The missing data problem greatly affects traffic analysis. In this paper, we put forward a new reliable method called probabilistic principal component analysis (PPCA) to impute the missing flow ...volume data based on historical data mining. First, we review the current missing data-imputation method and why it may fail to yield acceptable results in many traffic flow applications. Second, we examine the statistical properties of traffic flow volume time series. We show that the fluctuations of traffic flow are Gaussian type and that principal component analysis (PCA) can be used to retrieve the features of traffic flow. Third, we discuss how to use a robust PCA to filter out the abnormal traffic flow data that disturb the imputation process. Finally, we recall the theories of PPCA/Bayesian PCA-based imputation algorithms and compare their performance with some conventional methods, including the nearest/mean historical imputation methods and the local interpolation/regression methods. The experiments prove that the PPCA method provides significantly better performance than the conventional methods, reducing the root-mean-square imputation error by at least 25%.
The Mediator complex is an important component of the eukaryotic transcriptional machinery. As an essential link between transcription factors and RNA polymerase II, the Mediator complex transduces ...diverse signals to genes involved in different pathways. The plant Mediator complex was recently purified and comprises conserved and specific subunits. It functions in concert with transcription factors to modulate various responses. In this review, we summarize the recent advances in understanding the plant Mediator complex and its diverse roles in plant growth, development, defense, non-coding RNA production, response to abiotic stresses, flowering, genomic stability and metabolic homeostasis. In addition, the transcription factors interacting with the Mediator complex are also highlighted.
This work describes a new one‐step large‐scale electrochemical synthesis of graphene/polyaniline (PANI) composite films using graphite oxide (GO) and aniline as the starting materials. The size of ...the film could be controlled by the area of indium tin oxide (ITO). Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible absorption spectrum (UV–vis) results demonstrated that the graphene/PANI composite film was successfully synthesized. The obtained graphene/PANI composite film showed large specific area, high conductivity, good biocompatibility, and fast redox properties and had perfect layered and encapsulated structures. Electrochemical experiments indicated that the composite film had high performances and could be widely used in applied electrochemical fields. As a model, horseradish peroxidase (HRP) was entrapped onto the film‐modified glassy carbon electrode (GCE) and used to construct a biosensor. The immobilized HRP showed a pair of well‐defined redox peaks and high catalytic activity for the reduction of H2O2. Furthermore, the graphene/PANI composite film could be directly used as the supercapacitor electrode. The supercapacitor showed a high specific capacitance of 640 F g−1 with a retention life of 90% after 1000 charge/discharge cycles.
A new one‐step electrochemical synthesis of graphene/polyaniline composite films was developed using graphite oxide and aniline as the starting materials. Horseradish peroxidase was entrapped onto the film‐modified electrode and used to construct a H2O2 biosensor. A supercapacitor was also fabricated based on the composite film.
Unlike in animals, sperm in flowering plants are immotile and they are embraced as passive cargoes by a pollen tube which embarks on a long journey in the pistil to deliver them to the female ...gametophyte for fertilization. How the pollen tube switches from a rapid polarized growth towards its target to an abrupt disintegration for sperm cell release inside the female gametophyte is puzzling. Recent studies have shown that members of the Catharanthus roseus RLK1-like (CrRLK1L) receptor kinase family and their ligands, 5-kDa cysteine-rich peptide rapid alkalinization factors (RALFs), engage in an intricate balancing act involving autocrine and paracrine signaling to maintain pollen tube growth and induce timely tube rupture at the spatially confined pollen tube–female gametophyte interface. Here, we review recent progress related to pollen tube integrity control, mainly focusing on the molecular understanding of signaling as well as intracellular signaling nodes in Arabidopsis. Some missing links and future perspectives are also discussed.
Phase separation of proteins/nucleic acids to form non‐membrane organelles is crucial in cellular gene‐expression regulation. However, little is known about transcriptional regulator phase separation ...and the underlying molecular mechanism. Vernalization 1 (VRN1) encodes a crucial transcriptional repressor involved in plant vernalization that contains two B3 DNA‐binding domains connected by an intrinsic disorder region (IDR) and nonspecifically binds DNA. We found that the Arabidopsis VRN1 protein undergoes liquid–liquid phase separation (LLPS) with DNA that is driven by multivalent protein–DNA interactions (LLPS), and that both B3 domains are required. The distribution of charged residues in the VRN1 IDR modulates the interaction strength between VRN1 and DNA, and changes in the charge pattern lead to interconversion between different states (precipitates, liquid droplets, and no phase separation). We further showed that VRN1 forms puncta in plant cell nuclei, suggesting that it may stabilize the vernalized state by repressing gene expression through LLPS.
Charge patterns take charge: Both the acidic (red) and basic (blue) patches in the IDR region are important for VRN1–DNA coacervation (see picture). The charged patches tune the protein–DNA interaction strength to facilitate complex molecular rearrangement. The negative‐charge‐abundant mutant does not demix with DNA, while the positive‐charge‐rich mutant precipitates with DNA. Incorporation of both positive and negative‐charge‐enables liquid–liquid phase separation in cis or in trans.
•In angiosperms, successful double fertilization requires extensive male–female interactions between pollen tubes and female tissues.•Peptides, mainly cysteine-rich peptides (CRPs) secreted from male ...or female tissues, serve as signal ligands in male–female interactions.•Receptor-like kinases, paired with corresponding peptide signals, trigger different cytoplasmic responses during male–female interactions.
In flowering plants, extensive male–female interactions during pollen germination on the stigma, pollen tube growth and guidance in the transmitting tract, and pollen tube reception by the female gametophyte are required for successful double fertilization in which various signaling cascades are involved. Peptide/receptor-like kinase-mediated signaling has been found playing important roles in these male–female interactions. Here, we mainly summarized the progress made on the regulatory roles of peptide/receptor-like kinase-mediated signaling pathways in four critical stages during reproduction in higher plants.
Catharanthus roseus Receptor‐Like Kinase 1‐like (CrRLK1L) proteins contain two tandem malectin‐like modules in their extracellular domains (ECDs) and function in diverse signaling pathways in plants. ...Malectin is a carbohydrate‐binding protein in animals and recognizes a number of diglucosides; however, it remains unclear how the two malectin‐like domains in the CrRLK1L proteins sense the ligand molecule. In this study, we reveal the crystal structures of the ECDs of ANXUR1 and ANXUR2, two CrRLK1L members in Arabidopsis thaliana that have critical functions in controlling pollen tube rupture during the fertilization process. We show that the two malectin‐like domains in these proteins pack together to form a rigid architecture. Unlike animal malectin, these malectin‐like domains lack residues involved in binding to the diglucosides, suggesting that they have a distinct ligand‐binding mechanism. A cleft is observed between the two malectin‐like domains, which might function as a potential ligand‐binding pocket.
Interactive Figure 1 | PDB Code(s): 5Y96; 5Y92
Current enzyme‐responsive, fluorogenic probes fail to provide in situ information because the released fluorophores tend to diffuse away from the reaction sites. The problem of diffusive signal ...dilution can be addressed by designing a probe that upon enzyme conversion releases a fluorophore that precipitates. An excited‐state intramolecular proton transfer (ESIPT)‐based solid‐state fluorophore HTPQ was developed that is strictly insoluble in water and emits intense fluorescence in the solid state, with λex/em=410/550 nm, thus making it far better suited to use with a commercial confocal microscope. HTPQ was further utilized in the design of an enzyme‐responsive, fluorogenic probe (HTPQA), targeting alkaline phosphatase (ALP) as a model enzyme. HTPQA makes possible diffusion‐resistant in situ detection of endogenous ALP in live cells. It was also employed in the visualizing of different levels of ALP in osteosarcoma cells and tissue, thus demonstrating its interest for the diagnosis of this type of cancer.
A solid‐state fluorophore (HTPQ) that is well‐suited to confocal microscopy was developed. HTPQ was used to design an enzyme‐responsive, fluorogenic probe (HTPQA) targeting alkaline phosphatase (ALP) as a model enzyme. HTPQA makes possible diffusion‐resistant detection of endogenous ALP in live cells and visualization of ALP levels in Saos‐2 and U‐2OS osteosarcoma cells and tissue.
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