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l-Threonine aldolase (LTA) is an attractive tool in organic chemistry for catalyzing the formation of β-hydroxy-α-amino acids with two chiral centers. The enzyme has a strict selectivity for Cα of ...

A growing number of circular RNAs (circRNAs) have been identified and verified in several cancers. However, highly efficient therapeutic methods based on circRNAs in lung cancer remain largely unexplored. In the present study, we identified a novel circular RNA, hsa_circ_103820, based on Gene Expression Omnibus (GEO) data. Functionally, overexpression of hsa_circ_103820 showed significant inhibitory effects on the proliferation, migration and invasion of lung cancer cells, and knockdown of hsa_circ_103820 played promoting roles. Regarding the mechanism, we revealed that miR-200b-3p was a direct target of hsa_circ_103820 and that LATS2 and SOCS6 were the downstream target genes of miR-200b-3p. Therefore, we identified a novel potential tumor suppressive function of hsa_circ_103820 in lung cancer.

We investigate output power characteristics of a tunable thulium-doped fiber ring laser (TDFRL) by theoretical simulation. The effects of emission wavelength, active fiber length, output coupling ratio and total intracavity loss on laser output power are investigated.

Nowadays, the application of polymer in petroleum industries due to its feasibility with enhancing hole cleaning, less formation damage characteristics of drilling fluids has been particularly advantageous in deep well operation. However, figuring out the influence mechanism of temperature on the rheological behavior of polymer fluids and keeping the excellent rheological regulation at high temperature and high pressure (HTHP) are still serious issues for the mud designers. In this work, the rheological properties of a commonly used drilling fluid polymer treating agent named Driscal-D were tested under HTHP conditions by Fann 50SL rheometer. The effects of polymer addition, electrolyte, clay type and antioxidant on the rheological properties of Driscal-D solution were studied in high-temperature environments. Results showed that the viscosity of the solutions tends to increase with the polymer addition increases, making its pseudoplastic characteristics more noticeable. As the temperature rises, the fluid loses viscosity, causing the polymer solution to evolve from pseudoplastic fluid to Newtonian fluid. The presence of the electrolyte and the oxygen scavenger leads to a decrease in the viscosity of the solution, but in high-temperature environments, the solution adding formate or antioxidant has a higher viscosity retention rate than the pure solution at low shear rates (−1). The incorporation of the clay in Driscal-D solution enhances the rheological properties, which is beneficial for cuttings transportation. And the dispersion is best described by Herschel–Bulkley model.

The effects of formate salts on the rheological characteristics of water-based solutions were compared for two laboratory research methods, i.e., dynamic theological analysis at high temperature and high pressure (HTHP) and a static hot-roll aging test. Polymer muds were used for the measurements. HTHP rheology analysis showed that sodium formate retained effectively the dynamic viscosity at HTHP. Hot-roll tests showed that sodium formate had an obvious effect on the rheological characteristics of the polymer fluid at mom temperature after preliminary heating. The filtration loss of the polymer fluid with added sodium formate was slightly greater than that of pure polymer fluid although the filtration loss could be controlled by changing the formate concentration. Test results from both methods showed that sodium formate could be used successfully as a polymer drilling fluid stabilizer under HTHP operating conditions.

The extracellular matrix (ECM) is the natural microenvironment of stem cells survival, as well as proliferation, differentiation and metastasis, containing a variety of biological molecular complexes secreted by the resident cells in tissues and organs. Heparan sulfate proteoglycans (HSPG) is a major component of ECM, containing one or more covalently attached heparan sulfate chains. The heparan sulphate chains have high affinity with growth factors, chemokines and morphogens, acting as cytokine-binding domains with great importance in development and normal physiology. Herein, lentiviral single-guide RNA vectors were constructed to activate the endogenous HSPG2 expression in mouse embryonic fibroblasts based on CRISPR/Cas9 synergistic activation mediator system, and then HSPG2 functional cell-derived ECM (ECM HSPG2 ) was fabricated. The ECM HSPG2 is capable to enrich cytokines effectively, such as basic fibroblast growth factor (bFGF), which was about 3-flod stronger than binding with negative control ECM. With encapsulating abundant bFGF, ECM HSPG2 could maintain the neural stem cells (NSCs) stemness and promote the NSCs proliferation and differentiation in culture. These findings provide a novel and precise design strategy of smart and special functional cell-derived ECM for the biomaterials research and regenerative medicine.

Soil salinity is one of the major environmental threat for sustainable agriculture. Animal protein hydrolysates, as plant biostimulants, have received increasing attention because of their positive impacts on crop performances. However, their functions in crop tolerance to salt stress are unknown. We investigate the feasibility of pig blood-derived protein hydrolysates (Pp) in improving salt tolerance in tomato and the underlying mechanism. Pp application effectively ameliorated the salt stress-induced reduction in plant growth, chlorophyll levels, and photosynthetic efficiency. Salt-induced osmotic stress was indicated by lower relative water content, where higher Na+/K+ ratio indicated the ionic toxicity, whereas these phenomena were alleviated by Pp application, which might be due to the increased proline, soluble protein, sugars, K+, Ca2+, and Mg2+ contents. Salt stress also caused a significant increase in oxidative stress, as indicated by the enhanced H2O2 and O2− generation, malondialdehyde content and electrolyte leakage, which were mitigated significantly by Pp application via enhanced antioxidant enzyme (CAT, POD, and SOD) activities and the levels of non-enzymatic antioxidant including GSH and phenolic compounds. Pp application effectively enhanced tomato salt tolerance by regulating osmolytes biosynthesis, ion homeostasis, and antioxidant system responses. Thus, Pp may be proposed as effective methods to help plants overcome salt stress situations in agriculture.

Diastereoselectivity of l-threonine aldolase (LTA) was determined by paths of aldehydes attacking a pyridoxal phosphate-glycine complex. Thus, strategies of enhancing the syn path and blocking the anti path were performed to modify LTA. A mutant (Y31H/N305R) was constructed with a substrate preference increase from 3.32 to 42.04. Medium engineering was investigated. Consequently, the de value of l-syn-3-[4-(methylsulfonyl)phenylserine] reached 93.1% (87.2%conv). The study clarified the factors affecting diastereoselectivity of LTA and provided a theorem for rational modification of LTA's diastereoselectivity.

The application of natural biostimulants is proposed as an interesting approach to ensure sustainable yields and product quality in agricultural and horticultural crops. Here, the effects of foliar application of a protein hydrolysate derived from pig blood (Ppb) on biomass production, phenolic biosynthesis, and the correlation between phenolic profiles and antioxidant activities in lettuce were investigated. The Ppb application significantly enhanced the phenolic content and antioxidant properties in two genotypes of hydroponically cultivated lettuce by increasing the gene expression of enzymes (PAL, CHS, F3H, DFR, F35H, and UFGT) involved in phenolic biosynthesis. However, these changes occurred in a genotype-dependent manner. The results of HPLC and correlation analyses implied that the most contributory phenolic compositions to the increased antioxidant activities in Ppb-treated lettuce were flavonoids and anthocyanins. Meanwhile, no changes were observed in shoot and root fresh weights following Ppb application. These results clearly suggest that Ppb application is a useful strategy to improve antioxidant activities of lettuce by enhancing the biosynthesis of unique phenolic compounds without reducing plant yield.

A number of organic synthesis involve threonine aldolase (TA), a pyridoxal phosphate (PLP)-dependent enzyme. Although the addition of exogenous PLP is necessary for the reactions, it increases the cost and complicates the purification of the product. This work constructed a PLP self-sufficient biocatalysis system for TA, which included an improvement of the intracellular PLP level and co-immobilization of TA with PLP. Engineered strain BL-ST was constructed by introducing PLP synthase PdxS/T to Escherichia coli BL21(ED3). The intracellular PLP concentration of the strain increased approximately fivefold to 48.5 μmol/gDCW. l-TA, from Bacillus nealsonii (BnLTA), was co-expressed in the strain BL-ST with PdxS/T, resulting in the engineered strain BL-BnLTA-ST. Compared with the control strain BL-BnLTA (254.1 U/L), the enzyme activity of the strain BL-BnLTA-ST reached 1518.4 U/L without the addition of exogenous PLP. An efficient co-immobilization system was then designed. The epoxy resin LX-1000HFA wrapped by polyethyleneimine (PEI) acted as a carrier to immobilize the crude enzyme solution of the strain BL-BnLTA-ST mixed with an extra 100 μM of exogenous PLP, resulting in the catalyst HFAPEI-BnLTA-STPLP 100. HFAPEI-BnLTA-STPLP 100 exhibited a half-life of approximately 450 h, and the application of the catalyst in the continuous biosynthesis of 3-[4-(methylsulfonyl) phenyl] serine had more than 180 batch reactions (>60%conv) without the extra addition of exogenous PLP. The excellent compatibility and stability of the system were further confirmed by other TAs. This work introduced a PLP self-sufficient biocatalysis system that can reduce the cost of PLP and contribute to the industrial application of TA. In addition, the system may also be applied in other PLP-dependent enzymes.