纳米塑料和纳米二氧化钛食相暴露对凡纳滨对虾毒性效应研究

纳米技术的发展将导致一定量的纳米材料不可避免地释放到海洋生态系统中。纳米塑料和纳米二氧化钛（nano-TiO2）是两种使用较为广泛且在环境中普遍存在的纳米材料。纳米颗粒污染引发的生态毒理学效应是当前环境毒理领域的研究热点。本论文以聚苯乙烯（PS）纳米塑料和纳米TiO2作为研究对象，以凡纳滨对虾（Litopenaeus vannamei）作为实验动物模型，通过食相暴露途径研究了纳米塑料和纳米TiO2在凡纳滨对虾体内的富集情况，探讨了纳米PS塑料和纳米TiO2分别单独暴露对凡纳滨对虾生长、免疫能力、氧化应激、肠道和肝胰腺组织学结构以及肠道微生物的影响，研究结果可为纳米颗粒污染物的生态风险评估提供技术支撑。主要结果如下： （1）凡纳滨对虾在暴露于混有荧光纳米PS和纳米TiO2的饲料后，肠道和肌肉组织中的纳米PS和纳米TiO2含量呈现增长的趋势。净化期间，纳米PS含量呈指数下降；但净化5天后组织中仍然存在大量纳米TiO2。相较于纳米PS，纳米TiO2形状不规则且更容易团聚，因此更难被凡纳滨对虾排出体外。 （2）两种纳米材料暴露对凡纳滨对虾的生长具有一定的抑制作用。纳米PS和纳米TiO2暴露导致凡纳滨对虾增重率和特定生长率表现出降低的趋势，高浓度纳米PS处理的增重率和特定生长率与对照组相比显著降低。 （3）纳米PS和纳米TiO2会引起凡纳滨对虾氧化应激反应，影响免疫系统。纳米PS和纳米TiO2均导致凡纳滨对虾血细胞凋亡率显著上升，并且导致肝胰腺组织T-AOC、SOD和GST活性的不同程度升高以及Na＋/K＋-ATP酶活性显著降低。 （4）凡纳滨对虾肝胰腺和肠道组织表现出浓度依赖性的组织学变化。纳米PS和纳米TiO2均导致肝胰腺组织星状小管腔出现扩张，部分空泡出现并破裂。肠道黏膜层与对照组相比略微松散，黏膜层上皮细胞数量较少。纳米PS暴露还会导致肠道组织出现增生细胞。 （5）纳米PS和纳米TiO2暴露均可改变凡纳滨对虾免疫相关基因的表达。暴露14天，高浓度纳米TiO2处理组的Beta-glucan binding protein、LPS/β-glucan binding protein、HSP 70、TLR和Toll 1基因表达量显著上调。高浓度纳米PS暴露导致Beta-glucan binding protein、LPS/β-glucan binding protein、HSP 90和TLR基因的表达量显著升高。暴露28天，高浓度纳米TiO2暴露导致HSP 90和Toll 1基因表达量的显著升高以及LPS/β-glucan binding protein的表达量显著降低。纳米PS暴露导致TLR基因的显著上调和Toll 1基因的显著下调。 （6）纳米PS和纳米TiO2暴露导致凡纳滨对虾肠道菌群发生显著变化。两种纳米颗粒的暴露降低了肠道菌群的丰富度和多样性，纳米PS和纳米TiO2暴露诱导肠道菌群中的拟杆菌门丰度的降低以及变形菌门和放线菌门丰度的升高。与对照组相比，弧菌属（Vibrio）、Tenacibaculum属、微杆菌属（Microbacterium）、慢生根瘤菌属（Bradyrhizobium）和Demequina属在处理组中菌群比例均有所上升。通过Tax4Fun对凡纳滨对虾肠道菌群功能进行预测分析，结果表明两种纳米材料暴露均导致“代谢”、“环境信息处理”、“细胞过程”和“生物系统”等途径与对照组相比存在显著差异。这说明两种纳米颗粒引起肠道菌群发生显著变化，致病菌比例上升可能增加其感染的几率，并可能影响肠道菌群的代谢功能。 （7）两种纳米材料对凡纳滨对虾的毒性效应存在一定差异。其中，纳米PS暴露对凡纳滨对虾的主要影响为：诱导肠道组织出现增生细胞，扰乱肠道菌群稳态，并且降低凡纳滨对虾的增重率和特定生长率；纳米TiO2暴露导致凡纳滨对虾肝胰腺组织的GST酶活性和血细胞凋亡率与纳米PS暴露组相比显著升高，同时对Na+/K+-ATP酶活性的抑制程度也显著高于纳米PS暴露。综合生物标志物响应（IBR）分析表明，纳米TiO2暴露对凡纳滨对虾产生的氧化胁迫、能量代谢以及血细胞凋亡率的诱导程度均高于纳米PS暴露

Construction of Ecological Tidal Flat Ranch and Research Prospect

At present,the utilization of living marine resources needs transition and upgrading.It is particularly important to expand the area of marine ranching under the background of marine ranching development in China.In this study,we summarize the utilization status of coastal bioresources,and point out that the utilization of tidal flat resources mainly relying on traditional mudflat bivalve culture should be changed.Therefore,in order to protect and breed tidal flat organisms,the construction of tidal flat ranching by engineering technology under the guidance of ecological principles should be carried out.Tidal flat ranch can be classified into four categorizes based on their ecosystem types,including tidal flat mollusk,oyster reef,seagrass bed and mangrove.In addition,the key technology for site selection,seed breeding,environmental monitoring,ecological carrying capacity evaluation and efficient harvesting should be developed when constructing the tidal flat ranching.On this basis,the construction of coastal ecological farm which includes saline land ranch,tidal flat ranch and marine ranch will be an important direction of marine ranching

Effects of nanoplastics and nanosized titanium dioxide on hemocytes function and antioxidant enzyme activities of Litopenaeus vannamei via dietary exposure

The increasing use of nanoplastics and nanometal oxide particles in different fields have aroused concern about the environmental risks associated with these nanomaterials entering the aquatic system. In the present study, through dietary exposure route, the interference of hemocytes function and oxidative balance of the white shrimp Litopenaeus vannamei after exposure to 100 nm nano-PS and nano-TiO_2 was analyzed. Shrimps of treatment groups were fed with diets spiked with nano- PS and nano-TiO_2 at doses of 200 mg/kg and 2 000 mg/kg respectively for 28 days. The ROS production, phagocytosis and apoptosis rate of hemocytes as well as the enzymatic activities of total antioxidant capacity (T-AOC), superoxidase dismutase (SOD), glutathione-S-transferase (GST), malondialdehyde level (MDA) and Na+/K+-ATPase in hepatopancreas were measured at Day-14 and Day-28. The results showed that both nano-PS and nano-TiO_2 caused a significant increase in the apoptosis rate of hemocytes. Besides, the activities of T-AOC, SOD and GST in hepatopancreas were elevated to varying degrees, while the significant decrease of Na~+/K~+-ATPase activity was observed in the treatment groups. In addition, compared with nano-PS, nano-TiO_2 caused more serious oxidative damage to shrimps after 28 days of exposure

Toxic effects of polystyrene microplastics and pyrene on Ruditapes philippinarum

The pollution of microplastics and polycyclic aromatic hydrocarbons (PAHs) in marine environment is increasingly serious. The toxic effects of polystyrene microplastics and pyrene on the clam Ruditapes philippinarum were investigated in this study. R. philippinarum was exposed to two polystyrene microplastics sizes (0.3 mum and 6 mum, 20 mug/L) and two pyrene concentrations (10 mug/L and 100 mug/L) for 21 days, respectively. For individuals in each treatment, physiological responses (condition index and clearance rate), immune defense and oxidative stress parameters were measured. It was found that except for the pyrene single exposure group, the clearance rate of R. philippinarum in the other exposure groups was significantly lower than that of the control group, but the two pollutants had no significant effect on the condition index of R. philippinarum. Exposure to microplastics and pyrene led to impaired immune function of R. philippinarum, manifested by increased hemocyte apoptosis and inhibited phagocytosis. The apoptosis rate of hemocytes in the exposure group with small size microplastics and high concentration pyrene was significantly higher than that in the control group,and the apoptosis rate of hemocytes in the combined exposure group was the highest. Except for the large size microplastic exposure group,the phagocytic activity of hemocytes in each exposure group was significantly lower than that of the control group. The antioxidant system of R. philippinarum could not remove the free radicals produced in the body in time,leading to oxidative damage in the body,which was manifested as the change of antioxidant enzyme activity and the increase of malonic dialdehyde (MDA) content. The combined exposure of microplastics and pyrene significantly increased the activities of glutathione S-transferase (GST) in gill tissues, and significantly decreased the activities of catalase (CAT) and superoxide dismutase (SOD) in digestive gland tissues. Integrated biomarker response (IBR) analysis showed that the stress caused by combined exposure on R. philippinarum was higher than that of the single exposure group

上海天文台第三代卫星激光测距系统

本文介绍了中国科学院上海天文台的第三代卫星激光测距系统的性能及三年来对LAGEOS,AJISAI和STARLETTE等卫星的实测结果.卫星轨道拟合和地面靶的测距试验均表明,本系统的卫星测距精度(均方差)约±5cm