The role of MrUbp4, a deubiquitinase, in conidial yield, thermotolerance, and virulence in Metarhizium robertsii.

Ubiquitin-specific proteases (UBPs), the largest subfamily of deubiquitinating enzymes, regulate ubiquitin homeostasis and play diverse roles in eukaryotes. Ubp4 is essential for the growth, development, and pathogenicity of various fungal pathogens. However, its functions in the growth, stress responses, and virulence of entomopathogenic fungi remain unclear. In this study, we elucidated the role of the homolog of Ubp4, MrUbp4, in the entomopathogenic fungus Metarhizium robertsii. Deletion of MrUbp4 led to a notable increase in ubiquitination levels, demonstrating the involvement of MrUbp4 in protein deubiquitination. Furthermore, the ΔMrUbp4 mutant displayed a significant reduction in conidial yield, underscoring the pivotal role of MrUbp4 in conidiation. Additionally, the mutant exhibited heightened resistance to conidial heat treatment, emphasizing the role of MrUbp4 in thermotolerance. Notably, insect bioassays unveiled a substantial impairment in the virulence of the ΔMrUbp4 mutant. This was accompanied by a notable decrease in cuticle penetration ability and appressorium formation upon further analysis. In summary, our findings highlight the essential role of MrUbp4 in regulating the conidial yield, thermotolerance, and contributions to the virulence of M. robertsii.

Unusual 3,4-Oxidative Coupling Polymerization on 1,2,5-Trisubstituted Pyrroles for Novel Porous Organic Polymers.

Porous organic polymers (POPs) have demonstrated promising task-specific applications due to their structure designability and thus functionality. Herein, an unusual 3,4-polymerization on 1,2,5-trisubstituted pyrroles has been developed to give linear polypyrrole-3,4 in high efficiency, with Mn of 20000 and PDI of 1.7. This novel polymerization technique was applied to prepare a series of polypyrrole-based POPs (PY-POP-1-4), which exhibited high BET surface areas (up to 762 m2 g-1) with a meso-micro-supermicro hierarchically porous structure. Furthermore, PY-POPs were doped in the mixed matrix membranes based on the polysulfone matrix to enhance the gas permeability and gas pair selectivity, with H2/N2 selectivity up to 84.6 and CO2/CH4 and CO2/N2 selectivity up to 46.8 and 39.6.

The Deubiquitinating Enzyme MrUbp14 Is Involved in Conidiation, Stress Response, and Pathogenicity in Metarhizium robertsii.

Protein ubiquitination, which is involved in various biological processes in eukaryotic cells, is a reversible modification of proteins. Deubiquitinases can maintain ubiquitin homeostasis by removing ubiquitin or modulating protein degradation via the ubiquitin-proteasome system (UPS). Metarhizium robertsii, an entomopathogenic fungus, has become a model fungus for investigating the interactions between insects and fungal pathogens. To explore the possible effects of the deubiquitination process on the development, stress response, and virulence of M. robertsii, disruption of MrUbp14 (an ortholog of the yeast ubiquitin-specific protease gene, Ubp14) was performed. The results of this study showed that the deletion of MrUbp14 led to accelerated conidial germination, reduced conidial yields, and decreased expression levels of some genes involved in conidiation. Furthermore, the MrUbp14 mutant (ΔMrUbp14) exhibited decreased tolerance to cell wall-damaging stressors (Congo red and SDS) and heat stress. Importantly, the results of the bioassay demonstrated that the fungal virulence of the ΔMrUbp14 strain was largely reduced in cuticle infection, but not in direct injection, which was accompanied by a significant decline in appressorium formation and cuticle penetration. Moreover, our results demonstrated that the disruption of MrUbp14 resulted in significantly increased ubiquitination levels of total protein, suggesting that MrUbp14 acts as a deubiquitinating enzyme in M. robertsii. In summary, our phenotypic changes in the gene disruption mutants suggest that MrUbp14 is important for conidiation, stress response, and fungal virulence in M. robertsii.

Modeling of scaling of a diode longitudinally pumped metastable rare gas with a master oscillator power amplifier.

There has been recent interest in diode pumped metastable rare gas lasers (DPRGLs) and their scaling to higher powers, due to the advantages of excellent beam quality and high quantum efficiency. In this paper, a cw diode pumped rare gas amplifier (DPRGA) with single-pass longitudinally pumped configuration is studied theoretically based on master oscillator and power amplifier (MOPA). A five-level kinetic model of DPRGAs is first established. Then, the influences of gain medium density, pump and seed laser intensities and gain length on DPRGA performance are simulated and analyzed. The results of numerical simulation agree well with those of Rawlins et al.'s experiment. With the best set of working parameters, the amplification factor reaches 22.18 dB, at pump intensity of 50 kW/cm2 and seed laser intensity of 100 W/cm2. Parameter optimization is helpful for design of a relatively high-power DPRGL system.

Two-stage excitation model of diode pumped rare gas atoms lasers.

Diode pumped rare gas atoms lasers (DPRGLs) are potential candidates of the high-energy lasers, due to the advantages of high laser power and high optical conversion efficiency. In this paper, a two-stage excitation model of DPRGLs is established including gas discharge excitation and semiconductor laser pump to study energy loss mechanism and obtain total efficiency. The results of numerical simulation agree well with those of Rawlins et al.'s experiment. Through parameter optimization, the total efficiency and optical conversion efficiency reach 51.5% and 62.7% respectively, at pump intensity of 50 kW/cm2 and reduced electric field of 8 Td. Parameter optimization of two-stage excitation lasers is theoretically studied, which is significant for the DPRGLs design with high total efficiency.

Transmission electron microscopy study of pseudoperiodically twinned Zn2SnO4 nanowires.

The ternary oxide functional nanomaterial Zn2SnO4 has been synthesized by the thermal evaporation method. The products in general contain numerous kinds of nanowires. In the present work, a remarkable type of Zn2SnO4 nanowires with a pseudoperiodical twinning structure has been investigated by transmission electron microscopy (TEM). These nanowires with a diameter of about 100 nm grow along the 111 direction. High-resolution TEM examinations suggest that a large fraction of the (111) twin boundaries are extended to a thickness of a few nanometers. The twining plane for the perfect case is localized on the Zn atom layer.

Structural properties of silver nanorods with fivefold symmetry.

The microstructural features of silver nanorods with the average length of 50 microm and diameters of around 100 nm have been investigated by means of SEM, X-ray diffraction, and transmission-electron microscopy (TEM). Silver nanorods in general have a pentagonal shape with a remarkable fivefold symmetry as revealed in cross-section observations. The fivefold axis, i.e. the growth direction, normally goes along the [110]-zone axis direction of the basic fcc Ag-structure. The twinning relationships and relevant twin boundaries among the five subunits in the pentagonal nanorod have been examined by high-resolution TEM and selected-area electron diffraction. Defects and stacking faults in this kind of nanorods have been briefly analyzed.