Fibrotic Matrix Induces Mesenchymal Transformation of Epithelial Cells in Oral Submucous Fibrosis.

Oral submucous fibrosis (OSF) is a potentially malignant disorder of the oral mucosa; however, whether and how the fibrotic matrix of OSF is involved in the malignant transformation of epithelial cells remains unknown. Herein, oral mucosa tissue from patients with OSF, OSF rat models, and their controls were used to observe the extracellular matrix changes and epithelial-mesenchymal transformation (EMT) in fibrotic lesions. Compared with controls, oral mucous tissues from patients with OSF showed an increased number of myofibroblasts, a decreased number of blood vessels, and increased type I and type III collagen levels. In addition, the oral mucous tissues from humans and OSF rats showed increased stiffness, accompanied by increased EMT activities of epithelial cells. The EMT activities of stiff construct-cultured epithelial cells were increased significantly by exogenous piezo-type mechanosensitive ion channel component 1 (Piezo1) activation, and decreased by yes-associated protein (YAP) inhibition. During ex vivo implantation, oral mucosal epithelial cells of the stiff group showed increased EMT activities and increased levels of Piezo1 and YAP compared with those in the sham and soft groups. These results indicate that increased stiffness of the fibrotic matrix in OSF led to increased proliferation and EMT of mucosal epithelial cells, in which the Piezo1-YAP signal transduction is important.

Enzymatic characteristics of a recombinant protease (rPepD) from Aspergillus niger expressed in Pichia pastoris.

The Aspergillus niger AS3.350 protease gene (pepD) was successfully cloned and expressed in Pichia pastoris KM71. The rPepD activity was 331.5 U/ml, and the optimum temperature and pH were 45 °C and 8-9 respectively. In addition, enzyme activity was significantly inhibited by PMSF, EDTA, Mg2+, Fe2+ and Zn2+ ions, and stimulated by Ca2+ which selectively bound to the T302 and D323 residues. Mutation in either or both of the residues inhibited rPepD expression, indicating that binding to Ca2+ is necessary for PepD expression and activity. The rPepD showed a wide substrate range, and was particularly selective to those with hydrophobic amino acids. The degree of rPepD-mediated hydrolysis of soy protein isolate, corn flour and gluten meal were 8.7%, 38.1% and 33.6% respectively, which was higher than that by Alcalase, indicating that rPepD has potential applications in the food processing industry.

[Effect of Mn-Modified Biochar on the Characteristics of Aggregate Structure and the Content of Cd in Weakly Alkaline Cd-Contaminated Soil].

Field experiments were conducted to investigate the effects of Mn-based modified rice husk biochar on soil organic carbon, aggregate structure, mass load, and the content of available Cd in aggregates. The results showed that the concentration of soil organic carbon increased gradually with additional modified biochar, resulting in a 3.2%-32% increase compared with the CK. Modified biochar improved the composition structure and stability of soil aggregates, and increased the amount of large aggregates (5-8 mm and 2-5 mm), while micro-aggregate production was inhibited (≤0.25 mm). Compared with the CK, mean weight diameter (MWD), geometrical mean weight (GMD), and soil aggregate structural body (R0.25) of the soil aggregates increased by 15.1%-20.3%, 8.1%-22.4%, and 0.43%-7.6%, respectively. Cd was preferentially enriched on small aggregates, and the mass loading of Cd in soil aggregates increased gradually with decreasing particle size. The distribution factor of Cd showed significant enrichment in the 0.5-1 mm and 0.25-0.5 mm grain sizes, whereas it showed a clear loss in particle sizes of 5-8 mm and 2-5 mm. The addition of modified biochar reduced the content of DTPA-Cd in soil aggregates, causing 7.6%-15.1%, 15.6%-24.3%, 3.6%-13.8%, and 11.6%-13.7% reductions in 5-8, 2-5, 0.5-1.0, and 0.25-0.5 mm particle sizes, respectively. In general, modified biochar not only has a favorable optimizing function on the structure of soil aggregates, but also decreases the content of available Cd in different sizes of soil aggregates, increasing its significance in the remediation of Cd-contaminated soil.