ABSTRACT
Strigolactones (SLs) constitute essential phytohormones that control pathogen defense, resilience to phosphate deficiency and abiotic stresses. Furthermore, SLs are released into the soil by roots, especially in conditions in which there is inadequate phosphate or nitrogen available. SLs have the aptitude to stimulate the root parasite plants and symbiotic cooperation with arbuscular mycorrhizal (AM) fungi in rhizosphere. The use of mineral resources, especially phosphorus (P), by host plants is accelerated by AMF, which also improves plant growth and resilience to a series of biotic and abiotic stresses. Thus, these SL treatments that promote rhizobial symbiosis are substitutes for artificial fertilizers and other chemicals, supporting ecologically friendly farming practices. Moreover, SLs have become a fascinating target for abiotic stress adaptation in plants, with an array of uses in sustainable agriculture. In this review, the biological activity has been summarized that SLs as a signaling hormone for AMF symbiosis, nutrient acquisition, and abiotic stress tolerance through interaction with other hormones. Furthermore, the processes behind the alterations in the microbial population caused by SL are clarified, emphasizing the interplay with other signaling mechanisms. This review covers the latest developments in SL studies as well as the properties of SLs on microbial populations, plant hormone transductions, interactions and abiotic stress tolerance.
ABSTRACT
INTRODUCTION: Bentazon (BNTZ) is a selective contact herbicide widely used to control field weeds for crop production. Excessive use of BNTZ leads to its accumulation in soils and crops, becoming an environmental contaminant. Therefore, investigation of the mechanisms for BNTZ detoxification and degradation in crops is fundamentally important to reduce crop contamination and ensure food safety. OBJECTIVES: This study aims to elucidate the mechanism of detoxification and degradation pathways of the BNTZ complex in rice by creating transgenic lines expressing a rice ATP-binding cassette (OsABC) transporter gene through genetic engineering techniques combined with chemical analytical techniques and metabolomics approaches. METHODS: We established the rice transgenic lines overexpressing (OE) a rice OsABC transporter and its knockout lines by CRISPR-Cas9 to characterize the gene function and measured the accumulation of BNTZ residues in rice. The metabolites of BNTZ were characterized by LC/Q-TOF-HRMS/MS (Liquid chromatography/time of flight-high resolution mass spectrometry). RESULTS: Overexpression of OsABC significantly conferred rice resistance to BNTZ toxicity by increasing plant elongation, dry weight, and chlorophyll content, and significantly reducing cell membrane damage and BNTZ accumulation in rice tissues. Six different metabolites and ten conjugates were well defined in chemical structures. The reduced BNTZ levels and degradation products in the grains of the OE lines supported the robust activity of the OsABC gene function. Using UPLC-Q-TOF/MS, we further identified accumulated basic metabolites of various carbohydrates, amino acids, hormones, and flavonoids, and found that these metabolites involved in BNTZ degradation were increased more in OE lines than in wild-type (WT) rice. CONCLUSIONS: Our work demonstrates that the OsABC transporter plays a critical role in regulating the mobility and degradative metabolism of BNTZ in rice, thus revealing a regulatory mechanism underlying rice resistance to BNTZ toxicity and adaptation to the environmental stress.
ABSTRACT
Copper serves as an indispensable cofactor for all living organisms, and its excessive accumulation has been associated with a variety of diseases. Wilson's disease (WD) serves as an illustrative example of copper toxicity in humans, frequently presenting with liver and/or neuropsychiatric symptoms. The current therapeutic drugs, penicillamine (PA) and zinc gluconate (ZnG), have constraints, and research on their combination efficacy remains insufficient. It has been reported that melatonin (MLT) plays a vital role in binding to transition metals and exhibits strong antioxidant capacity. To investigate the therapeutic efficacy of MLT and combined treatment, rats were randomly divided into the following seven groups: the control (Con) group, copper-laden model rat (Mod) group, PA-treated group, ZnG-treated group, MLT- treated group, PA-ZnG-treated group, and PA-MLT-treated group. Then potential mechanisms and targets were investigated using a combination of metabolomics and network pharmacology and verified by molecular docking and qPCR. The findings revealed that MLT and the combination significantly improved behavior, pathology and copper levels in copper-laden rats. The results of the metabolomics study showed that profoundly altered metabolites were identified, and alanine, aspartate and glutamate metabolism, pyruvate metabolism, citrate cycle (TCA cycle), and glycolysis/gluconeogenesis were explored. In addition, molecular docking showed that MLT had high binding affinity with key targets, and qPCR results revealed that MLT could reverse the mRNA expression of targets GOT2 and PKM2. It was concluded that MLT effectively improves brain injury in copper-laden rats, and this effect was linked with the altered features of the metabolite profiles.
ABSTRACT
Background: Conflicting evidence exists on the predictive value of ultrasound characteristics for BRAFV600E gene expression in thyroid cancer. This study aimed to determine the predictive value of ultrasound features for BRAFV600E gene expression status in thyroid cancer. Methods: A systematic review of studies published before December 31, 2023, was conducted in the PubMed, Web of Science, and Cochrane Library databases. Studies evaluating the ultrasonographic features for predicting BRAFV600E gene mutations in thyroid cancer were included. The relevant data were extracted, and the quality of eligible studies was independently assessed by two reviewers. Statistical analysis was performed using RevMan 5.4 and Stata 12.0 software. Results: The meta-analysis included 13 studies involving a total of 2,250 thyroid cancer patients. Ultrasound features significantly associated with BRAFV600E gene expression status in thyroid cancer (P<0.05) comprised hypoechogenicity, absence of halo, irregular borders, and vertical orientation. Contrastingly, no significant differences were observed in solid composition, irregular shape, and microcalcifications (P>0.05). Among the seven ultrasound features, the ones with superior combined sensitivity for nodules were hypoechogenicity, solid composition, absence of halo, and irregular borders, with sensitivities of 0.93 [95% confidence interval (CI): 0.87-0.96], 0.93 (95% CI: 0.86-0.97), 0.83 (95% CI: 0.72-0.91), and 0.74 (95% CI: 0.64-0.83), respectively. Finally, the areas under the summary receiver operating characteristic (SROC) curve with the highest diagnostic performance were the absence of halo and hypoechogenicity, with area under the curve (AUC) of 0.84 (95% CI: 0.80-0.87) and 0.81 (95% CI: 0.77-0.84), respectively. Conclusions: The expression status of the BRAFV600E gene in thyroid cancer correlates with nodules exhibiting hypoechogenicity, absence of halo, irregular borders, and taller-than-wide shape. Notably, the absence of a halo and hypoechogenicity were identified as the most predictive ultrasonic features. However, due to the limited sample size, there may be bias in the meta-analysis results, and more extensive research is necessary.
ABSTRACT
This review explores the intricate roles of metal ions-iron, copper, zinc, and selenium-in glioma pathogenesis and immune evasion. Dysregulated metal ion metabolism significantly contributes to glioma progression by inducing oxidative stress, promoting angiogenesis, and modulating immune cell functions. Iron accumulation enhances oxidative DNA damage, copper activates hypoxia-inducible factors to stimulate angiogenesis, zinc influences cell proliferation and apoptosis, and selenium modulates the tumor microenvironment through its antioxidant properties. These metal ions also facilitate immune escape by upregulating immune checkpoints and secreting immunosuppressive cytokines. Targeting metal ion pathways with therapeutic strategies such as chelating agents and metalloproteinase inhibitors, particularly in combination with conventional treatments like chemotherapy and immunotherapy, shows promise in improving treatment efficacy and overcoming resistance. Future research should leverage advanced bioinformatics and integrative methodologies to deepen the understanding of metal ion-immune interactions, ultimately identifying novel biomarkers and therapeutic targets to enhance glioma management and patient outcomes.
ABSTRACT
Alleviating water scarcity is at the core of Sustainable Development Goal 6. Yet the timing of water scarcity in its onset and possible relief in different regions of the world due to climate change and changing human population dynamics remains poorly investigated. Here we assess the timing of the first emergence of water scarcity (FirstWS) and disappearance of water scarcity (EndWS), by using ensembles of simulations with six Global Hydrological Models under two representative concentration pathways (i.e., RCP2.6, RCP6.0) combined with two shared socioeconomic pathways (i.e., SSP2, SSP3) for 1901-2090. Historically (1901-2020), FirstWS occurred predominantly in Asia (e.g., China and India) and Africa (e.g., East Africa); the peak time of emerging water scarcity began around the 1980s. Under all the four future RCPs-SSPs scenarios (2021-2090), FirstWS will likely occur mainly in some regions of Africa, for which the newly added area is double that in Asia. On the other hand, EndWS will mostly occur in China after 2050, primarily due to the projected declining population. We, therefore, call for specific attention and effort to adapt to the looming water scarcity in Africa.
ABSTRACT
Background: Traditional Chinese Medicine (TCM) offers individualized treatment for Polycystic Ovary Syndrome (PCOS) through pattern differentiation, but the subjectivity of TCM diagnoses can lead to inconsistent outcomes. Integrating machine learning (ML) offers an objective basis to support TCM diagnoses. This study aims to evaluate various feature selection techniques and multi-label ML algorithms to develop an effective predictive model for classifying TCM patterns in PCOS patients, thereby enhancing diagnostic standardization and treatment personalization. Methods: The study utilized a dataset comprising 432 patients with PCOS, exhibiting one or more of five TCM patterns. Feature selection began with Variance Thresholding (VT), followed by a comparison of five advanced techniques: Statistical Analysis Test, Recursive Feature Elimination with Cross-Validation (RFECV), Least Absolute Shrinkage and Selection Operator Regression, BorutaShap, and ReliefF. To ascertain the most effective model for predicting PCOS TCM patterns, four ML algorithms-Support Vector Machine, Logistic Regression, Extreme Gradient Boosting (XGBoost), and Artificial Neural Networks-were evaluated against the identified feature set. Results: VT reduced the feature count from 224 to 174. RFECV emerged as the most effective feature selection method, identifying 67 key features. XGBoost emerged as the top-performing model, demonstrating superior testing accuracy (0.7870), F1 score (0.9519), and Hamming loss (0.0481) with RFECV-optimized features. Conclusions: The RFECV-XGBoost model proved effective for classifying TCM patterns in PCOS. It emphasizes the necessity of precise feature selection and the significant capabilities of ML in advancing TCM pattern diagnostics, marking a significant step toward enhancing precise and personalized healthcare in biomedical studies.
ABSTRACT
High-order harmonic generation (HHG) in condensed matter is highly important for potential applications in various fields, such as materials characterization, all-optical switches, and coherent light source generation. Linking HHG to the properties or dynamic processes of materials is essential for realizing these applications. Here, a bridge has been built between HHG and the transient properties of materials through the engineering of interband polarization in a photoexcited three-dimensional Dirac semimetal (3D-DSM). It has been found that HHG can be efficiently manipulated by the electronic relaxation dynamics of 3D-DSM on an ultrafast time scale of several hundred femtoseconds. Furthermore, time-resolved HHG (tr-HHG) has been demonstrated to be a powerful spectroscopy method for tracking electron relaxation dynamics, enabling the identification of electron thermalization and electron-phonon coupling processes and the quantitative extraction of electron-phonon coupling strength. This demonstration provides insights into the active control of HHG and measurements of the electron dynamics.
ABSTRACT
[This corrects the article DOI: 10.1515/tnsci-2022-0334.].
ABSTRACT
Purpose: This study sought to develop an unbalanced-ensemble model that could accurately predict death outcomes of patients with comorbid coronary heart disease (CHD) and hypertension and evaluate the factors contributing to death. Patients and Methods: Medical records of 1058 patients with coronary heart disease combined with hypertension and excluding those acute coronary syndrome were collected. Patients were followed-up at the first, third, sixth, and twelfth months after discharge to record death events. Follow-up ended two years after discharge. Patients were divided into survival and nonsurvival groups. According to medical records, gender, smoking, drinking, COPD, cerebral stroke, diabetes, hyperhomocysteinemia, heart failure and renal insufficiency of the two groups were sorted and compared and other influencing factors of the two groups, feature selection was carried out to construct models. Owing to data unbalance, we developed four unbalanced-ensemble prediction models based on Balanced Random Forest (BRF), EasyEnsemble, RUSBoost, SMOTEBoost and the two base classification algorithms based on AdaBoost and Logistic. Each model was optimised using hyperparameters based on GridSearchCV and evaluated using area under the curve (AUC), sensitivity, recall, Brier score, and geometric mean (G-mean). Additionally, to understand the influence of variables on model performance, we constructed a SHapley Additive explanation (SHAP) model based on the optimal model. Results: There were significant differences in age, heart rate, COPD, cerebral stroke, heart failure and renal insufficiency in the nonsurvival group compared with the survival group. Among all models, BRF yielded the highest AUC (0.810; 95% CI, 0.778-0.839), sensitivity (0.990; 95% CI, 0.981-1.000), recall (0.990; 95% CI, 0.981-1.000), and G-mean (0.806; 95% CI, 0.778-0.827), and the lowest Brier score (0.181; 95% CI, 0.178-0.185). Therefore, we identified BRF as the optimal model. Furthermore, red blood cell count (RBC), body mass index (BMI), and lactate dehydrogenase were found to be important mortality-associated risk factors. Conclusion: BRF combined with advanced machine learning methods and SHAP is highly effective and accurately predicts mortality in patients with CHD comorbid with hypertension. This model has the potential to assist clinicians in modifying treatment strategies to improve patient outcomes.
ABSTRACT
Cardenolides are a class of steroidal glycoside compounds that are mainly distributed in plants, have significant physiological activity in the heart, and have been used clinically for over 200 years. To provide a reference for further research and development of these compounds, the phytochemical and biological properties of natural cardenolides (295 compounds in total) isolated between 2010 and 2023 from 17 families and hundreds of species belonging to 70-80 genera were reviewed. In vitro and in vivo studies have indicated that antitumor, antibacterial, and antiviral activities are the most commonly reported pharmacological properties of cardenolides. Antitumor activities have been thoroughly studied to understand their structure-activity relationships, revealing numerous potential anticancer molecules that lay the theoretical foundation for further development of traditional Chinese medicinal herbs and the creation of new drugs.
ABSTRACT
Retinal vascular leakage is a major event in several retinal diseases, including diabetic retinopathy (DR). In a previous study, we demonstrated that the aqueous humor concentration of Cystatin C (CST3), a physiological inhibitor of cysteine protease, is negatively correlated with the severity of diabetic macular edema. However, its function in the retina has not been clearly elucidated. In this study, we found a significant decrease in the aqueous humor concentration of CST3 with DR progression. Furthermore, we found that CST3 was expressed in retinal endothelial cells and that its expression was significantly downregulated in high glucose-treated human retinal microvascular endothelial cells (HRMECs) and the retinal vessels of oxygen-induced retinopathy (OIR) mice. Silencing CST3 expression resulted in decreased HRMEC migration and tubule formation ability. Exogenous addition of the CST3 protein significantly improved HRMEC migration and tubular formation. In-vivo experiments demonstrated that CST3 silencing induced retinal vascular leakage in WT mice, while its intravitreal injection significantly reduced retinal leakage in OIR mice. Mechanistically, CST3 promoted the expression of the downstream adhesion molecules, claudin5, VE-cadherin, and ZO-1, in retinal vascular cells by regulating the Rap1 signaling pathway. Therefore, this study revealed a novel mechanism by which CST3 improves retinal vascular function and provided evidence that it is a potential therapeutic target for retinal vascular leakage.
ABSTRACT
OBJECTIVE: To evaluate the clinical efficacy of internal limiting membrane (ILM) peeling combined with perimacular hole massage versus ILM flap insertion in the management of patients with idiopathic macular holes was conducted. METHODS: 35 patients (total of 35 eyes) with idiopathic macular holes (with hole diameters ranging from 366 to 1430 µm) were divided into two groups-Group A consisted of 20 eyes that underwent pars plana vitrectomy (PPV) combined with ILM peeling and perimacular hole massage, while Group B comprised 15 eyes that underwent PPV combined with ILM flap insertion. Subsequent follow-up examinations were performed at 1 week, 1 month, and 3 months post-surgery. The study also involved a comparison of best corrected visual acuity (BCVA) and optical coherence tomography (OCT) classifications between both the patient groups. RESULTS: The macular hole closure rates in Group A were 60%, while in Group B, the closure rate was 93%. There was significant difference in hiatus healing rate between the two groups (tâ¯=â¯4.843, pâ¯=â¯0.048). The difference in BCVA at 3 months post-operation between the two groups was statistically significant (tâ¯=â¯3.221, pâ¯=â¯0.003). Three months post-operatively, the BCVA in Group B demonstrated improvement compared to the pre-operative BCVA, with a statistically significant difference (p > 0.05). Three months post-operatively, the BCVA in Group A demonstrated improvement compared to the pre-operative BCVA, but this difference was not statistically significant (p > 0.05). CONCLUSION: The combination of PPV with ILM flap insertion demonstrates favorable therapeutic efficacy in the treatment of idiopathic macular holes, leading to improved visual acuity.
ABSTRACT
Probiotic Bacillus pumilus SE5, heat-inactivated (HSE5) or active (ASE5), were supplemented to high soybean meal (HSM) (36 %) diet at whole term (0-56 days) and middle term (29-56 days) to investigate the preventing and repairing effects of B. pumilus SE5 in ameliorating the adverse effects of HSM in Epinephelus coioides. The results suggested that the HSM significantly decreased the weight gain rate (WGR), specific growth rate (SGR), and increased the feed conversion rate (FCR) at day 56 (P < 0.05), while HSE5 and ASE5 promoted the growth performance. The HSE5 and ASE5 showed preventive and reparative functions on the antioxidant capacity and serum immunity, with significantly increased the total antioxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GSH-PX) activities, and reduced malondialdehyde (MDA) level, and increased acid phosphatase (ACP), alkaline phosphatase (AKP), immunoglobulin M (IgM) and complement 3 (C3). The HSM impaired the intestinal health (destroyed the intestinal structure, significantly increased the contents of serum D-lactic acid and diamine oxidase, and reduced the expressions of claudin-3 and occludin), while HSE5 and ASE5 improved them at whole term and middle term. The HSM impaired the intestinal microbiota and reduced its diversity, and the HSE5 or ASE5 improved the intestinal microbiota (especially at whole term). HSE5 and ASE5 improved the intestinal mRNA expressions of anti-inflammatory genes (il-10 and tgf-ß1) and reduced the expressions of pro-inflammatory genes (il-1ß, il-8, il-12), and promoted the expressions of humoral immune factor-related genes (cd4, igm, mhcII-α) and antimicrobial peptide genes (ß-defensin, epinecidin-1 and hepcidin-1), and decreased the expressions of NF-κB/MAPK signaling pathway-related genes (ikk-α, nf-κb, erk-1), and improved the expressions of MAPK signaling pathway-related gene p38-α (P < 0.05). In conclusion, the heat-inactivated and active B. pumilus SE5 effectively prevented and repaired the suppressive effects of soybean meal in E. coioides, which underscored the potential of B. pumilus SE5 as a nutritional intervention agent in HSM diet in aquaculture.
ABSTRACT
The aim of this study was to investigate the impact and underlying molecular mechanisms of electroacupuncture on mice with poststroke depression (PSD). Mice were randomly allocated into sham, PSD, and electroacupuncture groups. Mice in the PSD and electroacupuncture groups underwent middle cerebral artery occlusion (MCAO) surgery following with sedentary behavior. Electroacupuncture targeting Zusanli (ST36) acupoint was performed 24â h after MCAO for 4â weeks in electroacupuncture group. The sucrose preference test, forced swimming test, open field test, tail suspension test, elevated plus maze, Catwalk analysis, RNA sequencing, Nissl staining, Golgi staining, TUNEL staining, Edu labeling, and doublecortin staining were performed. Lymphocyte subsets in peripheral blood and the levels of IL-1ß, IL-6, TNF-α, and expression of Iba1/CD86, Iba1/NLRP3, TLR4/p38/NF-κB/NLRP3 pathways in the hippocampus were detected. Electroacupuncture effectively protected against the development of depression-like symptoms. The number of granulosa cells and doublecortin-positive cells in the dentate gyrus (DG) were significantly decreased in PSD group, which were significantly upregulated (Pâ <â 0.01) by electroacupuncture. Electroacupuncture also significantly reduced (Pâ <â 0.05) TUNEL-positive cells in the DG and CA1. RNA-seq revealed that electroacupuncture may exert antidepressant effect by regulating the inflammation mediated by TLR4/NF-κB/NLRP3 pathway in hippocampus. Electroacupuncture remarkably elevated (Pâ <â 0.01) the ratio of CD4+ to CD8+ T cells and percentage of CD3-CD49b+ cells in CD45+CD49b+ cells in the peripheral blood. Electroacupuncture significantly reduced (Pâ <â 0.05) the high levels of IL-1ß, IL-6, TNF-α, iba1, TLR4, p-p38, p-NF-κB, and NLRP3 and sedentary behavior. Electroacupuncture was observed to mitigate depression symptoms and increase hippocampal neurogenesis in mice with PSD, possibly by inhibiting TLR4/p38/NF-κB/NLRP3 pathways and improving the microglia-mediated inflammatory microenvironment in the hippocampus.
ABSTRACT
Single-atom catalysts (SACs) have attracted considerable research interest owing to their combined merits of homogeneous and heterogeneous catalysts. However, the uniform and isolated active sites of SACs fall short in catalysing complex chemical processes that simultaneously involve multiple intermediates. In this Review, we highlight an emerging class of catalysts with adjacent binary active centres, which is called integrative catalytic pairs (ICPs), showing not only atomic-scale site-to-site electronic interactions but also synergistic catalytic effects. Compared with SACs or their derivative dual-atom catalysts (DACs), multi-interactive intermediates on ICPs can overcome kinetic barriers, adjust reaction pathways and break the universal linear scaling relations as the smallest active units. Starting from this active-site design principle, each single active atom can be considered as a brick to further build integrative catalytic clusters (ICCs) with desirable configurations, towards trimer or even larger multi-atom units depending on the requirement of a given reaction.
ABSTRACT
Mycoplasma synoviae (MS) infection is a serious threat to poultry industry in China. Tilmicosin is a semisynthetic macrolide antibiotic used only in animals and has shown potential efficacy against MS, but there were no reported articles concerning the pharmacokinetics/pharmacodynamics (PK/PD) interactions of tilmicosin against MS in vitro and vivo. This study aimed to assess the antibacterial activity of tilmicosin against MS in vitro and in vivo using PK/PD model to provide maximal efficacy. The minimum inhibitory concentration (MIC) and killing rates of different drug concentrations were measured using the microdilution method in vitro. Then, tilmicosin was administered orally to the MS-infected chickens at doses of 7.5 and 60 mg/kg, and the PK parameters of tilmicosin in joint dialysates were determined using high-pressure liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) combined with the microdialysis technique. The antibacterial effect (â³E) was calculated when the infected chickens were administered a single oral dose of tilmicosin at 4, 7.5, 15, 30, and 60 mg/kg b.w. The PK and PD data were fitted using the Sigmoid Emax model to evaluate the PK/PD interactions of tilmicosin against MS. The bactericidal activity of tilmicosin against MS was concentration dependent. Furthermore, the PK/PD index of AUC0-72h/MIC exhibited the most optimal fitting results (R2 = .98). The MS load decreased by 1, 2, and 3 Log10 CFU/mL, then AUC/MIC was determined as 13.99, 20.53, and 28.23 h, respectively, and the bactericidal effect can be achieved when the dose of MS-infected chickens is at 31.64 mg/kg b.w. The findings of this study hold significant implications for optimizing the treatment regimen for MS infection.
ABSTRACT
Anisopteromalus calandrae (Howard) shows great promise as an ectoparasitoid for controlling various coleopteran pests in warehouses. However, for a large-scale release, it is crucial to establish an ample supply of A. calandrae while carefully maintaining their quality and effectiveness. Appropriate cold storage techniques are the key to achieving these goals. Previous studies on cold storage have focused on specific developmental stages and explored cold storage conditions that can be applied only to those stages. Herein, we examined the development, survival and reproductive capacity of A. calandrae at different temperatures (13, 16, and 19 °C) and storage durations (30, 60, and 90 d) and evaluated the fitness of the offspring. A. calandrae completed its egg-to-larva development and pupated at 16 °C, but its development was arrested at an early pupal stage. Even after 90 d of cold storage at 16 °C, the survival rate of A. calandrae remained high at 77%, with no significant impact on reproductive capacity. Furthermore, cold storage showed no negative effect on the F1 generation. In contrast, eggs stored at 13 °C failed to hatch, whereas those stored at 19 °C developed. Adults emerged after > 60 d. This indicates that storage at 19 °C is only suitable for short durations. Our findings highlight the developmental pattern of A. calandrae at 16 °C, indicating that the parasitic wasp can be stored for a long time at this temperature across all stages of development before pupation, substantially facilitating its mass reproduction and industrial production.
ABSTRACT
Bacteria in the genus Chlamydia are a significant health burden worldwide. They infect a wide range of vertebrate animals, including humans and domesticated animals. In humans, C. psittaci can cause zoonotic pneumonia, while C. pneumoniae causes a variety of respiratory infections. Infections with C. trachomatis cause ocular or genital infections. All chlamydial species are obligate intracellular bacteria that replicate exclusively inside of eukaryotic host cells. Chlamydial infections are dependent on a complex infection cycle that depends on transitions between specific cell forms. This cycle consists of cell forms specialized for host cell invasion, the elementary body (EB), and a form specialized for intracellular replication, the reticulate body (RB). In addition to the EB and RB, there is a transitionary cell form that mediates the transformation between the RB and the EB, the intermediate body (IB). In this study, we ectopically expressed the regulatory protein Euo and showed that high levels of expression resulted in reversible arrest of the development cycle. The arrested chlamydial cells were trapped phenotypically at an early IB stage of the cycle. These cells had exited the cell cycle but had not shifted gene expression from RB like to IB/EB like. This arrested state was dependent on continued expression of Euo. When ectopic expression was reversed, Euo levels dropped in the arrested cells which led to the repression of native Euo expression and the resumption of the developmental cycle. Our data are consistent with a model where Euo expression levels impact IB maturation to the infectious EB but not the production of the IB form. IMPORTANCE: Bacterial species in the Chlamydiales order infect a variety of vertebrate animals and are a global health concern. They cause various diseases in humans, including genital and respiratory infections. The bacteria are obligate intracellular parasites that rely on a complex infectious cycle involving multiple cell forms. All species share the same life cycle, transitioning through different states to form the infectious elementary body (EB) to spread infections to new hosts. The Euo gene, encoding a DNA-binding protein, is involved in regulating this cycle. This study showed that ectopic expression of Euo halted the cycle at an early stage. This arrest depended on continued Euo expression. When Euo expression was reversed, the developmental cycle resumed. Additionally, this study suggests that high levels of Euo expression affect the formation of the infectious EB but not the production of the cell form committed to EB formation.