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Summary: Arabidopsis Col‐0 RPP2A and RPP2B confer recognition of Arabidopsis downy mildew (Hyaloperonospora arabidopsidis [Hpa]) isolate Cala2, but the identity of the recognized ATR2Cala2 effector was unknown.To reveal ATR2Cala2, an F2 population was generated from a cross between Hpa‐Cala2 and Hpa‐Noks1. We identified ATR2Cala2 as a non‐canonical RxLR‐type effector that carries a signal peptide, a dEER motif, and WY domains but no RxLR motif. Recognition of ATR2Cala2 and its effector function were verified by biolistic bombardment, ectopic expression and Hpa infection.ATR2Cala2 is recognized in accession Col‐0 but not in Ler‐0 in which RPP2A and RPP2B are absent. In ATR2Emoy2 and ATR2Noks1 alleles, a frameshift results in an early stop codon. RPP2A and RPP2B are essential for the recognition of ATR2Cala2. Stable and transient expression of ATR2Cala2 under 35S promoter in Arabidopsis and Nicotiana benthamiana enhances disease susceptibility.Two additional Col‐0 TIR‐NLR (TNL) genes (RPP2C and RPP2D) adjacent to RPP2A and RPP2B are quantitatively required for full resistance to Hpa‐Cala2. We compared RPP2 haplotypes in multiple Arabidopsis accessions and showed that all four genes are present in all ATR2Cala2‐recognizing accessions. [ABSTRACT FROM AUTHOR]

The effect of two different milling devices, namely attrition mill versus vibration mill, on the reactivity of fly ash was studied. High calcium fly ash from 4th Thermal power station of Ulaanbaatar (Mongolia) was used for the experiments. The raw and processed samples were characterized by XRD, SEM, Particle size distribution, BET, Blaine surface area and density measurements. The efficiency of 1 hour milling was evaluated with the Blaine surface area set to be more than 5000 cm2/g. The physical and chemical properties of the attrition milled fly ash changed not much compared to the vibration milled samples. For example the d50 particle size became reduced from 29 µm to 6 µm by attrition milling and in vibration milled fly ash it was reduced to 7 µm. The density increased from 2.44 g/cm3 of raw fly ash to 2.84 g/cm3 and 2.79 g/cm3 in attrition and vibration milled samples, respectively. Mechanical milling revealed not only a particle size reduction but also the formation of a denser microstructure. As a result the vibration milled fly ash showed a weaker interaction with the alkaline solution (8 M NaOH used here) compared to the attrition milled fly ash. Consequently, compressive strength of the binder prepared using the attrition milled fly ash was higher, 61 MPa, while for vibration milled fly ash it was 49 MPa. For comparison unmilled fly ash, it was 21 MPa.

The human immune response must continuously adapt to newly emerging SARS-CoV-2 variants. To investigate how B cells respond to repeated SARS-CoV-2 antigen exposure by Wu01 booster vaccination and Omicron breakthrough infection, we performed a molecular longitudinal analysis of the memory B cell pool. We demonstrate that a subsequent breakthrough infection substantially increases the frequency of B cells encoding SARS-CoV-2–neutralizing antibodies. However, this is not primarily attributable to maturation, but to selection of preexisting B cell clones. Moreover, broadly reactive memory B cells arose early and even neutralized highly mutated variants like XBB.1.5 that the individuals had not encountered. Together, our data show that SARS-CoV-2 immunity is largely imprinted on Wu01 over the course of multiple antigen contacts but can respond to new variants through preexisting diversity. Editor's summary: As the immune system is exposed to new SARS-CoV-2 variants, it must rapidly adapt, but how repeated antigen contacts influence the evolution of SARS-CoV-2–specific memory B cells is not well defined. Weber et al. explored how third dose SARS-CoV-2 vaccination and subsequent Omicron breakthrough infection influenced antibody and memory B cell responses. Serum antibodies had enhanced neutralization capacity after third dose vaccination. However, the SARS-CoV-2–specific memory B cell pool was significantly expanded only in individuals with a breakthrough infection after third dose. This was due to selection of pre-existing Omicron-neutralizing memory B cells that potently neutralized a broad range of variants that arose after initial vaccination. These findings demonstrate that SARS-CoV-2 immunity is imprinted during early antigen exposure and adapts to new variants. —Hannah Isles [ABSTRACT FROM AUTHOR]

RNA interference (RNAi) technology is a promising and effective approach for pest insect management. Owing to its sequence‐guided working mechanism, RNAi has a high degree of species‐selectivity, thus minimizing potential adverse effects on nontarget organisms. Recently, engineering plastid (chloroplast) genome, rather than the nuclear genome, to produce double‐stranded RNAs has emerged as a powerful way to protect plants from multiple arthropod pests. Here, we review the recent progresses in the plastid‐mediated RNAi (PM‐RNAi) approach for pest control and the factors influencing its efficacy, and propose the strategies for further efficiency improvement. We also discuss the current challenges and the biosafety‐related issues of PM‐RNAi technology that need to be addressed for commercial production. Summary statement: We review the recent progresses in the plastid‐mediated RNAi (PM‐RNAi) approach for pest control and the factors influencing its efficacy, and propose the strategies for further efficiency improvement. We also discuss the current challenges and the biosafety‐related issues of PM‐RNAi technology that need to be addressed for commercial production. [ABSTRACT FROM AUTHOR]