| Japanese scallop (Mizuhopecten yessoensis) has been cultured on a large-scale inChina for many years. However, serious marine pollution in recent years has resultedin considerable loss to this industry, especially the safety problems caused by heavymetal and POPs, etc. Moreover, due to the lack of genomic resources, limited relatedresearch about the toxicology mechanism caused by the marine pollutions has beencarried out on this species. In this study, the bioaccumulation in gill or digestive glandfollowing Cd or Cu exposure was investigated. Also, the responses of the antioxidantdefense system including SOD, CAT and GPx were studied. In order to betterannotation the transcripts, the transcriptome of adult M.yessoensis were investigatedbased on RNA-Seq technology. Then the different expressed genes (DEGs) weredetected in gill and digestive gland following Cd or Cu exposure. The detail resultswere as follows:1. The Cd concentration in gill or digestive gland of M.yessoensis displayed alinear relationship with the exposure doses and had a curvilinear change with timeextension. The maximum Cd concentration presented at10d (0.20mg/L,134.20μg/g)in gill and14d (0.1mg/L,109.2μg/g) in digestive gland, respectively. Theconcentration of Cd in gill was larger than that in digestive gland and suggested thatgill might be the main accumulation tissue of Cd in M.yessoensis.2. The maximum accumulation of copper (0.025mg/L,0.05mg/L,0.10mg/L) ingill occurred at14d (347.55μg/g),6d (340.72μg/g) and6d (302.30μg/g) respectively.With the time extension, accumulation of copper has a curvilinear relationship except0.10mg/L group. However, concentration of copper in0.10mg/L group of digestivegland presented liner changes with exposure time and the peak occurred at14d(60.88μg/g). The corresponding changes in0.025mg/L and0.05mg/L were curvilinear and even be decreased. Gill was the main accumulation tissue of Cu in M.yessoensis.3. SOD, CAT and GPx activities in gill or digestive gland respond to cadmiumexposure displayed curvilinear relationship with time extension. The SOD activity in0.10mg/L and0.20mg/L groups of both tissues reached to the peak at24h and that of0.05mg/L group both reached at72h. CAT activity in gill following Cd exposurepresented the same tendency with SOD activity. However, the peak value of CAT indigestive gland occurred at10d,6d and1d with doses increasing. GPx activity in gillfollowing Cd exposure presented the peak at6d,3d and1d with doses increasing and3d and1d in digestive gland. SOD might be the main antioxidant enzyme in gill ofM.yessoensis and CAT was the main antioxidant enzyme in digestive gland.4. SOD, CAT and GPx activities were significantly suppressed in gill followingcopper exposure. However, in digestive gland,0.025mg/L and0.05mg/L groups couldinduce the express of antioxidant enzymes in24h except GPx in0.05mg/L group. Theactivities of all the three enzymes in0.10mg/L group were suppressed during all theexperiment.5. Transcriptome of adult M. yessoensis (adductor muscle, digestive gland, gill,gonad (male and female), kidney, visceral mass and mantle) was analyzed byRNA-Seq. Totally194,839clean reads were produced and14,240clean reads wereclearly annotated in database. Totally721transcripts were founded in the GO term of‘response to stimulus’ and251transcripts were detected involved in13immunesystem pathways.6. Based on RNA-Seq (Quantification), totally7,556different expressed geneswere identified in gill following Cd exposure. Among them,3,673transcripts wereup-regulated and3,883were down-regulated. In digestive gland, a total of3,002DEGs were detected, with1,627up-regulated genes and1,375down-regulated genes.Also, amount of DEGs related with environment stress were founded by KEGGenrichment analysis.7. A total of3,459DEGs were detected in gill following copper exposure, with1,312genes up-regulated and2,237down-regulated. In digestive gland, totally1,718 DEGs were identified. Among them841genes were up-regulated and877genes weredown-regulated. At the same time, amount of DEGs related to ‘response to chemicalstimulus’ was detected by GO enrichment analysis. Also, the expressed level of genesinvolved in immune system was analyzed by KEGG.This thesis investigated the toxic mechanism of M.yessoensis respond tocadmium or copper and would be helpful for researching the toxicology of marinepollutants. Also, transcriptome of M. yessoensis would great enrich the sequencesresources in public database. These sensitive expressed genes could be used aspotential candidate genes for constructing early warning system and platform duringthe healthy aquaculture of Japanese scallop. |
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