Insight into microbial functional genes' role in geochemical distribution and cycling of uranium: The evidence from covering soils of uranium tailings dam.

There exists a research gap on microbial functional genes' role in U geochemical behavior and cycling in U contaminated soils, which has been poorly understood. Herein, 16S rRNA sequencing gene amplifiers and metagenome analysis were applied to probe microbial community structure and functional metabolism of different depth layers of covering soils in U tailings dam. Results showed that the soils were highly enriched with U (47.5-123.3 mg/kg) and a remarkable portion of 35-70% was associated with the labile fractions. It was found that U geochemical distribution was notably interacted with functional genes from N, S, Fe and P related microbes. Importantly, diminution in gene NirK and amplification in nrfH involving in nitrate reduction could induce microbial tolerance to U. Moreover, gene Sat in microbial sulfate reduction, NosZ and NorB in nitrate reduction, phnD, upgA and upgC in P transportation and phnI, phnK, phoA and opd in microbial organic P mineralization, were all closely linked to U geochemical distribution, species and cycling. All these findings disclose the functional genes that may control the transfer and transformation behavior of U in soil environment, which provides important and novel indications for the bio-remediation strategies towards U polluted sites.

Abscisic acid promotes selenium absorption, metabolism and toxicity via stress-related phytohormones regulation in Cyphomandra betacea Sendt. (Solanum betaceum Cav.).

High levels of selenium (Se) uptakes negatively affect plant growth. In this study, the possible molecular mechanism for the effects of abscisic acid (ABA) on Se absorption, metabolism and toxicity in Cyphomandra betacea Sendt. (Solanum betaceum Cav.) young plants were investigated. Se+ABA treatment promoted significant Se absorption in C. betacea while impeding plant growth as compared to Se treatment. The expression levels of sulfate/phosphate transporter protein genes indicated that Se+ABA triggered more S/Se absorption and transportation into chloroplast. Furthermore, Se+ABA promoted higher metabolisms of inorganic sulfur (S)/Se and organic S/Se. The organic Se might be in several forms (SeCysth, SeCys and SeMet) in Se+ABA treatment, whereas SeCysth was the major organic form in Se treatment. More reactive oxygen species production was suggested in Se+ABA treatment from a series of genes involved in antioxidant enzymes and molecules, including superoxide dismutase, peroxiredoxin, glutathione sulfur-transferase and glutathione. Se+ABA further improved the expression levels of genes involved in biosynthesis and signaling transduction genes involved in stress-related phytohormones (jasmonic acid and salicylic acid). Combining with the data in ABA treatment, we hypothesized a model that ABA might first affect the biosynthesis and signaling transduction pathways of stress-related phytohormones, and subsequently altered the metabolic processes responding to Se stress.

Microplastics and potentially toxic elements: A review of interactions, fate and bioavailability in the environment.

In recent years, microplastics (MPs) have obtained growing public concern due to widespread distribution and harmful impacts. Their distinctive features including porous structure, small size, as well as large specific surface area render MPs to be carriers for transporting other pollutants in the environment, especially potentially toxic elements (PTEs). Considering the hot topic of MPs, it is of great significance to comb the reported literature on environmental behaviors of co-occurrence of MPs and PTEs, and systematically discuss their co-mobility, transportation and biotoxicity to different living organisms in diverse environmental media. Therefore, the aim of this work is to systematically review and summarize recent advances on interactions and co-toxicity of MPs and PTEs, in order to provide in-depth understanding on the transport behaviors as well as environmental impacts. Electrostatic attraction and surface complexation mainly govern the interactions between MPs and PTEs, which are subordinated by other physical sorption processes. Besides, the adsorption behaviors are mainly determined by physicochemical properties regarding to different MPs types and various condition factors (e.g., ageing and PTEs concentrations, presence of substances). Generally speaking, recently published papers make a great progress in elucidating the mechanisms, impact factors, as well as thermodynamic and kinetic studies. Bioavailability and bioaccumulation by plant, microbes, and other organisms in both aquatic and terrestrial environment have also been under investigation. This review will shed novel perspectives on future research to meet the sustainable development goals, and obtain critical insights on revealing comprehensive mechanisms. It is crucial to promote efficient approaches on environmental quality improvement as well as management strategies towards the challenge of MPs-PTEs.

Modeling long COVID dynamics: Impact of underlying health conditions.

We propose a new mathematical model to investigate the population dynamics of long COVID, with a focus on the impact of chronic health conditions. Our model connects long COVID with the transmission of COVID-19 so as to accurately predict the prevalence of long COVID from the progression of the infection in the host population. The model additionally incorporates the effects of COVID-19 vaccination. We implement the model with data from both the US and the UK to demonstrate the real-world applications of this modeling framework.

Maximizing the carbon sink function of paddy systems in China with machine learning.

Developing low-carbon agriculture and alleviating the "carbon crisis" requires optimizing strategies that fully leverage the carbon sink function of paddy systems. Accurate assessment of the effects of various agricultural management practices (AMPs) on the carbon sink function of paddy systems is crucial to this end. Here, we have presented a soil organic carbon sequestration rate (SOCSR) database of paddy systems in China based on 1388 groups of experimental data from 143 peer-reviewed publications. We analyzed the impact trend of different AMPs on SOCSR, compared two traditional regression models, four classic machine learning models and two deep learning models, and established a data-driven SOCSR prediction model to quantify the impact of AMPs on SOCSR and provide the optimal strategies. Our model (Random Forest) had the characteristics of high accuracy (R2 = 0.71, RMSE = 0.53 Mg ha-1), strong flexibility, low time cost with a certain degree of interpretability for the regional scale of China. We found that inorganic N fertilizer, inorganic K fertilizer, organic fertilizer, tillage and residue management are relatively important AMPs for improving SOCSR. The carbon sink function of paddy systems would reach saturation when the application rate of inorganic N fertilizer, inorganic K fertilizer and organic fertilizer reached around 80 kg N ha-1, 40 kg K ha-1 and 2200 kg C ha-1, respectively. Compared to half residue returning and conventional tillage, full residue returning and no-tillage increased SOCSR by 39.8 % and 9.2 %, respectively. Our optimal combination of strategies could achieve SOCSR of 1.179 Mg ha-1 in paddy systems of China. Our work enables swift and precise evaluation of SOCSR in paddy systems, provides a new idea for assessing SOCSR of paddy systems on a regional scale, and serves as an essential part for the accurate assessment of the carbon footprint of rice production.

Biodegradation of sulfadiazine by ryegrass (Lolium perenne L.) in a soil system: Analysis of detoxification mechanisms, transcriptome, and bacterial communities.

The indiscriminate use of sulfadiazine has caused severe harm to the environment, and biodegradation is a viable method for the removal of sulfadiazine. However, there are few studies that consider sulfadiazine biodegradation mechanisms. To comprehensively investigate the process of sulfadiazine biodegradation by plants in a soil system, a potted system that included ryegrass and soil was constructed in this study. The removal of sulfadiazine from the system was found to be greater than 95% by determining the sulfadiazine residue. During the sulfadiazine removal process, a significant decrease in ryegrass growth and a significant increase in antioxidant enzyme activity were observed, which indicates the toxic response and detoxification mechanism of sulfadiazine on ryegrass. The ryegrass transcriptome and soil bacterial communities were further investigated. These results revealed that most of the differentially expressed genes (DEGs) were enriched in the CYP450 enzyme family and phenylpropanoid biosynthesis pathway after sulfadiazine exposure. The expression of these genes was significantly upregulated. Sulfadiazine significantly increased the abundance of Vicinamibacteraceae, RB41, Ramlibacter, and Microvirga in the soil. These key genes and bacteria play an important role in sulfadiazine biodegradation. Through network analysis of the relationship between the DEGs and soil bacteria, it was found that many soil bacteria promote the expression of plant metabolic genes. This mutual promotion enhanced the sulfadiazine biodegradation in the soil system. This study demonstrated that this pot system could substantially remove sulfadiazine and elucidated the biodegradation mechanism through changes in plants and soil bacteria.

Thallium uptake and risk in vegetables grown in pyrite past-mining contaminated soil amended with organic fertilizer (compost): A potential method for Tl contamination remediation.

Thallium (Tl) is a highly toxic trace metal that can cause severe pollution and damage to the ecological system. In this study, a field trial was conducted in a Tl-rich pyrite-barite past-mining area to unveil the fate of Tl in agricultural practice. Tuscany kale and red chicory cultivated in soil impacted by the dismissed mine of Valdicastello Carducci (Northern Tuscany, Italy) displayed significantly different uptake behaviors of Tl. Hyper-accumulation of Tl was observed in kale leaves and its content reached up to 17.1 mg kg-1 whereas only <0.70 mg kg-1 of Tl was found in leaves of red chicory. Due to the regionally polymetallic pollution, Tuscany kale grown in this area possessed a great Tl intake risk for the residents. As for the fertilization treatment, Tl in Tuscany kale leaves fertilized with mineral fertilizer (NPK) and compost were 21.4 and 12.8 mg kg-1. The results suggested a potential remediation ability of compost in diminishing Tl in the vegetable leaves and thus may reduce its risk in the soil-crop system. Since Tl poisoning emergency may occur in agricultural fields near past-mining zones, it is critical to establish possible remediation measures to ensure food safety surrounding former mining areas likewise.

Sterilization mechanism and nanotoxicity of visible light-driven defective carbon nitride and UV-excited TiO2.

The sterilization effect of photocatalysis and biotoxicity of nanomaterial catalysts have attracted high attention. In this study, the novel visible-driven defective carbon nitride (VL/DCN) system exhibits non-photoreactivation, non-toxic superior performance compared with traditional ultraviolet radiation (UV) and UV/titanium dioxide (UV/TiO2). The inactivation of antibiotic-resistant bacteria (ARB) by novel VL/DCN still reached 7 log within 4 h, and the reduction rates of aminoglycoside gene strB and tetracycline gene tetA exceeded 0.8 log and 1.2 log, respectively. Further, the sterilization mechanism and nanotoxicity were contrastively and systematically analyzed among above three systems as following. Firstly, in the VL/DCN system, reactive oxygen species (ROSs) generated from photocatalytic process leads to the destruction of cell membranes, resulting in dissolving out of potassium ion (K+), protein and cell membrane ATP content. Thus, resistant bacteria were completely inactivated and photoreactivation disappears. In contrast, the UV only acted on bacterial DNA and existed the light resurrection. The UV/TiO2 strictly dependent on ultraviolet light and can be used in limited scenarios. Secondly, in cell viability analysis by human lung cell line BEAS-2B experiments, the 10% inhibition of cell growth when DCN was 600 mg/L much lower than 28% inhibition of cell growth when TiO2 was only 200 mg/L. The expression of pro-inflammatory cytokines ((Interleukin, IL) -6), IL-8, IL-1ß) under the effect of DCN was 1.5-fold, 5.7-fold and 3.7-fold lower than TiO2, respectively. Meanwhile, DCN induced cells to produce less ROSs, malondialdehyde (MDA), and more superoxide dismutase (SOD). Above results demonstrated that DCN has far lower cytotoxicity than TiO2. This study provides theoretical support for the application of photocatalytic sterilization technology and the exploration of the toxicity of nanomaterials.

A new turn-on fluorescent probe for fast detection of diabetic biomarker beta-hydroxybutyrate in vitro.

Beta-hydroxybutyrate (ß-HB) serve as a valuable diagnostic biomarker for Diabetic Ketoacidosis (DKA). Here, a new Schiff base fluorescent probe T was designed and synthesized to detect ß-HB level in aqueous solution in vitro. The probe T can detect ß-HB sensitively and selectively in DMF solution (5.0 × 10-5 M) among other interfering species (cations, anions, amino acids, biomarkers). The detection limit of probe T for ß-HB was calculated to be 0.154 µM. These results demonstrate that the probe T may provide a convenient method for rapid detection of ß-HB to diagnose diabetic ketoacidosis.

Qinlian hongqu decoction ameliorates hyperlipidemia via the IRE1-α/IKKB-ß/NF-κb signaling pathway: Network pharmacology and experimental validation.

ETHNOPHARMACOLOGICAL RELEVANCE: Qinlian Hongqu decoction (QLHQD) is a traditional Chinese medicine (TCM) formula. It has previously been found to mitigate hyperlipidemia, although its mechanism requires further clarification. AIM OF THE STUDY: This study explored QLHQD's mechanism in treating hyperlipidemia based on network pharmacology and experimental validation. MATERIALS AND METHODS: The components of QLHQD were analyzed by means of ultrahigh performanceliquid chromatography-quadrupole/orbitrapmass spectrometry (UHPLC-Q-Orbitrap-HRMS) and the targets of hyperlipidemia were predicted using the Swiss ADME, GeneCards, OMIM, DrugBank, TTD, and PharmGKB databases. A drug-component-target-disease network was constructed using Cytoscape v3.7.1. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analyses were performed using the Bioinformatics platform. Based on the KEGG results, the non-alcoholic fatty liver disease signaling pathways were selected for experimental validation in an animal model. RESULTS: We identified 34 components of QLHQD, 94 targets of hyperlipidemia, and 18 lipid metabolism-related pathways from the KEGG analysis. The results of the animal experiment revealed that QLHQD alleviated lipid metabolism disorders, obesity, insulin resistance, and inflammation in rats with hyperlipidemia induced by high-fat diets. Additionally, it reduced the expression of IRE1-α, TRAF2, IKKB-ß, and NF-κB proteins in the liver of hyperlipidemic rats. CONCLUSION: QLHQD is able to significantly mitigate hyperlipidemia induced via high-fat diets in rats. The mechanism of action in this regard might involve regulating the IRE1-α/IKKB-ß/NF-κB signaling pathway in the liver, thereby attenuating inflammatory responses and insulin resistance.

High-efficiency all-fluorescent white organic light-emitting diode based on TADF material as a sensitizer.

The use of TADF materials as both sensitizers and emitters is a promising route to achieve high-efficiency all-fluorescent white organic light-emitting diodes (WOLEDs). In this study, the thermally-activated delayed-fluorescent (TADF) material DMAC-TRZ (9,9-dimethyl-9,10-dihydroacridine-2,4,6-triphenyl-1,3,5-triazine) was selected as a sensitizer for the conventional fluorescent emitter DCJTB (4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran), which was co-doped in a wide bandgap host of DPEPO (bis[2-(diphenylphosphino)phenyl]ether oxide) to fabricate WOLEDs. For the emitting layer of DPEPO:DMAC-TRZ:DCJTB, the DPEPO host can dilute the exciton concentration formed on the DMAC-TRZ sensitizer, which benefits the suppression of exciton quenching. The effect of the doping concentration of DCJTB on the carrier recombination and energy transfer process was investigated. With an optimized doping concentration of DCJTB as 0.8%, highly efficient WOLED was achieved with a maximum external quantum efficiency (EQE), power efficiency (PE), and current efficiency (CE) of 11.05%, 20.83 lm W-1, and 28.83 cd A-1, respectively, corresponding to the Commission Internationale de I' Eclairage (CIE) coordinates of (0.45, 0.46). These superior performances can be ascribed to the fact that the hole-trapping effect of the emitter and Dexter energy transfer (DET) from sensitizer to emitter can be suppressed simultaneously by the extremely low doping concentration.

Genome-wide analysis of transposable elements and satellite DNA in Humulus scandens, a dioecious plant with XX/XY1Y2 chromosomes.

Transposable elements (TEs) and satellite DNAs, two major categories of repetitive sequences, are expected to accumulate in non-recombining genome regions, including sex-linked regions, and contribute to sex chromosome evolution. The dioecious plant, Humulus scandens, can be used for studying the evolution of the XX/XY1Y2 sex chromosomes. In this study, we thoroughly examined the repetitive components of male and female H. scandens using next-generation sequencing data followed by bioinformatics analysis and florescence in situ hybridization (FISH). The H. scandens genome has a high overall repetitive sequence composition, 68.30% in the female and 66.78% in the male genome, with abundant long terminal repeat (LTR) retrotransposons (RTs), including more Ty3/Gypsy than Ty1/Copia elements, particularly two Ty3/Gypsy lineages, Tekay and Retand. Most LTR-RT lineages were found dispersed across the chromosomes, though CRM and Athila elements were predominately found within the centromeres and the pericentromeric regions. The Athila elements also showed clearly higher FISH signal intensities in the Y1 and Y2 chromosomes than in the X or autosomes. Three novel satellite DNAs were specifically distributed in the centromeric and/or telomeric regions, with markedly different distributions on the X, Y1, and Y2 chromosomes. Combined with FISH using satellite DNAs to stain chromosomes during meiotic diakinesis, we determined the synapsis pattern and distinguish pseudoautosomal regions (PARs). The results indicate that the XY1Y2 sex chromosomes of H. scandens might have originated from a centric fission event. This study improves our understanding of the repetitive sequence organization of H. scandens genome and provides a basis for further analysis of their chromosome evolution process.

GaN/Ga2O3 avalanche photodiodes with separate absorption and multiplication structure.

This article proposes a new, to the best of our knowledge, separate absorption and multiplication (SAM) APD based on GaN/ß-Ga2O3 heterojunction with high gains. The proposed APD achieved a high gain of 1.93 × 104. We further optimized the electric field distribution by simulating different doping concentrations and thicknesses of the transition region, resulting in the higher avalanche gain of the device. Furthermore, we designed a GaN/ß-Ga2O3 heterojunction instead of the single Ga2O3 homogeneous layer as the multiplication region. Owing to the higher hole ionization coefficient, the device offers up to a 120% improvement in avalanche gain reach to 4.24 × 104. We subsequently clearly elaborated on the working principle and gain mechanism of GaN/ß-Ga2O3 SAM APD. The proposed structure is anticipated to provide significant guidance for ultraweak ultraviolet light detection.

Association of possible sarcopenia with major chronic diseases and multimorbidity among middle-aged and older adults: Findings from a national cross-sectional study in China.

AIM: This study investigated the prevalence of possible sarcopenia (PSA) in a large sample of middle-aged and older adults, and determined the association between PSA, major chronic diseases and the number of chronic diseases. METHODS: A total of 14 917 adults aged ≥40 years were included in the analysis. The handgrip strength and the five-time chair stand test were used to assess PSA. The participants' major chronic diseases were divided into 14 categories. Four categories were created based on the participants' number of chronic illnesses: 0, 1, 2 and ≥3. RESULTS: The present study found an overall prevalence of PSA of 23.6% among Chinese middle-aged and older adults aged ≥40 years, with the risk increasing with advancing age. PSA was significantly associated with most categories of chronic diseases and multimorbidity. The closely independent associations were obtained for stroke; emotional, nervous or psychiatric problems; chronic lung disease, asthma, heart disease, hypertension and arthritis or rheumatism. Compared with participants with 0 chronic disease, those with two or more chronic diseases had higher odds for PSA. However, the association between PSA and the number of chronic diseases varied in different sex and age groups. CONCLUSIONS: The findings suggest that PSA is associated with major chronic diseases among middle-aged and older adults. People with two or more chronic diseases have a greater likelihood of PSA compared with those without chronic diseases, and the association between PSA and the number of chronic diseases largely depended on sex and age. Geriatr Gerontol Int 2023; ••: ••-••.

The homing of exogenous hair follicle mesenchymal stem cells into hair follicle niches.

Hair loss is a debilitating condition associated with the depletion of dermal papilla cells (DPCs), which can be replenished by dermal sheath cells (DSCs). Hence, strategies aimed at increasing the population of DPCs and DSCs hold great promise for the treatment of hair loss. In this study, we demonstrated that introducing exogenous DPCs and DSCs (hair follicle mesenchymal stem cells) could effectively migrate and integrate into the dermal papilla and dermal sheath niches, leading to enhanced hair growth and prolonged anagen phases. However, the homing rates of DPCs and DSCs were influenced by various factors, including recipient mouse depilation, cell passage number, cell dose, and immune rejection. Through in vitro and in vivo experiments, we further discovered that the CXCL13/CXCR5 pathway mediated the homing of DPCs and DSCs into hair follicle niches. This study underscores the potential of cell-based therapies for hair loss by targeted delivery of DPCs and DSCs to their respective niches, and sheds light on the intriguing concept that isolated mesenchymal stem cells can home back to their original niche microenvironment.

The development of orthography and phonology coupling in the ventral occipito-temporal cortex and its relation to reading.

The left ventral occipito-temporal (lvOT) cortex is considered to house the brain's representation of orthography (i.e., the spelling patterns of words). Because letter-sound coupling is crucial in reading, we investigated the engagement of the lvOT cortex in processing phonology (i.e., the sound patterns of words) as a function of reading acquisition. We tested 47 Polish children both at the beginning of formal literacy instruction and 2 years later. During functional magnetic resonance imaging, children performed auditory phonological tasks from small to large grain size levels (i.e., single phoneme, rhyme). We showed that orthographically relevant lvOT areas activated during small-grain size phonological tasks were skill-dependent, perhaps due to the relatively transparent mappings between orthography and phonology in Polish. We also studied activation pattern similarity between processing visual and auditory word stimuli in the lvOT. We found that a higher similarity level was observed in the anterior lvOT compared to the posterior lvOT after 2 years of schooling. This is consistent with models proposing a posterior-to-anterior shift in word processing during reading acquisition. We argue that the development of orthography-phonology coupling at the brain level reflects writing system-specific effects and a more universal pathway of the left vOT development in reading acquisition. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Targeting the Main Sources of Reactive Oxygen Species Production: Possible Therapeutic Implications in Chronic Pain.

Humans have long been combating chronic pain. In clinical practice, opioids are first- choice analgesics, but long-term use of these drugs can lead to serious adverse reactions. Finding new, safe and effective pain relievers that are useful treatments for chronic pain is an urgent medical need. Based on accumulating evidence from numerous studies, excess reactive oxygen species (ROS) contribute to the development and maintenance of chronic pain. Some antioxidants are potentially beneficial analgesics in the clinic, but ROS-dependent pathways are completely inhibited only by scavenging ROS directly targeting cellular or subcellular sites. Unfortunately, current antioxidant treatments donot achieve this effect. Furthermore, some antioxidants interfere with physiological redox signaling pathways and fail to reverse oxidative damage. Therefore, the key upstream processes and mechanisms of ROS production that lead to chronic pain in vivo must be identified to discover potential therapeutic targets related to the pathways that control ROS production in vivo. In this review, we summarize the sites and pathways involved in analgesia based on the three main mechanisms by which ROS are generated in vivo, discuss the preclinical evidence for the therapeutic potential of targeting these pathways in chronic pain, note the shortcomings of current research and highlight possible future research directions to provide new targets and evidence for the development of clinical analgesics.

The RRAS2 pathogenic variant (c.67G>T; p. Gly23Cys) produces Noonan syndrome with embryonal rhabdomyosarcoma.

BACKGROUND: Noonan syndrome (NS) due to the RRAS2 gene, the pathogenic variant is an extremely rare RASopathies. Our objective was to identify the potential site of RRAS2, combined with the literature review, to find the correlation between clinical phenotype and genotype. De novo missense mutations affect different aspects of the RRAS2 function, leading to hyperactivation of the RAS-MAPK signaling cascade. METHODS: Conventional G-banding was used to analyze the chromosome karyotype of the patient. Copy number variation sequencing (CNV-seq) was used to detect the chromosomal gene microstructure of the patient and her parents. The exomes of the patient and her parents were sequenced using trio-based whole exome sequencing (trio-WES) technology. The candidate variant was verified by Sanger sequencing. The pathogenicity of the variant was predicted with a variety of bioinformatics tools. RESULTS: Chromosome analysis of the proband revealed 46, XX, and no abnormality was found by CNV-seq. After sequencing and bioinformatics filtering, the variant of RRAS2(c.67G>T; p. Gly23Cys) was found in the proband, while the mutation was absent in her parents. To the best of our knowledge, our patient was with the typical Noonan syndrome, such as short stature, facial dysmorphism, and developmental delay. Furthermore, our study is the first case of NS with embryonal rhabdomyosarcoma (ERMS) caused by the RRAS2 gene mutation reported in China. CONCLUSIONS: Our investigations suggested that the heterozygous missense of RRAS2 may be a potential causal variant in a rare cause of Noonan syndrome, expanding our understanding of the causally relevant mutations for this disorder.

Role of OsbHLH156-OsIRO2 transcription factor complex in regulating manganese, copper and zinc transporters in rice.

Iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn) are essential micronutrients that are necessary for plant growth and development, but can be toxic at supra-optimal levels. Plants have evolved a complex homeostasis network that includes uptake, transport, and storage of these metals. It was shown that the transcription factor (TF) complex OsbHLH156/OsIRO2 is activated under Fe deficient condition and acts as the central regulators on Strategy II Fe acquisition. In this study, the role of the TF complex on Mn, Cu and Zn uptake was evaluated. While Fe deficiency led to significant increases in shoot Mn, Cu and Zn concentrations, the increases of these divalent metal concentrations were significantly suppressed in osbhlh156 and osiro2 mutants, suggesting that the TF complex plays roles on Mn, Cu and Zn uptake and transport. RNA-sequencing assay showed that the genes associated with Mn, Cu, and Zn uptake and transport were significantly suppressed in the osbhlh156 and osiro2 mutants. Transcriptional activation assays demonstrated that the TF complex could directly bind to the promoters of OsIRT1, OsYSL15, OsNRAMP6, OsHMA2, OsCOPT1/7 and OsZIP5/9/10 and activate their expression. In addition, the TF complex is required to activate the expression of nicotianamine (NA) and 2'deoxymugineic acid (DMA) synthesis genes, which in turn facilitate the uptake and transport of Mn, Cu and Zn. Furthermore, OsbHLH156 and OsIRO2 promote Cu accumulation to partially restore the Fe-deficiency symptom. Taken together, the OsbHLH156 and OsIRO2 TF function as core regulators not only in Fe homeostasis, but also in Mn, Cu and Zn accumulation.

Klebsiella pneumoniae carbapenemase variant 44 (KPC-44) acquires ceftazidime-avibactam resistance by altering the conformation of active site loops.

Klebsiella pneumoniae carbapenemase 2 (KPC-2) is an important source of drug resistance as it can hydrolyze and inactivate virtually all ß-lactam antibiotics. KPC-2 is potently inhibited by avibactam via formation of a reversible carbamyl linkage of the inhibitor with the catalytic serine of the enzyme. However, the use of avibactam in combination with ceftazidime (CAZ-AVI) has led to the emergence of CAZ-AVI resistant variants of KPC-2 in clinical settings. One such variant, KPC-44, bears a 15 amino-acid duplication in one of the active site loops (270-loop). Here, we show that the KPC-44 variant exhibits higher catalytic efficiency in hydrolyzing ceftazidime, lower efficiency towards imipenem and meropenem, and a similar efficiency in hydrolyzing ampicillin, when compared to the wild-type KPC-2 enzyme. In addition, the KPC-44 variant enzyme exhibits 12-fold lower avibactam carbamylation efficiency than the KPC-2 enzyme. An X-ray crystal structure of KPC-44 showed that the 15 amino acid duplication results in an extended and partially disordered 270-loop and also changes the conformation of the adjacent 240-loop, which in turn has altered interactions with the active-site omega loop. Furthermore, a structure of KPC-44 with avibactam revealed that formation of the covalent complex results in further disorder in the 270-loop, suggesting that rearrangement of the 270-loop of KPC-44 facilitates avibactam carbamylation. These results suggest that the duplication of 15 amino acids in the KPC-44 enzyme leads to resistance to CAZ-AVI by modulating the stability and conformation of the 270-, 240-, and omega-loops.