Fine structure and assembly pattern of a minimal myophage Pam3.

The myophage possesses a contractile tail that penetrates its host cell envelope. Except for investigations on the bacteriophage T4 with a rather complicated structure, the assembly pattern and tail contraction mechanism of myophage remain largely unknown. Here, we present the fine structure of a freshwater Myoviridae cyanophage Pam3, which has an icosahedral capsid of ~680 Å in diameter, connected via a three-section neck to an 840-Å-long contractile tail, ending with a three-module baseplate composed of only six protein components. This simplified baseplate consists of a central hub-spike surrounded by six wedge heterotriplexes, to which twelve tail fibers are covalently attached via disulfide bonds in alternating upward and downward configurations. In vitro reduction assays revealed a putative redox-dependent mechanism of baseplate assembly and tail sheath contraction. These findings establish a minimal myophage that might become a user-friendly chassis phage in synthetic biology.

Uridylation and the SKI complex orchestrate the Calvin cycle of photosynthesis through RNA surveillance of TKL1 in Arabidopsis.

RNA uridylation, catalyzed by terminal uridylyl transferases (TUTases), represents a conserved and widespread posttranscriptional RNA modification in eukaryotes that affects RNA metabolism. In plants, several TUTases, including HEN1 SUPPRESSOR 1 (HESO1) and UTP: RNA URIDYLYLTRANSFERASE (URT1), have been characterized through genetic and biochemical approaches. However, little is known about their physiological significance during plant development. Here, we show that HESO1 and URT1 act cooperatively with the cytoplasmic 3'-5' exoribonucleolytic machinery component SUPERKILLER 2 (SKI2) to regulate photosynthesis through RNA surveillance of the Calvin cycle gene TRANSKETOLASE 1 (TKL1) in Arabidopsis. Simultaneous dysfunction of HESO1, URT1, and SKI2 resulted in leaf etiolation and reduced photosynthetic efficiency. In addition, we detected massive illegitimate short interfering RNAs (siRNAs) from the TKL1 locus in heso1 urt1 ski2, accompanied by reduced TKL1/2 expression and attenuated TKL activities. Consequently, the metabolic analysis revealed that the abundance of many Calvin cycle intermediates is dramatically disturbed in heso1 urt1 ski2. Importantly, all these molecular and physiological defects were largely rescued by the loss-of-function mutation in RNA-DEPENDENT RNA POLYMERASE 6 (RDR6), demonstrating illegitimate siRNA-mediated TKL silencing. Taken together, our results suggest that HESO1- and URT1-mediated RNA uridylation connects to the cytoplasmic RNA degradation pathway for RNA surveillance, which is crucial for TKL expression and photosynthesis in Arabidopsis.

Subtypes of Job Satisfaction and Health-Related Quality of Life in Chinese Male Nurses: A Latent Profile Analysis.

In this cross-sectional study, we aimed to identify subgroups of job satisfaction and health-related quality of life (HRQoL) in Chinese male nurses and examine the factors associated with subgroup profiles. A convenience sample of 626 Chinese male nurses were enrolled from January to October 2021. Latent profile analysis was performed to identify profiles based on self-esteem, psychological resilience, social support, neuroticism, perceived prejudice, occupational stress, job satisfaction, and HRQoL. Chi-squared tests were used to examine predictors of profiles. Results indicated that a three-profile model provided the best fit: low job satisfaction and health (9.90%), moderate job satisfaction and health (64.06%), and high job satisfaction and health (26.04%). The average number of monthly night shifts was negatively correlated with the male nurses' subgroups. Psychological resilience, social support, and neuroticism were the key factors associated with the HRQoL of male nurses, while perceived prejudice, occupational stress, and self-esteem were the key factors associated with job satisfaction. Nurse administrators could improve their job satisfaction and health by reducing perceived prejudice, and job stress, increasing organizational support and resilience.

Low-Cost Plant-Protection Unmanned Ground Vehicle System for Variable Weeding Using Machine Vision.

This study presents a machine vision-based variable weeding system for plant- protection unmanned ground vehicles (UGVs) to address the issues of pesticide waste and environmental pollution that are readily caused by traditional spraying agricultural machinery. The system utilizes fuzzy rules to achieve adaptive modification of the Kp, Ki, and Kd adjustment parameters of the PID control algorithm and combines them with an interleaved period PWM controller to reduce the impact of nonlinear variations in water pressure on the performance of the system, and to improve the stability and control accuracy of the system. After testing various image threshold segmentation and image graying algorithms, the normalized super green algorithm (2G-R-B) and the fast iterative threshold segmentation method were adopted as the best combination. This combination effectively distinguished between the vegetation and the background, and thus improved the accuracy of the pixel extraction algorithm for vegetation distribution. The results of orthogonal testing by selected four representative spraying duty cycles-25%, 50%, 75%, and 100%-showed that the pressure variation was less than 0.05 MPa, the average spraying error was less than 2%, and the highest error was less than 5% throughout the test. Finally, the performance of the system was comprehensively evaluated through field trials. The evaluation showed that the system was able to adjust the corresponding spraying volume in real time according to the vegetation distribution under the decision-making based on machine vision algorithms, which proved the low cost and effectiveness of the designed variable weed control system.

A high-efficient and naked-eye visible CRISPR/Cas9 system in Arabidopsis.

MAIN CONCLUSION: Introducing 35S-dsRED2 into the Cas9 vector which expresses naked-eye visible dsRED2 greatly facilitates the genetic screening, and the WUS promoter driving the Cas9 expression can improve editing efficiency in Arabidopsis. CRISPR/Cas9-dependent genome editing has been applied to generate random insertions and deletions, targeted insertions or replacements, and precise base changes for both fundamental studies in many plant species and crop improvement. To simplify the screening procedure for target gene-edited transformants, we introduced a CaMV 35S-driven dsRED2 cassette (35S-dsRED2) into the Cas9 vector to express the naked-eye visible protein dsRED2, which can be observed under white light, greatly facilitated the genetic screening and reduced labor intensity without using any instrument. In addition, the WUS promoter was used to drive the expression of Cas9, which successfully improved the target genes editing efficiency and enabled the homozygous mutagenesis of two genes in T1 generation in Arabidopsis. Considering the conserved function and expression pattern of WUS across the plant species, this dsRED2-WUS/Cas9 system could also be used in many crops.

In-situ and fast classification of origins of Baishao (Radix Paeoniae Alba) slices based on auto-focus laser-induced breakdown spectroscopy.

In this Letter, a rapid origin classification device and method for Baishao (Radix Paeoniae Alba) slices based on auto-focus laser-induced breakdown spectroscopy (LIBS) is proposed. The enhancement of spectral signal intensity and stability through auto-focus was investigated, as were different preprocessing methods, with area normalization (AN) achieving the best results-increasing by 7.74%-but unable to replace the improved spectral signal quality provided by auto-focus. A residual neural network (ResNet) was used as both a classifier and feature extractor, achieving higher classification accuracy than traditional machine learning methods. The effectiveness of auto-focus was elucidated by extracting LIBS features from the last pooling layer output using uniform manifold approximation and projection (UMAP). Our approach demonstrated that auto-focus could efficiently optimize the LIBS signal, providing broad prospects for rapid origin classification of traditional Chinese medicines.

Recent advances and applications of laser-based imaging techniques in food crops and products: a critical review.

To meet the growing demand for food quality and safety, there is a pressing need for fast and visible techniques to monitor the food crop and product production processing, and to understand the chemical changes that occur during these processes. Herein, the fundamental principles, instruments, and characteristics of three major laser-based imaging techniques (LBITs), namely, laser-induced breakdown spectroscopy, Raman spectroscopy, and laser ablation-inductively coupled plasma-mass spectrometry, are introduced. Additionally, the advances, challenges, and prospects for the application of LBITs in food crops and products are discussed. In recent years, LBITs have played a crucial role in mapping primary metabolites, secondary metabolites, nanoparticles, toxic metals, and mineral elements in food crops, as well as visualizing food adulteration, composition changes, pesticide residue, microbial contamination, and elements in food products. However, LBITs are still facing challenges in achieving accurate and sensitive quantification of compositions due to the complex sample matrix and minimal laser sampling quantity. Thus, further research is required to develop comprehensive data processing strategies and signal enhancement methods. With the continued development of imaging methods and equipment, LBITs have the potential to further explore chemical distribution mechanisms and ensure the safety and quality of food crops and products.

Rubisco accumulation factor 1 (Raf1) plays essential roles in mediating Rubisco assembly and carboxysome biogenesis.

Carboxysomes are membrane-free organelles for carbon assimilation in cyanobacteria. The carboxysome consists of a proteinaceous shell that structurally resembles virus capsids and internal enzymes including ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), the primary carbon-fixing enzyme in photosynthesis. The formation of carboxysomes requires hierarchical self-assembly of thousands of protein subunits, initiated from Rubisco assembly and packaging to shell encapsulation. Here we study the role of Rubisco assembly factor 1 (Raf1) in Rubisco assembly and carboxysome formation in a model cyanobacterium, Synechococcus elongatus PCC7942 (Syn7942). Cryo-electron microscopy reveals that Raf1 facilitates Rubisco assembly by mediating RbcL dimer formation and dimer-dimer interactions. Syn7942 cells lacking Raf1 are unable to form canonical intact carboxysomes but generate a large number of intermediate assemblies comprising Rubisco, CcaA, CcmM, and CcmN without shell encapsulation and a low abundance of carboxysome-like structures with reduced dimensions and irregular shell shapes and internal organization. As a consequence, the Raf1-depleted cells exhibit reduced Rubisco content, CO2-fixing activity, and cell growth. Our results provide mechanistic insight into the chaperone-assisted Rubisco assembly and biogenesis of carboxysomes. Advanced understanding of the biogenesis and stepwise formation process of the biogeochemically important organelle may inform strategies for heterologous engineering of functional CO2-fixing modules to improve photosynthesis.

RCD1 Promotes Salt Stress Tolerance in Arabidopsis by Repressing ANAC017 Activity.

Plants have evolved diverse strategies to accommodate saline environments. More insights into the knowledge of salt stress regulatory pathways will benefit crop breeding. RADICAL-INDUCED CELL DEATH 1 (RCD1) was previously identified as an essential player in salt stress response. However, the underlying mechanism remains elusive. Here, we unraveled that Arabidopsis NAC domain-containing protein 17 (ANAC017) acts downstream of RCD1 in salt stress response, and its ER-to-nucleus transport is triggered by high salinity. Genetic and biochemical evidence showed that RCD1 interacts with transmembrane motif-truncated ANAC017 in the nucleus and represses its transcriptional activity. Transcriptome analysis revealed that genes associated with oxidation reduction process and response to salt stress are similarly dysregulated in loss-of-function rcd1 and gain-of-function anac017-2 mutants. In addition, we found that ANAC017 plays a negative role in salt stress response by impairing the superoxide dismutase (SOD) enzyme activity. Taken together, our study uncovered that RCD1 promotes salt stress response and maintains ROS homeostasis by inhibiting ANAC017 activity.

Sediment and residual feed from aquaculture water bodies threaten aquatic environmental ecosystem: Interactions among algae, heavy metals, and nutrients.

The effect of sediment and residual fish feed on aquaculture water bodies has gained increasing attention to alleviate the eutrophication and heavy metals enrichment induced by aquaculture. Thus, this study intended to reveal the possible interactions among nutrients, heavy metals, and Chlorella vulgaris (C. vulgaris) in aquaculture water bodies containing fish feed and sediment. The analyses showed that consistent with the composition of heavy metals in fish feed, manganese (Mn) and zinc (Zn) accounted for the highest proportions (68-78%) of heavy metals in sediment. Meanwhile, sediment in the centre of aquaculture water bodies (S2) contained more heavy metals than those in the perimeter (S1), but the released concentrations and rates (Rrelease) of heavy metals from S1 were higher than those from S2. Moreover, the biomass, growth rate, specific growth rate, and nitrogen and carbon fixation rate of C. vulgaris increased with adding fish feed, whereas superoxide dismutase (SOD) and malondialdehyde (MDA) decreased. In addition, with C. vulgaris, influenced by the release process from sediment and the uptake by C. vulgaris, the concentration and Rrelease of Mn, Pb, Cu, Mn, Cr and Cd from sediments coexisting with fish feed in water first increased and then decreased in general. The C. vulgaris biomass was significantly negatively related to Mn, Pb, Cu, Ni, Cr, and Cd and PO43-P (P < 0.05), which was caused by the uptake of C. vulgaris and indicated that C. vulgaris biomass is easily affected by these factors. Accordingly, the input of residual fish feed and sediment should be controlled.