Isolation, characterization, and genomic analysis of a novel bacteriophage vB_Kp_XP4 targeting hypervirulent and multidrug-resistant Klebsiella pneumoniae

IntroductionHypervirulent and multidrug-resistant Klebsiella pneumoniae (hvKP and MDR-KP) are significant public health threats. This study aimed to isolate a lytic bacteriophage targeting these high-risk strains, systematically characterize its biological properties, genomic features, and therapeutic efficacy, and establish a foundation for clinical phage therapy and novel antimicrobial development.MethodsThe phage vB_Kp_XP4 was isolated from river water using the double-layer agar plate method with the clinically isolated strain P4 as the host. Morphology was analyzed via transmission electron microscopy (TEM). Host range, pH, and thermal stability were assessed using spot assays and OD630 measurements. One-step growth curves determined the latent period and burst size. Whole-genome sequencing and phylogenetic analysis were performed. Therapeutic efficacy and safety were evaluated in a Galleria mellonella infection model.ResultsTEM revealed Phage vB_Kp_XP4 as a tailed phage with an icosahedral head and a long, flexible tail. It lysed an hvKP strain (carrying rmp, peg, iuc, iro genes) and an MDR-KP strain (resistant to carbapenems, fluoroquinolones, etc.), with an optimal MOI of 0.1 and latent period <10 minutes. Stability was maintained at pH 4–11 and ≤70°C. Whole-genome sequencing revealed a linear double-stranded DNA genome of 44,344 bp with a G+C content of 53.80%. The genome comprised 54 coding sequences and lacked lysogenic, virulence, or antibiotic resistance genes. Phylogenetic analysis positioned phage vB_Kp_XP4 as a novel species within the genus Drulisvirus, family Autographiviridae. In the Galleria mellonella model, vB_Kp_XP4 prolonged survival of P4-infected larvae (P < 0.001)ConclusionPhage vB_Kp_XP4 exhibits high stability, specificity, potent lytic activity, and no undesirable genes, demonstrating effective in vivo therapeutic efficacy, suggest its potential for clinical applications against Klebsiella pneumoniae infections. The presence of multiple halos during plaque formation further enhances its research value. The complete genome sequence has been submitted to GenBank under accession number PP663283

Low Concentrations of Caffeine and Its Analogs Extend the Lifespan of Caenorhabditis elegans by Modulating IGF-1-Like Pathway

Caffeine has been reported to delay aging and protect aging-associated disorders in Caenorhabditis elegans. However, the effects of low concentration of caffeine and its analogs on lifespan are currently missing. Herein, we report that at much lower concentrations (as low as 10 μg/ml), caffeine extended the lifespan of C. elegans without affecting food intake and reproduction. The effect of caffeine was dependent on IGF-1-like pathway, although the insulin receptor homolog, daf-2 allele, e1371, was dispensable. Four caffeine analogs, 1-methylxanthine, 7-methylxanthine, 1,3-dimethylxanthine, and 1,7-dimethylxanthine, also extended lifespan, whereas 3-methylxanthine and 3,7-dimethylxanthine did not exhibit lifespan-extending activity

Building a multipurpose insertional mutant library for forward and reverse genetics in Chlamydomonas

Abstract Background The unicellular green alga, Chlamydomonas reinhardtii, is a classic model for studying flagella and biofuel. However, precise gene editing, such as Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated protein (Cas9) system, is not widely used in this organism. Screening of random insertional mutant libraries by polymerase chain reaction provides an alternate strategy to obtain null mutants of individual gene. But building, screening, and maintaining such a library was time-consuming and expensive. Results By selecting a suitable parental strain, keeping individual mutants using the agar plate, and designing an insertion cassette-specific primer for library screening, we successfully generated and maintained ~150,000 insertional mutants of Chlamydomonas, which was used for both reverse and forward genetics analysis. We obtained 26 individual mutants corresponding to 20 genes and identified 967 motility-defect mutants including 10 mutants with defective accumulation of intraflagellar transport complex at the basal body. We also obtained 929 mutants defective in oil droplet assembly after nitrogen deprivation. Furthermore, a new insertion cassette with splicing donor sequences at both ends was also constructed, which increased the efficiency of gene interruption. Conclusion In summary, this library provides a multifunctional platform both for obtaining mutants of interested genes and for screening of mutants with specific phenotype

Research on Target Detection Algorithm for Solder Joint Defects Based on the Improved YOLOv8

Aiming at the problem of low accuracy in solder joint defect detection caused by the complex background and difficult to extract defect features of circuit boards using through-hole technology (THT), an improved YOLOv8 solder joint defect target detection algorithm was proposed. Firstly, the FasterNet module was used to improve the C2f module of the baseline model, and the Efficient Multi-Scale Attention (EMA) attention mechanism was integrated to reduce model parameters and make the algorithm pay more attention to the solder joint targets. Secondly, the neck network of the baseline model was reconstructed and the Slide Loss function was introduced. The fusion of bidirectional cross scale connections and weighted features improved the feature extraction ability of the model and the detection accuracy of solder joint defects. Finally, the improved algorithm was experimentally validated on the target detection dataset of solder joint defect, and its generalization ability was also verified. Results indicate that the algorithm not only has a good detection performance on solder joint defects, but also has strong generalization ability and robustness

Performance of the Rotation Gesture Based on Electrostatic Tactile Feedback Devices

 The application of electrostatic tactile feedback to a touchscreen can provide a real sense of immersion to enhance the user interaction experience. With a custom-designed electrostatic tactile feedback device, we explore the effect of electrostatic tactile feedback on performing rotation gestures. Specifically, we design three-part experiments that include no tactile feedback, tactile feedback in the target area and tactile feedback increased linearly in the process. The effect of electrostatic tactile feedback on performing rotation gestures is then examined. The results with 12 participants indicate that adding tactile feedback to the process or the target area significantly enhances the efficiency and accuracy of rotation operations. In addition, the relationship between the index of difficulty (ID) and rotation time (RT) is studied by applying electrostatic tactile feedback in the process and the target area. The results indicate that the relations between ID and RT under the above two conditions satisfy Fitts’ Law with correlation coefficients &amp;gt;0.96.</jats:p

Cold Acclimation and Supercooling Capacity of Agasicles hygrophila Adults

Agasicles hygrophila Selman and Vogt is used in the biological control of the invasive weed Alternanthera philoxeroides (Mart.) Griseb. However, with the northward establishment of A. philoxeroides in China, the weak adaptivity of A. hygrophila to cold weather has resulted in the ineffective control of A. philoxeroides in northern China. Cold acclimation can significantly enhance insect cold tolerance, enabling them to cope with more frequent climate fluctuations. To improve the biological control efficacy of A. hygrophila in cold climates, we compared the effects of rapid cold hardening and acclimation on A. hygrophila under laboratory conditions. On initially transferring adults from 26 to −10 °C for 2 h, mortality reached 80%. However, when pre-exposed to 0 °C for 2 h and then transferred to −10 °C for 2 h, adult mortality was reduced to 36.67%. These findings indicate that cold acclimation can enhance the cold tolerance of A. hygrophila under laboratory conditions. However, the beneficial cold acclimation effects waned after more than 15 min of recovery at 26 °C. Exposure to 15 °C for 24 h or gradual cooling from 0 to −10 °C at 1 °C·min−1 also induced cold acclimation, indicating that long-term cold and fluctuating cold acclimation are also potentially effective strategies for enhancing low-temperature tolerance.</jats:p