bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Feeding Spodoptera littoralis on Lima Bean Leaves. I. Membrane Potentials, Intracellular Calcium Variations, Oral Secretions, and Regurgitate Components
Authors: Maffei Massimo , Bossi Simone , Spiteller Dieter , Mithöfer Axel , Boland Wilhelm
Published: April 2004

Membrane potentials (V  m) and intracellular calcium variations were studied in Lima bean (Phaseolus lunatus) leaves when the Mediterranean climbing cutworm (Spodoptera littoralis) was attacking the plants. In addition to the effect of the feeding insect the impact of several N-acyl Glns (volicitin, N-palmitoyl-Gln, N-linolenoyl-Gln) from the larval oral secretion was studied. The results showed that the early events upon herbivore attack were: a) a strong V  m depolarization at the bite zone and an isotropic wave of V  m depolarization spreading throughout the entire attacked leaf; b) a V  m depolarization observed for the regurgitant but not with volicitin {N-(17-hydroxy-linolenoyl)-Gln} alone; c) an enhanced influx of Ca2+ at the very edge of the bite, which is halved, if the Ca2+ channel blocker Verapamil is used. Furthermore, the dose-dependence effects of N-acyl Gln conjugates-triggered influx of Ca2+ studied in transgenic aequorin-expressing soybean (Glycine max) cells, showed: a) a concentration-dependent influx of Ca2+; b) a configuration-independent effect concerning the stereochemistry of the amino acid moiety; c) a slightly reduced influx of Ca2+ after modification of the fatty acid backbone by functionalization with oxygen and; d) a comparable effect with the detergent SDS. Finally, the herbivore wounding causes a response in the plant cells that cannot be mimicked by mechanical wounding. The involvement of Ca2+ in signaling after herbivore wounding is discussed.
Characterization of Three Functional High-Affinity Ammonium Transporters in Lotus japonicus with Differential Transcriptional Regulation and Spatial Expression
Authors: D'Apuzzo Enrica , Rogato Alessandra , Simon-Rosin Ulrike , El Alaoui Hicham , Barbulova Ani , Betti Marco , Dimou Maria , Katinakis Panagiotis , Marquez Antonio , Marini Anne-Marie , Udvardi Michael K. , Chiurazzi Maurizio
Published: April 2004

Ammonium is a primary source of nitrogen for plants. In legume plants ammonium can also be obtained by symbiotic nitrogen fixation, and \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NH}_{4}^{{+}}\) \end{document} is also a regulator of early and late symbiotic interaction steps. Ammonium transporters are likely to play important roles in the control of nodule formation as well as in nitrogen assimilation. Two new genes, LjAMT1;2 and LjAMT1;3, were cloned from Lotus japonicus. Both were able to complement the growth defect of a yeast (Saccharomyces cerevisiae) ammonium transport mutant. Measurement of [14C]methylammonium uptake rates and competition experiments revealed that each transporter had a high affinity for \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NH}_{4}^{{+}}\) \end{document}. The K  i for ammonium was 1.7, 3, and 15 μ  m for LjAMT1;1, 1;2, and 1;3, respectively. Real-time PCR revealed higher expression of LjAMT1;1, 1;2, and 1;3 genes in leaves than in roots and nodule, with expression levels decreasing in the order LjAMT1;1 > 1;2 > 1;3 except in flowers, in which LjAMT1;3 was expressed at higher level than in leaves, and LjAMT1;1 showed the lowest level of expression. Expression of LjAMT1;1 and 1;2 in roots was induced by nitrogen deprivation. Expression of LjAMT1;1 was repressed in leaves exposed to elevated CO2 concentrations, which also suppress photorespiration. Tissue and cellular localization of LjAMT1 genes expression, using promoter-β-glucuronidase and in situ RNA hybridization approaches, revealed distinct cellular spatial localization in different organs, including nodules, suggesting differential roles in the nitrogen metabolism of these organs.
Gene and Enhancer Trap Tagging of Vascular-Expressed Genes in Poplar Trees
Authors: Groover Andrew , Fontana Joseph R. , Dupper Gayle , Ma Caiping , Martienssen Robert , Strauss Steven , Meilan Richard
Published: April 2004

We report a gene discovery system for poplar trees based on gene and enhancer traps. Gene and enhancer trap vectors carrying the β-glucuronidase (GUS) reporter gene were inserted into the poplar genome via Agrobacterium tumefaciens transformation, where they reveal the expression pattern of genes at or near the insertion sites. Because GUS expression phenotypes are dominant and are scored in primary transformants, this system does not require rounds of sexual recombination, a typical barrier to developmental genetic studies in trees. Gene and enhancer trap lines defining genes expressed during primary and secondary vascular development were identified and characterized. Collectively, the vascular gene expression patterns revealed that approximately 40% of genes expressed in leaves were expressed exclusively in the veins, indicating that a large set of genes is required for vascular development and function. Also, significant overlap was found between the sets of genes responsible for development and function of secondary vascular tissues of stems and primary vascular tissues in other organs of the plant, likely reflecting the common evolutionary origin of these tissues. Chromosomal DNA flanking insertion sites was amplified by thermal asymmetric interlaced PCR and sequenced and used to identify insertion sites by reference to the nascent Populus trichocarpa genome sequence. Extension of the system was demonstrated through isolation of full-length cDNAs for five genes of interest, including a new class of vascular-expressed gene tagged by enhancer trap line cET-1-pop1-145. Poplar gene and enhancer traps provide a new resource that allows plant biologists to directly reference the poplar genome sequence and identify novel genes of interest in forest biology.
Anchoring 9,371 Maize Expressed Sequence Tagged Unigenes to the Bacterial Artificial Chromosome Contig Map by Two-Dimensional Overgo Hybridization
Authors: Gardiner Jack , Schroeder Steven , Polacco Mary L. , Sanchez-Villeda Hector , Fang Zhiwei , Morgante Michele , Landewe Tim , Fengler Kevin , Useche Francisco , Hanafey Michael , Tingey Scott , Chou Hugh , Wing Rod , Soderlund Carol , Coe Edward H.
Published: April 2004

Our goal is to construct a robust physical map for maize (Zea mays) comprehensively integrated with the genetic map. We have used a two-dimensional 24 × 24 overgo pooling strategy to anchor maize expressed sequence tagged (EST) unigenes to 165,888 bacterial artificial chromosomes (BACs) on high-density filters. A set of 70,716 public maize ESTs seeded derivation of 10,723 EST unigene assemblies. From these assemblies, 10,642 overgo sequences of 40 bp were applied as hybridization probes. BAC addresses were obtained for 9,371 overgo probes, representing an 88% success rate. More than 96% of the successful overgo probes identified two or more BACs, while 5% identified more than 50 BACs. The majority of BACs identified (79%) were hybridized with one or two overgos. A small number of BACs hybridized with eight or more overgos, suggesting that these BACs must be gene rich. Approximately 5,670 overgos identified BACs assembled within one contig, indicating that these probes are highly locus specific. A total of 1,795 megabases (Mb; 87%) of the total 2,050 Mb in BAC contigs were associated with one or more overgos, which are serving as sequence-tagged sites for single nucleotide polymorphism development. Overgo density ranged from less than one overgo per megabase to greater than 20 overgos per megabase. The majority of contigs (52%) hit by overgos contained three to nine overgos per megabase. Analysis of approximately 1,022 Mb of genetically anchored BAC contigs indicates that 9,003 of the total 13,900 overgo-contig sites are genetically anchored. Our results indicate overgos are a powerful approach for generating gene-specific hybridization probes that are facilitating the assembly of an integrated genetic and physical map for maize.
A Rice WRKY Gene Encodes a Transcriptional Repressor of the Gibberellin Signaling Pathway in Aleurone Cells
Authors: Zhang Zhong-Lin , Xie Zhen , Zou Xiaolu , Casaretto Jose , Ho Tuan-hua David , Shen Qingxi J.
Published: April 2004

The molecular mechanism by which GA regulates plant growth and development has been a subject of active research. Analyses of the rice (Oryza sativa) genomic sequences identified 77 WRKY genes, among which OsWRKY71 is highly expressed in aleurone cells. Transient expression of OsWRKY71 by particle bombardment specifically represses GA-induced Amy32b  α-amylase promoter but not abscisic acid-induced HVA22 or HVA1 promoter activity in aleurone cells. Moreover, OsWRKY71 blocks the activation of the Amy32b promoter by the GA-inducible transcriptional activator OsGAMYB. Consistent with its role as a transcriptional repressor, OsWRKY71 is localized to nuclei of aleurone cells and binds specifically to functionally defined TGAC-containing W boxes of the Amy32b promoter in vitro. Mutation of the two W boxes prevents the binding of OsWRKY71 to the mutated promoter, and releases the suppression of the OsGAMYB-activated Amy32b expression by OsWRKY71, suggesting that OsWRKY71 blocks GA signaling by functionally interfering with OsGAMYB. Exogenous GA treatment decreases the steady-state mRNA level of OsWRKY71 and destabilizes the GFP:OsWRKY71 fusion protein. These findings suggest that OsWRKY71 encodes a transcriptional repressor of GA signaling in aleurone cells.
Evidence for Symplastic Involvement in the Radial Movement of Calcium in Onion Roots
Authors: Cholewa Ewa , Peterson Carol A.
Published: April 2004

The pathway of Ca2+ movement from the soil solution into the stele of the root is not known with certainty despite a considerable body of literature on the subject. Does this ion cross an intact, mature exodermis and endodermis? If so, is its movement through these layers primarily apoplastic or symplastic? These questions were addressed using onion (Allium cepa) adventitious roots lacking laterals. Radioactive Ca2+ applied to the root tip was not transported to the remainder of the plant, indicating that this ion cannot be supplied to the shoot through this region where the exodermis and endodermis are immature. A more mature zone, in which the endodermal Casparian band was present, delivered 2.67 nmol of Ca2+ mm−1 treated root length d−1 to the transpiration stream, demonstrating that the ion had moved through an intact endodermis. Farther from the root tip, a third zone in which Casparian bands were present in the exodermis as well as the endodermis delivered 0.87 nmol Ca2+ mm−1 root length d−1 to the transpiration stream, proving that the ion had moved through an unbroken exodermis. Compartmental elution analyses indicated that Ca2+ had not diffused through the Casparian bands of the exodermis, and inhibitor studies using La3+ and vanadate (VO4  3−) pointed to a major involvement of the symplast in the radial transport of Ca2+ through the endodermis. It was concluded that in onion roots, the radial movement of Ca2+ through the exodermis and endodermis is primarily symplastic.
Phytohormones Participate in an S6 Kinase Signal Transduction Pathway in Arabidopsis
Authors: Turck Franziska , Zilbermann Frederic , Kozma Sara C. , Thomas George , Nagy Ferenc
Published: April 2004

Addition of fresh medium to stationary cells of Arabidopsis suspension culture induces increased phosphorylation of the S6 ribosomal protein and activation of its cognate kinase, AtS6k. Analysis of the activation response revealed that medium constituents required for S6 kinase activation were the phytohormones 1-naphthylacetic acid (auxin) and kinetin. Pretreatment of cells with anti-auxin or PI3-kinase drugs inhibited this response. Consistent with these findings, LY294002, a PI3-kinase inhibitor, efficiently suppressed phytohormone-induced S6 phosphorylation and translational up-regulation of ribosomal protein S6 and S18A mRNAs without affecting global translation. These data indicate that (1) activation of AtS6k is regulated by phytohormones, at least in part, via a lipid kinase-dependent pathway, that (2) the translational regulation of ribosomal proteins appears to be conserved throughout the plant and animal kingdom, and that (3) these events are hallmarks of a growth-related signal transduction pathway novel in plants.
Identification and Characterization of Four Chrysanthemum MADS-Box Genes, Belonging to the APETALA1/FRUITFULL and SEPALLATA3 Subfamilies
Authors: Shchennikova Anna V. , Shulga Olga A. , Immink Richard , Skryabin Konstantin G. , Angenent Gerco C.
Published: April 2004

Four full-length MADS-box cDNAs from chrysanthemum, designated Chrysanthemum Dendrathema grandiflorum MADS (CDM) 8, CDM41, CDM111, and CDM44, have been isolated and further functionally characterized. Protein sequence alignment and expression patterns of the corresponding genes suggest that CDM8 and CDM41 belong to the FRUITFULL (FUL) clade, CDM111 is a member of the APETALA1 (AP1) subfamily, and CDM44 is a member of the SEPALLATA3 (SEP3) subfamily of MADS-box transcription factors. Overexpression of CDM111 in Arabidopsis plants resulted in an aberrant phenotype that is reminiscent of the phenotype obtained by ectopic expression of the AP1 gene. In addition, CDM111 was able to partially complement the ap1-1 mutant from Arabidopsis, illustrating that CDM111 is the functional equivalent to AP1. Yeast two- and three-hybrid studies were performed to investigate the potential protein interactions and complexes in which these chrysanthemum MADS-box proteins are involved. Based on these studies, we conclude that CDM44 is most likely the SEP3 functional equivalent, because the CDM44 protein interacts with CDM proteins of the AP1/FUL and AG subfamilies, and as a higher order complex with the heterodimer between the presumed B-type CDM proteins.
Ectopic Expression of Maize Polyamine Oxidase and Pea Copper Amine Oxidase in the Cell Wall of Tobacco Plants
Authors: Rea Giuseppina , de Pinto Maria Concetta , Tavazza Raffaela , Biondi Stefania , Gobbi Valentina , Ferrante Paola , De Gara Laura , Federico Rodolfo , Angelini Riccardo , Tavladoraki Paraskevi
Published: April 2004

To test the feasibility of altering polyamine levels by influencing their catabolic pathway, we obtained transgenic tobacco (Nicotiana tabacum) plants constitutively expressing either maize (Zea mays) polyamine oxidase (MPAO) or pea (Pisum sativum) copper amine oxidase (PCuAO), two extracellular and H2O2-producing enzymes. Despite the high expression levels of the transgenes in the extracellular space, the amount of free polyamines in the homozygous transgenic plants was similar to that in the wild-type ones, suggesting either a tight regulation of polyamine levels or a different compartmentalization of the two recombinant proteins and the bulk amount of endogenous polyamines. Furthermore, no change in lignification levels and plant morphology was observed in the transgenic plants compared to untransformed plants, while a small but significant change in reactive oxygen species-scavenging capacity was verified. Both the MPAO and the PCuAO tobacco transgenic plants produced high amounts of H2O2 only in the presence of exogenously added enzyme substrates. These observations provided evidence for the limiting amount of freely available polyamines in the extracellular space in tobacco plants under physiological conditions, which was further confirmed for untransformed maize and pea plants. The amount of H2O2 produced by exogenously added polyamines in cell suspensions from the MPAO transgenic plants was sufficient to induce programmed cell death, which was sensitive to catalase treatment and required gene expression and caspase-like activity. The MPAO and PCuAO transgenic plants represent excellent tools to study polyamine secretion and conjugation in the extracellular space, as well as to determine when and how polyamine catabolism actually intervenes both in cell wall development and in response to stress.
Phosphorylation of the Amino Terminus of Maize Sucrose Synthase in Relation to Membrane Association and Enzyme Activity
Authors: Hardin Shane C. , Winter Heike , Huber Steven C.
Published: April 2004

Sucrose synthase (SUS) is phosphorylated on a major, amino-terminal site located at Ser-15 (S15) in the maize (Zea mays) SUS1 protein. Site- and phospho-specific antibodies against a phosphorylated S15 (pS15) peptide allowed direct analysis of S15 phosphorylation in relation to membrane association. Immunoblots of the maize leaf elongation zone, divided into 4-cm segments, demonstrated that the abundance of soluble (s-SUS) and membrane (m-SUS) SUS protein showed distinct positional profiles. The content of m-SUS was maximal in the 4- to 8-cm segment where it represented 9% of total SUS and occurred as a peripheral membrane protein. In contrast, s-SUS was highest in the 12- to 16-cm segment. Relative to s-SUS, m-SUS was hypophosphorylated at S15 in the basal 4 cm but hyperphosphorylated in apical segments. Differing capabilities of the anti-pS15 and anti-S15 peptide antibodies to immunoprecipitate SUS suggested that phosphorylation of S15, or exposure of unphosphorylated SUS to slightly acidic pH, altered the structure of the amino terminus. These structural changes were generally coincident with the increased sucrose cleavage activity that occurs at pH values below 7.5. In vitro S15 phosphorylation of the S170A SUS protein by a maize calcium-dependent protein kinase (CDPK) significantly increased sucrose cleavage activity at low pH. Collectively, the results suggest that (1) SUS membrane binding is controlled in vivo; (2) relative pS15 content of m-SUS depends on the developmental state of the organ; and (3) phosphorylation of S15 affects amino-terminal conformation in a way that may stimulate the catalytic activity of SUS and influence membrane association.
Brassinosteroids Interact with Auxin to Promote Lateral Root Development in Arabidopsis
Authors: Bao Fang , Shen Junjiang , Brady Shari R. , Muday Gloria K. , Asami Tadao , Yang Zhenbiao
Published: April 2004

Plant hormone brassinosteroids (BRs) and auxin exert some similar physiological effects likely through their functional interaction, but the mechanism for this interaction is unknown. In this study, we show that BRs are required for lateral root development in Arabidopsis and that BRs act synergistically with auxin to promte lateral root formation. BR perception is required for the transgenic expression of the β-glucuronidase gene fused to a synthetic auxin-inducible promoter (DR5::GUS) in root tips, while exogenous BR promotes DR5::GUS expression in the root tips and the stele region proximal to the root tip. BR induction of both lateral root formation and DR5::GUS expression is suppressed by the auxin transport inhibitor N-(1-naphthyl) phthalamic acid. Importantly, BRs promote acropetal auxin transport (from the base to the tip) in the root. Our observations indicate that BRs regulate auxin transport, providing a novel mechanism for hormonal interactions in plants and supporting the hypothesis that BRs promote lateral root development by increasing acropetal auxin transport.
Mechanism of Gene Expression of Arabidopsis Glutathione S-Transferase, AtGST1, and AtGST11 in Response to Aluminum Stress
Authors: Ezaki Bunichi , Suzuki Masakatsu , Motoda Hirotoshi , Kawamura Masako , Nakashima Susumu , Matsumoto Hideaki
Published: April 2004

The gene expression of two Al-induced Arabidopsis glutathione S-transferase genes, AtGST1 and AtGST11, was analyzed to investigate the mechanism underlying the response to Al stress. An approximately 1-kb DNA fragment of the 5′-upstream region of each gene was fused to a β-glucuronidase (GUS) reporter gene (pAtGST1::GUS and pAtGST11::GUS) and introduced into Arabidopsis ecotype Landsberg erecta. The constructed transgenic lines showed a time-dependent gene expression to a different degree in the root and/or leaf by Al stress. The pAtGST1::GUS gene was induced after a short Al treatment (maximum expression after a 2-h exposure), while the pAtGST11::GUS gene was induced by a longer Al treatment (approximately 8 h for maximum expression). Since the gene expression was observed in the leaf when only the root was exposed to Al stress, a signaling system between the root and shoot was suggested in Al stress. A GUS staining experiment using an adult transgenic line carrying the pAtGST11::GUS gene supported this suggestion. Furthermore, Al treatment simultaneously with various Ca depleted conditions in root region enhanced the gene expression of the pAtGST11::GUS in the shoot region. This result suggested that the degree of Al toxicity in the root reflects the gene response of pAtGST11::GUS in the shoot via the deduced signaling system. Both transgenic lines also showed an increase of GUS activity after cold stress, heat stress, metal toxicity, and oxidative damages, suggesting a common induction mechanism in response to the tested stresses including Al stress.
Molecular Characterization of Cytokinin-Responsive Histidine Kinases in Maize. Differential Ligand Preferences and Response to cis-Zeatin
Authors: Yonekura-Sakakibara Keiko , Kojima Mikiko , Yamaya Tomoyuki , Sakakibara Hitoshi
Published: April 2004

Genes for cytokinin-responsive His-protein kinases (ZmHK1, ZmHK2, and ZmHK3a) were isolated from maize (Zea mays). Heterologous expression of each of the ZmHKs in Escherichia coli having the ΔrcsC and cps∷lacZ genetic background conferred cytokinin-inducibility of lacZ expression on the bacteria. In the recombinant E. coli system, ZmHK1 and ZmHK3a were more sensitive to free-base cytokinins than to the corresponding nucleosides; isopentenyladenine was most effective for ZmHK1, while ZmHK2 tended to be most sensitive to trans-zeatin and the riboside. In contrast to a known cytokinin receptor of Arabidopsis (AHK4/CRE1/WOL), all ZmHKs responded to cis-zeatin (cZ), which generally is believed to be inactive or only weakly active. In cultured maize cells, expression of ZmRR1, a cytokinin-inducible response regulator, was induced by cZ as well as by trans-zeatin. These results strongly suggest that maize cytokinin receptors differ in ligand preference, and that cZ is an active cytokinin at least in maize.
A Bifunctional 3,5-Epimerase/4-Keto Reductase for Nucleotide-Rhamnose Synthesis in Arabidopsis
Authors: Watt Gregory , Leoff Christine , Harper April D. , Bar-Peled Maor
Published: April 2004

l-Rhamnose is a component of plant cell wall pectic polysaccharides, diverse secondary metabolites, and some glycoproteins. The biosynthesis of the activated nucleotide-sugar form(s) of rhamnose utilized by the various rhamnosyltransferases is still elusive, and no plant enzymes involved in their synthesis have been purified. In contrast, two genes (rmlC and rmlD) have been identified in bacteria and shown to encode a 3,5-epimerase and a 4-keto reductase that together convert dTDP-4-keto-6-deoxy-Glc to dTDP-β-l-rhamnose. We have identified an Arabidopsis cDNA that contains domains that share similarity to both reductase and epimerase. The Arabidopsis gene encodes a protein with a predicated molecular mass of approximately 33.5 kD that is transcribed in all tissue examined. The Arabidopsis protein expressed in, and purified from, Escherichia coli converts dTDP-4-keto-6-deoxy-Glc to dTDP-β-l-rhamnose in the presence of NADPH. These results suggest that a single plant enzyme has both the 3,5-epimerase and 4-keto reductase activities. The enzyme has maximum activity between pH 5.5 and 7.5 at 30°C. The apparent K  m for NADPH is 90 μ  m and 16.9 μ  m for dTDP-4-keto-6-deoxy-Glc. The Arabidopsis enzyme can also form UDP-β-l-rhamnose. To our knowledge, this is the first example of a bifunctional plant enzyme involved in sugar nucleotide synthesis where a single polypeptide exhibits the same activities as two separate prokaryotic enzymes.
Arabidopsis CYP707As Encode (+)-Abscisic Acid 8′-Hydroxylase, a Key Enzyme in the Oxidative Catabolism of Abscisic Acid
Authors: Saito Shigeki , Hirai Nobuhiro , Matsumoto Chiaki , Ohigashi Hajime , Ohta Daisaku , Sakata Kanzo , Mizutani Masaharu
Published: April 2004

Abscisic acid (ABA) is involved in a number of critical processes in normal growth and development as well as in adaptive responses to environmental stresses. For correct and accurate actions, a physiologically active ABA level is controlled through fine-tuning of de novo biosynthesis and catabolism. The hydroxylation at the 8′-position of ABA is known as the key step of ABA catabolism, and this reaction is catalyzed by ABA 8′-hydroxylase, a cytochrome P450. Here, we demonstrate CYP707As as the P450 responsible for the 8′-hydroxylation of (+)-ABA. First, all four CYP707A cDNAs were cloned from Arabidopsis and used for the production of the recombinant proteins in insect cells using a baculovirus system. The insect cells expressing CYP707A3 efficiently metabolized (+)-ABA to yield phaseic acid, the isomerized form of 8′-hydroxy-ABA. The microsomes from the insect cells exhibited very strong activity of 8′-hydroxylation of (+)-ABA (K  m = 1.3 μ  m and k  cat = 15 min−1). The solubilized CYP707A3 protein bound (+)-ABA with the binding constant K  s = 3.5 μ  m, but did not bind (−)-ABA. Detailed analyses of the reaction products confirmed that CYP707A3 does not have the isomerization activity of 8′-hydroxy-ABA to phaseic acid. Further experiments revealed that Arabidopsis CYP707A1 and CYP707A4 also encode ABA 8′-hydroxylase. The transcripts of the CYP707A genes increased in response to salt, osmotic, and dehydration stresses as well as ABA. These results establish that the CYP707A family plays a key role in regulating the ABA level through the 8′-hydroxylation of (+)-ABA.
Phosphatidylglycerol Is Essential for Oligomerization of Photosystem I Reaction Center
Authors: Domonkos Ildikó , Malec Przemyslaw , Sallai Anna , Kovács László , Itoh Kunihiro , Shen Gaozhong , Ughy Bettina , Bogos Balázs , Sakurai Isamu , Kis Mihály , Strzalka Kazimierz , Wada Hajime , Itoh Shigeru , Farkas Tibor , Gombos Zoltán
Published: April 2004

Our earlier studies with the pgsA mutant of Synechocystis PCC6803 demonstrated the important role of phosphatidylglycerol (PG) in PSII dimer formation and in electron transport between the primary and secondary electron-accepting plastoquinones of PSII. Using a long-term depletion of PG from pgsA mutant cells, we could induce a decrease not only in PSII but also in PSI activity. Simultaneously with the decrease in PSI activity, dramatic structural changes of the PSI complex were detected. A 21-d PG depletion resulted in the degradation of PSI trimers and concomitant accumulation of monomer PSI. The analyses of PSI particles isolated by MonoQ chromatography showed that, following the 21-d depletion, PSI trimers were no longer detectable in the thylakoid membranes. Immunoblot analyses revealed that the PSI monomers accumulating in the PG-depleted mutant cells do not contain PsaL, the protein subunit thought to be responsible for the trimer formation. Nevertheless, the trimeric structure of PSI reaction center could be restored by readdition of PG, even in the presence of the protein synthesis inhibitor lincomycin, indicating that free PsaL was present in thylakoid membranes following the 21-d PG depletion. Our data suggest an indispensable role for PG in the PsaL-mediated assembly of the PSI reaction center.
The GATA Family of Transcription Factors in Arabidopsis and Rice
Authors: Reyes José C. , Muro-Pastor M. Isabel , Florencio Francisco J.
Published: April 2004

GATA transcription factors are a group of DNA binding proteins broadly distributed in eukaryotes. The GATA factors DNA binding domain is a class IV zinc finger motif in the form CX2CX17–20CX2C followed by a basic region. In plants, GATA DNA motifs have been implicated in light-dependent and nitrate-dependent control of transcription. Herein, we show that the Arabidopsis and the rice (Oryza sativa) genomes present 29 and 28 loci, respectively, that encode for putative GATA factors. A phylogenetic analysis of the 57 GATA factors encoding genes, as well as the study of their intron-exon structure, indicates the existence of seven subfamilies of GATA genes. Some of these subfamilies are represented in both species but others are exclusive for one of them. In addition to the GATA zinc finger motif, polypeptides of the different subfamilies are characterized by the presence of additional domains such as an acidic domain, a CCT (CONSTANS, CO-like, and TOC1) domain, or a transposase-like domain also found in FAR1 and FHY3. Subfamily VI comprises genes that encode putative bi-zinc finger polypeptides, also found in metazoan and fungi, and a tri-zinc finger protein which has not been previously reported in eukaryotes. The phylogeny of the GATA zinc finger motif, excluding flanking regions, evidenced the existence of four classes of GATA zinc fingers, three of them containing 18 residues in the zinc finger loop and one containing a 20-residue loop. Our results support multiple models of evolution of the GATA gene family in plants including gene duplication and exon shuffling.
Molecular Analyses of the Arabidopsis TUBBY-Like Protein Gene Family
Authors: Lai Chia-Ping , Lee Chang-Lung , Chen Po-Hsuan , Wu Shu-Hsing , Yang Chien-Chih , Shaw Jei-Fu
Published: April 2004

In mammals, TUBBY-like proteins play an important role in maintenance and function of neuronal cells during postdifferentiation and development. We have identified a TUBBY-like protein gene family with 11 members in Arabidopsis, named AtTLP1-11. Although seven of the AtTLP genes are located on chromosome I, no local tandem repeats or gene clusters are identified. Except for AtTLP4, reverse transcription-PCR analysis indicates that all these genes are expressed in various organs in 6-week-old Arabidopsis. AtTLP1, 2, 3, 6, 7, 9, 10, and 11 are expressed ubiquitously in all the organs tested, but the expression of AtTLP5 and 8 shows dramatic organ specificity. These 11 family members share 30% to 80% amino acid similarities across their conserved C-terminal tubby domains. Unlike the highly diverse N-terminal region of animal TUBBY-like proteins, all AtTLP members except AtTLP8 contain a conserved F-box domain (51–57 residues). The interaction between AtTLP9 and ASK1 (Arabidopsis Skp1-like 1) is confirmed via yeast (Saccharomyces cerevisiae) two-hybrid assays. Abscisic acid (ABA)-insensitive phenotypes are observed for two independent AtTLP9 mutant lines, whereas transgenic plants overexpressing AtTLP9 are hypersensitive to ABA. These results suggest that AtTLP9 may participate in the ABA signaling pathway.
Identification and Characterization of Respirasomes in Potato Mitochondria
Authors: Eubel Holger , Heinemeyer Jesco , Braun Hans-Peter
Published: April 2004

Plant mitochondria were previously shown to comprise respiratory supercomplexes containing cytochrome c reductase (complex III) and NADH dehydrogenase (complex I) of I1III2 and I2III4 composition. Here we report the discovery of additional supercomplexes in potato (Solanum tuberosum) mitochondria, which are of lower abundance and include cytochrome c oxidase (complex IV). Highly active mitochondria were isolated from potato tubers and stems, solubilized by digitonin, and subsequently analyzed by Blue-native (BN) polyacrylamide gel electrophoresis (PAGE). Visualization of supercomplexes by in-gel activity stains for complex IV revealed five novel supercomplexes of 850, 1,200, 1,850, 2,200, and 3,000 kD in potato tuber mitochondria. These supercomplexes have III2IV1, III2IV2, I1III2IV1, I1III2IV2, and I1III2IV4 compositions as shown by two-dimensional BN/sodium dodecyl sulfate (SDS)-PAGE and BN/BN-PAGE in combination with activity stains for cytochrome c oxidase. Potato stem mitochondria include similar supercomplexes, but complex IV is partially present in a smaller version that lacks the Cox6b protein and possibly other subunits. However, in mitochondria from potato tubers and stems, about 90% of complex IV was present in monomeric form. It was suggested that the I1III2IV4 supercomplex represents a basic unit for respiration in mammalian mitochondria termed respirasome. Respirasomes also occur in potato mitochondria but were of low concentrations under all conditions applied. We speculate that respirasomes are more abundant under in vivo conditions.
Repression of a Novel Isoform of Disproportionating Enzyme (stDPE2) in Potato Leads to Inhibition of Starch Degradation in Leaves But Not Tubers Stored at Low Temperature
Authors: Lloyd James R. , Blennow Andreas , Burhenne Kim , Kossmann Jens
Published: April 2004

A potato (Solanum tuberosum) cDNA encoding an isoform of disproportionating enzyme (stDPE2) was identified in a functional screen in Escherichia coli. The stDPE2 protein was demonstrated to be present in chloroplasts and to accumulate at times of active starch degradation in potato leaves and tubers. Transgenic potato plants were made in which its presence was almost completely eliminated. It could be demonstrated that starch degradation was repressed in leaves of the transgenic plants but that cold-induced sweetening was not affected in tubers stored at 4°C. No evidence could be found for an effect of repression of stDPE2 on starch synthesis. The malto-oligosaccharide content of leaves from the transgenic plants was assessed. It was found that the amounts of malto-oligosaccharides increased in all plants during the dark period and that the transgenic lines accumulated up to 10-fold more than the control. Separation of these malto-oligosaccharides by high-performance anion-exchange chromatography with pulsed-amperometric detection showed that the only one that accumulated in the transgenic plants in comparison with the control was maltose. stDPE2 was purified to apparent homogeneity from potato tuber extracts and could be demonstrated to transfer glucose from maltose to oyster glycogen.
Relationship between the Heat Tolerance of Photosynthesis and the Thermal Stability of Rubisco Activase in Plants from Contrasting Thermal Environments
Authors: Salvucci Michael E. , Crafts-Brandner Steven J.
Published: April 2004

Inhibition of net photosynthesis (Pn) by moderate heat stress has been attributed to an inability of Rubisco activase to maintain Rubisco in an active form. To examine this proposal, the temperature response of Pn, Rubisco activation, chlorophyll fluorescence, and the activities of Rubisco and Rubisco activase were examined in species from contrasting environments. The temperature optimum of Rubisco activation was 10°C higher in the creosote bush (Larrea tridentata) compared with the Antarctic hairgrass (Deschampsia antarctica), resembling the temperature response of Pn. Pn increased markedly with increasing internal CO2 concentration in Antarctic hairgrass and creosote bush plants subjected to moderate heat stress even under nonphotorespiratory conditions. Nonphotochemical quenching of chlorophyll fluorescence, the effective quantum yield of photochemical energy conversion (ΔF/Fm′) and the maximum yield of PSII (Fv/Fm) were more sensitive to temperature in Antarctic hairgrass and two other species endemic to cold regions (i.e. Lysipomia pumila and spinach [Spinacea oleracea]) compared with creosote bush and three species (i.e. jojoba [Simmondsia chinensis], tobacco [Nicotiana tabacum], and cotton [Gossypium hirsutum]) from warm regions. The temperature response of activity and the rate of catalytic inactivation of Rubisco from creosote bush and Antarctic hairgrass were similar, whereas the optimum for ATP hydrolysis and Rubisco activation by recombinant creosote bush, cotton, and tobacco activase was 8°C to 10°C higher than for Antarctic hairgrass and spinach activase. These results support a role for activase in limiting photosynthesis at high temperature.
Juvenile Xanthogranuloma Associated with Neurofibromatosis 1: 14 Patients without Evidence of Hematologic Malignancies
Authors: Cambiaghi Stefano , Restano Lucia , Caputo Ruggero
Published: April 2004

Abstract:  The clinical features and natural history of juvenile xanthogranuloma (JXG) in 14 children affected by neurofibromatosis 1 (NF1) are reported. Mean follow‐up in 11 of these patients was 4.3 years (range 1–10 years). None of the children developed hematologic malignancies during this period. The onset of JXG was in the first 2 years of life in 13 of the patients. In this series, the association between JXG and six or more café au lait spots more than 5 mm in diameter was a good marker for NF1 in the first few years of life. Overall the JXG in these patients did not show any features distinguishable from those of “classical” JXG.
The Etiology of Different Forms of Urticaria in Childhood
Authors: Sackesen Cansin , Sekerel Bulent E. , Orhan Fazil , Kocabas Can Naci , Tuncer Ayfer , Adalioglu Gonul
Published: April 2004

Abstract:  Urticaria is a common disease in children. In contrast to the ease of its diagnosis, etiologic factors are often difficult to determine. In order to study whether differences exist among various forms of urticaria in childhood and whether the patterns of different types of urticaria differ between adults and children, we extensively studied the possible causes of urticaria in children. Fifty‐four children (23 girls and 31 boys; ages 1–19 years) with various forms of urticaria were included in the study. In all cases, questions about food allergies, food additive intolerance, drug intake, signs of infection, causes of physical urticaria, insect bites, and personal and family history of atopy were asked. Clinical characteristics of the disease, such as duration, recurrence, and associated angioedema and symptoms of anaphylaxis were also investigated. Detailed laboratory tests, including serologic, autoimmune, and allergic analyses, were conducted to reveal the probable etiologies of urticaria. Of the study patients, 68.5% and 31.5% were diagnosed as having acute and chronic urticaria, respectively. The patient group with chronic urticaria was older and included more boys than the acute group. In the acute urticaria group, infection was the most frequently documented cause (48.6%), followed by drugs (5.4%), and food allergies (2.7%), whereas in chronic urticaria, physical factors were the leading cause (52.94%). The most frequently documented infection was urinary tract infection, followed by serologically determined infections of Chlamydia pneumoniae and Helicobacter pylori. In this study we found indications that infections were frequently associated with urticaria, which suggests that urticaria management should include a survey of certain infectious agents in addition to a detailed history.
Microbiology of Infected Hemangiomas in Children
Authors: Brook Itzhak
Published: April 2004

Abstract:  Bacterial infections are a common complication of hemangiomas in children. The objective of this study was to establish the aerobic and anaerobic microbiology of infected hemangiomas. A retrospective 8‐year review of clinical and microbiology laboratory records from patients with secondarily infected hemangiomas was carried out. Specimens from infected sites were processed for the presence of aerobic and anaerobic bacteria. Bacterial growth was present in 32 of 38 specimens. Aerobic bacteria alone were recovered in 12 infected hemangiomas (37.5%), anaerobic bacteria alone in 8 (33%), and mixed aerobic and anaerobic flora in 12 (37.5%). A total of 80 isolates (47 aerobes and 33 anaerobes) were recovered, giving an average of 2.5 isolates per specimen (1.5 aerobes and 1.0 anaerobes). The highest number of isolates were recovered in infections of the perineum (3.7 per site) and the legs (2.8 per site). The predominant aerobic isolates were Staphylococcus aureus, group A β‐hemolytic streptococci, and Enterobacteriaceae. The predominant anaerobes were Peptostreptococcus sp., gram‐negative bacilli, and Fusobacterium sp. Organisms that belong to the mucous membranes close to the lesions predominated in infections next to those membranes. The polymicrobial etiology of secondarily infected hemangiomas and the association of bacterial flora with the anatomic site of the lesions is thereby demonstrated.
“Proximal‐Type” Epithelioid Sarcoma in a Young Girl
Authors: Gambini Claudio , Sementa Angela , Rongioletti Franco
Published: April 2004

Abstract:  Epithelioid sarcoma is a rare, malignant soft‐tissue neoplasm occurring on the distal extremities of young adults. Its histologic features consist of a proliferation of rounded to plump, spindle‐shaped cells with abundant eosinophilic cytoplasm around areas of necrosis, simulating a granulomatous process. Recently a different type of epithelioid sarcoma has been described and named “proximal‐type” epithelioid sarcoma. It is found mostly in the pelvic and perineal areas of young to middle‐aged adults. On microscopic examination, the tumor is characterized by a proliferation of epithelioid‐like cells with rhabdoid features in the absence of a granuloma‐like pattern, and immunohistochemically it coexpresses vimentin, cytokeratin, epithelial membrane antigen, and CD34. As we found no report of proximal epithelioid sarcoma in the dermatologic literature, we describe an additional case in a 12‐year‐old girl. This type of tumor appears to be somewhat more aggressive than the classical, distal type and it should be considered in the differential diagnosis of tumors showing rhabdoid features, in particular extrarenal malignant rhabdoid tumor.
Juvenile Xanthogranuloma: A Congenital Giant Form Leading to a Wide Atrophic Sequela
Authors: Imiela A. , Carpentier O. , Segard‐Drouard M. , De Lassalle E. Martin , Piette F.
Published: April 2004

Abstract:  Juvenile xanthogranuloma is the most common non‐Langerhans cell histiocytosis of infancy and childhood. It is a benign disorder that usually regresses spontaneously, more often without or with limited skin changes. The clinical features are very pleomorphic and recognition of the atypical presentations should facilitate the diagnosis. We report a 9‐month‐old boy who had an extensive, atrophic lesion on the proximal thigh that followed the course of the congenital giant form. The large size of the lesion does not alter the clinical course or result in extracutaneous involvement, which remains rare. However, uncommon clinical presentations raise the problem of differential diagnosis, requiring biopsy to eliminate other tumors with a less favorable prognosis.
Cutaneous Manifestations of Hydroxyurea Therapy in Childhood: Case Report and Review
Authors: Issaivanan M. , Mitu P. Shrikande , Manisha Chakrabarti , Praveen Khairkar
Published: April 2004

Abstract:  Hydroxyurea is commonly used in the treatment of various myeloproliferative disorders. In conventional pediatric clinical practice, its use is limited to benign hematologic conditions such as sickle cell disease and thalassemia. Long‐term hydroxyurea use is associated with various adverse mucocutaneous effects including hyperpigmentation, alopecia, leg ulcers, and lichenoid eruptions. We report a 10‐year‐old boy with chronic myelogenous leukemia who presented with hyperpigmentation of the skin and nails 3 months after the start of hydroxyurea therapy. Melanonychia of all 20 nails with involvement of all three mucocutaneous areas (skin, nails, and mucosa) at presentation was a unique feature in our patient. With the recently increasing pediatric use of hydroxyurea in a variety of disorders, its benign and not so uncommon cutaneous adverse effects are emphasized here.
Focal Acral Hyperkeratosis: A Rare Cutaneous Disorder within the Spectrum of Costa Acrokeratoelastoidosis
Authors: Erkek Emel , Koçak Mukadder , Bozdoğan Önder , Atasoy Pınar , Ahu Bırol M.D.
Published: April 2004

Abstract:  Acrokeratoelastoidosis and focal acral hyperkeratosis share similar clinical features and identical histologic epidermal alterations. These disorders are distinguished solely on the basis of the absence of elastorrhexis in the latter. We present a case of focal acral hyperkeratosis in a 9‐year‐old girl. The lesions consisted of translucent polygonal papules clustered on the thenar regions of the palms and over the metacarpophalangeal and interphalangeal joints. Histopathologic examination revealed orthohyperkeratosis within focal clavus‐like depressions of the epidermis and prominent hypergranulosis. There was no evidence of alterations in elastic tissue. The clinicopathologic distinction between focal acral hyperkeratosis and acrokeratoelastoidosis is blurred. There is enough evidence to consider the former as a histologic variant of Costa acrokeratoelastoidosis syndrome, and a better nomenclature for this disorder would be “acrokeratoelastoidosis without elastorrhexis.”
Posttraumatic Port‐Wine Stain in a 4‐Year‐Old Girl: Fegeler Syndrome
Authors: Piaserico S. , Fortina A. Belloni
Published: April 2004

Abstract:  A 4‐year‐old girl presented with an acquired port‐wine stain in the distribution of the first branch of the trigeminal nerve. The lesion appeared after a head injury and slowly enlarged over the next 2 years. Including our patient, 25 instances of acquired port‐wine stains have been reported in children. Ten (40%) of these were trauma related. The possible etiopathogenesis of acquired posttraumatic port‐wine stains is discussed.
Generalized Lentiginosis in Two Children Lacking Systemic Associations: Case Report and Review of the Literature
Authors: Chong Wei‐Sheng , Klanwarin Waraporn , Giam Yoke‐Chin
Published: April 2004

Abstract:  Generalized lentigines associated with multiple noncutaneous features, as in the LEOPARD syndrome and the Carney complex, have been well reported in the literature. Reports of patients with generalized lentigines without systemic abnormalities (termed “generalized lentiginosis”) are increasing as well. Despite the lack of systemic features, patients with generalized lentigines only should be monitored for further development of other noncutaneous features, especially cardiac anomalies. We present two patients with generalized lentiginosis and propose a working algorithm in the approach to a child with this finding.
Giant Aplasia Cutis Congenita without Associated Anomalies
Authors: Benjamin Latanya T. , Trowers Andrea B. , Schachner Lawrence A.
Published: April 2004

Abstract:  Aplasia cutis congenita is a congenital condition in which skin, bone, and dura can be absent. The condition can present in isolation or with associated conditions such as limb anomalies or embryologic malformations. The majority of cases affect the scalp and are limited to the dermis and epidermis. Vertex aplasia cutis typically range in size from 0.5 to 3 cm. The rare larger scalp defects are prone to complications of hemorrhage and infection, and subsequently patients are at risk for death. For these reasons, surgical intervention for large defects may be required. We report the case of a 12‐month‐old Haitian boy who presented with aplasia cutis congenita of the scalp involving 10 cm of skin and 9 cm of underlying bone. There were no other associated anomalies.
Childhood Bullous Pemphigoid: Report of a Case with Life‐Threatening Course During Homeopathy Treatment
Authors: Kuenzli Stéphane , Grimaître Michel , Krischer Joachim , Saurat Jean‐Hilaire , Calza Anne‐Marie , Borradori Luca
Published: April 2004

Abstract:  Bullous pemphigoid (BP) is an autoimmune blistering disorder that may very rarely occur in childhood. We describe a 9‐month‐old child who developed bullous pemphigoid while she was being treated for presumptive atopic eczema with a homeopathic regimen comprising sulfur, mercury, cantharides, and Rhus (Toxicodendron). She had generalized bullae and a progressive worsening of her general condition with asthenia, dehydration, malnutrition. While the role of homeopathy in triggering the disease remains unclear, our observation attests to the potential life‐threatening course of childhood BP in instances where appropriate treatment is withheld.