonads indicators measuring damage. Theresults showed that: CHR organization of male and female individuals accumulatecontent, detoxification enzymes and indicators related genes and significant loss ofbiological macromolecules, digestive gland tissue than gills change significantly, butthere was no significant difference in the control group.Befor spawning/spermiationeach treatment group of male and female individuals gill, digestive gland, adductormuscle, gonad and the CHR levels were significantly higher in the software department within10d, showed significant time-dose effect, when the cumulativeorder: content gill> gonads> digestive gland> soft part> adductor muscle; afterspawning/ejaculation, content gill> digestive gland> gonads>soft part> adductormuscle. Gills and digestive gland of detoxification and antioxidant enzymes (AHH,EROD, GST, SOD) and related key genes (AhR, ARNT, CYP1A1, GST-pi,Cu/Zn-SOD, P-gp) and other indicators in the male and female between individuals ofdifferent trends，gills and digestive blind sac AhR and ARNT genes with similarexpression patterns, and exhibited dose-dependence; high concentration groupfemales EROD, GST, CYP1A1gene, GST-pi gene, P-gp gene as well as male andfemale individuals SOD, Cu/Zn-SOD gene in the latter experiment significantlyinhibited. Biological macromolecules damage index has a similar trend in gill anddigestive gland and changes in the gonads more complicated. Spawning/ejaculationbefore each treatment group, digestive gland and gonads MDA content, PC content at6d or10d showed a peak change reaching at3d or10d, and significantly lower thanthe control group. After spawning/ejaculation, the gill and digestive gland tissueMDA, PC reached maximum levels after remained stable5d, while the F valuecontinues to rise in the exposure time. Low concentrate of female and male low levelsof gonadal MDA concentration group showed a peak change at11d, significantlyhigher than the control group or restored to the level of the rest of MDA content ineach group showed a peak of gonadal changes in the11d, at11d reached themaximum, and significantly higher levels; and significantly higher; each treatmentgroup gonadal F values were changes in the11d peak, reached a minimum at1d or5d,and still significantly lower than the control group at15d. As mentioned above, theexcessive CHR accumulation in gonad of scallops resulted in the increase of LPOlevel, PC contents and DNA strand break level, and had a severe reproductive toxicity,and PC contents of ovary seemed to be proposed as a potential indicator to evaluatedamage effect of gonad of C. farreri.