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Precision Engineering of Evolution-Resilient Rice against Bacterial Blight.

The persistent conflict between rice and Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight, exemplifies a dynamic genetic arms race in agriculture. The cyclical deployment and erosion of major resistance (R) genes highlight the high adaptive potential of Xoo and the need for strategies that are durable rather than absolute. This review synthesizes a paradigm shift from reactive, single R-gene deployment toward proactive engineering of evolution-resilient resistance. We explore the molecular-genetic basis of Xoo adaptability, including TAL effector diversification, non-TAL virulence functions, genome variation, and immune suppression mechanisms. In response, we propose a framework for durable disease management with three connected components: precision disarmament through editing of susceptibility-gene effector-binding elements and executor/decoy designs; smart induction through targeted delivery and immune priming; and ecological fortification through protective microbiomes. We also discuss the limits, trade-offs, and field-validation requirements of these approaches. Integrating frontier technologies with evolutionary genetics, predictive genomics, and pathogen population dynamics can help develop rice varieties and deployment systems that are more difficult for Xoo populations to overcome.

CRISPR

Diverse effect of cytokine treatment of tumor cells on specific versus non-specific cytotoxicity.

The effect of IFN-gamma and TNF-alpha treatment of an ovarian carcinoma line on the sensitivity to lysis by specific CTL clones and non-specific Tumor Associated Lymphocytes (TAL), isolated from the ascites fluid, was analyzed. The in vitro established TAL line displayed a non-specific lytic activity against the autologous tumor as well as against several allogeneic tumor lines. Pretreatment with IFN-gamma alone, or in combination with TNF-alpha, rendered the carcinoma line less susceptible to lysis by the autologous TAL line. Conversely, susceptibility to lysis by tumor specific T cell clones, isolated from the TAL line, was increased as a result of cytokine pretreatment. Several TCR-alpha/beta+, CD8+ T-cell clones showing a more specific pattern of lysis against the autologous tumor were isolated. Lysis of the autologous tumor by these clones involved the TCR-alpha/beta via a MHC-class I restricted mechanism dependent on the adhesion molecules ICAM-1 and LFA-3, as inferred from antibody blocking studies. The enhanced sensitivity to specific CTL clones seen after cytokine treatment may be related to the enhanced expression of ICAM-1 molecules on the ovarian carcinoma. These results have implications for cytokine based immunotherapy, where IFN-gamma may enhance the effects of tumor associated specific CTL while decreasing that of non-specific effector cells.

Ascitic Fluid

Molecular Characterization of the Group A Streptococcus Virulence-Regulatory System FasBCAX.

By regulating the assortment and abundance of its virulence factors at different anatomic sites, the group A Streptococcus (GAS) can cause a range of human diseases. The Fas regulatory system is encoded by a four-gene locus, fasBCAX, with fasX encoding the FasX small regulatory RNA effector molecule. FasX post-transcriptionally regulates target mRNAs through well-characterized mechanisms. Less characterized are the layers of regulation that occur upstream of FasX activity, such as how the products of the fasBCA genes enhance FasX abundance 100-fold. Here, we present data consistent with FasBCA forming a three-component regulatory system, with FasBC being sensor kinase-like proteins that, upon recognizing one or more signals, heterodimerize and phosphorylate FasA, with phosphorylated FasA binding to the fasX promoter and inducing transcription. We identified key amino acids involved in phosphate flow, including H246 of FasC and D60 of FasA, and demonstrated that certain domains (e.g., the kinase domain of FasC) are dispensable for activity. Additionally, we show that a proteinaceous factor within human plasma activates the Fas system. This work represents the first molecular analysis of the Fas proteins which, by modulating FasX levels, play a critical role in the ability of GAS to coordinately regulate virulence factor production.

Streptococcus pyogenes

Effectidor II: a pan-genomic AI-based algorithm for the prediction of type III secretion system effectors.

MOTIVATION: Type III secretion systems are used by many Gram-negative bacteria to inject type 3 effectors (T3Es) directly into eukaryotic cells, promoting disease or provoking immune response. Because of these opposing evolutionary forces, T3E repertoires often vary within taxonomic groups. Identifying the full effector gene repertoire in genomes of related individuals is crucial for determining core and specialized effectors, understanding the disease dynamics, and developing appropriate management strategies against pathogens. It can also help uncover novel T3Es that have recently emerged in a population. Our previously published Effectidor web server successfully addressed the challenge of identifying T3Es in a single bacterial genome. Here, we enriched the web server with various novel capabilities, including the identification of T3Es from multiple genome sequences simultaneously. RESULTS: We present Effectidor II, a web server that relies on machine learning to predict T3E-encoding genes within bacterial pan-genomes. We demonstrate the benefit of learning based on features extracted from the entire sequences comprising the pan-genome and report a novel T3E discovered by it in Xanthomonas euroxanthea. AVAILABILITY AND IMPLEMENTATION: Effectidor II is available at: https://effectidor.tau.ac.il and the source code is available at: https://github.com/naamawagner/Effectidor. A stand-alone version of Effectidor II is available at: https://github.com/naamawagner/Effectidor/tree/StandAlone. The source code for the standalone version and the data used in this work are also provided in https://doi.org/10.5281/zenodo.15081636.

Type III Secretion Systems