Impacts of polypropylene microplastics on the distribution of cadmium, enzyme activities, and bacterial community in black soil at the aggregate level.

Microplastics (MPs) can co-occur widely with heavy metals in soil. This study intended to investigate the influences of the co-exposure of polyethylene MPs (0.5 %, w/w) and cadmium (Cd) in black soil on the Cd distribution, enzyme activities, and bacterial communities in both bulk soil and different sized soil aggregates (> 1, 0.50-1, 0.25-0.50, and < 0.25 mm aggregates) after a 90-day incubation. Our results showed that the existence of MPs increased the distributions of Cd in >1 mm and < 0.25 mm soil aggregates and decreased its distributions in 0.50-1 mm and 0.25-0.50 mm soil aggregates. About 12.15 %-17.65 % and 9.03 %-11.13 % of Cd were distributed in the exchangeable and oxidizable forms in bulk soil and various sized soil aggregates after the addition of MPs which were higher than those in the only Cd-treated soil (11.17 %-14.72 % and 8.66 %-10.43 %, respectively), while opposite tendency was found for Cd in the reducible form. Urease and ß-glucosidase activities in the Cd-treated soils were 1.14-1.18 and 1.07-1.31 times higher than those in the Cd-MPs treated soils. MPs disturbed soil bacterial community at phylum level and increased the bacteria richness in bulk soil. The levels of predicted functional genes which are linked to the biodegradation and metabolism of exogenous substances and soil C and N cycles were altered by the co-exposure of Cd and MPs. The findings of this study could help deepen our knowledge about the responses of soil properties, especially microbial community, to the co-occurrence of MPs and heavy metals in soil.

Primary Extra Nodal Diffuse Large B-Cell Lymphoma of the Maxillary Sinus with Symptoms of Acute Pulpitis.

Diffuse large B-cell lymphoma not otherwise specified (DLBCL-NOS) is a subtype of large B-cell non-Hodgkin lymphoma with various clinical and pathological manifestations. DLBCL-NOS which primarily arises from maxillary sinus is rare and hard to diagnose due to unique anatomy. Here, we present a case of DLBCL-NOS that developed in the left maxillary sinus of a 72-year-old male, who presented with severe toothache that resembled acute pulpitis. The lesion was diagnosed and treated based on radiographs, histological, immunohistological examinations, and PET-CT analysis. Despite its rare incidence, DLBCL-NOS should still be included in differential diagnoses to rule out malignancy in cases of endodontic disease.

Spectroscopic and metal binding properties of a de novo metalloprotein binding a tetrazinc cluster.

De novo design provides an attractive approach, which allows one to test and refine the principles guiding metalloproteins in defining the geometry and reactivity of their metal ion cofactors. Although impressive progress has been made in designing proteins that bind transition metal ions including iron-sulfur clusters, the design of tetranuclear clusters with oxygen-rich environments remains in its infancy. In previous work, we described the design of homotetrameric four-helix bundles that bind tetra-Zn2+ clusters. The crystal structures of the helical proteins were in good agreement with the overall design, and the metal-binding and conformational properties of the helical bundles in solution were consistent with the crystal structures. However, the corresponding apo-proteins were not fully folded in solution. In this work, we design three peptides, based on the crystal structure of the original bundles. One of the peptides forms tetramers in aqueous solution in the absence of metal ions as assessed by CD and NMR. It also binds Zn2+ in the intended stoichiometry. These studies strongly suggest that the desired structure has been achieved in the apo state, providing evidence that the peptide is able to actively impart the designed geometry to the metal cluster.

Designed peptides that assemble into cross-α amyloid-like structures.

Amyloids adopt 'cross-ß' structures composed of long, twisted fibrils with ß-strands running perpendicular to the fibril axis. Recently, a toxic peptide was proposed to form amyloid-like cross-α structures in solution, with a planar bilayer-like assembly observed in the crystal structure. Here we crystallographically characterize designed peptides that assemble into spiraling cross-α amyloid-like structures, which resemble twisted ß-amyloid fibrils. The peptides form helical dimers, stabilized by packing of small and apolar residues, and the dimers further assemble into cross-α amyloid-like fibrils with superhelical pitches ranging from 170 Å to 200 Å. When a small residue that appeared critical for packing was converted to leucine, it resulted in structural rearrangement to a helical polymer. Fluorescently tagged versions of the designed peptides form puncta in mammalian cells, which recover from photobleaching with markedly different kinetics. These structural folds could be potentially useful for directing in vivo protein assemblies with predetermined spacing and stabilities.

Visualizing Dynamics of Cell Signaling In Vivo with a Phase Separation-Based Kinase Reporter.

Visualizing dynamics of kinase activity in living animals is essential for mechanistic understanding of cell and developmental biology. We describe GFP-based kinase reporters that phase-separate upon kinase activation via multivalent protein-protein interactions, forming intensively fluorescent droplets. Called SPARK (separation of phases-based activity reporter of kinase), these reporters have large dynamic range (fluorescence change), high brightness, fast kinetics, and are reversible. The SPARK-based protein kinase A (PKA) reporter reveals oscillatory dynamics of PKA activities upon G protein-coupled receptor activation. The SPARK-based extracellular signal-regulated kinase (ERK) reporter unveils transient dynamics of ERK activity during tracheal metamorphosis in live Drosophila. Because of intensive brightness and simple signal pattern, SPARKs allow easy examination of kinase signaling in living animals in a qualitative way. The modular design of SPARK will facilitate development of reporters of other kinases.

Protein-directed self-assembly of a fullerene crystal.

Learning to engineer self-assembly would enable the precise organization of molecules by design to create matter with tailored properties. Here we demonstrate that proteins can direct the self-assembly of buckminsterfullerene (C60) into ordered superstructures. A previously engineered tetrameric helical bundle binds C60 in solution, rendering it water soluble. Two tetramers associate with one C60, promoting further organization revealed in a 1.67-Å crystal structure. Fullerene groups occupy periodic lattice sites, sandwiched between two Tyr residues from adjacent tetramers. Strikingly, the assembly exhibits high charge conductance, whereas both the protein-alone crystal and amorphous C60 are electrically insulating. The affinity of C60 for its crystal-binding site is estimated to be in the nanomolar range, with lattices of known protein crystals geometrically compatible with incorporating the motif. Taken together, these findings suggest a new means of organizing fullerene molecules into a rich variety of lattices to generate new properties by design.

Protective effect of metformin on renal injury of C57BL/6J mouse treated with high fat diet.

This study aimed to investigate the protective effect of metformin on renal injury of C57BL/6J mice treated with a high fat diet. High-fat diet for 12 weeks was used to establish the mice model of metabolism syndrome and the intervention of metformin (75 mg x kg(-1) x d(-1)) for 4 weeks, and plasma biochemical indicator and body weight were used to evaluate the model. Sterol regulatory element-binding protein (SERBP)-1c, TNF-α, NADPH Oxidase (NOX)4 mRNA was determined by real time-PCR. Phospho-AMP-activated protein kinase (P-AMPK)α protein was detected by western blotting. Oil Red O staining, Masson staining and HE staining were for observing renal pathological changes. At the end of 12th week, compared with mice on low fat diet (LFD), body weight (BW), the levels of fasting insulin (FINS), plasma and renal triglyceride (TG) were higher and plasma high density lipoprotein (HDL) and insulin sensitivity index (ISI) were significantly lower, but the levels of fasting blood glycemia (FBG), plasma total cholesterol (TC) and renal TC had no changes; Oil Red O staining revealed renal lipids deposition, Masson staining and HE staining revealed glomerular hypertrophy, matrix increasing, and inflammatory cells infiltration in glomerular; the expression of p-AMPKα protein decreased and the expression of SREBP-1c, TNF-α, NOX4 mRNA increased significantly in mouse treated with high fat diet (HFD). Compared with the HFD group, through metformin interventing, metabolic disorders were significantly improved, renal lipids deposition and other pathological changes were ameliorated, the expression of p-AMPKα protein increased and the expression of SREBP-1c, TNF-α, NOX4 mRNA decreased significantly. Metformin improved metabolic disorders, upregulated activity of renal AMPK, diminished the expression of renal SREBP-1c, TNF-α, NOX4 mRNA, decreased accumulation of renal lipids, and prevened renal injury.

[Heavy metal contents in insects collected from the Huludao City suffering pollution by zinc smelting and cholor-alkai production].

14 insect species, which were classified to three groups: the herbivorous, the polyphagous and the carnivorous, and earthworms were collected from the grasslands in Huludao City, Liaoning Province, China. Mercury, cadmium and lead contents in biota were determined to discuss the heavy metal pollution in organisms. Mercury, cadmium and lead contents were 0.168, 9.19 and 12.58 mg x kg(-1) in the herbivorous insects, respectively; 0.375, 24.43 and 17.71 mg x kg(-1) in the polyphagous insects, respectively; 0.928, 29.78 and 18.39 mg x kg(-1) in the carnivorous insects, respectively. It showed that heavy metal pollution in biota in Huludao City was heavy. Bioaccumulation abilities to heavy metals significantly differed with insect species. Snails and dragonflies could accumulate more mercury than the other insects and spiders could accumulate the most cadmium and lead in all insect species. These three metals investigated in insects were all sorted as the herbivorous < the polyphagous < the carnivorous. Cadmium and lead contents between the polyphagous and the carnivorous varied slightly. Correlation analysis showed that cadmium and lead contents were significantly related, but mercury and cadmium or mercury and lead were not. It indicated that cadmium and lead in insects were from the same pollution sources while mercury was more complex.

Molecular crowding enhances native structure and stability of alpha/beta protein flavodoxin.

To investigate the consequences of macromolecular crowding on the behavior of a globular protein, we performed a combined experimental and computational study on the 148-residue single-domain alpha/beta protein, Desulfovibrio desulfuricans apoflavodoxin. In vitro thermal unfolding experiments, as well as assessment of native and denatured structures, were probed by using far-UV CD in the presence of various amounts of Ficoll 70, an inert spherical crowding agent. Ficoll 70 has a concentration-dependent effect on the thermal stability of apoflavodoxin (DeltaT(m) of 20 degrees C at 400 mg/ml; pH 7). As judged by CD, addition of Ficoll 70 causes an increase in the amount of secondary structure in the native-state ensemble (pH 7, 20 degrees C) but only minor effects on the denatured state. Theoretical calculations, based on an off-lattice model and hard-sphere particles, are in good agreement with the in vitro data. The simulations demonstrate that, in the presence of 25% volume occupancy of spheres, native flavodoxin is thermally stabilized, and the free energy landscape shifts to favor more compact structures in both native and denatured states. The difference contact map reveals that the native-state compaction originates in stronger interactions between the helices and the central beta-sheet, as well as by less fraying in the terminal helices. This study demonstrates that macromolecular crowding has structural effects on the folded ensemble of polypeptides.