Developmental And Reproductive Toxicity Of Carbon Quantum Dots(CDs) To The Embryos/Larvae Of Rare Minnow(Gobiocypris Rarus)

Carbon quantum dots?CDs?bearing the advantage as higher thermostability,photostability,quantum yield and lower release rate of heavy metal ions than the traditional semiconductor quantum dots,CDs have been proposed broadly to the potential application in analytical chemistry,biological probing and imaging,drug delivery etc.Thus,the biological and environmental toxicity of CDs gradually attracted heavy research interests which is required for the safety evaluation for its further application.However as the production and application of CDs increase,their impact on the environment is widely,because CDs can release into the environment during the processes of production and application.And is there the an important issue regarding the potential health risks of CDs or not we cannot concerned now.So it is noteworthy for us that the security problem about the aquatic organism especially development of fish under influence by CDs.In experiment I,This research sets six CDs concentrations treatments,1,5,10,20,40,80mg/L and an control group.Providing theoretical basis to prevent teratogency or death in early embryo of fish by discussing the reason why embryo can be teratogency or death with CD's influence through biochemical indexes?include antioxidase,ATPase?,quantitative analysis of gene about development?Vezf1,Wnt8 a,Mstn and RAR??and DNA damage.In experiment II,this research sets five CDs concentrations treatments,20,40,80,160,320mg/L and an control group?0.6% NaCl?.Providing basic information to assesssecurity for organism which influenced by CDs through finding the toxic effect in earlydevelopment of fish by CDs and discussing the effect of the development of the embryo and reproduction of Gobiocypris rarus.The effective time and the activation rate of sperm,DNA damage of male sperm cells,behavior and morphological parameter measurement of offspring G.rarus embryos and the ovary of adult famale,the testis of adult male caused by different concentration of CDs intraperitoneal injected were tested.The toxic effects of CDs on rare minnow?Gobiocypris rarus?embryos at different developmental stages were investigated.The results showed that rare minnow embryos had decreased spontaneous movements,body length,increased heart rate,pericardial edema,yolk sac edema,tail/spinal curvature,various morphological malformations and decreased hatching rate.Biochemical analysis showed the CDs exposure significantly inhibited the activity of Na+/K+-ATPase,It might block the pumping out of the Na+ and the subsequent intracellular Na+ accumulation,which eventually result in the edema and destruction of cells.Moreover,the CDs exposure induced up-regulation of development-related genes?Wnt8a and Mstn?along with the down-regulation of Vezf1.CDs exposure significantly inhibited the activity of Ca²⁺-ATPase.The significant increased expression of Wnt8 a indicate the body axis extension were inhibited.Taken together,on one hand,both of the Wnt8 a expression upregulation and the inhibited Ca²⁺-ATPase activity promote the skeletal development and on the other,increased Mstn expression block the muscle development which could explain the observed tail and spinal curvatures in this study.The activity of SOD wereincreased following CDs treatments,synchronize the activity of SODwiththat of CAT.Moreover,due to the accumulating H2O2 generated from O2-by SOD,the CAT turn to active quickly to keeppacewith SOD.Also,the GPX activity is induced by the higher intensity of stress result from higher CDs concentration.Taken together,in rare minnow,the antioxidant enzyme system consist of SOD,CAT and GPX combinedtogetheract against oxidative stress and keepthe MDA content in a certainrange in lower CDs concentration group.However,long time of CDs exposure in20,40,80mg/L concentration groups break the organism antioxidant capacity and result in the increase of theMDA content,indicating that CDs exposure induced the oxidative stress to the embryo.Consequently,the defective development of rare minnow embryo appeared.With the increased CDs concentration and extended exposure time,serious DNA damage of rare minnow embryos/larvae cells were detected.It could be the reason of highermalformation and mortality rate.Furtherincreaseof the CDs concentrationresultsin moreserious DNA damage induced by the ROS attacking nucleotides.The damaged DNA can't berepairedintime thus the malformation rate and mortality rate increased significantly.The reproduction toxicity of CDs on rare minnow?Gobiocypris rarus?embryos at different developmental stages were investigated.The results showed that the effects of CDs on the testis of mature male are examined,the lobule membranes in the testis are swollen and form a cavity surrounding by basal membrane.Moreover,the GSI,the effective time and the activation rate decreased gradually with the increase of concentration of CDs.The increase of DNA percent in comet tail,tail length and TM implied that the DNA of sperm was damaged by CDs.Then some parameters of offspring were tested,including embryo the rate of malformationsfertilization.It suggested that the CDs exposure on rare minnow embryos had decreased fertilization rate,increased malformations rate,it mightthe testis of male and the DNA of sperm was damaged by CDs caused the effective time and the activation rate of spermdecreased,eventually caused malformations rate increased and fertilization rate decreased of offspring embryo.Moreover,frequency of spawn were decreased following CDs treatments?20,80,320mg/L?.cells of the ovaries degenerated,and that might be a reason for frequency of spawn decreased.The main conclusion as follow:?1?In summary,the higher concentration of CDs have significantly development toxicity on rare minnow embryos which could be characterized as decreased spontaneous movements and body length,increased heart rate,and pericardial edema,yolk sac edema and tail/spinal curvature,various morphological malformations and decreased hatching rate.The underlying mechanism of this developmental toxicity appears to be related to the generation of oxidative stress,repressed DNA repair efficacy and altered development related gene expression.?2?The higher concentration of CDs have reproduction toxicity on rare minnow which could be characterized as decreased GSI,the effective time,the activation rate and the DNA of spermdamaged,testis of male changed caused fertilization rate,increased malformations rate.Morever,cells of the ovaries degenerated,and that might be a reason for frequency of spawn decreased.