bluuebunny/crossref_metadata_2025 huggingface dataset:
Zinc-Dependent Global Transcriptional Control, Transcriptional Deregulation, and Higher Gene Copy Number for Genes in Metal Homeostasis of the HyperaccumulatorArabidopsis halleri
Authors: Talke Ina N. , Hanikenne Marc , Krämer Ute
Published: July 2006

The metal hyperaccumulator Arabidopsis halleri exhibits naturally selected zinc (Zn) and cadmium (Cd) hypertolerance and accumulates extraordinarily high Zn concentrations in its leaves. With these extreme physiological traits, A. halleri phylogenetically belongs to the sister clade of Arabidopsis thaliana. Using a combination of genome-wide cross species microarray analysis and real-time reverse transcription-PCR, a set of candidate genes is identified for Zn hyperaccumulation, Zn and Cd hypertolerance, and the adjustment of micronutrient homeostasis in A. halleri. Eighteen putative metal homeostasis genes are newly identified to be more highly expressed in A. halleri than in A. thaliana, and 11 previously identified candidate genes are confirmed. The encoded proteins include HMA4, known to contribute to root-shoot transport of Zn in A. thaliana. Expression of either AtHMA4 or AhHMA4 confers cellular Zn and Cd tolerance to yeast (Saccharomyces cerevisiae). Among further newly implicated proteins are IRT3 and ZIP10, which have been proposed to contribute to cytoplasmic Zn influx, and FRD3 required for iron partitioning in A. thaliana. In A. halleri, the presence of more than a single genomic copy is a hallmark of several highly expressed candidate genes with possible roles in metal hyperaccumulation and metal hypertolerance. Both A. halleri and A. thaliana exert tight regulatory control over Zn homeostasis at the transcript level. Zn hyperaccumulation in A. halleri involves enhanced partitioning of Zn from roots into shoots. The transcriptional regulation of marker genes suggests that in the steady state, A. halleri roots, but not the shoots, act as physiologically Zn deficient under conditions of moderate Zn supply.
The Ethylene-InsensitivesickleMutant ofMedicago truncatulaShows Altered Auxin Transport Regulation during Nodulation
Authors: Prayitno Joko , Rolfe Barry G. , Mathesius Ulrike
Published: July 2006

We studied the ethylene-insensitive, hypernodulating mutant, sickle (skl), to investigate the interaction of ethylene with auxin transport during root nodulation in Medicago truncatula. Grafting experiments demonstrated that hypernodulation in skl is root controlled. Long distance transport of auxin from shoot to root was reduced by rhizobia after 24 h in wild type but not in skl. Similarly, the ethylene precursor 1-amino cyclopropane-1-carboxylic acid inhibited auxin transport in wild type but not in skl. Auxin transport at the nodule initiation zone was significantly reduced by rhizobia after 4 h in both wild type and skl. After 24 h, auxin transport significantly increased at the nodule initiation zone in skl compared to wild type, accompanied by an increase in the expression of the MtPIN1 and MtPIN2 (pin formed) auxin efflux transporters. Response assays to different auxins did not show any phenotype that would suggest a defect of auxin uptake in skl. The auxin transport inhibitor N-1-naphthylphtalamic acid inhibited nodulation in wild type but not skl, even though N-1-naphthylphtalamic acid still inhibited auxin transport in skl. Our results suggest that ethylene signaling modulates auxin transport regulation at certain stages of nodule development, partially through PIN gene expression, and that an increase in auxin transport relative to the wild type is correlated with higher nodule numbers. We also discuss the regulation of auxin transport in skl in comparison to previously published data on the autoregulation mutant, super numerary nodules (van Noorden et al., 2006).
ZmPIN1aandZmPIN1bEncode Two Novel Putative Candidates for Polar Auxin Transport and Plant Architecture Determination of Maize
Authors: Carraro Nicola , Forestan Cristian , Canova Sabrina , Traas Jan , Varotto Serena
Published: July 2006

Shoot apical meristems produce organs in a highly stereotypic pattern that involves auxin. Auxin is supposed to be actively transported from cell to cell by influx (AUXIN/LIKE AUXIN proteins) and efflux (PIN-FORMED proteins) membrane carriers. Current hypotheses propose that, at the meristem surface, PIN proteins create patterns of auxin gradients that, in turn, create patterns of gene expression and morphogenesis. These hypotheses are entirely based on work in Arabidopsis (Arabidopsis thaliana). To verify whether these models also apply to other species, we studied the behavior of PIN proteins during maize (Zea mays) development. We identified two novel putative orthologs of AtPIN1 in maize and analyzed their expression pattern during development. The expression studies were complemented by immunolocalization studies using an anti-AtPIN1 antibody. Interestingly, the maize proteins visualized by this antibody are almost exclusively localized in subepidermal meristematic layers. Both tassel and ear were characterized by a compact group of cells, just below the surface, carrying PIN. In contrast to or to complement what was shown in Arabidopsis, these results point to the importance of internally localized cells in the patterning process. We chose the barren inflorescence2 (bif2) maize mutant to study the role of auxin polar fluxes in inflorescence development. In severe alleles of bif2, the tassel and the ear present altered ZmPIN1a and ZmPIN1b protein expression and localization patterns. In particular, the compact groups of cells in the tassel and ear of the mutant were missing. We conclude that BIF2 is important for PIN organization and could play a role in the establishment of polar auxin fluxes in maize inflorescence, indirectly modulating the process of axillary meristem formation and development.
Polyamine Oxidase Is One of the Key Elements for Oxidative Burst to Induce Programmed Cell Death in Tobacco Cultured Cells
Authors: Yoda Hiroshi , Hiroi Yoshinobu , Sano Hiroshi
Published: July 2006

Programmed cell death plays a critical role during the hypersensitive response in the plant defense system. One of components that triggers it is hydrogen peroxide, which is generated through multiple pathways. One example is proposed to be polyamine oxidation, but direct evidence for this has been limited. In this article, we investigated relationships among polyamine oxidase, hydrogen peroxide, and programmed cell death using a model system constituted of tobacco (Nicotiana tabacum) cultured cell and its elicitor, cryptogein. When cultured cells were treated with cryptogein, programmed cell death occurred with a distinct pattern of DNA degradation. The level of hydrogen peroxide was simultaneously increased, along with polyamine oxidase activity in apoplast. With the same treatment in the presence of α-difluoromethyl-Orn, an inhibitor of polyamine biosynthesis, production of hydrogen peroxide was suppressed and programmed cell death did not occur. A gene encoding a tobacco polyamine oxidase that resides in the apoplast was isolated and used to construct RNAi transgenic cell lines. When these lines were treated with cryptogein, polyamines were not degraded but secreted into culture medium and hydrogen peroxide was scarcely produced, with a concomitant suppression of cell death. Activities of mitogen-activated protein kinases (wound- and salicylic acid-induced protein kinases) were also suppressed, indicating that phosphorylation cascade is involved in polyamine oxidation-derived cell death. These results suggest that polyamine oxidase is a key element for the oxidative burst, which is essential for induction of programmed cell death, and that mitogen-activated protein kinase is one of the factors that mediate this pathway.
Natural Genetic Variation of Freezing Tolerance in Arabidopsis
Authors: Hannah Matthew A. , Wiese Dana , Freund Susanne , Fiehn Oliver , Heyer Arnd G. , Hincha Dirk K.
Published: July 2006

Low temperature is a primary determinant of plant growth and survival. Using accessions of Arabidopsis (Arabidopsis thaliana) originating from Scandinavia to the Cape Verde Islands, we show that freezing tolerance of natural accessions correlates with habitat winter temperatures, identifying low temperature as an important selective pressure for Arabidopsis. Combined metabolite and transcript profiling show that during cold exposure, global changes of transcripts, but not of metabolites, correlate with the ability of Arabidopsis to cold acclimate. There are, however, metabolites and transcripts, including several transcription factors, that correlate with freezing tolerance, indicating regulatory pathways that may be of primary importance for this trait. These data identify that enhanced freezing tolerance is associated with the down-regulation of photosynthesis and hormonal responses and the induction of flavonoid metabolism, provide evidence for naturally increased nonacclimated freezing tolerance due to the constitutive activation of the C-repeat binding factors pathway, and identify candidate transcriptional regulators that correlate with freezing tolerance.
Expression of CAP2, an APETALA2-Family Transcription Factor from Chickpea, Enhances Growth and Tolerance to Dehydration and Salt Stress in Transgenic Tobacco
Authors: Shukla Rakesh K. , Raha Sumita , Tripathi Vineeta , Chattopadhyay Debasis
Published: July 2006

The APETALA2 (AP2) domain defines a large family of DNA-binding proteins that play important roles in plant morphology, development, and stress response. We describe isolation and characterization of a gene (CAP2) from chickpea (Cicer arietinum) encoding a novel AP2-family transcription factor. Recombinant CAP2 protein bound specifically to C-repeat/dehydration-responsive element in gel-shift assay and transactivated reporter genes in yeast (Saccharomyces cerevisiae) one-hybrid assay. CAP2 appeared to be a single/low copy intronless gene, and the protein product localized in the nucleus. Transcript level of CAP2 increased by dehydration and by treatment with sodium chloride, abscisic acid, and auxin, but not by treatment with low temperature, salicylic acid, and jasmonic acid. The 35S promoter-driven expression of CAP2 in tobacco (Nicotiana tabacum) caused drastic increase in the leaf cell size, and, thereby, in leaf surface area and number of lateral roots. Transgenic plants demonstrated more tolerance to dehydration and salt stress than the wild-type plants. Transgenic plants expressed higher steady-state transcript levels of abiotic stress-response genes NtERD10B and NtERD10C and auxin-response genes IAA4.2 and IAA2.5. Taken together, our results indicated a mutual interrelation between plant growth-development and abiotic stress-response pathways and a probable involvement of CAP2 in both the signaling pathways.
Circadian Clock Regulation of Starch Metabolism Establishes GBSSI as a Major Contributor to Amylopectin Synthesis in Chlamydomonas reinhardtii
Authors: Ral Jean-Philippe , Colleoni Christophe , Wattebled Fabrice , Dauvillée David , Nempont Clément , Deschamps Philippe , Li Zhongyi , Morell Matthew K. , Chibbar Ravindra , Purton Saul , d'Hulst Christophe , Ball Steven G.
Published: July 2006

Chlamydomonas reinhardtii displays a diurnal rhythm of starch content that peaks in the middle of the night phase if the algae are provided with acetate and CO2 as a carbon source. We show that this rhythm is controlled by the circadian clock and is tightly correlated to ADP-glucose pyrophosphorylase activity. Persistence of this rhythm depends on the presence of either soluble starch synthase III or granule-bound starch synthase I (GBSSI). We show that both enzymes play a similar function in synthesizing the long glucan fraction that interconnects the amylopectin clusters. We demonstrate that in log phase-oscillating cultures, GBSSI is required to obtain maximal polysaccharide content and fully compensates for the loss of soluble starch synthase III. A point mutation in the GBSSI gene that prevents extension of amylopectin chains, but retains the enzyme's normal ability to extend maltooligosaccharides, abolishes the function of GBSSI both in amylopectin and amylose synthesis and leads to a decrease in starch content in oscillating cultures. We propose that GBSSI has evolved as a major enzyme of amylopectin synthesis and that amylose synthesis comes as a secondary consequence of prolonged synthesis by GBSSI in arrhythmic systems. Maintenance in higher plant leaves of circadian clock control of GBSSI transcription is discussed.
Wounding Stimulates the Accumulation of Glycerolipids Containing Oxophytodienoic Acid and Dinor-Oxophytodienoic Acid in Arabidopsis Leaves
Authors: Buseman Christen M. , Tamura Pamela , Sparks Alexis A. , Baughman Ethan J. , Maatta Sara , Zhao Jian , Roth Mary R. , Esch Steven Wynn , Shah Jyoti , Williams Todd D. , Welti Ruth
Published: July 2006

Although oxylipins can be synthesized from free fatty acids, recent evidence suggests that oxylipins are components of plastid-localized polar complex lipids in Arabidopsis (Arabidopsis thaliana). Using a combination of electrospray ionization (ESI) collisionally induced dissociation time-of-flight mass spectrometry (MS) to identify acyl chains, ESI triple-quadrupole (Q) MS in the precursor mode to identify the nominal masses of complex polar lipids containing each acyl chain, and ESI Q-time-of-flight MS to confirm the identifications of the complex polar lipid species, 17 species of oxylipin-containing phosphatidylglycerols, monogalactosyldiacylglycerols (MGDG), and digalactosyldiacylglycerols (DGDG) were identified. The oxylipins of these polar complex lipid species include oxophytodienoic acid (OPDA), dinor-OPDA (dnOPDA), 18-carbon ketol acids, and 16-carbon ketol acids. Using ESI triple-Q MS in the precursor mode, the accumulation of five OPDA- and/or dnOPDA-containing MGDG and two OPDA-containing DGDG species were monitored as a function of time in mechanically wounded leaves. In unwounded leaves, the levels of these oxylipin-containing complex lipid species were low, between 0.001 and 0.023 nmol/mg dry weight. However, within the first 15 min after wounding, the levels of OPDA-dnOPDA MGDG, OPDA-OPDA MGDG, and OPDA-OPDA DGDG, each containing two oxylipin chains, increased 200- to 1,000-fold. In contrast, levels of OPDA-hexadecatrienoic acid MGDG, linolenic acid (18:3)-dnOPDA MGDG, OPDA-18:3 MGDG, and OPDA-18:3 DGDG, each containing a single oxylipin chain, rose 2- to 9-fold. The rapid accumulation of high levels of galactolipid species containing OPDA-OPDA and OPDA-dnOPDA in wounded leaves is consistent with these lipids being the primary products of plastidic oxylipin biosynthesis.
Genetic Control of Fruit Vitamin C Contents
Authors: Davey Mark W. , Kenis Katrien , Keulemans Johan
Published: July 2006

An F1 progeny derived from a cross between the apple (Malus x domestica) cultivars Telamon and Braeburn was used to identify quantitative trait loci (QTL) linked to the vitamin C (l-ascorbate [l-AA]) contents of fruit skin and flesh (cortex) tissues. We identified up to three highly significant QTLs for both the mean l-AA and the mean total l-AA contents of fruit flesh on both parental genetic linkage maps, confirming the quantitative nature of these traits. These QTLs account for up to a maximum of 60% of the total population variation observed in the progeny, and with a maximal individual contribution of 31% per QTL. QTLs common to both parents were identified on linkage groups (LGs) 6, 10, and 11 of the Malus reference map, while each parent also had additional unique QTLs on other LGs. Interestingly, one strong QTL on LG-17 of the Telamon linkage map colocalized with a highly significant QTL associated with flesh browning, and a minor QTL for dehydroascorbate content, supporting earlier work that links fruit l-AA contents with the susceptibility of hardfruit to postharvest browning. We also found significant minor QTLs for skin l-AA and total l-AA (l-AA + dehydroascorbate) contents in Telamon. Currently, little is known about the genetic determinants underlying tissue l-AA homeostasis, but the presence of major, highly significant QTL in both these apple genotypes under field conditions suggests the existence of common control mechanisms, allelic heterozygosity, and helps outline strategies and the potential for the molecular breeding of these traits.
The Multigene Family Encoding Germin-Like Proteins of Barley. Regulation and Function in Basal Host Resistance
Authors: Zimmermann Grit , Bäumlein Helmut , Mock Hans-Peter , Himmelbach Axel , Schweizer Patrick
Published: July 2006

Germin-like proteins (GLPs) have been shown to be encoded by multigene families in several plant species and a role of some subfamily members in defense against pathogen attack has been proposed based on gene regulation studies and transgenic approaches. We studied the function of six GLP subfamilies of barley (Hordeum vulgare) by selecting single mRNAs for gene expression studies as well as overexpression and gene-silencing experiments in barley and Arabidopsis (Arabidopsis thaliana). Expression of all six subfamilies was high in very young seedlings, including roots. The expression pattern gradually changed from developmental to conditional with increasing plant age, whereby pathogen attack and exogenous hydrogen peroxide application were found to be the strongest signals for induction of several GLP subfamilies. Transcripts of four of five GLP subfamilies that are expressed in shoots were predominantly accumulating in the leaf epidermis. Transient overexpression of HvGER4 or HvGER5 as well as transient silencing by RNA interference of HvGER3 or HvGER5 protected barley epidermal cells from attack by the appropriate powdery mildew fungus Blumeria graminis f. sp. hordei. Silencing of HvGER4 induced hypersusceptibility. Transient and stable expression of subfamily members revealed HvGER5 as a new extracellular superoxide dismutase, and protection by overexpression could be demonstrated to be dependent on superoxide dismutase activity of the encoded protein. Data suggest a complex interplay of HvGER proteins in fine regulation of basal resistance against B. graminis.
The TATA-Box Sequence in the Basal Promoter Contributes to Determining Light-Dependent Gene Expression in Plants
Authors: Kiran Kanti , Ansari Suraiya A. , Srivastava Rakesh , Lodhi Niraj , Chaturvedi Chandra Prakash , Sawant Samir V. , Tuli Rakesh
Published: July 2006

A prototype 13-bp TATA-box sequence, TCACTATATATAG, was mutated at each nucleotide position and examined for its function in the core promoter. Specific nucleotides in the first TATA, the second TATA, as well as the flanking sequences influenced promoter function in transient transformation of tobacco (Nicotiana tabacum var Petit Havana) leaves. The effect of a given mutation on reporter gene expression in light versus dark was variable and sometimes contrasting. Some mutations, like T7 or A8→C or G, completely inactivated the expression of the minimal promoter in light but not in dark. In general, the sequence requirement for dark expression was less stringent than that for light expression. The selective effect of TATA-box mutations on light versus dark expression was exerted on core promoter function in the chromatin-integrated state also. Even in the presence of an upstream light response activator element, TATA-box mutations influenced modulation of the promoter by light. An A at the eighth position was specifically involved in the red light response of the promoter. Selectivity in gene expression was associated with a high level of transcript initiation from a site that was not active in the dark. Nuclear proteins from dark- and light-grown seedlings showed that the sequence variation within the TATA-box governs the formation of alternative transcriptional complexes. The experiments give direct evidence for the role of a core TATA-box sequence in determining the level as well as selectivity of gene expression in plants.
The Role of Pheophorbide a Oxygenase Expression and Activity in the Canola Green Seed Problem
Authors: Chung Davyd W. , Pružinská Adriana , Hörtensteiner Stefan , Ort Donald R.
Published: July 2006

Under normal field growth conditions, canola (Brassica napus) seeds produce chloroplasts during early seed development and then catabolize the photosynthetic machinery during seed maturation, producing mature seeds at harvest that are essentially free of chlorophyll (Chl). However, frost exposure early in canola seed development disrupts the normal programming of Chl degradation, resulting in green seed at harvest and thereby significantly devaluing the crop. Pheophorbide a oxygenase (PaO), a key control point in the overall regulation of Chl degradation, was affected by freezing. Pheophorbide a, the substrate of PaO, accumulated during late stages of maturation in seeds that had been exposed to freezing during early seed development. Freezing interfered with the induction of PaO activity that normally occurs in the later phases of canola seed development when Chl should be cleared from the seed. Moreover, we found that the induction of PaO activity in canola seed was largely posttranslationally controlled and it was at this level that freezing interfered with PaO activation. The increased accumulation of PaO transcript and protein levels during seed development was not altered by the freezing episode, and the increase in PaO protein was small compared to the increase in PaO activity. We found that PaO could be phosphorylated and that phosphorylation decreased with increasing activity, implicating PaO dephosphorylation as an important posttranslational control mechanism for this enzyme. Two PaO genes, BnPaO1 and BnPaO2, were identified in senescing canola leaves and during early seed development, but only BnPaO2 was expressed in maturing, degreening seeds.
The Medicago truncatula Lysine Motif-Receptor-Like Kinase Gene Family Includes NFP and New Nodule-Expressed Genes
Authors: Arrighi Jean-François , Barre Annick , Ben Amor Besma , Bersoult Anne , Soriano Lidia Campos , Mirabella Rossana , de Carvalho-Niebel Fernanda , Journet Etienne-Pascal , Ghérardi Michèle , Huguet Thierry , Geurts René , Dénarié Jean , Rougé Pierre , Gough Clare
Published: July 2006

Rhizobial Nod factors are key symbiotic signals responsible for starting the nodulation process in host legume plants. Of the six Medicago truncatula genes controlling a Nod factor signaling pathway, Nod Factor Perception (NFP) was reported as a candidate Nod factor receptor gene. Here, we provide further evidence for this by showing that NFP is a lysine motif (LysM)-receptor-like kinase (RLK). NFP was shown both to be expressed in association with infection thread development and to be involved in the infection process. Consistent with deviations from conserved kinase domain sequences, NFP did not show autophosphorylation activity, suggesting that NFP needs to associate with an active kinase or has unusual functional characteristics different from classical kinases. Identification of nine new M. truncatula LysM-RLK genes revealed a larger family than in the nonlegumes Arabidopsis (Arabidopsis thaliana) or rice (Oryza sativa) of at least 17 members that can be divided into three subfamilies. Three LysM domains could be structurally predicted for all M. truncatula LysM-RLK proteins, whereas one subfamily, which includes NFP, was characterized by deviations from conserved kinase sequences. Most of the newly identified genes were found to be expressed in roots and nodules, suggesting this class of receptors may be more extensively involved in nodulation than was previously known.
PoplarFT2Shortens the Juvenile Phase and Promotes Seasonal Flowering
Authors: Hsu Chuan-Yu , Liu Yunxia , Luthe Dawn S. , Yuceer Cetin
Published: July 2006

Many woody perennials, such as poplar (Populus deltoides), are not able to form flower buds during the first several years of their life cycle. They must undergo a transition from the juvenile phase to the reproductive phase to be competent to produce flower buds. After this transition, trees begin to form flower buds in the spring of each growing season. The genetic factors that control flower initiation, ending the juvenile phase, are unknown in poplar. The factors that regulate seasonal flower bud formation are also unknown. Here, we report that poplar FLOWERING LOCUS T2 (FT2), a relative of the Arabidopsis thaliana flowering-time gene FT, controls first-time and seasonal flowering in poplar. The FT2 transcript is rare during the juvenile phase of poplar. When juvenile poplar is transformed with FT2 and transcript levels are increased, flowering is induced within 1 year. During the transition between vegetative and reproductive growth in mature trees, FT2 transcripts are abundant during reproductive growth under long days. Subsequently, floral meristems emerge on flanks of the axillary inflorescence shoots. These findings suggest that FT2 is part of the flower initiation pathway in poplar and plays an additional role in regulating seasonal flower initiation that is integrated with the poplar perennial growth habit.
ArabidopsisABA INSENSITIVE4 Regulates Lipid Mobilization in the Embryo and Reveals Repression of Seed Germination by the Endosperm
Authors: Penfield Steven , Li Yi , Gilday Alison D. , Graham Stuart , Graham Ian A.
Published: July 2006

Regulation of seed germination requires coordinate action by the embryo and surrounding endosperm. We used Arabidopsis thaliana to establish the relative roles of embryo and endosperm in the control of seed germination and seedling establishment. We previously showed that endospermic oil reserves are used postgerminatively via gluconeogenesis to fuel seedling establishment and that lipid breakdown is repressed by abscisic acid (ABA) in embryo but not endosperm tissues. Here, we use RNA amplification to describe the transcriptome of the endosperm and compare the hormone responses of endosperm and embryo tissues. We show that the endosperm responds to both ABA and gibberellin but that ABA in particular regulates nuclear but not plastid-encoded photosynthetic gene expression in the embryo. We also show that ABA INSENSITIVE4 (ABI4) expression is confined to the embryo, accounts for the major differences in embryo response to ABA, and defines a role for ABI4 as a repressor of lipid breakdown. Furthermore, ABI5 expression in the endosperm defines a second region of altered ABA signaling in the micropylar endosperm cap. Finally, embryo and endosperm ABA signaling mutants demonstrate the spatial specificity of ABA action in seed germination. We conclude that the single cell endosperm layer plays an active role in the regulation of seed germination in Arabidopsis.
Distinct Domains in the ARC Region of the Potato Resistance Protein Rx Mediate LRR Binding and Inhibition of Activation
Authors: Rairdan Gregory J. , Moffett Peter
Published: July 2006

Plant nucleotide binding and leucine-rich repeat (NB-LRR) proteins contain a region of homology known as the ARC domain located between the NB and LRR domains. Structural modeling suggests that the ARC region can be subdivided into ARC1 and ARC2 domains. We have used the potato (Solanum tuberosum) Rx protein, which confers resistance to Potato virus X (PVX), to investigate the function of the ARC region. We demonstrate that the ARC1 domain is required for binding of the Rx N terminus to the LRR domain. Domain-swap experiments with Rx and a homologous disease resistance gene, Gpa2, showed that PVX recognition localized to the C-terminal half of the LRR domain. However, inappropriate pairings of LRR and ARC2 domains resulted in autoactive molecules. Thus, the ARC2 domain is required to condition an autoinhibited state in the absence of elicitor as well as for the subsequent elicitor-induced activation. Our data suggest that the ARC region, through its interaction with the LRR, translates elicitor-induced modulations of the C terminus into a signal initiation event. Furthermore, we demonstrate that physical disruption of the LRR–ARC interaction is not required for signal initiation. We propose instead that this activity can lead to multiple rounds of elicitor recognition, providing a means of signal amplification.
Analysis of thePetunia TM6MADS Box Gene Reveals Functional Divergence within theDEF/AP3Lineage
Authors: Rijpkema Anneke S. , Royaert Stefan , Zethof Jan , van der Weerden Gerard , Gerats Tom , Vandenbussche Michiel
Published: July 2006

Antirrhinum majus DEFICIENS (DEF) and Arabidopsis thaliana APETALA3 (AP3) MADS box proteins are required to specify petal and stamen identity. Sampling of DEF/AP3 homologs revealed two types of DEF/AP3 proteins, euAP3 and TOMATO MADS BOX GENE6 (TM6), within core eudicots, and we show functional divergence in Petunia hybrida euAP3 and TM6 proteins. Petunia DEF (also known as GREEN PETALS [GP]) is expressed mainly in whorls 2 and 3, and its expression pattern remains unchanged in a blind (bl) mutant background, in which the cadastral C-repression function in the perianth is impaired. Petunia TM6 functions as a B-class organ identity protein only in the determination of stamen identity. Atypically, Petunia TM6 is regulated like a C-class rather than a B-class gene, is expressed mainly in whorls 3 and 4, and is repressed by BL in the perianth, thereby preventing involvement in petal development. A promoter comparison between DEF and TM6 indicates an important change in regulatory elements during or after the duplication that resulted in euAP3- and TM6-type genes. Surprisingly, although TM6 normally is not involved in petal development, 35S-driven TM6 expression can restore petal development in a def (gp) mutant background. Finally, we isolated both euAP3 and TM6 genes from seven solanaceous species, suggesting that a dual euAP3/TM6 B-function system might be the rule in the Solanaceae.
Functional Analyses of Two TomatoAPETALA3Genes Demonstrate Diversification in Their Roles in Regulating Floral Development
Authors: de Martino Gemma , Pan Irvin , Emmanuel Eyal , Levy Avraham , Irish Vivian F.
Published: July 2006

The floral homeotic APETALA3 (AP3) gene in Arabidopsis thaliana encodes a MADS box transcription factor required for specifying petal and stamen identities. AP3 is a member of the euAP3 lineage, which arose by gene duplication coincident with radiation of the core eudicots. Although Arabidopsis lacks genes in the paralogous Tomato MADS box gene 6 (TM6) lineage, tomato (Solanum lycopersicum) possesses both euAP3 and TM6 genes, which have functionally diversified. A loss-of-function mutation in Tomato AP3 (TAP3) resulted in homeotic transformations of both petals and stamens, whereas RNA interference–induced reduction in TM6 function resulted in flowers with homeotic defects primarily in stamens. The functional differences between these genes can be ascribed partly to different expression domains. When overexpressed in an equivalent domain, both genes can partially rescue the tap3 mutant, indicating that relative levels as well as spatial patterns of expression contribute to functional differences. Our results also indicate that the two proteins have differing biochemical capabilities. Together, these results suggest that TM6 and TAP3 play qualitatively different roles in floral development; they also support the ideas that the ancestral role of AP3 lineage genes was in specifying stamen development and that duplication and divergence in the AP3 lineage allowed for the acquisition of a role in petal specification in the core eudicots.
Tobacco Tsip1, a DnaJ-Type Zn Finger Protein, Is Recruited to and Potentiates Tsi1-Mediated Transcriptional Activation
Authors: Ham Byung-Kook , Park Jeong Mee , Lee Suk-Bae , Kim Min Jung , Lee In-Ju , Kim Ki-Jeong , Kwon Chang Seob , Paek Kyung-Hee
Published: July 2006

Tobacco stress-induced1 (Tsi1) is an ethylene-responsive-element binding protein/APETALA2–type transcription factor that plays an important role in both biotic and abiotic stress signaling pathways. We show that Tsi1-interacting protein1 (Tsip1), a DnaJ-type Zn finger protein, interacts with Tsi1 in vitro and in yeast (Saccharomyces cerevisiae). The transcript level of Tsip1 in tobacco (Nicotiana tabacum) increased upon treatment with salicylic acid (SA), ethylene, gibberellic acid, NaCl, and virus challenge. Tsip1 appeared to be physically associated with the chloroplast surface but dissociated from it after SA treatment. Tsip1 colocalized and coimmunoprecipitated with Tsi1 in plant cells following SA treatment. Tsip1 expression increased Tsi1-mediated transcription and was able to functionally compensate for loss of the Tsi1 transcriptional activation domain through a direct interaction with Tsi1. Transgenic plants simultaneously coexpressing Tsi1 and Tsip1 displayed stronger pathogen resistance and salt tolerance than did transgenic plants expressing either Tsi1 or Tsip1 alone. Concurrent with this, the expression of a subset of stress-related genes was induced in a cooperative manner in Tsi1/Tsip1 transgenic plants. These results together implied that Tsi1 recruits Tsip1 to the promoters of stress-related genes to potentiate Tsi1-mediated transcriptional activation.
Users' assessment of library security: a Nigerian university case study
Authors: Ajegbomogun F.O.
Published: July 2006

The paper examines the incidence of theft and mutilation of library materials, and gives users’ assessment of library security and factors that influence theft and mutilation among library users in Nigerian university libraries. Questionnaire method was used to obtain data. Of the users surveyed, 62.63 percent admitted that stealing and mutilation were common phenomena among library users. Some reasons given for this are: limited copies of library books, fear that one may not find the materials on the shelf and negligence of library security men. Suggestions were made on how to deal with culprits caught. The paper concludes by offering some useful suggestions on the way out of these problems.
Automation of high throughput screening
Authors: Delorme Denis S.
Published: July 2006

Advanced software is the key to successful laboratory automation. This article first describes a process known as high throughput screening used in the discovery of new drugs. The automation of high throughput screening is then outlined at three different scales of investment and resultant throughput. Finally, a comprehensive software architecture is presented. This architecture addresses the key concerns of end users: reliability, flexibility, modularity and ease of use.
Cleanroom robots become cleaner and more reliable
Authors: Kochan Anna
Published: July 2006

Reviews the application of industrial robots in cleanroom environments. Outlines how trends in electronics design are increasing the demand for cleanroom robots. Reviews how cleanroom robots can be used in disk drive and semiconductor production. Outlines how cleanroom robots are also necessary in the pharmaceutical industry.
Human scale robots have a role to play in British hospitals
Authors: Wilson Graham
Published: July 2006

Discusses the use of robots in pharmaceutical laboratories for repetitive tasks and dealing with dangerous substances such as radioisotopes. Presents a project undertaken by BNFL, Amercare Ltd and Middlesex University to develop a fully automated radiopharmaceutical dispensing system. Discusses the testing of this system at Guys Hospital.
Laser‐interferometry‐based tracking for dynamic measurements
Authors: Shirinzadeh Bijan
Published: July 2006

The accurate measurement of the position and orientation of a robot end‐effector is the most critical issue for calibrating of robotic devices. Calibration methods provide tools to improve the accuracy of robots without modification to the mechanical unit or its control architecture. However, such calibration techniques require a large number of measurements. Dynamic measurement of position and orientation not only provides a solution to this problem, it also establishes the foundation for development of techniques to improve the robot’s dynamic accuracy. The concept of laser‐interferometry‐based measurement has been proposed. A system based on this concept is generally referred to as a laser tracking system (LTS). This paper describes the principle of laser‐interferometry‐based tracking. Further, the structure and various components within such a system are presented. A kinematic model for laser tracking is described and the performance of the system in its present configuration is presented. The application potential of such an approach to position and orientation (pose) measurement is also briefly described.
Passive compliance versus active compliance in robot‐based automated assembly systems
Authors: Wang Wei , Loh Robert N.K. , Gu Edward Y.
Published: July 2006

Industrial robots have found great potential in applications to assembly‐line automation. Programmable robot‐based assembly systems are often needed, in particular for circumstances in which special assembly equipments is not available or well‐trained operators could not be employed economically. Robots with enough compliance can perform not only classic automation tasks, such as spot welding, cargo carrying, etc., but also can operate those tasks which demand the compliant motion capacity of robots. Therefore, the research on robot compliance is especially important for parts assembly by robots, where robot compliant motions and manipulations are essential requirements. This paper presents a number of important issues in robot compliance research, including the specification of robot end‐effector compliance; properties of a robot compliance matrix at its end‐effector; discussions on passive compliance and active compliance and their comparisons; and derivation of the compliance at the end‐effector required for tasks.
RoboKent ‐ a case study in man‐machine interfaces
Authors: Larson Jan
Published: July 2006

The idea of robotic floor cleaning landed on the housekeeping industry like an alien from outer space in the early part of the decade. An industry that had seen little progress in the past 100 years suddenly was faced with a method of scrubbing and sweeping floors without a human being trailing a machine. It was frightening for employees unfamiliar with computers and afraid of losing their jobs and it was no small outlay for the housekeeping budget. It has taken less than five years for an industry, managers and staff alike, to realize the benefits and lead the way into the future with service robots.
HelpMate, a service robot with experience
Authors: Engelberger Gay
Published: July 2006

With almost a decade of experience, HelpMate is a material transport service robot that works in hospitals, side‐by‐side with human co‐workers, delivering equipment and supplies to and from nursing units. Much has been written about the technology that allows HelpMate to navigate autonomously in such non‐structured environments, but little attention has been paid to the non‐technical aspects of these service applications. What special conditions exist in non‐manufacturing environments that a service robot must be able to cope with? How should a service robot be introduced into such environments? How is such a robot received by its fellow human beings? This paper shares the lessons that HelpMate has learned.
M2VIP ‐ mechatronics walking and swimming down under
Authors: Maxwell Andrew
Published: July 2006

Mechatronics, the art of combining robotics, computer control, and electronics, was the topic at the recent annual M2VIP conference (mechatronics and machine vision in practice) held at the University of Southern Queensland, Toowoomba, Australia, 23‐25 September. This was the fourth conference in the series which originated in Toowoomba in 1994, followed by Hong Kong in 1995 and Portugal in 1996. Papers from all around the globe were presented showing varied aspects of research ranging from mechatronic education, sensor design, mobile legged robots, self learning systems, robots in manufacturing, through to novel applications of mechatronics in sport. Some of the more memorable articles for the author are highlighted including mechatronic education, sport mechatronic systems, almost‐human walking robots, and autonomous underwater surveillance submarines.
The man‐machine interface get friendlier at Manufacturing Week
Authors: Rooks Brian
Published: July 2006

A report on robots at the Manufacturing Week exhibition, highlighting some of the developments on show in the man‐machine interface field. This reveals that the Windows environment is becoming increasingly popular for robot manufacturers. Special attention is given to the exhibits of two robot companies. In the first, a new robot off‐line programming and simulation system from Kuka is described. Its uniqueness is that the robot controller logic module and software is embedded into the off‐line programming PC, so that developed programs can be directly downloaded to the robot. The second, shown by System Devices, is a Windows‐based programming support package developed by Epson for its SCARA robots.
Military look to flying insect robots
Authors: Hollingum Jack
Published: July 2006

Reviews a presentation by Professor Robert Michelson of Georgia Institute of Technology in the USA about the growing interest in unmanned aerial vehicles, which can be used for military purposes, but also for tasks like traffic surveillance. Michelson has a particular interest in micro aerial vechiles, and he has a team at Georgia Tech Research Institute developing an insect‐like flapping wing vehicle called an “entomopter”, which is expected to fly in 1998. Michelson has also instituted a series of international aerial robotics competitions, of which the most ambitious it to be held in the millennial year. The competition will simulate search and rescue operations in a disaster situation. The rules are published and qualifying tests will begin in 1998.
Sensor‐referenced multiple robot cooperation for material handling
Authors: Xi Ning , Tarn Tzyh‐Jong
Published: July 2006

In this paper, a new cooperation control scheme for multiple robot material handling is presented. First, the event‐based planning and control method is introduced, which lays down the foundation for sensor‐referenced cooperation of multiple robot systems. The key step is the development of event‐based action reference. Based on the real‐time sensory information, the event‐based action reference drives the system to achieve the best possible coordination. The event‐based cooperation control scheme can easily be implemented in a distributed computer system. A real‐time control and computing architecture is proposed to implement this scheme in a parallel computation. The new multiple robot cooperation scheme has been experimentally implemented and tested on two 6‐DOF PUMA 560 robots. The experimental results have demonstrated the advantages of the scheme.
Issues and experimental results in vision‐guided robotic grasping of static or moving objects
Authors: Papanikolopoulos Nikolaos , Smith Christopher E.
Published: July 2006

Many research efforts have turned to sensing, and in particular computer vision, to create more flexible robotic systems. Computer vision is often required to provide data for the grasping of a target. Using a vision system for grasping of static or moving objects presents several issues with respect to sensing, control, and system configuration. This paper presents some of these issues in concept with the options available to the researcher and the trade‐offs to be expected when integrating a vision system with a robotic system for the purpose of grasping objects. The paper includes a description of our experimental system and contains experimental results from a particular configuration that characterize the type and frequency of errors encountered while performing various vision‐guided grasping tasks. These error classes and their frequency of occurrence lend insight into the problems encountered during visual grasping and into the possible solution of these problems.
Surgeons’ realizations of RoboDoc
Authors: Pransky Joanne
Published: July 2006

Describes interviews with the two surgeons that have performed the most surgeries worldwide using the RoboDoc system, an integrated system that combines computer‐based medical imaging and surgical robotics systems. For both doctors, the RobDoc system has exceeded their initial expectations. The article also describes the benefits of the RobDoc system as compared to the manual method of cementless implantation.
Section 404 implementation
Authors: Cenker William J. , Nagy Albert L.
Published: July 2006

Section 404 of the Sarbanes‐Oxley Act requires management to include in the annual report a report on the effectiveness of the company's internal control over financial reporting. This assessment must be supported by evidential matter, including documentation, regarding both the design of internal controls and the testing process. Understandably, many executives are seeking the assistance from their internal auditors in satisfying the Section 404 requirements, leaving internal auditors with the important task of ensuring that the corporation's internal control system is properly documented and tested. This paper discusses how nine leading internal auditors of large publicly listed corporations are assisting their respective companies in implementing the Section 404 requirements. Further discusses some of the significant issues that these auditors are addressing and their prediction on the expected future impact of Section 404.
Object detecting artificial retina
Authors: Wilson James G. , Mitchell Richard J.
Published: July 2006

This paper describes the novel use of agent and cellular neural Hopfield network techniques in the design of a self‐contained, object detecting retina. The agents, which are used to detect features within an image, are trained using the Hebbian method which has been modified for the cellular architecture. The success of each agent is communicated with adjacent agents in order to verify the detection of an object. Initial work used the method to process bipolar images. This has now been extended to handle grey scale images. Simulations have demonstrated the success of the method and further work is planned in which the device is to be implemented in hardware.
The forecasting performance of Cartesian ARIMA search and a vector‐valued state space model
Authors: Östermark Ralf
Published: July 2006

The performance of Aoki’s state space algorithm and the Cartesian ARIMA search algorithm (CARlMA) of Östermark and Höglund is compared. The analysis is carried out on a set of stock prices on the Helsinki (Finland) and Stockholm (Sweden) Stock Exchanges. Demonstrates that the Finnish and Swedish stock markets differ in predictability of stock prices. With Finnish stock data, Aoki’s state space algorithm outperforms the subset of MAPE minimizing forecasts. In contrast, with Swedish stock data, ARIMA‐models of a fairly simple structure outperform Aoki’s algorithm. The stock markets are seen to differ in complexity of time series models as well as in predictability of individual asset prices.
Generation of α‐dense curves and application to global optimization
Authors: Ziadi A. , Cherruault Y.
Published: July 2006

The reducing transformation and global optimization technique called Alienor has been developed in the 1980s by Cherruault and Guillez. These methods are based on the approximating properties of α ‐dense curves. The aim of this work is to give a very large class of functions generating α ‐dense curves in a hyper‐rectangle of Rn.
Automation seen as delegation
Authors: Bucki Janusz , Pesqueux Yvon
Published: July 2006

Companies are becoming more and more dependent on data processing systems. In this context, cybernetics again finds its meaning dealing with man‐machine communication problems. The two professions (data‐processing and management) have to find an answer to the same question: how to present a model of a company as a complex system? Decision system analysis follows this trend and suggests a set of concepts and approaches that allows us to analyze and conceive complex systems, whether they be human organizations or systems of artefacts. Despite the fact that it belongs to the cybernetic trend of thinking, the analysis integrates such notions as culture, creativity, well‐being, goals, real time, suggesting a more complete vision of these aspects starting from a logical deductive model, to a renewed cybernetic vision.