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CRISPR–Cas systems have revolutionized genome editing across a broad range of biotechnological endeavors. Many CRISPR-Cas nucleases have been identified and engineered for improved capabilities. Given the modular structure of such enzymes, we hypothesized that engineering chimeric sequences would generate non-natural variants that span the kinetic parameter landscape, and thus provide for the rapid selection of nucleases fit for a particular editing system. Here, we design a chimeric Cas12a-type library with approximately 560 synthetic chimeras, and select several functional variants. We demonstrate that certain nuclease domains can be recombined across distantly related nuclease templates to produce variants that function in bacteria, yeast, and human cell lines. We further characterize selected chimeric nucleases and find that they have different protospacer adjacent motif (PAM) preferences and the M44 chimera has higher specificity relative to wild-type (WT) sequences. This demonstration opens up the possibility of generating nuclease sequences with implications across biotechnology. CRISPR-Cas systems have well characterized, modular structures. Here the authors use that architecture to design a Cas12a library of 560 synthetic chimeras, with altered PAM preferences and specificities.

In this paper, a kind of multi-functional polylactic acid-based membrane with adjustable aggregate thickness and properties was prepared. When the number of assembled layers was 20 bilayers, the mean thickness of every bilayer was found to be 10.75±0.25 nm, and the tensile strength was increased by 20% compared with the polylactic acid (PLA) films. The assembled layered double hydroxides (LDHs) could serve as a type of promising organic-inorganic luminescent material, and endow PLA with photoluminescent properties. Besides, the photoluminescence of the composite films was discovered to be highly tunable by simply adjusting the structural constituents of LDHs, and the fluorescence intensity was uniformly enhanced as the number of assembled layers increases, which was not eliminated by the isolation due to cellulose nanocrystals (CNCs). Moreover, the composite films exhibited excellent fluorescence stability in comparison with the literature. After being repeatedly bleached 1000 times by confocal laser scanning fluorescence microscope, the fluorescence intensity of the PLA/(CNCs/MgAl-Eu LDHs)10 film remained 96%. It could be concluded that the immobilization of CNCs and LDHs realized the microscopic controllability of the optical functional molecular spacing. With satisfactory fluorescence, the resulting PLA-based membranes exhibited considerable application potential in optoelectronic devices and anti-counterfeiting packaging.

To investigate the effects of selenium and light wavelengths on the growth of liquid-cultured Cordyceps militaris and the main active components’ accumulation, culture conditions as selenium selenite concentrations and light of different wavelengths were studied. The results are: adenosine accumulation proved to be significantly selenium dependent ( R 2  = 0.9403) and cordycepin contents were determined to be not significantly selenium dependent ( R 2  = 0.3845) but significantly enhanced by selenium except for 20 ppm; there were significant differences in cordycepin contents, adenosine contents, and mycelium growth caused by light wavelengths: cordycepin, blue light > pink light > daylight, darkness, red light; adenosine, red light > pink light, darkness, daylight, blue light; and mycelium growth, red light > pink light, darkness, daylight > blue light. In conclusion, light wavelength had a significant influence on production of mycelia, adenosine, and cordycepin, so lightening wavelength should be changed according to target products in the liquid culture of C. militaris .

The crystallographic alignment, microstructure and magnetic properties were studied for La0.6Ca0.6Sr0.1Fe12.4Co0.4O19 ferrite permanent magnets prepared with standard ceramic method. The effect of cold isostatic pressing (CIP) and sintering temperature on the structural and magnetic properties of the magnets were investigated. The CIP significantly improves the density of the green compact and final magnets, but undermines the crystallographic alignment of the magnets simultaneously. As a result, the remanence of the magnet achieves optimal value under the compromise between the increased density and the degraded alignment. Moreover, the coercivity of the magnet increases linearly with the increment of the CIP pressure due the fact that CIP processed samples bear more uniform and finer grains in favor of high coercivity. Under optimal CIP pressure and sintering temperature, the magnet obtains best magnetic properties of Br of 0.439 T, Hcj of 396 kA m−1, Hcb of 311 kA m−1, and (BH)maxof 35.8 kJ m−3.

A gradient honeycomb absorber with a layer of carbon-based conductive coating was developed in this work. The geometrical parameters and EM performance were investigated through both numerical simulation and free-space measurement. It is found from measurement results that honeycomb absorber has good absorption properties within frequency from 18 to 40 GHz, and superior power handling capability up to 5 kw/m 2 . The reflectivity over the whole frequency band is better than − 43 dB. Also, the numerical simulation achieves sound agreement with the free-space measurement. It can be promising candidate for measurement chambers of 5G millimeter phase-array antenna which needs to withstand high radiation power and high temperature.

Glutathione (GSH) significantly declines in the aging rat liver. Because GSH levels are partly a reflection of its synthetic capacity, we measured the levels and activity of γ-glutamylcysteine ligase (GCL), the rate-controlling enzyme in GSH synthesis. With age, both the catalytic (GCLC) and modulatory (GCLM) subunits of GCL decreased by 47% and 52%, respectively (P < 0.005). Concomitant with lower subunit levels, GCL activity also declined by 53% (P < 0.05). Because nuclear factor erythroid2-related factor 2 (Nrf2) governs basal and inducible GCLC and GCLM expression by means of the antioxidant response element (ARE), we hypothesized that aging results in dysregulation of Nrf2-mediated GCL expression. We observed an ≈50% age-related loss in total (P < 0.001) and nuclear (P < 0.0001) Nrf2 levels, which suggests attenuation in Nrf2-dependent gene transcription. By using gel-shift and supershift assays, a marked reduction in Nrf2/ARE binding in old vs. young rats was noted. To determine whether the constitutive loss of Nrf2 transcriptional activity also affects the inducible nature of Nrf2 nuclear translocation, old rats were treated with (R)-α-lipoic acid (LA; 40 mg/kg i.p. up to 48 h), a disulfide compound shown to induce Nrf2 activation in vitro and improve GSH levels in vivo. LA administration increased nuclear Nrf2 levels in old rats after 12 h. LA also induced Nrf2 binding to the ARE, and, consequently, higher GCLC levels and GCL activity were observed 24 h after LA injection. Thus, the age-related loss in GSH synthesis may be caused by dysregulation of ARE-mediated gene expression, but chemoprotective agents, like LA, can attenuate this loss.