Vegetative cell wall protein OsGP1 regulates cell wall mediated soda saline-alkali stress in rice.

Plant growth and development are inhibited by the high levels of ions and pH due to soda saline-alkali soil, and the cell wall serves as a crucial barrier against external stresses in plant cells. Proteins in the cell wall play important roles in plant cell growth, morphogenesis, pathogen infection and environmental response. In the current study, the full-length coding sequence of the vegetative cell wall protein gene OsGP1 was characterized from Lj11 (Oryza sativa longjing11), it contained 660 bp nucleotides encoding 219 amino acids. Protein-protein interaction network analysis revealed possible interaction between CESA1, TUBB8, and OsJ_01535 proteins, which are related to plant growth and cell wall synthesis. OsGP1 was found to be localized in the cell membrane and cell wall. Furthermore, overexpression of OsGP1 leads to increase in plant height and fresh weight, showing enhanced resistance to saline-alkali stress. The ROS (reactive oxygen species) scavengers were regulated by OsGP1 protein, peroxidase and superoxide dismutase activities were significantly higher, while malondialdehyde was lower in the overexpression line under stress. These results suggest that OsGP1 improves saline-alkali stress tolerance of rice possibly through cell wall-mediated intracellular environmental homeostasis.

Identification of platelet-related subtypes and diagnostic markers in pediatric Crohn's disease based on WGCNA and machine learning.

Background: The incidence of pediatric Crohn's disease (PCD) is increasing worldwide every year. The challenges in early diagnosis and treatment of PCD persist due to its inherent heterogeneity. This study's objective was to discover novel diagnostic markers and molecular subtypes aimed at enhancing the prognosis for patients suffering from PCD. Methods: Candidate genes were obtained from the GSE117993 dataset and the GSE93624 dataset by weighted gene co-expression network analysis (WGCNA) and differential analysis, followed by intersection with platelet-related genes. Based on this, diagnostic markers were screened by five machine learning algorithms. We constructed predictive models and molecular subtypes based on key markers. The models were evaluated using the GSE101794 dataset as the validation set, combined with receiver operating characteristic curves, decision curve analysis, clinical impact curves, and calibration curves. In addition, we performed pathway enrichment analysis and immune infiltration analysis for different molecular subtypes to assess their differences. Results: Through WGCNA and differential analysis, we successfully identified 44 candidate genes. Following this, employing five machine learning algorithms, we ultimately narrowed it down to five pivotal markers: GNA15, PIK3R3, PLEK, SERPINE1, and STAT1. Using these five key markers as a foundation, we developed a nomogram exhibiting exceptional performance. Furthermore, we distinguished two platelet-related subtypes of PCD through consensus clustering analysis. Subsequent analyses involving pathway enrichment and immune infiltration unveiled notable disparities in gene expression patterns, enrichment pathways, and immune infiltration landscapes between these subtypes. Conclusion: In this study, we have successfully identified five promising diagnostic markers and developed a robust nomogram with high predictive efficacy. Furthermore, the recognition of distinct PCD subtypes enhances our comprehension of potential pathogenic mechanisms and paves the way for future prospects in early diagnosis and personalized treatment.

Inferring circRNA-drug sensitivity associations via dual hierarchical attention networks and multiple kernel fusion.

Increasing evidence has shown that the expression of circular RNAs (circRNAs) can affect the drug sensitivity of cells and significantly influence drug efficacy. Therefore, research into the relationships between circRNAs and drugs can be of great significance in increasing the comprehension of circRNAs function, as well as contributing to the discovery of new drugs and the repurposing of existing drugs. However, it is time-consuming and costly to validate the function of circRNA with traditional medical research methods. Therefore, the development of efficient and accurate computational models that can assist in discovering the potential interactions between circRNAs and drugs is urgently needed. In this study, a novel method is proposed, called DHANMKF , that aims to predict potential circRNA-drug sensitivity interactions for further biomedical screening and validation. Firstly, multimodal networks were constructed by DHANMKF using multiple sources of information on circRNAs and drugs. Secondly, comprehensive intra-type and inter-type node representations were learned using bi-typed multi-relational heterogeneous graphs, which are attention-based encoders utilizing a hierarchical process. Thirdly, the multi-kernel fusion method was used to fuse intra-type embedding and inter-type embedding. Finally, the Dual Laplacian Regularized Least Squares method (DLapRLS) was used to predict the potential circRNA-drug sensitivity associations using the combined kernel in circRNA and drug spaces. Compared with the other methods, DHANMKF obtained the highest AUC value on two datasets. Code is available at https://github.com/cuntjx/DHANMKF .

Predicting potential microbe-disease associations based on auto-encoder and graph convolution network.

The increasing body of research has consistently demonstrated the intricate correlation between the human microbiome and human well-being. Microbes can impact the efficacy and toxicity of drugs through various pathways, as well as influence the occurrence and metastasis of tumors. In clinical practice, it is crucial to elucidate the association between microbes and diseases. Although traditional biological experiments accurately identify this association, they are time-consuming, expensive, and susceptible to experimental conditions. Consequently, conducting extensive biological experiments to screen potential microbe-disease associations becomes challenging. The computational methods can solve the above problems well, but the previous computational methods still have the problems of low utilization of node features and the prediction accuracy needs to be improved. To address this issue, we propose the DAEGCNDF model predicting potential associations between microbes and diseases. Our model calculates four similar features for each microbe and disease. These features are fused to obtain a comprehensive feature matrix representing microbes and diseases. Our model first uses the graph convolutional network module to extract low-rank features with graph information of microbes and diseases, and then uses a deep sparse Auto-Encoder to extract high-rank features of microbe-disease pairs, after which the low-rank and high-rank features are spliced to improve the utilization of node features. Finally, Deep Forest was used for microbe-disease potential relationship prediction. The experimental results show that combining low-rank and high-rank features helps to improve the model performance and Deep Forest has better classification performance than the baseline model.

Preparation of leaf protoplasts from Populus (Populus × xiaohei T. S. Hwang et Liang) and establishment of transient expression system.

Poplar, as a typical woody plant, is an ideal raw material for the production of lignocellulose biofuel. However, the longer life cycle is not conducive to the rapid identification of poplar genes. At present, protoplasts have been used for gene function identification and high-throughput analysis in many model plants. In this paper, a simplified and efficient protoplast isolation and transient expression system of Populus (Populus × xiaohei T. S. Hwang et Liang) is described. Firstly, we proposed an efficient enzyme hydrolysis method for isolating protoplasts from leaves of Populus × xiaohei. Secondly, we optimized the conditions of protoplast transformation mediated by PEG, and established an efficient transient expression system of protoplasts of Populus × xiaohei. Finally, the subcellular localization of three identified Dof transcription factors (PnDof19, PnDof20 and PnDof30) was also observed in the nucleus by using this scheme, which proved that the method was feasible. In general, this efficient method of protoplast isolation and transformation can be used for the study of protein subcellular localization and can be applied to other fields of molecular biology, such as protein interaction, gene activation and so on.

[Predictive value of hemoglobin to serum creatinine ratio combined with serum uric acid for in-hospital mortality after emergency percutaneous coronary intervention in patients with acute myocardial infarction].

OBJECTIVE: To investigate the clinical value of hemoglobin to serum creatinine ratio (Hb/SCr) combined with blood uric acid (SUA) in predicting in-hospital mortality after emergency percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI). METHODS: The clinical data of AMI patients who underwent emergency PCI in the First Affiliated Hospital of Kangda College of Nanjing Medical University from January 2017 to December 2021 were retrospectively analyzed. The general information, underlying medical history, blood routine, liver and kidney function, blood coagulation routine, SUA and other indicators were collected from patients. The primary composite endpoint was defined as in-hospital death, including in-hospital all-cause death during PCI and 15-day post-procedure hospitalization. Multivariate Logistic regression was used to analyze factors associated with in-hospital death after emergency PCI in patients with AMI. Multivariate Logistic regression was used to analyze the independent related factors and construct a risk prediction model. The Hosmer-Lemeshow method and receiver operator characteristic curve (ROC curve) were used to test the goodness of fit and predictive effect of the model and correlates, respectively. RESULTS: A total of 1 976 patients were enrolled, 92 died in hospital and 1 884 survived. SUA was higher in the death group than that in the survival group (µmol/L: 476.88±132.04 vs. 354.87±105.31, P < 0.01), and the Hb/SCr ratio was significantly lower than that in the survival group (13.84±5.48 vs.19.20±5.74, P < 0.01). Pearson analysis showed a linear negative correlation between SUA and Hb/SCr ratio (r = -0.502, P < 0.01). Logistic regression risk model analysis finally included age [odds ratio (OR) = 0.916], Hb/SCr ratio (OR = 0.182), white blood cell count (WBC, OR = 2.733), C-reactive protein (CRP, OR = 3.611), SUA (OR = 4.667), blood glucose (Glu, OR = 2.726), homocysteine (Hcy, OR = 2.688) 7 factors to construct a risk prediction model, which were independent correlation factors for in-hospital death in AMI patients after emergency PCI (all P < 0.05). Hosmer-Lemeshow test verified the fitting effect of the model, and the result showed P = 0.447. The area under the ROC curve (AUC) of the model for predicting in-hospital death in AMI patients after emergency PCI was 0.764 [95% confidence interval (95%CI) was 0.712-0.816, P = 0.001]. When the cut-off value was 0.565 8, the sensitivity was 70.7%, the specificity was 70.2%, and the Yoden index was 0.410. When Hb/SCr ratio+SUA, SUA, Hb/SCr ratio, Hb and SCr were used to predict in-hospital death in AMI patients after emergency PCI, the AUC of Hb/SCr ratio+SUA was the largest, which was 0.810. When the optimal cut-off value was -0.847, the sensitivity was 77.7%, the specificity was 74.5%, and the Youden index was 0.522. CONCLUSIONS: Age, SUA, Hb/SCr ratio, WBC, CRP, Glu, and Hcy are independent risk factors for in-hospital death after emergency PCI in AMI patients. The lower the Hb/SCr ratio and the higher the SUA at admission, the higher the risk of in-hospital death after emergency PCI in AMI patients. Hb/SCr ratio combined with SUA has a higher predictive value for in-hospital death after emergency PCI in AMI patients than single index, which is helpful for early identification of high-risk patients.

Functional Identification and Genetic Transformation of the Ammonium Transporter PtrAMT1;6 in Populus.

The ammonium transporter (AMT) family gene is an important transporter involved in ammonium uptake and transfer in plants and is mainly engaged in the uptake and transport of ammonium from the environment by roots and the reabsorption of ammonium in the aboveground parts. In this study, the expression pattern, functional identification, and genetic transformation of the PtrAMT1;6 gene, a member of the ammonium transporter protein family in P. trichocarpa, were investigated as follows: (1) Fluorescence quantitative PCR demonstrated that the PtrAMT1;6 gene was preferentially expressed in the leaves, with both dark-induced and light-inhibited expression patterns. (2) A functional restoration assay using the yeast ammonium transporter protein mutant strain indicated that the PtrAMT1;6 gene restored the ability of the mutant to transport ammonium with high affinity. (3) Arabidopsis was transformed with pCAMBIA-PtrAMT1;6P, and the transformed lines were stained with GUS, which showed that the rootstock junction, cotyledon petioles, and the leaf veins and pulp near the petioles of the transformed plants could be stained blue, indicating that the promoter of the PtrAMT1;6 gene had promoter activity. (4) The overexpression of the PtrAMT1;6 gene caused an imbalance in carbon and nitrogen metabolism and reduced nitrogen assimilation ability in '84K' poplar and ultimately reduced biomass. The above results suggest that PtrAMT1;6 may be involved in ammonia recycling during nitrogen metabolism in aboveground parts, and overexpression of PtrAMT1;6 may affect the process of carbon and nitrogen metabolism, as well as nitrogen assimilation in plants, resulting in stunted growth of overexpression plants.

Analysis of the chloroplast genome and phylogenetic evolution of three species of Syringa.

BACKGROUND: By the time our study was completed, the chloroplast genomes of Syringa oblata, S. pubescents subsp. Microphylla, and S. reticulate subsp. Amurensis had not been sequenced, and their genetic background was not clear. THE RESEARCH CONTENT: In this study, the chloroplast genomes of Syringa oblata, S. pubescents subsp. Microphylla, S. reticulate subsp. Amurensis, and five other species of Syringa were sequenced for a comparative genomics analysis, inverted repeat (IR) boundary analysis, collinearity analysis, codon preference analysis and a nucleotide variability analysis. Differences in the complete chloroplast genomes of 30 species of Oleaceae were compared with that of S. oblata as the reference species, and Ginkgo biloba was used as the out group to construct the phylogenetic tree. RESULTS: The results showed that the chloroplast genomes of S. oblata, S. pubescents subsp. Microphylla, and S. reticulate subsp. Amurensis were similar to those of other angiosperms and showed a typical four-segment structure, with full lengths of 155,569, 160,491, 155,419, and protein codes of 88, 95, and 87, respectively. Because the IR boundary of S. pubescents subsp. Microphylla was significantly expanded to the large single copy (LSC) region, resulting in complete replication of some genes in the IR region, the LSC region of S. pubescents subsp. Microphylla was significantly shorter than those of S. oblate and S. reticulate subsp. Amurensis. Similar to most higher plants, these three species have a preference for their codons ending with A/T. CONCLUSIONS: We consider the genus Syringa to be a synphyletic group. The nucleotide variability and phylogenetic analyses showed that Syringa differentiated before Ligustrum and Ligustrum developed from Syringa. We propose removing the existing section division and directly dividing Syringa into five series.

The complete chloroplast genome of Salix matsudana f. tortuosa.

In this study, the complete chloroplast genome of Salix matsudana f. tortuosa was sequenced and analyzed. The genome of Salix matsudana f. tortuosa was 155,673 bp in length and was quadripartite in structure, containing a large single-copy region with a length of 84,447 bp, a small single-copy region with a length of 16,320 bp, and two inverted repeats of 27,453 bp in length. The chloroplast genome contains 130 genes, including 85 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The GC content is 36.64%. The phylogenetic tree shows that Salix matsudana f. tortuosa, Salix matsudana, and Salix babylonica are closely related and located on the same branch. The chloroplast genome of Salix matsudana f. tortuosa will provide important data for further systematic study of Salicaceae and the genus Salix.

Selection and functional identification of Dof genes expressed in response to nitrogen in Populus simonii × Populus nigra.

In plants, Dof transcription factors are involved in regulating the expression of a series of genes related to N uptake and utilization. Therefore, the present study investigated how DNA-binding with one finger (Dof) genes are expressed in response to nitrogen (N) form and concentration to clarify the role of Dof genes and their functions in promoting N assimilation and utilization in poplar. The basic characteristics and expression patterns of Dof genes in poplar were analyzed by the use of bioinformatics methods. Dof genes expressed in response to N were screened, after which the related genes were cloned and transformed into Arabidopsis thaliana; the physiological indexes and the expression of related genes were subsequently determined. The function of Dof genes was then verified in Arabidopsis thaliana plants grown in the presence of different N forms and concentrations. Forty-four Dof genes were identified, most of which were expressed in the roots and young leaves, and some of the Dof genes were expressed under ammonia- and nitrate-N treatments. Three genes related to N induction were cloned, their proteins were found to localize in the nucleus, and PnDof30 was successfully transformed into Arabidopsis thaliana for functional verification. On comparing Arabidopsis thaliana with WT Arabidopsis thaliana plants, Arabidopsis thaliana plants overexpressing the Dof gene grew better under low N levels; the contents of soluble proteins and chlorophyll significantly increased, while the soluble sugar content significantly decreased. The expressions of several AMT, NRT, and GS genes were upregulated, while the expressions of several others were downregulated, and the expression of PEPC and PK genes significantly increased. In addition, the activity of PEPC, PK, GS, and NR enzymes significantly increased. The results showed that overexpression of PnDof30 significantly increased the level of carbon and N metabolism and improved the growth of transgenic Arabidopsis thaliana plants under low-N conditions. The study revealed the biological significance of poplar Dof transcription factors in N response and regulation of related downstream gene expression and provided some meaningful clues to explain the huge difference between poplar and Arabidopsis thaliana transformed by exogenous Dof gene, which could promote the comprehensive understanding of the molecular mechanism of efficient N uptake and utilization in trees.

[Construction and evaluation of a model for predicting ischemic stroke risk in patients with sudden sensorineural hearing loss].

Objective:To explore the related factors of sudden sensorineural hearing loss complicated with ischemic stroke, construct the risk prediction model, and verify the prediction effect of the model. Methods:A retrospective analysis was performed on 901 sudden sensorineural hearing loss patients hospitalized from January 2017 to December 2020, The patients were divided into the ischemic stroke group（100 cases） and the sudden deafness group（801 cases） according to whether they were complicated with ischemic stroke, The independent correlation factors of sudden deafness complicated with ischemic stroke were screened by univariate analysis and multivariate Logistic regression model, and the risk prediction model and internal verification were established. The original data were randomly divided into the modeling group（631 cases） and the validation group（270 cases） at a 7∶3 ratio. Hosmer-Lemeshow and receiver operating characteristic curve were used to test the goodness of fit and predictive effect of the model, and 270 patients were included again in the application research of the model and to test the prediction effect of the model. Results:The results of single factor analysis showed that age, NEUR, NC, NLR, PLR, TC, HDL-C, BUN, TC-HDL-C, TG/HDL-C, LDL-C/HDL-C, Hcy, FIB and cervical vascular plaque were related factors of sudden sensorineural hearing loss complicated with ischemic stroke（P<0.05）. Age（OR=2.816）, NEUR（OR=2.707）, Hcy（OR=88.833）, FIB（OR=1.389）, TC-HDL-C（OR=1.613）, cervical vascular plaque（OR=2.862） are the independent risk factors of SNHL complicated with ischemic stroke. These 6 factors are used to construct a prediction model. Hosmer-lemeshow test results, the area under the ROC curve of the modeling group was 0.846, P=0.555, Youden index was 0.564, sensitivity was 0.820, and specificity was 0.744. In the validation group, the area under ROC curve was 0.847, P=0.288, Youden index was 0.432, sensitivity was 0.783, and specificity was 0.649. Conclusion:The risk prediction model constructed in this study shows good prediction efficiency. which can provide references for the clinical screening of ischemic stroke risks in patients with sudden sensorineural hearing loss and early interventions in early stage.

The complete chloroplast genome sequence of Trollius macropetalus.

The complete chloroplast genome of Trollius macropetalus was sequenced in this study. It has a cyclic tetrad structure typical of angiosperms. The total length is 160,094 bp, including a large single copy region (LSC) with a length of 88,555 bp, a small single copy region (SSC) with a length of 18,291 bp and two equal-length inverted repeat regions (IRA/IRB) with a length of 26,624 bp. It encodes a total of 137 genes, including 87 protein-coding genes, 42 tRNA genes, and 8 rRNA genes, with a CG content of 38.03%.

PacBio and Illumina RNA Sequencing Identify Alternative Splicing Events in Response to Cold Stress in Two Poplar Species.

In eukaryotes, alternative splicing (AS) is a crucial regulatory mechanism that modulates mRNA diversity and stability. The contribution of AS to stress is known in many species related to stress, but the posttranscriptional mechanism in poplar under cold stress is still unclear. Recent studies have utilized the advantages of single molecular real-time (SMRT) sequencing technology from Pacific Bioscience (PacBio) to identify full-length transcripts. We, therefore, used a combination of single-molecule long-read sequencing and Illumina RNA sequencing (RNA-Seq) for a global analysis of AS in two poplar species (Populus trichocarpa and P. ussuriensis) under cold stress. We further identified 1,261 AS events in P. trichocarpa and 2,101 in P. ussuriensis among which intron retention, with a frequency of more than 30%, was the most prominent type under cold stress. RNA-Seq data analysis and annotation revealed the importance of calcium, abscisic acid, and reactive oxygen species signaling in cold stress response. Besides, the low temperature rapidly induced multiple splicing factors, transcription factors, and differentially expressed genes through AS. In P. ussuriensis, there was a rapid occurrence of AS events, which provided a new insight into the complexity and regulation of AS during cold stress response in different poplar species for the first time.

A colorimetric fluorescent probe for rapid and specific detection of nitrite.

The method of fluorescent probes has been an important technique for detection of nitrite (NO2 - ). As an important inorganic salt, excessive nitrite would threaten humans and the environment. In this paper, a colorimetric fluorescent probe P-N (1,2-diaminoanthraquinone) with rapid response and high selectivity, which could detect NO2 - by visual colour changes and fluorescence spectroscopy is presented. The probe P-N solution (pH 1) changed from pink to colourless with the addition of NO2 - and fluorescence intensity at 639 nm clearly decreased. Good linear exists between fluorescence intensities and NO2 - concentrations for the range 0-16 µM, and the detection limit was 54 nM (based on a 3σ/slope). Moreover, probe P-N could also detect NO2 - in real water samples, and results were all satisfactory. Probe P-N shows great practical application value for detecting NO2 - in the environment.

The transcriptional events and their relationship to physiological changes during poplar seed germination and post-germination.

BACKGROUND: Seed germination, the foundation of plant propagation, involves a series of changes at the molecular level. Poplar is a model woody plant, but the molecular events occurring during seed germination in this species are unclear. RESULTS: In this study, we investigated changes in gene transcriptional levels during different germination periods in poplar by high-throughput sequencing technology. Analysis of genes expressed at specific germination stages indicated that these genes are distributed in many metabolic pathways. Enrichment analysis of significantly differentially expressed genes based on hypergeometric testing revealed that multiple pathways, such as pathways related to glycolysis, lipid, amino acid, protein and ATP synthesis metabolism, changed significantly at the transcriptional level during seed germination. A comparison of ΣZ values uncovered a series of transcriptional changes in biological processes related to primary metabolism during poplar seed germination. Among these changes, genes related to CHO metabolism were the first to be activated, with subsequent expression of genes involved in lipid metabolism and then those associated with protein metabolism. The pattern of metabolomic and physiological index changes further verified the sequence of some biological events. CONCLUSIONS: Our study revealed molecular events occurring at the transcriptional level during seed germination and determined their order. These events were further verified by patterns of changes of metabolites and physiological indexes. Our findings lay a foundation for the elucidation of the molecular mechanisms responsible for poplar seed germination.

Construction and characterization of immunoliposomes targeting fibroblast growth factor receptor 3.

Fibroblast growth factor receptor 3 (FGFR3) plays an important regulatory role in tumor cell proliferation and drug resistance. FGFR3 is often constitutively active in many tumors. To deliver drugs into tumor cells by targeting FGFR3 will be a promising and potential strategy for cancer therapy. In this study, a novel fusion protein, ScFv-Cys containing a single chain variable fragment (ScFv) and an additional C-terminal cysteine residue, was generated at a rate of 10 mg/L of bacterial culture and purified at 95% by Ni-NTA chromatography. Subsequently, the recombinant ScFv-Cys was coupled with malPEG2000-DSPE and incorporated into liposomes to generate the immunoliposomes. The results indicated that immunoliposomes can specifically deliver the fluorescent molecules, Dio into bladder cancer cells highly expressing FGFR3. In conclusion, we successfully generated FGFR3-specific immunoliposomes, and proved its targeting effect and delivering ability.

Comprehensive dissection of transcript and metabolite shifts during seed germination and post-germination stages in poplar.

BACKGROUND: Seed germination, a complex, physiological-morphogenetic process, is a critical stage in the life cycle of plants. Biological changes in germinating seeds have not been investigated in poplar, a model woody plant. RESULTS: In this study, we exploited next-generation sequencing and metabolomics analysis and uncovered a series of significantly different genes and metabolites at various stages of seed germination and post germination. The K-means method was used to identify multiple transcription factors, including AP2/EREBP, DOF, and YABBY, involved in specific seed germination and post-germination stages. A weighted gene coexpression network analysis revealed that cell wall, amino acid metabolism, and transport-related pathways were significantly enriched during stages 3 and 5, with no significant enrichment observed in primary metabolic processes such as glycolysis and the tricarboxylic acid cycle. A metabolomics analysis detected significant changes in intermediate metabolites in these primary metabolic processes, while a targeted correlation network analysis identified the gene family members most relevant to these changing metabolites. CONCLUSIONS: Taken together, our results provide important insights into the molecular networks underlying poplar seed germination and post-germination processes. The targeted correlation network analysis approach developed in this study can be applied to search for key candidate genes in specific biochemical reactions and represents a new strategy for joint multiomics analyses.

Functional Research on Three Presumed Asparagine Synthetase Family Members in Poplar.

Asparagine synthetase (AS), a key enzyme in plant nitrogen metabolism, plays an important role in plant nitrogen assimilation and distribution. Asparagine (Asn), the product of asparagine synthetase, is one of the main compounds responsible for organic nitrogen transport and storage in plants. In this study, we performed complementation experiments using an Asn-deficient Escherichia coli strain to demonstrate that three putative asparagine synthetase family members in poplar (Populussimonii× P.nigra) function in Asn synthesis. Quantitative real-time PCR revealed that the three members had high expression levels in different tissues of poplar and were regulated by exogenous nitrogen. PnAS1 and PnAS2 were also affected by diurnal rhythm. Long-term dark treatment resulted in a significant increase in PnAS1 and PnAS3 expression levels. Under long-term light conditions, however, PnAS2 expression decreased significantly in the intermediate region of leaves. Exogenous application of ammonium nitrogen, glutamine, and a glutamine synthetase inhibitor revealed that PnAS3 was more sensitive to exogenous glutamine, while PnAS1 and PnAS2 were more susceptible to exogenous ammonium nitrogen. Our results suggest that the various members of the PnAS gene family have distinct roles in different tissues and are regulated in different ways.

Highly selective and sensitive fluorescent probe for the rapid detection of mercury ions.

Mercury (Hg) is one of the major toxic heavy metals, harmful to the environment and human health. Thus, it is significantly important to find an easy and quick method to detect Hg2+. In this study, we designed and synthesized a simple fluorescent probe with excellent properties, such as high sensitivity and selectivity, rapid response, and outstanding water solubility. When Hg2+ (5 µM) was added to the probe solution, it exhibited a very large fluorescent enhancement (about 350-fold stronger than the free probe) with the help of hydrogen peroxide (H2O2). Probe HCDC could quantitatively detect Hg2+ in the range of 0-10 µM using the fluorescence spectroscopy method and the detection limit was measured to be about 0.3 nM (based on a 3σ/slope). Analytical application was also studied, and the probe HCDC exhibited excellent response to Hg2+ with the addition of H2O2 in real water samples. So, our proposed probe HCDC provided a practical and promising method for determining Hg2+ in the environment.

Genome-wide identification and expression profile analysis of CCH gene family in Populus.

Copper plays key roles in plant physiological activities. To maintain copper cellular homeostasis, copper chaperones have important functions in binding and transporting copper to target proteins. Detailed characterization and function analysis of a copper chaperone, CCH, is presently limited to Arabidopsis. This study reports the identification of 21 genes encoding putative CCH proteins in Populus trichocarpa. Besides sharing the conserved metal-binding motif MXCXXC and forming a ßαßßαß secondary structure at the N-terminal, all the PtCCHs possessed the plant-exclusive extended C-terminal. Based on their gene structure, conserved motifs, and phylogenetic analysis, the PtCCHs were divided into three subgroups. Our analysis indicated that whole-genome duplication and tandem duplication events likely contributed to expansion of the CCH gene family in Populus. Tissue-specific data from PlantGenIE revealed that PtCCH genes had broad expression patterns in different tissues. Quantitative real-time RT-PCR (qRT-PCR) analysis revealed that PnCCH genes of P. simonii × P. nigra also had different tissue-specific expression traits, as well as different inducible-expression patterns in response to copper stresses (excessive and deficiency). In summary, our study of CCH genes in the Populus genome provides a comprehensive analysis of this gene family, and lays an important foundation for further investigation of their roles in copper homeostasis of poplar.