The cyanobacterium Synechocystis sp. PCC 6803 possesses multiple inorganic carbon (Ci) uptake systems that are regulated by Ci availability. The control mechanisms of these systems and their integration with other cell functions remain to be clarified. An analysis of the changes in global gene expression in response to Ci downshift and the inactivation of ndhR (sll1594), a LysR family regulator of Ci uptake is presented in this report. Mild Ci limitation (3% CO 2 (v/v) in air to air alone) induced a dramatic up-regulation of genes encoding both inducible CO 2 and HCO 3 ؊ uptake systems. An induction of ndhD5/ndhD6 and other genes in a probable transcriptional unit was observed, suggesting a function in inducible Ci uptake. The expression of slr1513 and sll1735, physically clustered with sbtA and ndhF3/ ndhD3/cupA, respectively, were also coordinated with upstream genes encoding the essential components for HCO 3 ؊ and CO 2 uptake. Ci limitation induced the regulatory genes slr1214, sll1292, slr1594, sigD, sigG, and sigH, among which slr1214, a two-component response regulator, showed the earliest induction, implying a role for the early response to Ci limitation. Opposite regulation of genes encoding the assimilation of carbon and nitrogen demonstrated a striking coordination of expression to balance C-and N-fluxes. The analyses revealed that ndhR inactivation up-regulated the expression of sbtA/sbtB, ndhF3/ndhD3/cupA/sll1735, and slr2006-13 including ndhD5 and ndhD6, indicating a vital role of this regulatory gene in both CO 2 and HCO 3 ؊ acquisition of the cyanobacterium. We therefore suggest that ndhR be renamed ccmR to better represent its broader regulatory characteristics.

This paper summarizes the current knowledge regarding the possible modes of action and nutritional factors involved in the use of essential oils (EOs) for swine and poultry. EOs have recently attracted increased interest as feed additives to be fed to swine and poultry, possibly replacing the use of antibiotic growth promoters which have been prohibited in the European Union since 2006. In general, EOs enhance the production of digestive secretions and nutrient absorption, reduce pathogenic stress in the gut, exert antioxidant properties and reinforce the animal’s immune status, which help to explain the enhanced performance observed in swine and poultry. However, the mechanisms involved in causing this growth promotion are far from being elucidated, since data on the complex gut ecosystem, gut function, in vivo oxidative status and immune system are still lacking. In addition, limited information is available regarding the interaction between EOs and feed ingredients or other feed additives (especially pro- or prebiotics and organic acids). This knowledge may help feed formulators to better utilize EOs when they formulate diets for poultry and swine.

The control of surface properties of all inorganic cesium lead halide perovskite (CsPbX3; X = Cl, Br, or I) quantum dots (QDs) is essential to achieve excellent stability and high photoluminescence quantum yields (PLQYs). Herein, a facile method was performed to simultaneously enhance the stability and PLQYs of CsPbX3 QDs by a ZnX2/hexane solution post-treatment. We show that the halogen defect on the surface of CsPbX3 QDs can be treated in a controlled way, whereby the “black dots” that adhered on the surface as observed by transmission electron microscopy have be completely removed, resulting in enhanced stability and photoluminescence. The PLQYs of CsPbCl3, CsPbBr3, and CsPbI3 increased from 4, 58, and 63% to 86, 93, and 95%, respectively, and the origin of the “black dots” as well as their transformation mechanism has been demonstrated. As a result, the poly­(dimethylsiloxane) composite films created by encapsulating stable and nearly defect-free green-emitting CsPbBr3, the red-emitting K2SiF6:Mn4+ phosphor, and a blue emission GaN chip were prepared and used to fabricate a remote-type white light-emitting diode device, which exhibits a high luminescence efficiency (≤98 lm/W) and a wide color gamut (∼130% of the National Television Standard Committee standard), suggesting the potential for liquid crystal display backlight application.

Good interfacial compatibility is the key to realize the full potential of metal−organic framework-based mix matrix membranes for gas separation. Here we report a new approach that uses polyimide brushes covalently grafted on the MOF surface to engineer the MOF-polymer interface. Benefiting from the strong brush−brush interaction, polyimide grafted MOF particles can form a stand-alone membrane at 88 wt % MOF loading without the addition of polymeric matrix. Compared to traditional mixed-matrix membranes, the modified membranes exhibit improved ductility up to 472%, reduced interfacial tearing phenomenon under shear force, decreased matrix chain mobility, and improved plasticization resistance against CO 2 . Most importantly, with increasing MOF loading, only the modified membranes exhibit simultaneous increase of selectivity and permeability for CO 2 /N 2 and CO 2 /CH 4 separation, following the trend predicted by the modified Maxwell model.

We report a new class of porous liquids (PLs) using internally functionalized metal–organic framework (MOF) particles as pore carriers and poly­(dimethylsiloxane) as bulky solvents. Using a generalizable noncovalent surface-initiated controlled radical polymerization technique, a series of isoreticular UiO-66 particles were dispersed in a liquid PDMS matrix with excellent homogeneity and colloidal stability. Benefiting from the inherent properties of PDMS, the PLs exhibit low vapor pressure, high thermal stability, and fluidity down to −35 °C. Attributed to the bulkiness of PDMS and its inherent high permeability, the sorption properties of the MOF fillers can be largely retained in their respective PLs as confirmed by low-pressure CO2, N2, Xe, and H2O sorption isotherms. The permanent porosity of the PLs can also be largely preserved even after 15 months of storage. Finally, we demonstrate that by tuning the molecular weight and polymer chain architecture of PDMS, it is possible to preserve the permanent porosity of a mesoporous MOF, MIL-101­(Cr), within a PL.

Background: As important players in cell-to-cell communication, exosomes (exo) are believed to play a similar role in promoting fracture healing. This study investigated whether exosomes derived from bone marrow mesenchymal stem cells (BMMSC-Exos) could improve fracture healing of nonunion. Methods: BMMSC-Exos were isolated and transplanted into the fracture site in a rat model of femoral nonunion (Exo group) every week. Moreover, equal volumes of phosphate-buffered saline (PBS) and exosome-depleted conditioned medium (CM-Exo) were injected into the femoral fracture sites of the rats in the control and CM-Exo groups. Bone healing processes were recorded and evaluated by radiographic methods on weeks 8, 14 and 20 after surgery. Osteogenesis and angiogenesis at the fracture sites were evaluated by radiographic and histological methods on postoperative week 20. The expression levels of osteogenesis-or angiogenesis-related genes were evaluated in vitro by western blotting and immunohistochemistry. The ability to internalize exosomes was assessed using the PKH26 assay. Altered proliferation and migration of human umbilical vein endothelial cells (HUVECs) and mouse embryo osteoblast precursor cells (MC3TE-E1s) treated with BMMSC-Exos were determined by utilizing EdU incorporation, immunofluorescence staining, and scratch wound assay. The angiogenesis ability of HUVECs was evaluated through tube formation assays. Finally, to explore the effect of exosomes in osteogenesis via the BMP-2/ Smad1/RUNX2 signalling pathway, the BMP-2 inhibitors noggin and LDN193189 were utilized, and their subsequent effects were observed. Results: BMMSC-Exos were observed to be spherical with a diameter of approximately 122 nm. CD9, CD63 and CD81 were expressed. Transplantation of BMMSC-Exos obviously enhanced osteogenesis, angiogenesis and bone healing processes in a rat model of femoral nonunion. BMMSC-Exos were taken up by HUVECs and MC3T3-E1 in vitro, and their proliferation and migration were also improved. Finally, experiments with BMP2 inhibitors confirmed that the BMP-2/Smad1/RUNX2 signalling pathway played an important role in the pro-osteogenesis induced by BMMSC-Exos and enhanced fracture healing of nonunion.

Cell entry of severe acute respiratory syndrome coronavirus (SARS-CoV) is mediated by the viral spike (S) protein. Amino acids 319-510 on the S protein have been mapped as the receptor-binding domain (RBD), which mediates binding to the SARS-CoV receptor angiotensin converting enzyme 2 (ACE2) on SARS-CoV susceptible cells. In this study, we expressed a fusion protein containing the human codon-optimized RBD of the SARS-CoV spike protein linked to the Fc portion of human IgG1 (named RBD-Fc) in HEK293 cells. The RBD-Fc protein was purified by affinity chromatography. The flow cytometry assay showed that the purified RBD-Fc protein could bind to ACE2. We demonstrated that the RBD spike protein alone could be internalized into SARS-CoV susceptible cells together with ACE2. We also showed that the removal of N-glycans from the RBD spike protein did not abolish this phenomenon. Our discoveries may have some implications for the development of the SARS vaccine.

Intercellular communication in adjacent cell layers determines cell fate and polarity, thus orchestrating tissue specification and differentiation. Here we use the maize stomatal apparatus as a model to investigate cell fate determination. Mutations in ZmBZU2 (bizui2, bzu2) confer a complete absence of subsidiary cells (SCs) and normal guard cells (GCs), leading to failure of formation of mature stomatal complexes. Nuclear polarization and actin accumulation at the interface between subsidiary mother cells (SMCs) and guard mother cells (GMCs), an essential pre-requisite for asymmetric cell division, did not occur in Zmbzu2 mutants. ZmBZU2 encodes a basic helix-loop-helix (bHLH) transcription factor, which is an ortholog of AtMUTE in Arabidopsis (BZU2/ZmMUTE). We found that a number of genes implicated in stomatal development are transcriptionally regulated by BZU2/ZmMUTE. In particular, BZU2/ZmMUTE directly binds to the promoters of PAN1 and PAN2, two early regulators of protodermal cell fate and SMC polarization, consistent with the low levels of transcription of these genes observed in bzu2-1 mutants. BZU2/ZmMUTE has the cell-to-cell mobility characteristic similar to that of BdMUTE in Brachypodium distachyon. Unexpectedly, BZU2/ZmMUTE is expressed in GMC from the asymmetric division stage to the GMC division stage, and especially in the SMC establishment stage. Taken together, these data imply that BZU2/ZmMUTE is required for early events in SMC polarization and differentiation as well as for the last symmetrical division of GMCs to produce the two GCs, and is a master determinant of the cell fate of its neighbors through cell-to-cell communication.