[Occurrence Characteristics of Microplastics in Multi-environmental Media and Bellamya aeruginosa of Manao River].

Microplastic pollution poses threats to aquatic ecosystems and human health. In this study, in order to investigate the characteristics of microplastic occurrence in different environmental media, the abundance, particle size, shape, color, and composition types of microplastics in the water column, sediment, riparian zone soil, and the benthic snail Bellamya aeruginosa of the Manao River were analyzed using field sampling, microscopic observation, and Fourier infrared spectroscopy. The results showed that the average abundance of microplastics in the surface water of the Manao River was (5.9±0.26) n·L-1; the abundance of microplastics in the upper sediment (by dry weight) was (1.35±0.1) n·g-1, and that in the lower sediment (by dry weight) was (0.93±0.12) n·g-1. The abundance of microplastics in the near riparian zone soil (by dry weight) was (0.68±0.16) n·g-1, and that in the far riparian zone soil (by dry weight) was (0.69±0.14) n·g-1, and the abundance of microplastics in the B. aeruginosa was (2.06±0.25) n·g-1. The analysis results showed that the abundance of microplastics in the upper and lower sediments were positively correlated; the abundance of microplastics in B. aeruginosa was positively correlated with the abundance of microplastics in the upper and lower sediments, respectively; and the abundance of microplastics in the near and far riparian zone soils were also correlated. Most of the microplastics within each environmental medium and B. aeruginosa were <0.1 mm in size, mainly in the form of fibers and fragments, mainly blue and black in color, and mainly composed of polypropylene (PP) and polyethylene (PE). It was found that microplastics in riparian zone soils mainly originated from the fragmentation and decomposition of agricultural plastic films. The results of this study shed light on the accumulation of microplastics in macrobenthic organisms through the investigation of microplastics in multi-environmental media and in the B. aeruginosa, which helps us to understand the potential ecological risk of microplastics in a comprehensive manner.

[Assessment of Microplastic Pollution and Estimation of Annual Emission Volume in the Dongshan Canal of Yichang City].

Microplastics, as an emerging pollutant, have garnered global attention. Urban areas are key hotspots for the generation of microplastic pollution, whereas urban water bodies act as vital conduits for the dissemination of microplastics to other freshwater environments. In this study, the Dongshan Canal in the urban area of Yichang City was selected as the research subject. Through field sampling, microscopic observation, and Fourier infrared spectroscopy analysis conducted in July and October 2022, the occurrence characteristics and potential pollution sources of microplastics in the water body of the Dongshan Canal were identified and analyzed. The ecological risk and annual emission volume of microplastics in the water body were quantitatively assessed using the risk index (H), pollution load index (PLI) model, and proportional flow method. The results indicated that the average abundances of microplastics in the surface water of the Dongshan Canal were (7 295±1 051) n·m-3 (July) and (5 145±762.6) n·m-3 (October). Fibrous microplastics (27.63%-63.23%), microplastics with a size of <0.5 mm (75.68%-96.2%), and colored microplastics (22.73%-61.83%) dominated the samples, with PE (30.1%) and PET (26.33%) being the predominant materials. The assessment results from the two models classified the ecological risk index of the Dongshan Canal as class Ⅲ, whereas the overall pollution load fell into class I, with certain sampling points reaching class Ⅱ. Estimates revealed that the Dongshan Canal transports approximately 3.37 t of microplastics to the Yangtze River annually. Overall, the microplastic pollution level in the Dongshan Canal of Yichang City could be considered moderate, with potential sources of pollution including laundry wastewater, personal care products, and plastic waste.

Norcantharidin induces cell cycle arrest and inhibits progression of human leukemic Jurkat T cells through mitogen-activated protein kinase-mediated regulation of interleukin-2 production.

Norcantharidin (NCTD) is a potential anti-cancer agent that inhibits proliferation and induces cell death through regulation of mitogen-activated protein kinases (MAPK). This study examined the effect of NCTD on tumor cells by using a model of phorbol 12-myristate 13-acetate plus ionomycin (PMAI)-activated leukemia Jurkat T cells. The results showed that NCTD significantly inhibited the viability of cells with and without PMAI treatment. NCTD induced cell cycle arrest at G2/M phase, down-regulated the expression of calcineurin and, by itself or in combination with Cyclosporine A, reduced calcineurin phosphatase activity. Furthermore, NCTD up-regulates the expression of phosphorylated (p)-P38 and p-ERK1/2, but not JNK in PMAI-activated Jurkat T cells, in accordance with the alteration in viability. Regarding major cytokine and chemokine secretion profile, NCTD attenuates PMAI-augmented production of IL-2, but slightly increases or has no effect on TNF-α and IL-8. By blockade of various MAPK, NCTD regulates PMAI-augmented IL-2 production through activation of P38 and ERK1/2, in accordance with the aforementioned MAPK expression. In conclusion, NCTD inhibited IL-2 production in PMAI-activated human leukemia Jurkat T cells through activation of P38 and ERK1/2, suggesting that NCTD might have the potential of being used as a chemopreventive agent to inhibit tumor progression in the future.

A newly proposed mechanism for arginine-assisted protein refolding--not inhibiting soluble oligomers although promoting a correct structure.

Arginine has been demonstrated to be capable of suppressing aggregation during protein refolding. However, the pathway and the mechanism for arginine to participate in and to assist refolding process still remains unclear. In this study, arginine-assisted refolding of recombinant consensus interferon (rIFN-con1) was investigated. It was found that although arginine minimized the formation of protein precipitate, it failed to prevent the formation of the soluble oligomeric species. The amount of the oligomers increased with the increase in arginine concentration. This phenomenon has not been reported. On the other hand, arginine was able to promote the yield of correctly refolded rIFN-con1, which was more than 2 times higher than that in the absence of arginine. A proposed mechanism is the stabilization of different soluble species by arginine, which slowed down the conformational movement. The stabilization effect on native-like structure formation overwhelmed the oligomeric promotion effect, which resulted in a composite effect of increased refolding yield for rIFN-con1 when arginine concentration was below 0.5M.

[Separation of correctly refolded and mis-refolded consensus interferon by hydrophobic interaction chromatography].

Hydrophobic interaction chromatography was used to separate correctly refolded and mis-refolded consensus interferon. The effects of ligand types, salt concentration, pH and flow rate were investigated. The best result could be obtained by using Butyl Sepharose 4 Fast Flow, 0.8 mol/L of ammonium sulfate, pH 8.3 and 90cm/h of linear flow rate. Reverse-phase HPLC analysis showed the purity of the pooled fraction was as high as 99.6%. The specific activity of purified consensus interferon was 2.3 x 10(9) IU/mg, The mass recovery of targeth protein was 36.7%.

Hydrophobic interaction chromatography correctly refolding proteins assisted by glycerol and urea gradients.

Chromatographic columns packed with commercially available hydrophobic interaction chromatography (HIC) media were found to be able to suppress aggregation and nevertheless had a tendency to promote the structural misfolding resulting in higher soluble protein recovery and lower specific activity than that by dilution when they were used to refold lysozyme, a model protein. Moreover, this misfolding effect was exacerbated with increasing hydrophobicity of media. A novel strategy involving the combination of glycerol, a typical osmolyte, a urea gradient and commercially available HIC media was introduced to facilitate protein refolding correctly as well as improve mass recovery by providing a gradual change of the refolding environment in the HIC column. In this process, unfolded lysozyme was bound to Poros PE HIC column at high salt concentration and was released by a urea gradient followed by elution with refolding buffer in the presence of 50 % (v/v) glycerol, resulting in 86.3% activity yield and 85% mass recovery with the refolded product of native specific activity. For the absence of glycerol, only 50.9% activity yield and 59% specific activity recovery was obtained although mass recovery was closed to that in the presence of glycerol. It was also discovered that glycerol addition during elution process was necessary for correct refolding compared to mixing of glycerol with post-column fraction. The possible mechanism for refolding with this system was proposed to be relevant to the formation of an on-pathway intermediate that could slowly reactivate.