[Composition Characteristics and Construction Mechanism of Microbial Community on Microplastic Surface in Typical Redox Environments].

Microplastics are widely distributed in the biogeochemical cycle driven by microbes. Their surface is enriched with unique microbial communities, called plastispheres. Various redox environments that exist widely in the natural environment can affect the microbial composition in the plastisphere and the fate of the microplastics. To explore the microbial community composition and construction mechanism on the surface of microplastics in typical redox environments, three microplastics, PHA (polyhydroxyalkanoates), PLA (polylactic acid), and PVC (polyvinyl chloride), were placed in five specific redox environments:aerobic, nitrate reduction, iron oxide reduction, sulfate reduction, and methane production. The culture experiment simulated the microcosm, which was inoculum by sludge. The results showed that microplastic factors affected 18.94% and 46.67% of the microbial communities on the plastisphere in taxonomy and phylogeny, respectively. Redox factors affected 31.04% and 90.00% of the microbial communities on the plastisphere in taxonomy and phylogeny, respectively. Compared with that in sludge, the microbial community richness and diversity were reduced on the three microplastics. The most apparent reduction was found on the plastisphere of more degradable PHA. At the same time, microbial communities on the refractory PLA and PVC surfaces remained similar. Anaerocolumna (26.44%) was the dominant genus on the surface of PHA microplastics, whereas microbes related to the redox reaction were less enriched. Clostridium_sensu_stricto_7 (15.49% and 11.87%) was the dominant strain on PLA and PVC microplastics, and the microbes related to the redox reaction were significantly enriched. Thus, characteristic microbes involved in the redox reaction will be enriched in the surface of refractory microplastics, and microplastics may affect the rate of biogeochemical cycling.

A highly efficient diatomic nickel electrocatalyst for CO2 reduction.

We report a facile but effective approach to construct a highly dispersed diatomic catalyst. A carbon-embedded diatomic Ni2 catalyst was synthesized from carbon black, polyaniline and nickel(ii) salts. The resulting catalyst exhibits excellent activity for the CO2 reduction reaction (CO2RR) at low Ni content with a faradaic efficiency of CO over 95% in the potential range from -0.6 V to -1.0 V vs. reversible hydrogen electrode (RHE). A high specific current density of 37.2 A mg-1 Ni was recorded at -1.1 V, among the highest reported values for Ni-based electrocatalysts.

Self-Assembled Peptide Functionalized Gold Nanopolyhedrons with Excellent Chiral Optical Properties.

Because of the unique optical properties of gold nanomaterials, the preparation of gold nanomaterials with excellent chirality has received extensive attention. In order to develop a simple fabrication method for three-dimensional chiral Au nanostructures with a size of several hundred nanometers, chiral gold nanoparticles were developed to transfer chirality of a peptide to gold nanoparticles. In this study, the controlled synthesis of asymmetric gold nanopolyhedrons was achieved. The asymmetric gold nanopolyhedrons prepared via peptide-directed growth can exhibit strong circular dichroism (∼±50 mdeg) couplets in the visible range (500-600 nm). Also, the morphology of chiral Au nanododecahedrons-peptide particles showed distorted and asymmetric properties. In order to prove that the size and spatial structure of gold nanopolyhedrons have an influence on their chiral optical properties, Au nanotrioctahedron-peptide particles were prepared by using Au nanotrioctahedrons with different morphologies. Au nanotrioctahedron-peptide particles also exhibited circular dichromatic couplets in the visible region.

Self-assembled CpG oligodeoxynucleotides conjugated hollow gold nanospheres to enhance cancer-associated immunostimulation.

To realize efficiently cellular uptake and enhance the immunostimulation, thiolated cytosine-phosphate-guanine (CpG) oligodeoxynucleotides (ODNs) were self-assembled on hollow gold nanospheres (HGNs) to form CpG-HGNs. The cellular uptake of CpG-HGNs in immune cells was studied in RAW 264.7 cells. Due to the enhanced delivery efficiency, CpG-HGNs exhibited a higher immune stimulatory activity compared with CpG ODNs, resulting in a dramatically enhanced secretion of proinflammatory cytokines. In addition, CpG-HGNs showed low cytotoxicity in RAW 264.7 cells. CpG-HGNs could potentially realize synergistic photothermal therapy and immunotherapy in vivo.

Ultrastructure of vegetative cells and resting cysts, and live observations of the encystation and excystation processes in Diophrys oligothrix Borror, 1965 (Protista, Ciliophora).

Ciliated protists can form cysts to resist unfavorable environmental conditions and then excyst when environmental conditions become favorable. This study used electron and light microscopy to investigate the structure of vegetative cells and resting cysts, as well as the encysting and excysting processes of Diophrys oligothrix. For the first time, ampules were revealed beneath the pellicle in the genus Diophrys, and their extrusome types differed between Diophrys species. Membrane-packed discs of diverse shapes were found in the cytoplasm just beneath the pellicle around the cytopharynx and were separated by rows of microtubule units. Beneath the discs, some double-layer microtubule structures were detected as well. During encystment, the ventral ciliature was folded in a ventral cavity of the cell, and the caudal cirri were retracted directly into the cyst in a separate cavity on the dorsal side. In the resting cysts, high autophagic activity occurred, possibly including digestion of membrane-packed discs and ampules. Two macronuclear nodules kept their basic shape, although the chromatin aggregation and fusion region were observed in ultrathin sections. The cyst wall contained two layers, namely, the ectocyst, and endocyst. In mature cysts, basal bodies and ciliary shafts were observed, demonstrating that D. oligothrix forms non-kinetosome-resorbing cysts. The process of excystment occurred in two modes, either with or without participation of a contractile vacuole.

Cloning a novel endo-1,4-ß-D-glucanase gene from Trichoderma virens and heterologous expression in E. coli.

Endo-1,4-ß-D-glucanase (EG), as a key constituent of cellulase taking the responsibility of cutting ß-1,4 glycosidic bonds, plays the essential role in the process of degrading cellulose by cellulase. Cloning and expressing the EG gene is important to the cellulase research and application. In this work, a novel EG gene was cloned from Trichoderma virens ZY-01, which was a cellulase secreting microbe isolated by our laboratory. The DNA sequence showed that the length of the cloned EG is 1069 bp, which had 95.2% similarity to the EG IV from T. viride AS 3.3711. Further, the expression vector pET-32a-EG was constructed and was successfully heterologously expressed in Escherichia coli. The expression product was purified with Ni2+ affinity chromatography and its enzymatic properties were investigated. The SDS-PAGE showed the target protein is 39 kDa, which is consistent with the translated result from the DNA sequence. The kinetic parameter for the expression product was Km = 13.71 mg/mL and Vmax=0.51 µmol/min·mL. The optimal reaction pH and temperature was pH = 7.0 and T = 40 °C, which is similar to the native EG produced by Trichoderma virens ZY-01. It provides the foundation for the endo-1,4-ß-D-glucanase further evolution and application.

[Construction of a eukaryotic vector expressing E2F-1 Gene and its effect on proliferation of gastric cancer cell line MKN-45].

BACKGROUND & OBJECTIVE: E2F-1 is overexpressed in many tumors and functions as an oncogene or tumor suppressor gene. This study was to construct the recombinant eukaryotic vector expressing E2F-1 cDNA, and explore the effect of E2F-1 overexpression on the proliferation of human gastric carcinoma cell line MKN-45. METHODS: The fragment of E2F-1 gene was amplified by polymerase chain reaction (PCR). A eukaryotic vector expressing E2F-1 (pCMV-E2F1-HA) was constructed with pCMV-HA, and transfected into COS-7 cells to identify whether E2F-1 was successfully subcloned into the eukaryotic vector. pCMV-E2F1-HA was transfected into MKN-45 cells. The expression of E2F-1 in MKN-45 cells was detected by Western blot. The proliferation of MKN-45 cells was observed by colony formation assay and MTS method. Cell cycle was analyzed by flow cytometry (FCM). RESULTS: Recombinant plasmid pCMV-E2F1-HA was successfully constructed and transfected into COS-7 and MKN-45 cells. MKN-45 cell clones were significantly fewer in pCMV-E2F1-HA group than in pCMV-HA group (4.7+/-1.8 vs. 30.2+/-6.7, P<0.01). The proliferation rate of MKN-45 cells was significantly lower in pCMV-E2F1-HA group (73.5% on Day 5, 63.5% on Day 6, 56.1% on Day 7) than in pCMV-HA group (100%, P<0.01). The G0/G1 phase proportion of MKN-45 cells was significantly higher in pCMV-E2F1-HA group than in pCMV-HA group (71.4% vs. 59.7%, P<0.05); the S phase proportion was significantly lower in pCMV-E2F1-HA group than in pCMV-HA group (18.7% vs. 30.7%, P<0.05). CONCLUSION: Overexpression of E2F-1 suppresses the proliferation of gastric cancer MKN-45 cells.