bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of a locus controlling Verticillium disease symptom response in Arabidopsis thaliana
Authors: Veronese Paola , Narasimhan Meena L. , Stevenson Rebecca A. , Zhu Jian‐K. , Weller Stephen C. , Subbarao Krishna V. , Bressan Ray A. 
Published: August 2003

Summary Verticillium dahliae Klebahn is a soil‐borne fungal pathogen causing vascular diseases. The pathogen penetrates the host through the roots, spreads through the xylem, and systemically colonizes both resistant and susceptible genotypes. To elucidate the genetic and molecular bases of plant–Verticillium interactions, we have developed a pathosystem utilizing Arabidopsis thaliana and an isolate of V. dahliae pathogenic to both cruciferous and non‐cruciferous crops. Relative tolerance (based on symptom severity) but no immunity was found in a survey of Arabidopsis ecotypes. Anthocyanin accumulation, stunting, and chlorosis were common symptoms. Specific responses of the more susceptible ecotype Columbia were induction of early flowering and dying. The more tolerant ecotype C‐24 was characterized by pathogen‐induced delay of transition to flowering and mild chlorosis symptoms. Genetic analysis indicated that a single dominant locus, Verticillium dahliae‐tolerance (VET1), likely functioning also as a negative regulator of the transition to flowering, was able to convey increased tolerance. VET1 was mapped on chromosome IV. The differential symptom responses observed between ecotypes were not correlated with different rates of fungal tissue colonization or with differential transcript accumulation of PR‐1 and PDF1.2 defense genes whose activation was not detected during the Arabidopsis–V. dahliae interaction. Impairment in salicylic acid (SA)‐ or jasmonic acid (JA)‐dependent signaling did not cause hypersensitivity to the fungal infection, whereas ethylene insensitivity led to reduced chlorosis and ABA deficiency to reduced anthocyanin accumulation. The results of this study clearly indicated that the ability of V. dahliae to induce disease symptoms is also connected to the genetic control of development and life span in Arabidopsis.
Phosphorylation of sucrose synthase at serine 170: occurrence and possible role as a signal for proteolysis
Authors: Hardin Shane C. , Tang Guo‐Qing , Scholz Anke , Holtgraewe Daniela , Winter Heike , Huber Steven C. 
Published: August 2003

SummarySequence analysis identified serine 170 (S170) of the maize (Zea mays L.) SUS1 sucrose synthase (SUS) protein as a possible, second phosphorylation site. Maize leaves contained two calcium‐dependent protein kinase activities and a calcium‐independent kinase activity with characteristics of an sucrose non‐fermenting 1 (SNF1)‐related protein kinase. Phosphorylation of the novel S170 and the known serine 15 (S15) site by these protein kinases was determined in peptide substrates and detected in SUS1 protein substrates utilizing sequence‐ and phosphorylation‐specific antibodies. We demonstrate phosphorylation of S170 in vitro and in vivo. The calcium‐dependent protein kinases phosphorylated both S170 and S15, whereas SNF1‐related protein kinase activity was restricted to S15. Calcium‐dependent protein‐kinase‐mediated S170 and S15 phosphorylation kinetics were determined in wild‐type and mutant SUS1 substrates. These analyses revealed that kinase specificity for S170 was threefold lower than that for S15, and that phosphorylation of S170 was stimulated by prior phosphorylation at the S15 site. The SUS‐binding peptides encoded by early nodulin 40 (ENOD40) specifically antagonized S170 phosphorylation in vitro. A model wherein S170 phosphorylation functions as part of a mechanism targeting SUS for proteasome‐mediated degradation is supported by the observations that SUS proteolytic fragments: (i) were detected and possessed relatively high phosphorylated‐S170 (pS170) stoichiometry; (ii) were spatially coincident with proteasome activity within developing leaves; and (iii) co‐sedimented with proteasome activity. In addition, full‐length pS170‐SUS protein was less stable than S170‐SUS in cultured leaf segments and was stabilized by proteasome inhibition. Post‐translational control of SUS protein level through pS170‐promoted proteolysis may explain the specific and significant decrease in SUS abundance that accompanies the sink‐to‐source transition in developing maize leaves.
Different pathways of homologous recombination are used for the repair of double‐strand breaks within tandemly arranged sequences in the plant genome
Authors: Orel Nadiya , Kyryk Anzhela , Puchta Holger 
Published: August 2003

SummaryDifferent DNA repair pathways that use homologous sequences in close proximity to genomic double‐strand breaks (DSBs) result in either an internal deletion or a gene conversion. We determined the efficiency of these pathways in somatic plant cells of transgenic Arabidopsis lines by monitoring the restoration of the β‐glucuronidase (GUS) marker gene. The transgenes contain a recognition site for the restriction endonuclease I‐SceI either between direct GUS repeats to detect deletion formation (DGU.US), or within the GUS gene to detect gene conversion using a nearby donor sequence in direct or inverted orientation (DU.GUS and IU.GUS). Without expression of I‐SceI, the frequency of homologous recombination (HR) was low and similar for all three constructs. By crossing the different lines with an I‐SceI expressing line, DSB repair was induced, and resulted in one to two orders of magnitude higher recombination frequency. The frequencies obtained with the DGU.US construct were about five times higher than those obtained with DU.GUS and IU.GUS, irrespective of the orientation of the donor sequence. Our results indicate that recombination associated with deletions is the most efficient pathway of homologous DSB repair in plants. However, DSB‐induced gene conversion seems to be frequent enough to play a significant role in the evolution of tandemly arranged gene families like resistance genes.
The SOC1 MADS‐box gene integrates vernalization and gibberellin signals for flowering in Arabidopsis
Authors: Moon Jihyun , Suh Sung‐Suk , Lee Horim , Choi Kyu‐Ri , Hong Choo Bong , Paek Nam‐Chon , Kim Sang‐Gu , Lee Ilha 
Published: August 2003

SummaryThe floral transition in Arabidopsis is regulated by at least four flowering pathways: the long‐day, autonomous, vernalization, and gibberellin (GA)‐dependent pathways. Previously, we reported that the MADS‐box transcription factor SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1) integrates the long‐day and vernalization/autonomous pathways. Here, we present evidences that SOC1 also integrates signaling from the GA‐dependent pathway, a major flowering pathway under non‐inductive short days. Under short days, the flowering time of GA‐biosynthetic and ‐signaling mutants was well correlated with the level of SOC1 expression; overexpression of SOC1 rescued the non‐flowering phenotype of ga1‐3, and the soc1 null mutant showed reduced sensitivity to GA for flowering. In addition, we show that vernalization‐induced repression of FLOWERING LOCUS C (FLC), an upstream negative regulator of SOC1, is not sufficient to activate SOC1; positive factors are also required. Under short days, the GA pathway provides a positive factor for SOC1 activation. In contrast to SOC1, the GA pathway does not regulate expression of other flowering integrators FLC and FT. Our results explain why the GA pathway has a strong effect on flowering under short days and how vernalization and GA interact at the molecular level.
The Arabidopsis TDS4 gene encodes leucoanthocyanidin dioxygenase (LDOX) and is essential for proanthocyanidin synthesis and vacuole development
Authors: Abrahams Sharon , Lee Elizabeth , Walker Amanda R. , Tanner Gregory J. , Larkin Philip J. , Ashton Anthony R. 
Published: August 2003

SummaryThe anthocyanin and proanthocyanidin (PA) biosynthetic pathways share common intermediates until leucocyanidin, which may be used by leucoanthocyanidin dioxygenase (LDOX) to produce anthocyanin, or the enzyme leucoanthocyanidin reductase (LAR) to produce catechin, a precursor of PA. The Arabidopsis mutant tannin deficient seed 4 (tds4‐1) has a reduced PA level and altered pattern PA accumulation. We identified the TDS4 gene as LDOX by complementation of the tds4‐1 mutation either with a cosmid encoding LDOX or a 35S:LDOX construct. Independent Arabidopsis lines with a T‐DNA insertion in the LDOX gene had a similar phenotype, and one was allelic to tds4‐1. The seed phenotype of ban tds4 double mutants showed that LDOX precedes BANYULS (BAN) in the PA pathway, confirming recent biochemical characterisation of BAN as an anthocyanidin reductase. Double mutant analysis was also used to order the other TDS genes. Analysis of the PA intermediates in tds4‐1 revealed three dimethylaminocinnamaldehyde (DMACA) reacting compounds that accumulated in extracts from developing seeds. Analysis of Arabidopsis PA and its precursors indicates that Arabidopsis, unlike many other plants, exclusively uses the epicatechin and not the catechin pathway to PA. Transmission electron microscopy (TEM) showed that the pattern observed when seeds of tds4 were stained with DMACA was a result of the accumulation of PA intermediates in the cytoplasm of endothelial cells. Fluorescent marker dyes were used to show that tds4 endothelial cells had multiple small vacuoles, instead of a large central vacuole as observed in the wild types (WT). These results show that in addition to its established role in the formation of anthocyanin, LDOX is also part of the PA biosynthesis pathway.
ars1, an Arabidopsis mutant exhibiting increased tolerance to arsenate and increased phosphate uptake
Authors: Lee David A. , Chen Alice , Schroeder Julian I. 
Published: August 2003

SummaryArsenic is one of the most toxic pollutants at contaminated sites, yet little is known about the mechanisms by which certain plants survive exposure to high arsenic levels. To gain insight into the mechanisms of arsenic tolerance in plants, we developed a genetic screen to isolate Arabidopsis thaliana mutants with altered tolerance to arsenic. We report here on the isolation of a mutant arsenic resisant 1 (ars1) with increased tolerance to arsenate. ars1 germinates and develops under conditions that completely inhibit growth of wild‐type plants and shows a semi‐dominant arsenic resistance phenotype. ars1 accumulates levels of arsenic similar to that accumulated by wild‐type plants, suggesting that ars1 plants have an increased ability to detoxify arsenate. However, ars1 plants produce phytochelatin levels similar to levels produced by the wild type, and the enhanced resistance of ars1 is not abolished by the γ‐glutamylcysteine synthetase inhibitor l‐buthionine sulfoxime (BSO). Furthermore, ars1 plants do not show resistance to arsenite or other toxic metals such as cadmium and chromium. However, ars1 plants do show a higher rate of phosphate uptake than that shown by wild‐type plants, and wild‐type plants grown with an excess of phosphate show increased tolerance to arsenate. Traditional models of arsenate tolerance in plants are based on the suppression of phosphate uptake pathways and consequently on the reduced uptake of arsenate. Our data suggest that arsenate tolerance in ars1 could be due to a new mechanism mediated by increased phosphate uptake in ars1. Models discussing how increased phosphate uptake could contribute to arsenate tolerance are discussed.
Nuclear translocation of the photoreceptor phytochrome B is necessary for its biological function in seedling photomorphogenesis
Authors: Huq Enamul , Al‐Sady Bassem , Quail Peter H. 
Published: August 2003

SummaryThe phytochrome (phy) family of sensory photoreceptors (phyA to phyE in Arabidopsis) enables plants to optimize their growth and development under natural light environments. Subcellular localization studies have shown that the photoreceptor molecule is induced to translocate from cytosol to nucleus by light, but direct evidence of the functional relevance of this translocation has been lacking. Here, using a glucocorticoid receptor‐based fusion protein system, we demonstrate that both photoactivation and nuclear translocation combined are necessary and sufficient for the biological function of phyB. Conversely, neither artificial nuclear translocation of non‐photoactivated phyB nor artificial retention of photoactivated phyB in the cytosol provides detectable biological activity. Together these data indicate that signal transfer from photoactivated phyB to its primary signaling partner(s) is localized in the nucleus, and conversely suggest the absence of a cytosolic pathway from photoactivated phyB to light‐responsive genes.
A novel procedure for the localization of viral RNAs in protoplasts and whole plants
Authors: Zhang Fengli , Simon Anne E. 
Published: August 2003

SummaryAnalysis of virus spread using co‐expressed reporter proteins has provided important details on cell‐to‐cell and long‐distance movement of viruses in plants. However, most viruses cannot tolerate insertion of large non‐viral segments or loss of any open‐reading frames, procedures required to detect viruses non‐evasively. A technique used to localize mRNAs intracellularly in yeast has been modified for detection of viral RNAs in whole plants. The technique makes use of the binding of the coat protein of MS2 bacteriophage (CPMS2) to a 19 base hairpin (hp). A fusion protein, consisting of the CPMS2, green fluorescent protein (GFP), and a nuclear localization signal (NLS), was nuclear‐localized upon transient expression in protoplasts. However, addition of the hp to the 3′ untranslated region of Turnip crinkle virus (TCV‐hp) and co‐transfection of the virus and fusion protein construct into protoplasts resulted in the re‐location of GFP to the cytoplasm. Neither the insertion of the hp nor the interaction with the fusion protein impaired any viral functions. Transgenic plants expressing the GFP‐NLS‐CPMS2 fusion protein were generated, and GFP was detected in nuclei of young plant cells. Foci of GFP cytoplasmic fluorescence were detected in TCV‐hp‐inoculated leaves at 2 days post‐inoculation. Later, GFP was detected in young leaves near the midvein and in the base (support) cells of trichomes in the vicinity of secondary and tertiary veins. In older leaves, cytoplasmic GFP could be visualized throughout many of the leaves. This technique should be amenable for detection of any virus with a transformable plant (or animal) host and may also prove useful for localizing properly engineered host RNAs.
Factors associated with the difference in score between women's and doctors' decisional conflict about hormone therapy: a multilevel regression analysis
Authors: Légaré France , Tremblay Stéphane , O'Connor Annette M. , Graham Ian D. , Wells Georges A. , Jacobsen Mary Jane 
Published: August 2003

AbstractObjective: To explore factors associated with the difference in score between women's and doctors’ decisional conflict about hormone therapy (HT).Design: Secondary analysis. Setting and participants: family doctors were randomized to prepare women for counselling about HT using either a decision aid or a pamphlet.Main variables studied: After each counselling session, decisional conflict was assessed in women and doctors using the Decisional Conflict Scale (DCS) and the Provider Decision Process Assessment Instrument (PDPAI), respectively. The difference in score between the DCS and PDPAI was computed and entered as the dependent variable in a multilevel regression analysis.Main outcome results: A total of 40 doctors and 167 women were included in the analysis. The intra‐doctor correlation coefficient was 0.25. Factors associated with women experiencing higher decisional conflict than their doctor were: age of doctor >45 years, women who were undecided about the best choice after the counselling session, women with a university degree and women who said that their doctor usually does not give them control over treatment decision. Factors associated with doctors experiencing more decisional conflict than women were: doctors who were undecided about the quality of the decision, length of visit <30 min and women who thought that the decision was shared with their doctor.Conclusion: In order to reduce the disparities between women's and doctors’ decisional conflict about HT, interventions aimed at raising awareness of doctors about shared decision‐making should be encouraged.
Isolation and Antimicrobial Susceptibility of Aeromonas salmonicida in rainbow trout (Oncorhynchus mykiss) in Turkey Hatchery Farms
Authors: Kırkan Ş. , Göksoy E. Ö. , Kaya O. 
Published: August 2003

SummaryThree Aeromonas salmonicida strains were isolated from the livers of 265 rainbow trouts sampled. The antibiotic susceptibility test results showed that A. salmonicida strains were susceptible to streptomycine and ciprofloxacin. However, they were resistant to amoxycilline + clavulanic acid, penicillin, erythromycine, oxytetracycline and cefuroxime sodium.
The Effect of Commercial Steam Pasteurization on the Levels of Enterobacteriaceae and Escherichia coli on Naturally Contaminated Beef Carcasses
Authors: Minihan D. , Whyte P. , O'Mahony M. , Collins J. D. 
Published: August 2003

SummaryThe aim of the study was to assess the reduction achieved by steam pasteurization of beef carcasses of Escherichia coli, Enterobacteriaceae and total aerobic mesophilic plate counts (APCs). In total, 30 carcass halves were exposed to steam pasteurization (90°C, 10 s exposure time) and the 30 corresponding carcass halves remained as untreated controls. The neck, midline and rump were sampled on each carcass half. Significant reductions in E. coli incidence (P < 0.05) and counts, 0.5 log10 CFU 1000 cm−2 (P < 0.05), were observed on rump sites only. Significant reductions (>0.8 log10 CFU 1000 cm−2) of Enterobacteriaceae were observed at all carcass sites sampled (P < 0.05). Enterobacteriaceae reductions (>2 log10 CFU 1000 cm−2) were highly significant at the more contaminated sites (P < 0.001). Reductions in total APCs were inconsistent. Steam pasteurization significantly reduced the level of E. coli and Enterobacteriaceae at more contaminated sites, but did not result in complete decontamination. Therefore, steam pasteurization should be classed as an aid to hygienic beef processing, but not as a critical control point.
Positive Identification of Newcastle Disease Virus Vaccine Strains and Detection of Contamination in Vaccine Batches by Restriction Site Analysis of the Matrix Protein Gene
Authors: Farsang A. , Wehmann E. , Soós T. , Lomniczi B. 
Published: August 2003

SummaryTwelve vaccine batches prepared from avirulent vaccine strains of Newcastle disease virus produced by seven manufacturers were identified by analysis of the matrix (M) protein gene with restriction enzymes MboI and HinfI. The analyses have revealed the presence of the strain indicated by the manufacturers (namely B‐1, LaSota or Ulster 2C), except in one case when the vaccine contained strain V4 Queensland instead of VGGA as indicated. In addition, several batches of both monovalent and combined vaccines containing strain LaSota of the same company consistently disclosed contamination with strain B‐1. The mixed nature of the preparations was verified not only by the dual patterns of restriction fragments but also by separating the two components and identifying them individually. Restriction analysis of the M gene, by allowing positive identification of each of the lentogenic vaccine strains, should provide an improvement in controlling vaccine batches by revealing homologous contaminants or exchange of the vaccine strain.
Nitric oxide, human diseases and the herbal products that affect the nitric oxide signalling pathway
Authors: Achike Francis I , Kwan Chiu‐Yin 
Published: August 2003

Summary1. Nitric oxide (NO) is formed enzymatically from l‐arginine in the presence of nitric oxide synthase (NOS). Nitric oxide is generated constitutively in endothelial cells via sheer stress and blood‐borne substances. Nitric oxide is also generated constitutively in neuronal cells and serves as a neurotransmitter and neuromodulator in non‐adrenergic, non‐cholinergic nerve endings. Furthermore, NO can also be formed via enzyme induction in many tissues in the presence of cytokines.2. The ubiquitous presence of NO in the living body suggests that NO plays an important role in the maintenance of health. Being a free radical with vasodilatory properties, NO exerts dual effects on tissues and cells in various biological systems. At low concentrations, NO can dilate the blood vessels and improve the circulation, but at high concentrations it can cause circulatory shock and induce cell death. Thus, diseases can arise in the presence of the extreme ends of the physiological concentrations of NO.3. The NO signalling pathway has, in recent years, become a target for new drug development. The high level of flavonoids, catechins, tannins and other polyphenolic compounds present in vegetables, fruits, soy, tea and even red wine (from grapes) is believed to contribute to their beneficial health effects. Some of these compounds induce NO formation from the endothelial cells to improve circulation and some suppress the induction of inducible NOS in inflammation and infection.4. Many botanical medicinal herbs and drugs derived from these herbs have been shown to have effects on the NO signalling pathway. For example, the saponins from ginseng, ginsenosides, have been shown to relax blood vessels (probably contributing to the antifatigue and blood pressure‐lowering effects of ginseng) and corpus cavernosum (thus, for the treatment of men suffering from erectile dysfunction; however, the legendary aphrodisiac effect of ginseng may be an overstatement). Many plant extracts or purified drugs derived from Chinese medicinal herbs with proposed actions on NO pathways are also reviewed.
Choline potentiates the pressor response evoked by glycyl‐glutamine or naloxone in haemorrhaged rats
Authors: Gürün M Sibel , Millington William R , Ulus Ismail H 
Published: August 2003

Summary1. Severe blood loss initially lowers arterial pressure through a central mechanism that is thought to involve opioid and cholinergic neurons. The present study tested the hypothesis that simultaneous administration of a cholinergic agonist and an opioid receptor antagonist would produce a synergistic effect in the treatment of haemorrhage. Specifically, we tested whether choline, a precursor of acetylcholine, potentiates the pressor effect of the β‐endorphin derived peptide glycyl‐glutamine (Gly‐Gln) or the opioid receptor antagonist naloxone following acute haemorrhage.2. Conscious rats were treated intracerebroventricularly (i.c.v.) with choline chloride (180 nmol) alone or combined with Gly‐Gln (10 nmol) or naloxone (10 nmol) 2 min after blood withdrawal (2.5 mL/100 g bodyweight over 20 min) was completed; mean arterial pressure and heart rate were monitored for 30 min.3. Combined treatment with choline and Gly‐Gln elevated mean arterial pressure but did not affect heart rate significantly. Choline and Gly‐Gln had no effect on cardiovascular function when administered alone to haemorrhaged rats or when given together to normotensive animals. Choline also potentiated the pressor and tachycardic effect of naloxone in haemorrhaged rats.4. These data show that choline potentiates the pressor effect of Gly‐Gln and naloxone in haemorrhaged rats.