Publications by authors named "Zhongyi Wu"

16 Publications

  • Page 1 of 1

Isoorientin Affects Markers of Alzheimer's Disease via Effects on the Oral and Gut Microbiota in APP/PS1 Mice.

J Nutr 2021 Oct 12. Epub 2021 Oct 12.

Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China.

Background: There is growing evidence of strong associations between the pathogenesis of Alzheimer's disease (AD) and dysbiotic oral and gut microbiota. Recent studies demonstrated that isoorientin (ISO) is anti-inflammatory and alleviates markers of AD, which were hypothesized to be mediated by the oral and gut microbiota.

Objectives: We studied the effects of oral administration of ISO on AD-related markers and the oral and gut microbiota in mice.

Methods: Eight-month-old amyloid precursor protein/presenilin-1 (AP) transgenic male mice were randomly allocated to 3 groups of 15 mice each: vehicle (AP) alone or with a low dose of ISO (AP + ISO-L; 25 mg/kg) or a high dose of ISO (AP + ISO-H; 50 mg/kg). Age-matched wild-type (WT) C57BL/6 male littermates were used as controls. The 4 groups were treated intragastrically with ISO or sterilized ultrapure water for 2 months. AD-related markers in the brain, serum, colon, and liver were analyzed with immunohistochemical and histochemical staining, Western blotting, and ELISA. Oral and gut microbiotas were analyzed using 16S ribosomal RNA gene sequencing.

Results: The high-dose ISO treatment significantly decreased amyloid beta 42-positive deposition by 38.1% and 45.2% in the cortex and hippocampus, respectively, of AP mice (P < 0.05). Compared with the AP group, both ISO treatments reduced brain phospho-Tau, phosphor-p65, phosphor-inhibitor of NF-κB, and brain and serum LPS and TNF-α by 17.9%-72.5% and increased brain and serum IL-4 and IL-10 by 130%-210% in the AP + ISO-L and AP + ISO-H groups (P < 0.05). Abundances of 26, 25, and 23 microbial taxa in oral, fecal and cecal samples, respectively, were increased in both the AP + ISO-L and AP + ISO-H groups relative to the AP group [linear discriminant analysis (LDA) >3.0; P < 0.05]. Gram-negative bacteria, Alteromonas, Campylobacterales, and uncultured Bacteroidales bacterium were positively correlated (rho = 0.28-0.59; P < 0.05) with the LPS levels and responses of inflammatory cytokines.

Conclusions: The microbiota-gut-brain axis is a potential mechanism by which ISO reduces AD-related markers in AP mice.
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http://dx.doi.org/10.1093/jn/nxab328DOI Listing
October 2021

Material decomposition for simulated dual-energy breast computed tomography via hybrid optimization method.

J Xray Sci Technol 2020 ;28(6):1037-1054

Department of Medical Imaging, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China.

Background: Dual-energy breast CT reconstruction has a potential application that includes separation of microcalcification from healthy breast tissue for assisting early breast cancer detection.

Objective: To investigate and validate the noise suppression algorithm applied in the decomposition of the simulated breast phantom into microcalcification and healthy breast.

Methods: The proposed hybrid optimization method (HOM) uses a simultaneous algebraic reconstruction technique (SART) output as a prior image, which is then incorporated into the self-adaptive dictionary learning. This self-adaptive dictionary learning seeks each group of patches to faithfully represent the learned dictionary, and the sparsity and non-local similarity of group patches are used to enforce the image regularization term of the prior image. We simulate a numerical phantom by adding different levels of Gaussian noise to test performance of the proposed method.

Results: The mean value of peak signal-to-noise ratio (PSNR), structural similarity (SSIM), and root mean square error (RMSE) for the proposed method are (49.043±1.571), (0.997±0.002), (0.003±0.001) and (51.329±1.998), (0.998±0.002), (0.003±0.001) for 35 kVp and 49 kVp, respectively. The PSNR of the proposed method shows greater improvement over TWIST (5.2%), SART (34.6%), FBP (40.4%) and TWIST (3.7%), SART (39.9%), FBP (50.3%) for 35 kVp and 49 kVp energy images, respectively. For the proposed method, the signal-to-noise ratio (SNR) of decomposed normal breast tissue (NBT) is (22.036±1.535), which exceeded that of TWIST, SART, and FBP by 7.5%, 49.6%, and 96.4%, respectively. The results reveal that the proposed algorithm achieves the best performance in both reconstructed and decomposed images under different levels of noise and the performance is due to the high sparsity and good denoising ability of minimization exploited to solve the convex optimization problem.

Conclusions: This study demonstrates the potential of applying dual-energy reconstruction in breast CT to detect and separate clustered MCs from healthy breast tissues without noise amplification. Compared to other competing methods, the proposed algorithm achieves the best noise suppression performance for both reconstructed and decomposed images.
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http://dx.doi.org/10.3233/XST-190639DOI Listing
October 2021

Identifying key regulatory genes of maize root growth and development by RNA sequencing.

Genomics 2020 11 19;112(6):5157-5169. Epub 2020 Sep 19.

Beijing Agriculture Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China. Electronic address:

Root system architecture (RSA), the spatio-temporal configuration of roots, plays vital roles in maize (Zea mays L.) development and productivity. We sequenced the maize root transcriptome of four key growth and development stages: the 6th leaf stage, the 12th leaf stage, the tasseling stage and the milk-ripe stage. Differentially expressed genes (DEGs) were detected. 81 DEGs involved in plant hormone signal transduction pathway and 26 transcription factor (TF) genes were screened. These DEGs and TFs were predicted to be potential candidate genes during maize root growth and development. Several of these genes are homologous to well-known genes regulating root architecture or development in Arabidopsis or rice, such as, Zm00001d005892 (AtERF109), Zm00001d027925 (AtERF73/HRE1), Zm00001d047017 (AtMYC2, OsMYC2), Zm00001d039245 (AtWRKY6). Identification of these key genes will provide a further understanding of the molecular mechanisms responsible for maize root growth and development, it will be beneficial to increase maize production and improve stress resistance by altering RSA traits in modern breeding.
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http://dx.doi.org/10.1016/j.ygeno.2020.09.030DOI Listing
November 2020

A radiomics method to classify microcalcification clusters in digital breast tomosynthesis.

Med Phys 2020 Aug 19;47(8):3435-3446. Epub 2020 May 19.

Department of Medical Imaging, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, 215163, China.

Purpose: Digital breast tomosynthesis (DBT) is becoming increasingly used in clinical practice. In DBT, the microcalcification clusters may span across multiple slices, which makes it difficult for radiologists to directly assess these distributed clusters for diagnosis. We investigated a radiomics method to classify microcalcification clusters in DBT based on a semiautomatic segmentation process.

Methods: We performed a retrospective study on a cohort of 275 patients (including 79 benign and 196 malignant cases) with a total of 550 DBT volumes. Our method consisted of three steps. The initial step was to semiautomatically segment the microcalcification clusters. Then, radiomics features were extracted from the initially segmented microcalcification clusters. Finally, the benign and malignant microcalcification clusters were differentiated by the random forest (RF) classifier using selected subset features. The radiomics models were evaluated both on view-based and case-based modes with features selected from different domains. The receiver operating characteristic (ROC) curve and area under the ROC curve (AUC) were used to evaluate the classification performance.

Results: Twenty-six key features were selected from a total of 170 radiomics features and these features show promising classification performance. The highest AUC was 0.834 for view-based mode and 0.868 for case-based mode when using features selected from the 3D-domain. The 2D-domain radiomics features showed a statistically similar performance to the 3D features (P > 0.05).

Conclusion: Radiomics models can provide encouraging performance in classification between malignant and benign microcalcification clusters which are semiautomatically segmented in DBT.
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http://dx.doi.org/10.1002/mp.14216DOI Listing
August 2020

Analyses of the Complete Genome Sequence of the Strain Bacillus pumilus ZB201701 Isolated from Rhizosphere Soil of Maize under Drought and Salt Stress.

Microbes Environ 2019 Sep 23;34(3):310-315. Epub 2019 Aug 23.

Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences.

Bacillus pumilus ZB201701 is a rhizobacterium with the potential to promote plant growth and tolerance to drought and salinity stress. We herein present the complete genome sequence of the Gram-positive bacterium B. pumilus ZB201701, which consists of a linear chromosome with 3,640,542 base pairs, 3,608 protein-coding sequences, 24 ribosomal RNAs, and 80 transfer RNAs. Genome analyses using bioinformatics revealed some of the putative gene clusters involved in defense mechanisms. In addition, activity analyses of the strain under salt and simulated drought stress suggested its potential tolerance to abiotic stress. Plant growth-promoting bacteria-based experiments indicated that the strain promotes the salt tolerance of maize. The complete genome of B. pumilus ZB201701 provides valuable insights into rhizobacteria-mediated salt and drought tolerance and rhizobacteria-based solutions for abiotic stress in agriculture.
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http://dx.doi.org/10.1264/jsme2.ME18096DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6759339PMC
September 2019

Distribution of Four Bioactive Flavonoids in Maize Tissues of Five Varieties and Correlation with Expression of the Biosynthetic Genes.

J Agric Food Chem 2018 Oct 2;66(40):10431-10437. Epub 2018 Oct 2.

Beijing Agro-Biotechnology Research Center , Beijing Academy of Agriculture and Forestry Sciences , Beijing 100097 , China.

Flavonoids are characteristic in maize and have diverse biological functions. C-Glycosylflavones are neuroprotective against β-amyloid-induced tau hyperphosphorylation and neurotoxicity in SH-SY5Y cells, which is relevant to Alzheimer's disease prevention and treatment. The content of the flavonoids eriodictyol, luteolin, isoorientin, and maysin varied in pollens, silks, tassels, and seeds among five maize varieties. Eriodictyol content was high (51-322 ng/g dw) in pollens, while luteolin content was low (0.2-106 ng/g dw) in all four tissues. The isoorientin content was approximately 3- to 10-fold greater than eriodictyol in pollens and tassels, particularly in the hybrid M1 and sweet corn M5 varieties. Maysin content was high in most silks and tassels. The differential expression of five genes involved in the maysin biosynthesis correlated well with the profiles of the four flavonoids among tissues and varieties. The present study offers valuable data for maize breeding and the use of maize flavonoids as functional food components.
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http://dx.doi.org/10.1021/acs.jafc.8b03865DOI Listing
October 2018

A low-cost home-built NMR using Halbach magnet.

J Magn Reson 2018 Sep 21;294:162-168. Epub 2018 Jul 21.

Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, Jiangsu, China. Electronic address:

The objective of this work is to develop a low-cost compact desktop NMR system based on Halbach magnets with the advantages of small size and ability to generate relatively high field strength. Considering the cost of manufacturing and assembling the magnetic blocks, the system utilized a 3-layer Halbach magnet and a wedge-shaped mechanical structure, which was designed for magnet rapid assembling. The comparison between simulation and calculation results of the initial magnetic field strength distribution showed that design theory and practice were in accordance. The initial homogeneity was 576 ppm in a square with a length of 5 mm. After passive shimming with two magnetic blocks and steel pieces, the uniformity reached 120 ppm in the same area. We developed and tested a compact single board spectrometer with digital modulation and demodulation in order to enhance the system mobility and improve the SNR. A self-made probe was used to carry out experiments with the spectrometer, and the spectral width at half-height reached 20 ppm in a cylinder with a diameter of 1.5 mm and a length of 1 mm. Compact structure and low cost of the system will facilitate and extend the application of desktop NMR system.
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http://dx.doi.org/10.1016/j.jmr.2018.07.014DOI Listing
September 2018

The complete genome sequence of Bacillus halotolerans ZB201702 isolated from a drought- and salt-stressed rhizosphere soil.

Microb Pathog 2018 Oct 17;123:246-249. Epub 2018 Jul 17.

Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China; Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing, 100097, China. Electronic address:

Bacillus halotolerans is a rhizobacterium with the potential to promote plant growth and tolerance to drought and salinity stress. Here, we present the complete genome sequence of B. halotolerans ZB201702, which consists of 4,150,000 bp in a linear chromosome, including 3074 protein-coding sequences, 30 rRNAs, and 85 tRNAs. Genome analysis revealed many putative gene clusters involved in defense mechanisms. Activity analysis of the strain under salt and simulated drought stress suggests tolerance to abiotic stresses. The complete genome information of B. halotolerans ZB201702 could provide valuable insights into rhizobacteria-mediated plant salt and drought tolerance and rhizobacteria-based solutions for abiotic stress agriculture.
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http://dx.doi.org/10.1016/j.micpath.2018.07.019DOI Listing
October 2018

Gaussian diffusion sinogram inpainting for X-ray CT metal artifact reduction.

Biomed Eng Online 2017 Jan 5;16(1). Epub 2017 Jan 5.

Medical Imaging Department, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Science, Suzhou, China.

Background: Metal objects implanted in the bodies of patients usually generate severe streaking artifacts in reconstructed images of X-ray computed tomography, which degrade the image quality and affect the diagnosis of disease. Therefore, it is essential to reduce these artifacts to meet the clinical demands.

Methods: In this work, we propose a Gaussian diffusion sinogram inpainting metal artifact reduction algorithm based on prior images to reduce these artifacts for fan-beam computed tomography reconstruction. In this algorithm, prior information that originated from a tissue-classified prior image is used for the inpainting of metal-corrupted projections, and it is incorporated into a Gaussian diffusion function. The prior knowledge is particularly designed to locate the diffusion position and improve the sparsity of the subtraction sinogram, which is obtained by subtracting the prior sinogram of the metal regions from the original sinogram. The sinogram inpainting algorithm is implemented through an approach of diffusing prior energy and is then solved by gradient descent. The performance of the proposed metal artifact reduction algorithm is compared with two conventional metal artifact reduction algorithms, namely the interpolation metal artifact reduction algorithm and normalized metal artifact reduction algorithm. The experimental datasets used included both simulated and clinical datasets.

Results: By evaluating the results subjectively, the proposed metal artifact reduction algorithm causes fewer secondary artifacts than the two conventional metal artifact reduction algorithms, which lead to severe secondary artifacts resulting from impertinent interpolation and normalization. Additionally, the objective evaluation shows the proposed approach has the smallest normalized mean absolute deviation and the highest signal-to-noise ratio, indicating that the proposed method has produced the image with the best quality.

Conclusions: No matter for the simulated datasets or the clinical datasets, the proposed algorithm has reduced the metal artifacts apparently.
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http://dx.doi.org/10.1186/s12938-016-0292-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5234134PMC
January 2017

Isolation, structural analysis, and expression characteristics of the maize nuclear factor Y gene families.

Biochem Biophys Res Commun 2016 09 4;478(2):752-8. Epub 2016 Aug 4.

Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, China; College of Agriculture, Yangtze University, Hubei Collaborative Innovation Center for Grain Industry, Jingzhou 434023, Hubei, China. Electronic address:

NUCLEAR FACTOR-Y (NF-Y) has been shown to play an important role in growth, development, and response to environmental stress. A NF-Y complex, which consists of three subunits, NF-YA, NF-YB, and, NF-YC, binds to CCAAT sequences in a promoter to control the expression of target genes. Although NF-Y proteins have been reported in Arabidopsis and rice, a comprehensive and systematic analysis of ZmNF-Y genes has not yet been performed. To examine the functions of ZmNF-Y genes in this family, we isolated and characterized 50 ZmNF-Y (14 ZmNF-YA, 18 ZmNF-YB, and 18 ZmNF-YC) genes in an analysis of the maize genome. The 50 ZmNF-Y genes were distributed on all 10 maize chromosomes, and 12 paralogs were identified. Multiple alignments showed that maize ZmNF-Y family proteins had conserved regions and relatively variable N-terminal or C-terminal domains. The comparative syntenic map illustrated 40 paralogous NF-Y gene pairs among the 10 maize chromosomes. Microarray data showed that the ZmNF-Y genes had tissue-specific expression patterns in various maize developmental stages and in response to biotic and abiotic stresses. The results suggested that ZmNF-YB2, 4, 8, 10, 13, and 16 and ZmNF-YC6, 8, and 15 were induced, while ZmNF-YA1, 3, 4, 6, 7, 10, 12, and 13, ZmNF-YB15, and ZmNF-YC3 and 9 were suppressed by drought stress. ZmNF-YA3, ZmNF-YA8 and ZmNF-YA12 were upregulated after infection by the three pathogens, while ZmNF-YA1 and ZmNF-YB2 were suppressed. These results indicate that the ZmNF-Ys may have significant roles in the response to abiotic and biotic stresses.
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http://dx.doi.org/10.1016/j.bbrc.2016.08.020DOI Listing
September 2016

Isolation, structural analysis, and expression characteristics of the maize TIFY gene family.

Mol Genet Genomics 2015 Oct 11;290(5):1849-58. Epub 2015 Apr 11.

Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China.

TIFY, previously known as ZIM, comprises a plant-specific family annotated as transcription factors that might play important roles in stress response. Despite TIFY proteins have been reported in Arabidopsis and rice, a comprehensive and systematic survey of ZmTIFY genes has not yet been conducted. To investigate the functions of ZmTIFY genes in this family, we isolated and characterized 30 ZmTIFY (1 TIFY, 3 ZML, and 26 JAZ) genes in an analysis of the maize (Zea mays L.) genome in this study. The 30 ZmTIFY genes were distributed over eight chromosomes. Multiple alignment and motif display results indicated that all ZmTIFY proteins share two conserved TIFY and Jas domains. Phylogenetic analysis revealed that the ZmTIFY family could be divided into two groups. Putative cis-elements, involved in abiotic stress response, phytohormones, pollen grain, and seed development, were detected in the promoters of maize TIFY genes. Microarray data showed that the ZmTIFY genes had tissue-specific expression patterns in various maize developmental stages and in response to biotic and abiotic stresses. The results indicated that ZmTIFY4, 5, 8, 26, and 28 were induced, while ZmTIFY16, 13, 24, 27, 18, and 30 were suppressed, by drought stress in the maize inbred lines Han21 and Ye478. ZmTIFY1, 19, and 28 were upregulated after infection by three pathogens, whereas ZmTIFY4, 13, 21, 23, 24, and 26 were suppressed. These results indicate that the ZmTIFY family may have vital roles in response to abiotic and biotic stresses. The data presented in this work provide vital clues for further investigating the functions of the genes in the ZmTIFY family.
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http://dx.doi.org/10.1007/s00438-015-1042-6DOI Listing
October 2015

Purification and characterization of ZmRIP1, a novel reductant-inhibited protein tyrosine phosphatase from maize.

Plant Physiol 2012 Jun 23;159(2):671-81. Epub 2012 Apr 23.

College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China.

Protein tyrosine phosphatases (PTPases) have long been thought to be activated by reductants and deactivated by oxidants, owing to the presence of a crucial sulfhydryl group in their catalytic centers. In this article, we report the purification and characterization of Reductant-Inhibited PTPase1 (ZmRIP1) from maize (Zea mays) coleoptiles, and show that this PTPase has a unique mode of redox regulation and signaling. Surprisingly, ZmRIP1 was found to be deactivated by a reductant. A cysteine (Cys) residue (Cys-181) near the active center was found to regulate this unique mode of redox regulation, as mutation of Cys-181 to arginine-181 allowed ZmRIP1 to be activated by a reductant. In response to oxidant treatment, ZmRIP1 was translocated from the chloroplast to the nucleus. Expression of ZmRIP1 in Arabidopsis (Arabidopsis thaliana) plants and maize protoplasts altered the expression of genes encoding enzymes involved in antioxidant catabolism, such as At1g02950, which encodes a glutathione transferase. Thus, the novel PTPase identified in this study is predicted to function in redox signaling in maize.
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http://dx.doi.org/10.1104/pp.111.191510DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3375933PMC
June 2012

Plasma membrane-associated proline-rich extensin-like receptor kinase 4, a novel regulator of Ca signalling, is required for abscisic acid responses in Arabidopsis thaliana.

Plant J 2009 Oct 30;60(2):314-27. Epub 2009 Jun 30.

Henan Key Laboratory of Plant Stress Biology, Department of Biology, Henan University, Kaifeng, China.

Plant roots respond to environmental stresses or the exogenous plant hormone abscisic acid (ABA) by undergoing marked physiological and morphological changes. We show here that PERK4, a gene that encodes a member of the Arabidopsis thaliana proline-rich extensin-like receptor kinase family, plays an important role in ABA responses. Mutation of PERK4 by T-DNA insertion decreased sensitivity to ABA with respect to seed germination, seedling growth and primary root tip growth. The effect on root growth was due to enhanced cell elongation rather than cell division. The cytosolic free calcium concentration and Ca(2+) channel currents were lower in perk4 root cells than in wild-type cells in the presence of ABA. Root growth was similar in wild-type and perk4 plants after the application of a Ca(2+) channel blocker. PERK4 localised to the plasma membrane, and was shown to be an ABA- and Ca(2+)-activated protein kinase. Our data suggest that the receptor-like kinase encoded by PERK4 functions at an early stage of ABA signalling to inhibit root cell elongation by perturbing Ca(2+) homeostasis.
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http://dx.doi.org/10.1111/j.1365-313X.2009.03956.xDOI Listing
October 2009

A distinct endosomal Ca2+/Mn2+ pump affects root growth through the secretory process.

Plant Physiol 2008 Aug 20;147(4):1675-89. Epub 2008 Jun 20.

Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742-5815, USA.

Ca(2+) is required for protein processing, sorting, and secretion in eukaryotic cells, although the particular roles of the transporters involved in the secretory system of plants are obscure. One endomembrane-type Ca-ATPase from Arabidopsis (Arabidopsis thaliana), AtECA3, diverges from AtECA1, AtECA2, and AtECA4 in protein sequence; yet, AtECA3 appears similar in transport activity to the endoplasmic reticulum (ER)-bound AtECA1. Expression of AtECA3 in a yeast (Saccharomyces cerevisiae) mutant defective in its endogenous Ca(2+) pumps conferred the ability to grow on Ca(2+)-depleted medium and tolerance to toxic levels of Mn(2+). A green fluorescent protein-tagged AtECA3 was functionally competent and localized to intracellular membranes of yeast, suggesting that Ca(2+) and Mn(2+) loading into internal compartment(s) enhanced yeast proliferation. In mesophyll protoplasts, AtECA3-green fluorescent protein associated with a subpopulation of endosome/prevacuolar compartments based on partial colocalization with the Ara7 marker. Interestingly, three independent eca3 T-DNA disruption mutants showed severe reduction in root growth normally stimulated by 3 mm Ca(2+), indicating that AtECA3 function cannot be replaced by an ER-associated AtECA1. Furthermore, root growth of mutants is sensitive to 50 microm Mn(2+), indicating that AtECA3 is also important for the detoxification of excess Mn(2+). Curiously, Ateca3 mutant roots produced 65% more apoplastic protein than wild-type roots, as monitored by peroxidase activity, suggesting that the secretory process was altered. Together, these results demonstrate that the role of AtECA3 is distinct from that of the more abundant ER AtECA1. AtECA3 supports Ca(2+)-stimulated root growth and the detoxification of high Mn(2+), possibly through activities mediated by post-Golgi compartments that coordinate membrane traffic and sorting of materials to the vacuole and the cell wall.
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http://dx.doi.org/10.1104/pp.108.119909DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2492598PMC
August 2008

Stomatal movement in response to long distance-communicated signals initiated by heat shock in partial roots of Commelina communis L.

Sci China C Life Sci 2006 Feb;49(1):18-25

School of Life Science, Sichuan University, Chengdu 610064, China.

The systematic or long-distance signal transmission plays crucial roles in animal lives. Compared with animals, however, much less is known about the roles of long-distance signal communication in plant lives. Using the model plant Commelina communis L., we have probed the root to shoot communication mediated by heat-shock signals. The results showed that a heat shock of 5 min at 40 degrees C in partial roots, i.e. half or even 1/4 root system, could lead to a significant decrease in stomatal conductance. The regulation capability depends on both heat shock temperature and the amount of root system, i.e. with higher temperature and more roots stressed, the leaf conductance would decrease more significantly. Interestingly, the stomatal regulation by heat shock signal is in a manner of oscillation: when stomata conductance decreased to the lowest level within about 30 min, it would increase rapidly and sometimes even exceed the initial level, and after several cycles the stomata conductance would be finally stabilized at a lower level. Feeding xylem sap collected from heat-shocked plants could lead to a decrease in stomata conductance, suggesting that the heat shock-initiated signal is basically a positive signal. Further studies showed that heat shock was not able to affect ABA content in xylem sap, and also, not able to lead to a decrease in leaf water status, which suggested that the stomatal regulation was neither mediated by ABA nor by a hydraulic signal. Heat shock could lead to an increase in xylem sap H2O2 content, and moreover, the removal of H2O2 by catalase could partially recover the stomatal inhibition by xylem sap collected from heat-shocked plants, suggesting that H2O2 might be able to act as one of the root signals to control the stomatal movement. Due to the fact that heat-shock and drought are usually two concomitant stresses, the stomatal regulation by heat-shock signal should be of significance for plant response to stresses. The observation for the stomatal regulation in an oscillation manner by presently identified new signals should contribute to further understanding of the mystery for the pant systematic signaling in response to stresses.
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http://dx.doi.org/10.1007/s11427-005-0117-8DOI Listing
February 2006

An endoplasmic reticulum-bound Ca(2+)/Mn(2+) pump, ECA1, supports plant growth and confers tolerance to Mn(2+) stress.

Plant Physiol 2002 Sep;130(1):128-37

Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742, USA.

Plants can grow in soils containing highly variable amounts of mineral nutrients, like Ca(2+) and Mn(2+), though the mechanisms of adaptation are poorly understood. Here, we report the first genetic study to determine in vivo functions of a Ca(2+) pump in plants. Homozygous mutants of Arabidopsis harboring a T-DNA disruption in ECA1 showed a 4-fold reduction in endoplasmic reticulum-type calcium pump activity. Surprisingly, the phenotype of mutant plants was indistinguishable from wild type when grown on standard nutrient medium containing 1.5 mM Ca(2+) and 50 microM Mn(2+). However, mutants grew poorly on medium with low Ca(2+) (0.2 mM) or high Mn(2+) (0.5 mM). On high Mn(2+), the mutants failed to elongate their root hairs, suggesting impairment in tip growth processes. Expression of the wild-type gene (CAMV35S::ECA1) reversed these conditional phenotypes. The activity of ECA1 was examined by expression in a yeast (Saccharomyces cerevisiae) mutant, K616, which harbors a deletion of its endogenous calcium pumps. In vitro assays demonstrated that Ca(2+), Mn(2+), and Zn(2+) stimulated formation of a phosphoenzyme intermediate, consistent with the translocation of these ions by the pump. ECA1 provided increased tolerance of yeast mutant to toxic levels of Mn(2+) (1 mM) and Zn(2+)(3 mM), consistent with removal of these ions from the cytoplasm. These results show that despite the potential redundancy of multiple Ca(2+) pumps and Ca(2+)/H(+) antiporters in Arabidopsis, pumping of Ca(2+) and Mn(2+) by ECA1 into the endoplasmic reticulum is required to support plant growth under conditions of Ca(2+) deficiency or Mn(2+) toxicity.
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http://dx.doi.org/10.1104/pp.004440DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC166546PMC
September 2002
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