Diploid mycelia of Ustilago esculenta fails to maintain sustainable proliferation in host plant

Smut fungi display a uniform life cycle including two phases: a saprophytic phase in vitro and a parasitic phase in host plants. Several apathogenic smut fungi are found, lacking suitable hosts in their habitat. Interestingly, MT-type Ustilago esculenta was found to maintain a parasitic life, lacking the saprophytic phase. Its long period of asexual proliferation in plant tissue results in severe defects in certain functions. In this study, the growth dynamics of U. esculenta in plant tissues were carefully observed. The mycelia of T- and MT-type U. esculenta exhibit rapid growth after karyogamy and aggregate between cells. While T-type U. esculenta successfully forms teliospores after aggregation, the aggregated mycelia of MT-type U. esculenta gradually disappeared after a short period of massive proliferation. It may be resulted by the lack of nutrition such as glucose and sucrose. After overwintering, infected Zizania latifolia plants no longer contained diploid mycelia resulting from karyogamy. This indicated that diploid mycelia failed to survive in plant tissues. It seems that diploid mycelium only serves to generate teliospores. Notably, MT-type U. esculenta keeps the normal function of karyogamy, though it is not necessary for its asexual life in plant tissue. Further investigations are required to uncover the underlying mechanism, which would improve our understanding of the life cycle of smut fungi and help the breeding of Z. latifolia

Identification and genomic analyses of a novel endophytic actinobacterium Streptomyces endophytica sp. nov. with potential for biocontrol of yam anthracnose

Anthracnose disease caused by Colletotrichum gloeosporioides is one of the devastating diseases of yams (Dioscorea sp.) worldwide. In this study, we aimed to isolate endophytic actinobacteria from yam plants and to evaluate their potential for the control of yam anthracnose based on bioassays and genomic analyses. A total of 116 endophytic actinomycete strains were isolated from the surface-sterilized yam tissues from a yam orchard in Hainan Province, China. In total, 23 isolates showed antagonistic activity against C. gloeosporioides. An endophytic actinomycete, designated HNM0140T, which exhibited strong antifungal activities, multiple biocontrol, and plant growth-promoting (PGP) traits was subsequently selected to colonize in the tissue-cultured seedlings of yam and was tested for its in vivo biocontrol potential on yam anthracnose. The results showed that treatment with strain HNM0140T markedly reduced the severity and incidence of yam anthracnose under greenhouse conditions. Morphological and chemotaxonomic analyses showed that strain HNM0140T was assigned to the genus Streptomyces. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain HNM0140T formed a separate cluster together with Streptomyces lydicus ATCC 25470T (99.45%), Streptomyces chattanoogensis NRRL ISP-5002T (99.45%), and Streptomyces kronopolitis NEAU-ML8T (98.97%). The phylogenomic tree also showed that strain HNM0140T stably clustered with Streptomyces lydicus ATCC 25470T. The ANI and dDDH between strain HNM0140T and its closest related-type species were well below the recommended thresholds for species demarcation. Hence, based on the phylogenetic, genomic, and phenotypic analyses, strain HNM0140T should represent a new streptomycete species named Streptomyces endophytica sp. nov. Genomic analysis revealed that strain HNM0140T harbored 18 putative BGCs for secondary metabolites, some PGP-related genes, and several genes coding for antifungal enzymes. The presented results indicated that strain HNM0140T was a promising biocontrol agent for yam anthracnose

TLTC, a T5 exonuclease–mediated low-temperature DNA cloning method

Molecular cloning is used in a wide variety of biological and medical research. Here, we developed a rapid and efficient DNA-assembling method for routine laboratory work. We discovered that the cleavage speed of T5 exonuclease is approximately 3 nt/min at 0°C and hence developed a T5 exonuclease–mediated low-temperature sequence- and ligation-independent cloning method (TLTC). Two homologous regions of 15 bp–25 bp compatible with the ends of the vector backbones were introduced into the inserts through PCR. Approximately 120 fmol of inserts and linear vectors was mixed at a molar ratio of approximately 3:1 and treated with 0.5 U of T5 exonuclease at 0°C for 5 min. Then, the mixture was transformed into Escherichia coli to generate recombinant plasmids. Single segment and multi-segments can be assembled efficiently using TLTC. For single segment, the overall cloning efficiency is above 95%. Moreover, extra nucleotides in the vectors can be removed during TLTC. In conclusion, an extremely simple and fast DNA cloning/assembling method was established in the present study. This method facilitates routine DNA cloning and synthesis of DNA fragments

The impact of immunoglobulin G N-glycosylation level on COVID-19 outcome: evidence from a Mendelian randomization study

BackgroundThe coronavirus disease 2019 (COVID-19) pandemic has exerted a profound influence on humans. Increasing evidence shows that immune response is crucial in influencing the risk of infection and disease severity. Observational studies suggest an association between COVID‐19 and immunoglobulin G (IgG) N-glycosylation traits, but the causal relevance of these traits in COVID-19 susceptibility and severity remains controversial.MethodsWe conducted a two-sample Mendelian randomization (MR) analysis to explore the causal association between 77 IgG N-glycosylation traits and COVID-19 susceptibility, hospitalization, and severity using summary-level data from genome-wide association studies (GWAS) and applying multiple methods including inverse-variance weighting (IVW), MR Egger, and weighted median. We also used Cochran’s Q statistic and leave-one-out analysis to detect heterogeneity across each single nucleotide polymorphism (SNP). Additionally, we used the MR-Egger intercept test, MR-PRESSO global test, and PhenoScanner tool to detect and remove SNPs with horizontal pleiotropy and to ensure the reliability of our results.ResultsWe found significant causal associations between genetically predicted IgG N-glycosylation traits and COVID-19 susceptibility, hospitalization, and severity. Specifically, we observed reduced risk of COVID-19 with the genetically predicted increased IgG N-glycan trait IGP45 (OR = 0.95, 95% CI = 0.92–0.98; FDR = 0.019). IGP22 and IGP30 were associated with a higher risk of COVID-19 hospitalization and severity. Two (IGP2 and IGP77) and five (IGP10, IGP14, IGP34, IGP36, and IGP50) IgG N-glycosylation traits were causally associated with a decreased risk of COVID-19 hospitalization and severity, respectively. Sensitivity analyses did not identify any horizontal pleiotropy.ConclusionsOur study provides evidence that genetically elevated IgG N-glycosylation traits may have a causal effect on diverse COVID-19 outcomes. Our findings have potential implications for developing targeted interventions to improve COVID-19 outcomes by modulating IgG N-glycosylation levels

The Role Of The Surface Morphology And Segmented Cracks On The Damage Forms Of Laser Re-Melted Thermal Barrier Coatings In Presence Of A Molten Salt (Na2So4 + V2O5)

Hot corrosion behaviour of yttria-stabilized zirconia thermal barrier coatings (TBCs) with various segmented cracks and surface morphologies, obtained using ultrasonic-assisted laser re-melting, was investigated during exposure to Na2SO4 + V2O5salt at 1100 °C. It is demonstrated, that the damage types of TBCs were significantly affected by segmented cracks and surface morphology. Four main damage mechanisms: (i) chemical reaction, (ii) Coefficient thermal mismatch stress, (iii) oxidation of bond coating and (iv) intergranular corrosion, based on the observed transport behaviour of oxygen and molten salt, stress-tolerance and self-healing of various segmented cracks, were discussed to account for the failure behaviour

Enhanced Cyclic Oxidation Resistance Through The Self-Healing Of Segmented Cracks Using Nano-Al2O3/Ni-20 Wt%Al Particles In Laser Re-Melted Thermal Barrier Coatings

This paper introduces a novel and effective self-healing method of segmented cracks in laser re-melted ZrO2-7 wt% Y2O3 thermal barrier coatings (TBCs). The method uses pressure sintering of nano-Al2O3/Ni-20 wt%Al particles at 1150 °C for 12 h. After treatment to facilitate self-healing, a very dense and metallurgically bonded nano-Al2O3 reinforced Ni-matrix sealed film formed in the segmented gaps. Cyclic oxidation results indicate that dense sealed films can effectively suppress the growth of thermally grown oxides (TGO) and prevent the formation of other brittle and fragile oxides (i.e., spinels) at the top coat/bond coat (TC/BC) interface. Using the pressure-sintering effect, any aluminums contained in the sealed particles or films becomes prone to diffusion into the TC/BC interface to facilitate the formation of a thin-continuous TGO during the initial oxidation. This results in a significantly enhanced anti-oxidation effect of laser re-melted TBCs

Disturbance Identification and Adaptive Compensation Method in Optical Target Tracking System

External disturbance suppression is critical in high-precision optical target tracking systems. Although the traditional disturbance observation compensator (DOBC) method can improve anti-disturbance performance, its fixed structure limits its ability to handle variable disturbances. To improve the suppression ability of time-varying narrowband disturbances, we propose a disturbance identification and adaptive compensation method based on DOBC (DIAC-DOBC). The peak frequency of the observed disturbance can be obtained with high precision using AR parameter model identification. To design the Q filter, an improved notch filter structure is proposed, with parameters that can be adjusted automatically and a stronger suppression ability. Furthermore, the conditions for closed-loop stability and robust stability are detailed. Finally, the method's effectiveness is demonstrated through simulation and actual experimentation on an optical target tracking system with disturbances

Effect Of Drilling Allowance On Tbc Delamination, Spatter And Re-Melted Cracks Characteristics In Laser Drilling Of Tbc Coated Superalloys

Laser drilling of inclined holes on Ni-based superalloys coated with thermal barrier coatings (TBC) was studied using numerical simulation and experiments. Two types of drilling, three steps-laser drilling (TSLD) method and the one step laser drilling (OSLD), were employed for making comparison. The simulation results demonstrate that relatively strong vortex effect of assist gas at hole entrance and the drilling allowance of the substrate hole can deflect the trajectories of melt flow from leading edge TBC wall. This phenomenon may isolate leading edge of the hole from the ejecting molten material. Thus, shearing stress effect was prevented. The characteristics of TBC delamination, spatter at the TBC leading edge and re-melted cracks along the TBC trailing edge are investigated by comparing the characteristics of the melt flow obtained via simulation and experiment. The combined results suggest that the TBC/substrate multilayer can avoid these defects applying the TSLD technology

Evaluation Of Microstructural Evolution And Corrosion Types In Ultrasonic Assisted Laser Re-Melted Thermal Barrier Coatings Under Exposure To Molten Salts

In this study, yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) with improved microstructure and properties were re-melted using the novel ultrasonic assisted laser re-melting technique and its hot corrosion behavior was investigated in 50 wt% Na2SO4+50 wt% V2O5 molten salts at 1100 °C. The results indicated that the microstructure and corrosion types of the laser re-melted TBCs were significantly affected by the ultrasonic vibration power output (UVPO). The increased convection effect of low UVPO (20%) caused the enhanced nucleation of equiaxed grain and improvement in crack distribution and size. High strain tolerance led to the enhancement in the self-healing (eliminate cracks spacing) performance of cracks when exposed to the thermal expansion and phase transformation volume expansion, and seal the macroscopic diffusion channels of particles, thus promoting the propagation of only intergranular corrosion (internal corrosion). However, intensive ultrasonic nonlinear effect of high UVPO (50%) led to the generation of the uneven surface with coarse irregularly distributed cracks that are not entirely self-healing when exposed to volume expansion. Thus, the massive coatings particles could migrate preferentially outward through the cracks and voids to react with molten salts on the surface (external corrosion), leading to formation of the corrosion products