Occurrence and distribution of microplastics in China's largest freshwater lake system.

Although microplastics (MPs; < 5 mm) have been recognized as one of the most challenging environmental pollutants in the ocean, our understanding of the environmental fate of freshwater MPs falls far behind, particularly on smaller MPs (<0.1 mm). Here, we seek to reveal the latest MP pollution status in the largest freshwater lake of China, Poyang Lake, by comprehensively assessing the abundance, distribution, size, shape, polymer composition, and micro-morphology of MPs in water and sediment, covering a large geographic area of the Lake and its five main river tributaries. High levels of MPs were detected in water (up to 1064 ± 90 MP/m3) and sediment (up to 1936 ± 121 MP/kg), with the highest concentrations in the Gan River and the lowest in the national Nature Reserves. While a positive correlation was identified between MP abundance in water and sediment, the size distribution of MPs in between water and sediment was distinct. The dominant MP form in sediment and water was fragment and fiber, respectively. Infrared spectroscopy analysis confirmed the dominant polymer types including polypropylene, polyvinyl chloride, polyethylene, polystyrene, and polyvinyl alcohol. Moreover, both µ-FTIR and SEM results suggested significant features of weathering and fragmentation of MPs. This study provides comprehensive data to understand the environmental behavior and pollution magnitude of MPs in China's largest freshwater lake and highlights the significant contribution of smaller-size fractions (0.03-0.1 mm) to improve future MP studies in freshwater systems.

Tumour extracellular vesicle-derived Complement Factor H promotes tumorigenesis and metastasis by inhibiting complement-dependent cytotoxicity of tumour cells.

The complement system is involved in the immunosurveillance of pathogens and tumour cells. Proteomic profiling revealed that extracellular vesicles (EVs) released by metastatic hepatocellular carcinoma (HCC) cells contained a significant number of complement proteins. Complement Factor H (CFH), an abundant soluble serum protein that inhibits the alternative complement pathway, was found to be highly expressed in EVs of metastatic HCC cell lines. Here, we investigated the functional role of EV-CFH and explored the therapeutic efficacy of targeting EV-CFH with an anti-CFH antibody in HCC. The results showed that EVs that are enriched in CFH promoted HCC cell growth, migration, invasiveness and enhanced liver tumour formation in mice. EV-CFH also promoted metastasis, which was significantly abrogated when treated with an anti-CFH antibody. These findings demonstrate an unexplored function of EV-CFH in protecting HCC cells by evading complement attack, thereby facilitating tumorigenesis and metastasis. Lastly, we demonstrated the therapeutic efficacy of an anti-CFH antibody in suppressing tumour formation in a syngeneic mouse model. This study suggests a new therapeutic strategy for HCC, by inhibiting EV-CFH with a tumour specific anti-CFH antibody.

[Pollution Characteristics of Microplastics in Migratory Bird Habitats Located Within Poyang Lake Wetlands].

Microplastic pollution (plastics with particle sizes<5 mm) has become a serious problem. In this study, we sampled the surface water, sediment, and bird excrement from the shore, center of the lake, and active areas for birds in Baisha Lake, which is key habitat for migratory birds in the Poyang Lake wetlands. The microplastics were separated by flotation separation, and then, we analyzed the pollution characteristics of this area. The main results were as follows. ① There were significant differences in the abundance of microplastics in water and sediment at different sampling points in the study area. The average abundance of microplastics in water and sediment were 263.28 per·m-3 and 215.9 per·kg-1, respectively. The average abundance of microplastics in migratory bird feces was 4.93 per·g-1. ② There were four kinds of microplastics in the surface water in terms of the different morphologies of particles, namely, pellets, films, fragments, and fibers, among which pellets were the major type. The main colors of microplastics were red, yellow, green, blue, purple, black, and transparent. The rank in terms of the size of microplastics was follows: < 1 mm > 1-2 mm > 2-3 mm > 3-5 mm, and the abundance decreased with the increase of particle size. ③ There were also four kinds of microplastics with different morphologies in the sediment, namely, pellets, films, fragments, and fibers. The main colors of these microplastics were red, yellow, blue, purple, black, and transparent. Microplastic sizes on the shore of the lake and bird habitat were mainly < 1 mm, and 1-2 mm particles were mainly detected in the center of the lake. ④ There were four types of microplastics in the excrement of migratory birds, namely, pellets, films, fragments, and fibers. The colors of these microplastics were red, yellow, green, purple, and transparent, and the particle size was mainly < 1 mm. ⑤ There was no consistency in the types of microplastics in the water body, sediment, and bird droppings. However, the size distribution for water and bird excrement was consistent. The results indicate that Poyang Lake bird habitat is polluted by microplastics, and the birds are inevitably exposed to microplastics. This study warns that microplastics will be an emerging threat to migratory birds.

Distribution and characteristics of microplastics in the sediments of Poyang Lake, China.

Microplastics are considered to be a widespread environmental contaminant, posing a serious threat to the aquatic environment. We addressed this issue based on field observations and laboratory analysis of samples from Poyang Lake. We collected sediment samples from 10 sites across Poyang Lake during 2017. Data were analyzed by one-way analysis of variance (ANOVA). Results showed that the abundance of microplastics ranged from 11 to 3,153 items/kg dw in the sediment samples. Except at Nanjishan, the amount of microplastics in different periods decreased in the order: December > April > July. Microplastics with a size <1 mm were the most abundant fraction in sediments, reaching over 50%. Observations under microscope revealed four types of microplastics in Poyang Lake: fragments, films, foams and fibers. Fragments were more common in sediments. Microplastics have complex surface topography, typically including rough surfaces, porous structures, cracks and extensive damage. Energy dispersive X-ray analysis indicated that most microplastics contained Si, Na, Ca, Cl and Al. Overall, the results provided strong evidence of high levels of microplastics in Poyang Lake, suggested that the microplastics pollution status in Poyang Lake should continue to be monitored.