Molecular cloning, expression and characterization of a novel geneβ-N-acetylglucosaminidase from Bombyxmori

Previously, we have reported that a gene encoding Bombyxmoriβ-N-acetylglucosaminidase 2 (BmGlcNAcase2) has been identified differentially expressed in the midgut of Bombyxmori strain NB resistant to nucleopolyhedrovirus (BmNPV), strain 306 susceptible to NPV and a near isogenic line BC9 with similar genetic background to 306 but resistant to NPV by two-dimensional gel electrophoresis (2-DE). To get more knowledge about the relationship between β-N-acetylglucosaminidase and the resistance of NPV, in this study, the 1542 bp open reading frame of a putative bombyxmoriβ-N-acetylglucosaminidase 2 gene (BmGlcNAcase2) was amplified from a pool of bombyxmoricDNAs and inserted into the prokaryotic expression plasmid pET-30a(+).Western blotting analysis showed that BmGlcNAcase2 was expressed in hemolymph, ovary, testis, fat body, trachea, midgut and silk gland of fifth instar larvae respectively . Immunofluoresence analysis indicated that BmGlcNAcase2 was mainly located to the cytoplasm or some structure in cytoplasm.

ASF1 regulates asexual and sexual reproduction in Stemphylium eturmiunum by DJ-1 stimulation of the PI3K/AKT signaling pathway

Most fungi display a mixed mating system with both asexual and sexual reproduction.The timing of the two modes of reproduction must be carefully coordinated through signal perception and coordination in the cell along with chromatin modification.Here,we investigated coordination of reproductive output by investigating the function of the histone chaper-one anti-silencing factor 1(ASF1)in a fungal species amenable to characterization of both asexual and sexual reproduction.We used knockout approach to show that SeASF1 influenced asexual and sexual reproduction in Stemphylium eturmiunum.SeASF1-deleted strains failed to produce pseudothecia,but produce abnormal conidia and showed an irregular distribution of nuclei in mycelium.Transcriptome sequencing was then used to identify genes with altered expression in the SeASF1-deleted strains.The transcriptional expression of the identified SeDJ-1 was strongly regulated by SeASF1.The interaction of SeDJ-1 and SeASF1 was confirmed using Y2H,Co-IP,and pull-down.Due to some components of phosphatidylinositol 3-kinase/protein kinase B(PI3K/AKT)signaling pathway were known to interact with DJ-1 in mammals,we verified SePI3K,an element of PI3K/AKT signaling pathway in S.eturmiunum,was directly linked to SeDJ-1 and then these two proteins were defined as a coordinator of reproduction.However,knockout of SeDJ-1 or SePI3K altered the asexual and sexual repro-duction,but SePI3K recovered the asexual and sexual development of∆Sedj-1.The SeDJ-1-M6 segment of SeDJ-1 was essential for its interaction with SePI3K and played a critical role in restoring sexual reproduction in the∆Sepi3k,providing a deep understanding of the regulatory mechanism of SeDJ-1 in S.eturmiunum development.Summarily,SeASF1 is able to trigger SeDJ-1 and SeDJ-1can also activate SePI3K,which is orchestrally involved in asexual and sexual reproduction in S.eturmiunum.All these results reveal that SeASF1 manipulates asexual and sexual reproduction in S.eturmiunum by SeDJ-1 perception of PI3K/AKT signaling pathway.These data highlight the deep similarities in coordinating asexual and sexual processes in both fungi and eukaryotes in general.

Graphitic carbon nitride-based photocatalysts in the applications of environmental catalysis

Semiconductor photocatalytic technology has shown great prospects in converting solar energy into chemical energy to mitigate energy crisis and solve environmental pollution problems.The key issue is the development of high-efficiency photocatalysts.Various strategies in the state-of-the-art advancements,such as heterostructure construction,heteroatom doping,metal/single atom loading,and defect engineering,have been presented for the graphitic carbon nitride(g-C3N4)-based nanocomposite catalysts to design their surface chemical environments and internal electronic structures to make them more suitable for different photocatalytic applications.In this review,nanoarchitecture design,synthesis methods,photochemical properties,potential photocatalytic applications,and related reaction mechanisms of the modified high-efficiency carbon nitride-based photocatalysts were briefly summarized.The superior photocatalytic performance was identified to be associated with the enhanced visible-light response,fast photoinduced electron-hole separation,efficient charge migration,and increased unsaturated active sites.Moreover,the further advance of the visible-light harvesting and solar-to-energy conversions are proposed.

Experimental study on flow excursion instability of supercritical hydrocarbon fuel in scramjet regenerative cooling parallel channels

Flow instability of supercritical hydrocarbon fuel is a crucial issue in scramjet regenerative cooling structure. In this study, flow excursion instability and flow distribution in parallel tubes were experimentally studied for supercritical fluids. Two types of flow excursion occur in a single tube. Type Ⅰ and Type Ⅱ excursions, and they are corresponding to decreasing and increasing flow rate respectively. They can trigger flow maldistribution between parallel tubes and the hysteresis phenomenon of flow distribution. The effects of system parameters, including inlet temperature,system pressure, and heat flux, on flow distribution were analyzed. In addition, the relationship between flow excursion and the pseudo-critical interval proposed in the literature was established according to the heated tube outlet temperature at the onset of flow instability. Finally, the flow excursion instability boundary was obtained using two dimensionless parameters. These experimental results can provide helpful insight on the mechanism of Scramjet regenerative cooling.

Refractory black carbon aerosols in rainwater in the summer of 2019 in Beijing:Mass concentration,size distribution and wet scavenging ratio

Black carbon(BC)aerosols in the atmosphere play a significant role in climate systems due to their strong ability to absorb solar radiation.The lifetime of BC depends on atmospheric transport,aging and consequently on wet scavenging processes(in-cloud and below-cloud scavenging).In this study,sequential rainwater samples in eight rainfall events collected in 2 mm interval were measured by a tandem system including a single particle soot photometer(SP2)and a nebulizer.The results showed that the volume-weighted average(VWA)mass concentrations of refractory black carbon(rBC)in each rainfall event varied,ranging from 10.8 to 78.9μg/L.The highest rBC concentrations in the rainwater samples typically occurred in the first fraction from individual rainfall events.The geometric mean median mass-equivalent diameter(MMD)decreased under precipitation,indicating that rBC with larger sizes was relatively aged and preferentially removed by wet scavenging.A positive correlation(R2=0.73)between the VWA mass concentrations of rBC in rainwater and that in ambient air suggested the important contribution of scavenging process.Additionally,the contributions of in-cloud and below-cloud scavenging were distinguished and accounted for 74%and 26%to wet scavenging,respectively.The scavenging ratio of rBC particles was estimated to be 0.06 on average.This study provides helpful information for better understanding the mechanism of rBC wet scavenging and reducing the uncertainty of numerical simulations of the climate effects of rBC.

Chemical formation and source apportionment of PM_(2.5) at an urban site at the southern foot of the Taihang mountains

The region along the Taihang Mountains in the North China Plain(NCP) is characterized by serious fine particle pollution. To clarify the formation mechanism and controlling factors, an observational study was conducted to investigate the physical and chemical properties of the fine particulate matter in Jiaozuo city, China. Mass concentrations of the water-soluble ions(WSIs) in PM_(2.5) and gaseous pollutant precursors were measured on an hourly basis from December 1, 2017, to February 27, 2018. The positive matrix factorization(PMF) method and the FLEXible PARTicle(FLEXPART) model were employed to identify the sources of PM_(2.5). The results showed that the average mass concentration of PM_(2.5) was 111 μg/m^(3) during the observation period. Among the major WSIs, sulfate, nitrate, and ammonium(SNA) constituted 62% of the total PM_(2.5) mass, and NO_(3)^(-) ranked the highest with an average contribution of 24.6%. NH_(4)^(+) was abundant in most cases in Jiaozuo. According to chemical balance analysis, SO_(2)-4, NO_(3)^(-), and Cl^(-) might be present in the form of(NH_4)_(2)SO_4, NH_4NO_3, NH_4Cl, and KCl. The liquid-phase oxidation of SO_(2) and NO_(2) was severe during the haze period. The relative humidity and pH were the key factors influencing SO_(4)^(2-) formation. We found that NO_(3)^(-) mainly stemmed from homogeneous gas-phase reactions in the daytime and originated from the hydrolysis of N_(2)O_5 in the nighttime, which was inconsistent with previous studies. The PMF model identified five sources of PM_(2.5) : secondary origin(37.8%), vehicular emissions(34.7%), biomass burning(11.5%), coal combustion(9.4%), and crustal dust(6.6%).

眼科3D打印技术新进展

3D打印技术的原理是通过逐层添加材料来创建对象,对于构建形状复杂和材料繁多的零件具有明显优势。3D打印技术不仅改进了制作眼科器械的方法,在打印眼组织方面亦取得进展,但因其制作成本较高及精细度不足等问题在现今仍未普及,本综述介绍了3D打印技术在眼科领域的相关发展,就该技术在眼科的应用及前景进行探讨。

Cross-boundary transport and source apportionment for PM_(2.5) in a typical industrial city in the Hebei Province,China:A modeling study

Cross-boundary transport of air pollution is a difficult issue in pollution control for the North China Plain.In this study,an industrial district(Shahe City)with a large glass manufactur-ing sector was investigated to clarify the relative contribution of fine particulate matter(PM_(2.5))to the city's high levels of pollution.The Nest Air Quality Prediction Model System(NAQPMS),paired with Weather Research and Forecasting(WRF),was adopted and applied with a spatial resolution of 5 km.During the study period,the mean mass concentrations of PM_(2.5),SO_(2),and NO_(2)were observed to be 132.0,76.1,and 55.5μg/m^(3),respectively.The model reproduced the variations in pollutant concentrations in Shahe at an acceptable level.The simulation of online source-tagging revealed that pollutants emitted within a 50-km radius of downtown Shahe contributed 63.4%of the city's total PM_(2.5)concentration.This contribu-tion increased to 73.9±21.2%when unfavorable meteorological conditions(high relative hu-midity,weak wind,and low planetary boundary layer height)were present;such conditions are more frequently associated with severe pollution(PM_(2.5)≥250μg/m^(3)).The contribution from Shahe was 52.3±21.6%.The source apportionment results showed that industry(47%),transportation(10%),power(17%),and residential(26%)sectors were the most important sources of PM_(2.5)in Shahe.The glass factories(where chimney stack heights were normally<70 m)in Shahe contributed 32.1%of the total PM_(2.5)concentration in Shahe.With an in-crease in PM_(2.5)concentration,the emissions from glass factories accumulated vertically and narrowed horizontally.At times when pollution levels were severe,the horizontally influ-enced area mainly covered Shahe.Furthermore,sensitivity tests indicated that reducing emissions by 20%,40%,and 60% could lead to a decrease in themass concentration of PM_(2.5) of of 12.0%,23.8%,and 35.5%,respectively.