Glandular papilloma in lung parenchyma.

Solitary respiratory papilloma is a rare epithelial tumour that can be categorized into multiple subtypes. The glandular type (Glandular papilloma, GP) is the rarest. Most GP occurs in the proximal airways and is only rarely found in the lung parenchyma. In this article, we reported a case of GP in lung parenchyma.

Intelligent Rapid Detection Techniques for Low-Content Components in Fruits and Vegetables: A Comprehensive Review.

Fruits and vegetables are an important part of our daily diet and contain low-content components that are crucial for our health. Detecting these components accurately is of paramount significance. However, traditional detection methods face challenges such as complex sample processing, slow detection speed, and the need for highly skilled operators. These limitations fail to meet the growing demand for intelligent and rapid detection of low-content components in fruits and vegetables. In recent years, significant progress has been made in intelligent rapid detection technology, particularly in detecting high-content components in fruits and vegetables. However, the accurate detection of low-content components remains a challenge and has gained considerable attention in current research. This review paper aims to explore and analyze several intelligent rapid detection techniques that have been extensively studied for this purpose. These techniques include near-infrared spectroscopy, Raman spectroscopy, laser-induced breakdown spectroscopy, and terahertz spectroscopy, among others. This paper provides detailed reports and analyses of the application of these methods in detecting low-content components. Furthermore, it offers a prospective exploration of their future development in this field. The goal is to contribute to the enhancement and widespread adoption of technology for detecting low-content components in fruits and vegetables. It is expected that this review will serve as a valuable reference for researchers and practitioners in this area.

Enabling efficient ample-level oxygen evolution on nickel-iron Prussian blue analogue/hydroxide via hierarchical mass transfer channel construction.

Enhancing double-phase mass transfer capability and reducing overpotential at high currents are critical in the oxygen evolution reaction (OER) catalyst design. In this work, nickel-iron layered double hydroxide (NiFe-LDH) loaded on nickel foam (NF) was used as a self-sacrificing template for subsequent growth of nickel-iron Prussian blue (NiFe-PBA) hollow nanocubes on its sheet arrays. The triple-scale porous structure is therefore in-situ constructed in the produced NiFe-PBA@LDH/NF catalyst, where NiFe-PBA nanocubes, NiFe-LDH sheets and NF skeletons provide pores at hundred-nanometers, microns and hundred-microns, respectively. Due to the successful construction of hierarchical mass transfer channels in the catalyst, the overpotential required to deliver 1000 mA cm-2 OER is only 396 mV, which is 80 mV lower than that of NiFe-LDH/NF with a double-scale porous structure, manifesting the importance of the appropriate mass transfer channels, promoting the potential application of the NiFe-PBA@LDH/NF catalyst in industrial-scale electrolysers.

Computed tomography manifestations of a case of varicella zoster virus (VZV) pneumonia.

Disseminated VZV infections is rare in healthy adults. Several studies have reported VZV reactivation and eruption happens in an immunocompromised host especially after solid organ transplantation. Nonetheless, diffuse bilateral lung VZV infections is also rare. We report a case of disseminated VZV pneumonia after renal transplantation and methylprednisolone treatment. This report highlights the computed tomography manifestations of disseminated VZV pneumonia.

A case of tuberculous pleurisy characterized by bleeding and necrosis documented by medical thoracoscope.

Tuberculous pleurisy is a main cause of pleural effusions. The main histological abnormalities in pleural biopsy of tuberculous pleurisy are caseating granulomas and epithelioid cell granuloma. In our case, chronic inflammation of fibrous tissue with bleeding, necrosis, and exudation were observed during a medical thoracoscopy as manifestations of tuberculous pleurisy.

Enhancing Nix-dependent mitophagy relieves AKI by restricting TREM-1-mediated hyperactivation of inflammasome in platelets.

Platelets are highly involved in inflammation and organ injury under pathological conditions. The mitophagy in platelets may restrict hyperactivation of the inflammasome and relieve acute kidney injury (AKI). Cecal ligation puncture (CLP)/LPS-induced AKI Triggering receptor expressed on myeloid cells (TREM-1)-knockout mice models were established. Additionally, septic patients with AKI were also included. TREM-1 expression in platelets and inflammasome activation were examined. Platelet transfer assays were performed to investigate the contribution of platelet TREM-1 to renal injury. Mitophagy was evaluated in the context of inflammation. BNIP3L/Nix knockout mice were used to examine the relationship between platelet mitophagy and inflammatory activation. The results showed that the level of TREM-1 was increased and the platelet inflammasome was hyperactivated in CLP mice and septic patients, and TREM-1 activated platelet inflammasomes. TREM-1 deletion significantly abrogated hyperactivation of the platelet inflammasome and dramatically reduced AKI, whereas ablation of the mitophagy receptor BNIP3L/Nix induced the accumulation of damaged mitochondria and hyperactivation of platelet inflammasomes in CLP mice. BNIP3L/Nix controlled platelet inflammasome activation, and an amplification loop of platelet inflammasome activation and dysfunctional mitochondria controlled sepsis-related AKI. Therefore, targeting TREM-1 and NLRP3/BNIP3L in platelets may represent a novel therapeutic strategy for treating septic AKI.

Risk-dependent conditional survival analysis and annual hazard rate of inflammatory breast cancer.

PURPOSE: The real-time prognosis of patients with inflammatory breast cancer (IBC) after surviving for several years was unclear. We aimed to estimate survival over time in IBC using conditional survival (CS) and annual hazard functions. PATIENTS AND METHODS: This study recruited 679 patients diagnosed with IBC between 2010 and 2019 from the Surveillance, Epidemiology, and End Results (SEER) database. We used the Kaplan-Meier method to estimate overall survival (OS). CS was the probability of surviving for another y years after surviving for x years after the diagnosis, and the annual hazard rate was the cumulative mortality rate of follow-up patients. Cox regression analyses were used to identify prognostic factors, and changes in real-time survival and immediate mortality in surviving patients were assessed within these prognostic factors. RESULTS: CS analysis showed real-time improvement in survival, with 5-year OS updated annually from the initial 43.5% to 52.2%, 65.3%, 78.5%, and 89.0% (surviving 1-4 years, respectively). However, this improvement was relatively small in the first two years after diagnosis, and the smoothed annual hazard rate curve showed increasing mortality during this period. Cox regression identified seven unfavorable factors at diagnosis, but only distant metastases remained after five years of survival. Analysis of the annual hazard rate curves showed that mortality continued to decrease for most survivors, except for metastatic IBC. CONCLUSION: Real-time survival of IBC improved dynamically over time, and the magnitude of this improvement was non-linear, depending on survival time and clinicopathological characteristics.

PET/d-PET (PdP) Pairing for the Design of Dual-Channel Probes.

Design principles of two-channel fluorescence probes are limited. Herein, we report a new principle, i.e., PET/d-PET (PdP) pairing, for the rational design of two-channel probes. Two fluorophores are required in such a PdP-type probe. They mutually quench their fluorescence via PET and d-PET. In the presence of an analyte-of-interest, such a PdP pair is converted into a FRET pair for signaling. The embodiment of such a principle is Rh-TROX, by tethering a rhodamine fluorophore with an ROS-sensitive probe (TotalROX). Fluorescence of both fluorophores in Rh-TROX was quenched as expected. The addition of highly reactive oxidative species led to the recovery of the fluorescence properties of both. The simultaneous fluorescence enhancement in two channels is a viable way to avoid false-positive signals. The new PdP principle could potentially be applied to the development of probes for another range of substrates.

A method for analyzing programmed cell death in xylem development by flow cytometry.

Programmed cell death (PCD) is a genetically regulated developmental process leading to the death of specific types of plant cells, which plays important roles in plant development and growth such as wood formation. However, an efficient method needs to be established to study PCD in woody plants. Flow cytometry is widely utilized to evaluate apoptosis in mammalian cells, while it is rarely used to detect PCD in plants, especially in woody plants. Here, we reported that the xylem cell protoplasts from poplar stem were stained with a combination of fluorescein annexin V-FITC and propidium iodide (PI) and then sorted by flow cytometry. As expected, living cells (annexin V-FITC negative/PI negative), early PCD cells (annexin V-FITC positive/PI negative), and late PCD cells (annexin V-FITC positive/PI positive) could be finely distinguished through this method and then subjected for quantitative analysis. The expression of cell-type- and developmental stages-specific marker genes was consistent with the cell morphological observation. Therefore, the newly developed fluorescence-activated cell sorting (FACS) method can be used to study PCD in woody plants, which will be beneficial for studying the molecular mechanisms of wood formation.

A novel conditional survival nomogram for monitoring real-time prognosis of non-metastatic triple-negative breast cancer.

Background: Conditional survival (CS) is defined as the possibility of further survival after patients have survived for several years since diagnosis. This may be highly valuable for real-time prognostic monitoring, especially when considering individualized factors. Such prediction tools were lacking for non-metastatic triple-negative breast cancer (TNBC). Therefore, this study estimated CS and developed a novel CS-nomogram for real-time prediction of 10-year survival. Methods: We recruited 32,836 non-metastatic TNBC patients from the Surveillance, Epidemiology, and End Results (SEER) database (2010-2019), who were divided into training and validation groups according to a 7:3 ratio. The Kaplan-Meier method estimated overall survival (OS), and the CS was calculated using the formula CS(y|x) =OS(y+x)/OS(x), where OS(x) and OS(y+x) were the survival of x- and (x+y)-years, respectively. The least absolute shrinkage and selection operator (LASSO) regression identified predictors to develop the CS-nomogram. Results: CS analysis reported gradual improvement in real-time survival over time since diagnosis, with 10-year OS updated annually from an initial 69.9% to 72.8%, 78.1%, 83.0%, 87.0%, 90.3%, 93.0%, 95.0%, 97.0%, and 98.9% (after 1-9 years of survival, respectively). The LASSO regression identified age, marriage, race, T status, N status, chemotherapy, surgery, and radiotherapy as predictors of CS-nomogram development. This model had a satisfactory predictive performance with a stable 10-year time-dependent area under the curves (AUCs) between 0.75 and 0.86. Conclusions: Survival of non-metastatic TNBC survivors improved dynamically and non-linearly with survival time. The study developed a CS-nomogram that provided more accurate prognostic data than traditional nomograms, aiding clinical decision-making and reducing patient anxiety.

Physiological Regulation of Pulmonary Microcirculation under Mechanical Ventilation at Different Cardiac Outputs and Positive End-Expiratory Pressures in a Porcine Model.

This study was performed to visualize the hemodynamic effects of pulmonary microcirculation and ventilation/perfusion (V/Q) matching after mechanical ventilation under different cardiac outputs and positive end-expiratory pressures (PEEPs). Ten experimental pigs were randomly divided into high and low tidal volume groups, and ventilation/perfusion were measured by electrical impedance tomography (EIT) at different PEEPs. Then, all the pigs were redivided into high cardiac output (CO) and low CO groups and measured by EIT at different PEEP levels with a low tidal volume. Additionally, sidestream dark field (SDF) was used to measure pulmonary microcirculation. Hemodynamic parameters and respiratory mechanics parameters were recorded. As PEEP increased at high tidal volume, blood flow was impaired at a higher PEEP (20 cmH2O) compared with low tidal volume (shunt: 30.01 ± 0.69% vs. 17.95 ± 0.72%; V/Q ratio: 65.12 ± 1.97% vs. 76.57 ± 1.25%, p < 0.01). Low tidal volume combined with an appropriate PEEP is the best option from the match between ventilation and pulmonary blood flow. Increasing PEEP can solve the problem of excessive shunt at high CO, and the V/Q ratio tends to match. At low CO, the increased dead space can reach as high as 64.64 ± 7.13% when PEEP = 20 cmH2O. With increasing PEEP, the microcirculation index deteriorates, including total vessel density (TVD), proportion of perfused vessel (PPV), perfused vessel density (PVD), and microcirculatory flow index (MFI). The periodic collapse of pulmonary capillaries or interruption of blood flow obviously occurred with high PEEP. The hemodynamic parameters indicated that the transpulmonary capillary wall pressure (Pcap) of the low CO group was negative at PEEP = 5 cmH2O, which determines the opening and closing of the pulmonary microcirculation and controls lung perfusion and the production of extravascular lung water. Therefore, it is essential to couple macrocirculation and pulmonary microcirculation during mechanical ventilation by improving shunting and optimizing Pcap.

Conditional survival nomogram predicting real-time prognosis of locally advanced breast cancer: Analysis of population-based cohort with external validation.

Background: Locally advanced breast cancer (LABC) is generally considered to have a relatively poor prognosis. However, with years of follow-up, what is its real-time survival and how to dynamically estimate an individualized prognosis? This study aimed to determine the conditional survival (CS) of LABC and develop a CS-nomogram to estimate overall survival (OS) in real-time. Methods: LABC patients were recruited from the Surveillance, Epidemiology, and End Results (SEER) database (training and validation groups, n = 32,493) and our institution (testing group, n = 119). The Kaplan-Meier method estimated OS and calculated the CS at year (x+y) after giving x years of survival according to the formula CS(y|x) = OS(y+x)/OS(x). y represented the number of years of continued survival under the condition that the patient was determined to have survived for x years. Cox regression, best subset regression, and the least absolute shrinkage and selection operator (LASSO) regression were used to screen predictors, respectively, to determine the best model to develop the CS-nomogram and its network version. Risk stratification was constructed based on this model. Results: CS analysis revealed a dynamic improvement in survival occurred with increasing follow-up time (7 year survival was adjusted from 63.0% at the time of initial diagnosis to 66.4, 72.0, 77.7, 83.5, 89.0, and 94.7% year by year [after surviving for 1-6 years, respectively]). In addition, this improvement was non-linear, with a relatively slow increase in the second year after diagnosis. The predictors identified were age, T and N status, grade, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER 2), surgery, radiotherapy and chemotherapy. A CS-nomogram developed by these predictors and the CS formula was used to predict OS in real-time. The model's concordance indexes (C-indexes) in the training, validation and testing groups were 0.761, 0.768 and 0.810, which were well-calibrated according to the reality. In addition, the web version was easy to use and risk stratification facilitated the identification of high-risk patients. Conclusions: The real-time prognosis of LABC improves dynamically and non-linearly over time, and the novel CS-nomogram can provide real-time and personalized prognostic information with satisfactory clinical utility.

Development of a nomogram for predicting grade 2 or higher acute hematologic toxicity of cervical cancer after the pelvic bone marrow sparing radiotherapy.

Background: Acute hematologic toxicity (HT) is a common complication during radiotherapy of cervical cancer which may lead to treatment delay or interruption. Despite the use of intensity-modulated radiation therapy (IMRT) with the pelvic bone marrow (PBM) sparing, some patients still suffer from acute HT. We aimed to identify predictors associated with HT and develop a nomogram for predicting grade 2 or higher (G2+) acute HT in cervical cancer following the PBM sparing strategy. Methods: This study retrospectively analyzed 125 patients with cervical cancer who underwent IMRT with the PBM sparing strategy at our institution. Univariate and multivariate logistic regression, best subset regression, and least absolute shrinkage and selection operator (LASSO) regression, respectively, were used for predictor screening, and Akaike information criterion (AIC) was used to determine the best model for developing the nomogram. Finally, we quantified the risk of G2+ acute HT based on this model to establish a risk stratification. Results: The independent predictors used to develop the nomogram were histological grade, pre-radiotherapy chemotherapy, pre-radiotherapy HT, and radiotherapy [IMRT alone vs. concurrent chemoradiotherapy (CCRT)] which were determined by the univariate and multivariate logistic regression with the minimum AIC of 125.49. Meanwhile, the heat map showed that there is no multicollinearity among the predictors. The nomogram was well-calibrated to reality, with a Brier score of 0.15. The AUC value was 0.82, and the median Brier score and AUC in 1000 five-fold cross-validation were 0.16 and 0.80, respectively. The web version developed together was very easy to use. The risk stratification indicated that high-risk patients (risk point > 195.67) were more likely to develop G2+ acute HT [odds ratio (OR) = 2.17, 95% confidence interval (CI): 1.30-3.05]. Conclusion: This nomogram well-predicted the risk of G2+ acute HT during IMRT in cervical cancer after the PBM sparing strategy, and the constructed risk stratification could assist physicians in screening high-risk patients and provide a useful reference for future prevention and treatment strategies for acute HT.

Development and Validation a Survival Prediction Model and a Risk Stratification for Elderly Locally Advanced Breast Cancer.

PURPOSE: we aimed to develop an individualized survival prediction model for elderly locally advanced breast cancer (LABC) and stratify its risk to assist in the treatment and follow-up of patients. METHODS: Elderly LABC data were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. The best model was screened using Cox, least absolute shrinkage and selection operator (LASSO) and best subset regression to construct the nomogram. After internal and external validation of this model, risk stratification was established, and differences between risk groups were assessed using Kaplan-Meier method. RESULTS: A total of 10,697 elderly LABC patients were divided into a training group (n = 7131) and a validation group (n = 3566) with a 5-year overall survival rate of 57.6% [confidence interval (CI): 56.4%-58.7%]. A nomogram was developed using age, marital status, histological grading, estrogen and progesterone receptors, surgery, radiation therapy, and chemotherapy as predictors. This model was evaluated and validated to perform well, with a discrimination index of 0.744 (95% CI: 0.734-0.753). Patients were divided into low, medium and high groups based on risk scores, and there was a significant difference in survival between the 3 groups. CONCLUSION: The prognosis of elderly LABC was poor. The nomogram constructed based on prognostic factors could accurately predict the prognosis, which would provide a reference for treatment and follow-up.

An Efficient Agrobacterium-Mediated Transformation Method for Hybrid Poplar 84K (Populus alba × P. glandulosa) Using Calli as Explants.

A highly efficient Agrobacterium-mediated transformation method is needed for the molecular study of model tree species such as hybrid poplar 84K (Populus alba × P. glandulosa cv. '84K'). In this study, we report a callus-based transformation method that exhibits high efficiency and reproducibility. The optimized callus induction medium (CIM1) induced the development of calli from leaves with high efficiency, and multiple shoots were induced from calli growing on the optimized shoot induction medium (SIM1). Factors affecting the transformation frequency of calli were optimized as follows: Agrobacterium concentration sets at an OD600 of 0.6, Agrobacterium infective suspension with an acetosyringone (AS) concentration of 100 µM, infection time of 15 min, cocultivation duration of 2 days and precultivation duration of 6 days. Using this method, transgenic plants are obtained within approximately 2 months with a transformation frequency greater than 50%. Polymerase chain reaction (PCR), reverse transcription-PCR (RT-PCR) and ß-galactosidase (GUS) histochemical staining analyses confirmed the successful generation of stable transformants. Additionally, the calli from leaves were subcultured and used to obtain new explants; the high transformation efficiency was still maintained in subcultured calli after 6 cycles. This method provides a reference for developing effective transformation protocols for other poplar species.

Conditional survival analysis and real-time prognosis prediction for cervical cancer patients below the age of 65 years.

Background: Survival prediction for cervical cancer is usually based on its stage at diagnosis or a multivariate nomogram. However, few studies cared whether long-term survival improved after they survived for several years. Meanwhile, traditional survival analysis could not calculate this dynamic outcome. We aimed to assess the improvement of survival over time using conditional survival (CS) analysis and developed a novel conditional survival nomogram (CS-nomogram) to provide individualized and real-time prognostic information. Methods: Cervical cancer patients were collected from the Surveillance, Epidemiology, and End Results (SEER) database. The Kaplan-Meier method estimated cancer-specific survival (CSS) and calculated the conditional CSS (C-CSS) at year y+x after giving x years of survival based on the formula C-CSS(y|x) =CSS(y+x)/CSS(x). y indicated the number of years of further survival under the condition that the patient was determined to have survived for x years. The study identified predictors by the least absolute shrinkage and selection operator (LASSO) regression and used multivariate Cox regression to demonstrate these predictors' effect on CSS and to develop a nomogram. Finally, the CSS possibilities predicted by the nomogram were brought into the C-CSS formula to create the CS-nomogram. Results: A total of 18,511 patients aged <65 years with cervical cancer from 2004 to 2019 were included in this study. CS analysis revealed that the 15-year CSS increased year by year from the initial 72.6% to 77.8%, 84.5%, 88.8%, 91.5%, 93.5%, 94.8%, 95.7%, 96.4%, 97.3%, 98.0%, 98.5%, 99.1%, and 99.4% (after surviving for 1-13 years, respectively), and found that when survival exceeded 5-6 years, the risk of death from cervical cancer would be less than 5% in 10-15 years. The CS-nomogram constructed using tumor size, lymph node status, distant metastasis status, and histological grade showed strong predictive performance with a concordance index (C-index) of 0.805 and a stable area under the curve (AUC) between 0.795 and 0.816 over 15 years. Conclusions: CS analysis in this study revealed the gradual improvement of CSS over time in long-term survived cervical cancer patients. We applied CS to the nomogram and developed a CS-nomogram successfully predicting individualized and real-time prognosis.

A ROS-responsive fluorescent probe detecting experimental colitis by functional polymeric nanoparticles.

Current evidence shows that oxidative stress plays an essential role in the pathogenesis and progression of inflammatory bowel disease (IBD). TotalROX (λabs/λem = 425/525 nm) is a ratiometric probe with high detection sensitivity and a superior capacity to monitor total cellular oxidative capacity. Herein, we investigated the potential of combining totalROX with an oral nanoparticle delivery system to detect the degree of colitis. This detection system also featured pH-responsive Eudragit S100, hyaluronic acid with high affinity to the CD44 receptor, and chitosan, and demonstrated improved loading efficiency and stability. An experimental mouse model of experimental colitis was induced by dextran sodium sulfate do that we could investigate the ability of our nanoparticles to target the colon and determine the degree of inflammation. We also determined and validated the positive correlation between the fluorescence intensity of the detection product (Ox670, λabs/λem = 650/675 nm) and myeloperoxidase activity (R2 = 0.97) and the histopathological score (R2 = 0.98). TotalROX had significant ability to measure reactive oxygen species (ROS) produced by cells under inflammatory conditions, as confirmed by in vitro experiments with Caco-2 cells. Collectively, the data generated demonstrate that when loaded with totalROX, these functional nanoparticles are promising tools for cellular imaging after oral administration. This is the first description of a ROS-responsive fluorescent probe to evaluate the degree of colitis in experimental animal models and provides a promising approach for the diagnosis of inflammation in IBD with fluorescence-guided colonoscopy.

Effects of Simulated Microgravity on the Physiology of Stenotrophomonas maltophilia and Multiomic Analysis.

Many studies have shown that the space environment plays a pivotal role in changing the characteristics of conditional pathogens, especially their pathogenicity and virulence. However, Stenotrophomonas maltophilia, a type of conditional pathogen that has shown to a gradual increase in clinical morbidity in recent years, has rarely been reported for its impact in space. In this study, S. maltophilia was exposed to a simulated microgravity (SMG) environment in high-aspect ratio rotating-wall vessel bioreactors for 14days, while the control group was exposed to the same bioreactors in a normal gravity (NG) environment. Then, combined phenotypic, genomic, transcriptomic, and proteomic analyses were conducted to compare the influence of the SMG and NG on S. maltophilia. The results showed that S. maltophilia in simulated microgravity displayed an increased growth rate, enhanced biofilm formation ability, increased swimming motility, and metabolic alterations compared with those of S. maltophilia in normal gravity and the original strain of S. maltophilia. Clusters of Orthologous Groups (COG) annotation analysis indicated that the increased growth rate might be related to the upregulation of differentially expressed genes (DEGs) involved in energy metabolism and conversion, secondary metabolite biosynthesis, transport and catabolism, intracellular trafficking, secretion, and vesicular transport. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed that the increased motility might be associated the upregulation of differentially expressed proteins (DEPs) involved in locomotion, localization, biological adhesion, and binding, in accordance with the upregulated DEGs in cell motility according to COG classification, including pilP, pilM, flgE, flgG, and ronN. Additionally, the increased biofilm formation ability might be associated with the upregulation of DEPs involved in biofilm formation, the bacterial secretion system, biological adhesion, and cell adhesion, which were shown to be regulated by the differentially expressed genes (chpB, chpC, rpoN, pilA, pilG, pilH, and pilJ) through the integration of transcriptomic and proteomic analyses. These results suggested that simulated microgravity might increase the level of corresponding functional proteins by upregulating related genes to alter physiological characteristics and modulate growth rate, motility, biofilm formation, and metabolism. In conclusion, this study is the first general analysis of the phenotypic, genomic, transcriptomic, and proteomic changes in S. maltophilia under simulated microgravity and provides some suggestions for future studies of space microbiology.

A Small Guanosine Triphosphate Binding Protein PagRabE1b Promotes Xylem Development in Poplar.

Rab GTPases are the subfamily of the small guanosine triphosphate (GTP)-binding proteins which participated in the regulation of various biological processes. Recent studies have found that plant Rabs play some specific functions. However, the functions of Rabs in xylem development in trees remain unclear. In this study, functional identification of PagRabE1b in Populus was performed. Quantitative reverse transcription PCR (qRT-PCR) results showed that PagRabE1b was highly accumulated in stems, especially in phloem and xylem tissues. Overexpression of PagRabE1b in poplar enhanced programmed cell death (PCD) and increased the growth rate and the secondary cell wall (SCW) thickness. Quantitative analysis of monosaccharide content showed that various monosaccharides were significantly increased in secondary xylem tissues of the overexpressed lines. Flow cytometry analysis revealed that the number of apoptotic cells in PagRabE1b-OE lines is more than a wild type (WT), which indicated that PagRabE1b may play an important role in PCD. Further studies showed that overexpression of PagRabE1b increased the expression level of genes involved in SCW biosynthesis, PCD, and autophagy. Collectively, the results suggest that PagRabE1b plays a positive role in promoting the xylem development of poplar.