bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanism of cell death and disease resistance induction by transgenic expression of bacterio‐opsin
Authors: Pontier Dominique , Mittler Ron , Lam Eric 
Published: March 2003

SummaryOne of the earliest signal transduction events that trigger the hypersensitive response (HR) of plants against pathogen attack is thought to be an alteration of proton flux across the plasma membrane (PM). However, no direct genetic evidence for the involvement of PM‐localised proton channels or pumps in the induction of this response has been reported. We previously showed that expression of the bacterial proton pump bacterio‐opsin (bO) in transgenic plants resulted in the spontaneous activation of the HR. Here we show that the bO protein is likely localised to the PM in transgenic tobacco plants. Furthermore, mutational analysis shows that induction of the HR by bO expression is dependent upon the capability of bO to translocate protons. Although bO functions as a light‐driven proton pump in Halobacteria when assembled with retinal, we also show by mutational analysis that this chromophore binding is unnecessary for its in planta activity. Taken together, our results suggest that expression of bO in plants leads to the insertion of a passive proton channel into the PM. The activity of this channel in the PM results in spontaneous activation of cell death and HR‐associated phenotypes including enhanced resistance to a broad spectrum of plant pathogens. Our work provides direct molecular evidence to support a working model in which alterations in ionic homeostasis at the level of the PM may work as one of the critical steps in the signalling pathway for the activation of the HR.
Decreased Rubisco activity leads to dramatic changes of nitrate metabolism, amino acid metabolism and the levels of phenylpropanoids and nicotine in tobacco antisense RBCS transformants
Authors: Matt Petra , Krapp Anne , Haake Volker , Mock Hans‐Peter , Stitt Mark 
Published: March 2003

SummaryTobacco transformants that express an antisense RBCS construct were used to investigate the consequences of a lesion in photosynthetic carbon metabolism for nitrogen metabolism and secondary metabolism. The results show that an inhibition of photosynthesis and decrease in sugar levels leads to a general inhibition of nitrogen metabolism, and dramatic changes in the levels of secondary metabolites. The response was particularly clear in plants that received excess nitrogen. In these conditions, a decrease of Rubisco activity led to an inhibition of nitrate reductase activity, accumulation of nitrate, a decrease of amino acid levels that was larger than the decrease of sugars, and a large decrease of chlorogenic acid and of nicotine, which are the major carbon‐ and nitrogen‐rich secondary metabolites in tobacco leaves, respectively. Similar changes were seen when nitrogen‐replete wild‐type tobacco was grown in low light. The inhibition of nitrogen metabolism was partly masked when wild‐type plants and antisense RBCS transformants were compared in marginal or in limiting nitrogen, because the lower growth rate of the transformants alleviated the nitrogen deficiency, leading to an increase of amino acids. In these conditions, chlorogenic acid always decreased but the decrease of nicotine was ameliorated or reversed. When the changes in internal pools are compared across all the genotypes and growth conditions, two conclusions emerge. First, decreased levels of primary metabolites lead to a dramatic decrease in the levels of secondary metabolites. Second, changes of the amino acid : sugar ratio are accompanied by changes of the nicotine:chlorogenic acid ratio.
Maize DRE‐binding proteins DBF1 and DBF2 are involved in rab17 regulation through the drought‐responsive element in an ABA‐dependent pathway
Authors: Kizis Dimosthenis , Pagès Montserrat 
Published: March 2003

SummaryThe abscisic acid‐responsive gene rab17 of maize is expressed during late embryogenesis, and is induced by ABA and desiccation in embryo and vegetative tissues. ABRE and DRE cis‐elements are involved in regulation of the gene by ABA and drought. Using yeast one‐hybrid screening, we isolated two cDNAs encoding two new DRE‐binding proteins, designated DBF1 and DBF2, that are members of the AP2/EREBP transcription factor family. Analysis of mRNA accumulation profiles showed that DBF1 is induced during maize embryogenesis and after desiccation, NaCl and ABA treatments in plant seedlings, whereas the DBF2 mRNA is not induced. DNA‐binding preferences of DBFs were analysed by electrophoretic mobility shift assays, and showed that both DBF1 and DBF2 bound to the wild‐type DRE2 element, but not to the DRE2 mutant or to the DRE1 element which differs only in a single nucleotide. Transactivation activity using particle bombardment showed that DBF1 functioned as activator of DRE2‐dependent transcription of rab17 promoter by ABA, whereas DBF2 overexpression had a repression action downregulating not only the basal promoter activity, but also the ABA effect. These results show that ABA plays a role in the regulation of DBF activity, and suggests the existence of an ABA‐dependent pathway for the regulation of genes through the C‐repeat/DRE element.
Flux control of sulphate assimilation in Arabidopsis thaliana: adenosine 5′‐phosphosulphate reductase is more susceptible than ATP sulphurylase to negative control by thiols
Authors: Vauclare Pierre , Kopriva Stanislav , Fell David , Suter Marianne , Sticher Liliane , Von Ballmoos Peter , Krähenbühl Urs , Den Camp Roel Op , Brunold Christian 
Published: March 2003

SummaryThe effect of externally applied l‐cysteine and glutathione (GSH) on ATP sulphurylase and adenosine 5′‐phosphosulphate reductase (APR), two key enzymes of assimilatory sulphate reduction, was examined in Arabidopsis thaliana root cultures. Addition of increasing l‐cysteine to the nutrient solution increased internal cysteine, γ‐glutamylcysteine and GSH concentrations, and decreased APR mRNA, protein and extractable activity. An effect on APR could already be detected at 0.2 mm l‐cysteine, whereas ATP sulphurylase was significantly affected only at 2 mm l‐cysteine. APR mRNA, protein and activity were also decreased by GSH at 0.2 mm and higher concentrations. In the presence of l‐buthionine‐S, R‐sulphoximine (BSO), an inhibitor of GSH synthesis, 0.2 mm l‐cysteine had no effect on APR activity, indicating that GSH formed from cysteine was the regulating substance. Simultaneous addition of BSO and 0.5 mm GSH to the culture medium decreased APR mRNA, enzyme protein and activity. ATP sulphurylase activity was not affected by this treatment. Tracer experiments using 35SO42– in the presence of 0.5 mm l‐cysteine or GSH showed that both thiols decreased sulphate uptake, APR activity and the flux of label into cysteine, GSH and protein, but had no effect on the activity of all other enzymes of assimilatory sulphate reduction and serine acetyltransferase. These results are consistent with the hypothesis that thiols regulate the flux through sulphate assimilation at the uptake and the APR step. Analysis of radioactive labelling indicates that the flux control coefficient of APR is more than 0.5 for the intracellular pathway of sulphate assimilation. This analysis also shows that the uptake of external sulphate is inhibited by GSH to a greater extent than the flux through the pathway, and that the flux control coefficient of APR for the pathway, including the transport step, is proportionately less, with a significant share of the control exerted by the transport step.
Lipid peroxidation in cotton: Xanthomonas interactions and the role of lipoxygenases during the hypersensitive reaction
Authors: Jalloul A. , Montillet J. L. , Assigbetsé K. , Agnel J.P. , Delannoy E. , Triantaphylidès C. , Daniel J.F. , Marmey P. , Geiger J.P. , Nicole M. 
Published: March 2003

SummaryLipid peroxidation, often associated with hypersensitive cell death, may be initiated either by active oxygen species (AOS) or lipoxygenases (LOX). Here we report a detailed analysis of this oxidative process in both incompatible and compatible interactions between the cotton cultivar Reba B50 and Xanthomonas campestris pv. malvacearum (Xcm). The hypersensitive reaction (HR) was characterized by a massive production of polyunsaturated fatty acid (PUFA) hydroperoxides together with typical tissue dehydration. Among these, isomers peroxidized on carbon 9, largely predominant, were chiral, showing an excess in the S enantiomer. The HR process was accompanied by an increase in 9S‐LOX activity and preceded by transcription of a LOX gene (GhKLox1). These results showed that: (i) AOS produced during the oxidative burst were not involved in PUFA peroxidation during HR; and (ii) as previously described in elicited leaves of tobacco, the massive enzymatic lipid peroxidation was closely associated with hypersensitive cell death. During disease development in this cotton cultivar, the 9‐lipoxygenation of PUFAs was late, weak, preceded by a faint accumulation of GhKLox1 transcripts, and associated with chlorosis but not with necrosis. Consequently, the main difference between incompatible and compatible interactions was in the precocity and intensity of the oxidative process, rather than in its nature. These data provide the evidence for a correlation between lipid peroxidation and hypersensitive cell death induced by pathogens.
NAN fusions: a synthetic sialidase reporter gene as a sensitive and versatile partner for GUS
Authors: Kirby J. , Kavanagh T. A. 
Published: March 2003

SummaryGUS continues to be the reporter of choice for many gene fusion applications, due to the unparalleled sensitivity of the encoded enzyme and the ease with which it can be quantified in cell‐free extracts and visualized histochemically in cells and tissues. A compatible and functionally equivalent reporter gene would facilitate dual promoter studies and internal standardization of expression analyses in the same plant. A search for a candidate enzyme activity not found in plants, which might form the basis of a novel GUS‐compatible reporter system, led us to investigate nanH, a Clostridium perfringens gene which encodes the so‐called ‘small’ cytoplasmic sialidase. Expression of the native, AT‐rich nanH gene in transgenic plants did not, however, result in detectable sialidase activity. For this reason, a codon‐optimized derivative, NAN, was synthesized which possesses a GC content similar to that found in highly expressed plant genes. NAN enzyme activity was expressed at high levels in both stably and transiently transformed cells, possessed kinetic and stability properties similar to those of GUS, and showed optimal activity in GUS buffer. Moreover, NAN and GUS activity could be visualized simultaneously in polyacrylamide gels using the corresponding methylumbelliferone‐based substrates, and in whole seedlings and tissue sections using the histochemical substrates 5‐bromo‐4‐chloro‐3‐indolyl α‐d‐N‐acetylneuraminic acid (X‐NeuNAc) and 5‐bromo‐6‐chloro‐3‐indolyl β‐d‐glucuronide (X‐GlucM), respectively.
Chemical regulated production of cDNAs from genomic DNA fragments in plants
Authors: Møller Simon Geir , Chua Nam‐Hai 
Published: March 2003

SummaryWe have developed a new chemical inducible genetic system that allows for the isolation of any cDNA molecule from in vitro generated genomic transgenes in transgenic plants. This system, termed regulated in vivo cDNA generation (RIDE), permits both targeted isolation of individual full‐length cDNA molecules and random isolation of any partial or full‐length cDNA from in planta genomic libraries. The RIDE system makes use of the 17‐β estradiol‐inducible promoter system linked to intron donor and acceptor sites in a new binary vector configuration. In transgenic Arabidopsis and tobacco plants, we show that the RIDE system can isolate low‐abundance full‐length cDNAs previously unattainable by conventional means at high efficiencies (75–85%). The ability to randomly isolate individual exons and exons spliced together from genomic libraries in planta suggest that this system can be used for the isolation of any cDNA molecules. The RIDE system thus appears to be an efficient and versatile system for the generation of potentially any cDNA molecule. Moreover, the ORF structural data generated will be of value in both verifying and correcting computational ORF predications in the databases available to the scientific community.
Pasticcino2 is a protein tyrosine phosphatase‐like involved in cell proliferation and differentiation in Arabidopsis
Authors: Bellec Yannick , Harrar Yaël , Butaeye Christelle , Darnet Sylvain , Bellini Catherine , Faure Jean‐Denis 
Published: March 2003

SummaryThe pasticcino2 (pas2) mutant shows impaired embryo and seedling development associated with cell de‐differentiation and proliferation. This process is specifically enhanced in presence of cytokinins leading to callus‐like structure of the apical part of the seedling. Cell proliferation concerns localized and stochastic nodules of dividing cells. In absence of cytokinins, cell proliferation leads to small calli on stems but, most often, cell proliferation is associated with post‐genital organ fusion. The PAS2 gene was identified by positional cloning. PAS2 expression was found in every plant organ and was not regulated by PAS1 and PAS3 genes. PAS2 encodes the Arabidopsis member of the protein tyrosine phosphatase‐like (Ptpl) family, a new PTP family originally described in mice and humans and characterized by a mutated PTP active site. This family of proteins has a yeast homolog that is essential for cell viability. The absence of yeast PAS2 homolog can be functionally replaced by the Arabidopsis PAS2 protein, demonstrating that PAS2 function is conserved between higher and lower eukaryotes.
Spatio‐temporal expression of patatin‐like lipid acyl hydrolases and accumulation of jasmonates in elicitor‐treated tobacco leaves are not affected by endogenous levels of salicylic acid
Authors: Dhondt Sandrine , Gouzerh Guillaume , Müller Axel , Legrand Michel , Heitz Thierry 
Published: March 2003

SummaryWe have previously isolated three tobacco genes (NtPat) encoding patatin‐like proteins, getting rapidly induced during the hypersensitive response (HR) to tobacco mosaic virus, in advance to jasmonate accumulation. NtPAT enzymes are lipid acyl hydrolases that display high phospholipase A2 (PLA2) activity and may mobilize fatty acid precursors of oxylipins. Here, we performed a detailed study of NtPat gene regulation under various biotic and abiotic stresses. PLA2 activity was poorly induced in response to drought, wounding, reactive oxygen intermediates, salicylic acid (SA) or methyl‐jasmonate (MJ) whereas the ethylene (ET) precursor, 1‐aminocyclopropane‐1‐carboxylic acid (ACC), provoked a moderate induction. In contrast, PLA2 activity was strongly induced when ACC was combined with MJ, and in response to the bacterium Erwinia carotovora or to the fungus Botrytis cinerea, as well as to treatment with β‐megaspermin, a cell death‐inducing protein elicitor. A simplified system based on the infiltration of β‐megaspermin into leaves was used to dissect the spatio‐temporal activation of PLA2 activity with regards to the accumulation of jasmonates and to the influence of endogenous SA. NtPat‐encoded PLA2 activity was rapidly induced in the infiltrated zone before the appearance of cell death and with some delay in the surrounding living cells. A massive accumulation of 12‐oxo‐phytodienoic and jasmonic acids occurred in the elicitor‐infiltrated zone, but only low levels were detectable outside this area. A similar picture was found in SA‐deficient plants, showing that in tobacco, accumulation of jasmonates is not affected by the concomitant HR‐induced build‐up of endogenous SA. Finally, ET‐insensitive plants showed a weakened induction of PLA2 activity outside the elicitor‐infiltrated tissue.
AGL24 acts as a promoter of flowering in Arabidopsis and is positively regulated by vernalization
Authors: Michaels Scott D. , Ditta Gary , Gustafson‐Brown Cindy , Pelaz Soraya , Yanofsky Martin , Amasino Richard M. 
Published: March 2003

SummaryMADS‐domain‐containing transcription factors comprise a large family of regulators that have diverse roles in plant development, including the regulation of flowering time. AGAMOUS‐LIKE 20/SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) and FRUITFUL act to promote flowering, whereas FLOWERING LOCUS C (FLC), FLOWERING LOCUS M/MADS AFFECTING FLOWERING1, and SHORT VEGETATIVE PHASE are inhibitors of flowering. Here we report that AGAMOUS‐LIKE 24 (AGL24) also plays a role in the regulation of flowering time. agl24 mutants are late flowering and overexpression of AGL24 causes early flowering in wild‐type and late‐flowering‐mutant backgrounds. The effect of AGL24 overexpression is most pronounced in autonomous‐pathway‐mutant and FRIGIDA‐containing backgrounds. The behavior of AGL24 is most similar to that of SOC1. Like SOC1, AGL24 mRNA levels are upregulated by vernalization. Unlike SOC1, however, AGL24 mRNA levels are not affected by FLC, and therefore AGL24 may represent an FLC‐independent target of the vernalization pathway. There is also evidence for cross‐talk between AGL24 and SOC1. When overexpressed, SOC1 and AGL24 are able to upregulate each other's expression. Thus, AGL24 represents another component in a network of MADS‐domain‐containing transcription factors that regulate flowering time.
The reduction of HIV transfusion risk in southern Brazil in the 1990s
Authors: Kupek E. J. 
Published: March 2003

A retrospective study of blood donor records was undertaken to obtain risk estimates for transfusing HIV‐contaminated blood due to an infectious window period in a large blood bank in the south of Brazil in the 1990s. An incidence/window period model was used to estimate HIV incidence and risk of seroconversion among 11 286 repeat donors with 8917 person‐years of follow‐up. Separate estimates were calculated for the periods of 1991–94, 1995–96 and 1997–99. Although the residual risk of HIV‐positive transfusion decreased from 1 : 5000 in 1991–94 and 1 : 3794 in 1995–96 to 1 : 48 777 in 1997–99, this is still almost 10 times higher than in developed countries. The risk reduction is likely to have resulted from improved donor selection. Despite a 10‐fold reduction in the risk of transfusing HIV‐contaminated blood because of the screening test's failure to detect the virus during the infectious window period in the 1990s, additional measures are urgently needed to reduce the risk further. To this end, PCR screening of pooled blood donations might be considered in areas of high HIV prevalence when justified by cost‐effectiveness calculations.
National audit of citrate toxicity in plateletpheresis donors
Authors: Makar Y. F. , Butler M. O. , Cockersole G. M. , Gabra G. , Serevitch J. M. 
Published: March 2003

Summary  Citrate toxicity complicating plateletpheresis is not uncommon. However, the scale and severity of the problem have never been formally addressed. In order to answer these questions we undertook a national audit of 13 070‐platelet procedures throughout 17 apheresis centres in England over a 3‐month period from 1 April to 30 June 2000. A standard form was distributed to each centre to record the symptoms/signs of citrate toxicity which were then graded (grades 1–5) according to their severity. The following variables were studied to determine whether they influenced the frequency and severity of citrate toxicity:

The type of manufacturer's cell separator used (Cobe Spectra, Haemonetics, Baxter Amicus and Trima).
The type of procedure: single needle, dual needle, single, double or triple dose.
The way in which donors were instructed to report symptoms of citrate toxicity.

Outcome  Plateletpheresis is a relatively safe procedure provided that donors who experience severe reactions receive appropriate treatment.The incidence of severe citrate toxicity (0·03% procedures) is comparable to that of severe faints following whole blood donation, indicating a comparable margin of safety.Donors should be warned of the symptoms of citrate toxicity at their first attendance only. More frequent reminders encourage donors to over‐report symptoms of mild citrate toxicity.
Albendazole plus praziquantel versus albendazole alone as a pre‐operative treatment in intra‐abdominal hydatidosis caused by Echinococcus granulosus
Authors: Cobo  , Yarnoz  , Sesma  , Fraile  , Aizcorbe  , Trujillo  , Diaz‐de‐Liaño  , Ciga  
Published: March 2003

Summary
objective To compare the effects of a combined medication of albendazole (10 mg/kg/day) plus praziquantel (25 mg/kg/day) to those of albendazole alone at different doses (10 and 20 mg/kg/day). method The protoscoleces9 viability was studied in a consecutive series of patients affected by intra‐abdominal hydatidosis caused by Echinococcus granulosus. In all cases the drugs were given during the month prior to surgery. results A significant increase of patients with nonviable protoscoleces was observed in the group treated with the scolicides combination compared to those treated with albendazole alone, both at a dose of 10 mg/kg/day (P = 0.004) and at a dose of 20 mg/kg/day (P = 0.03). Albendazole sulphoxide levels in serum and in cyst fluid were higher in patients given the combined therapy than in those who received only albendazole (10 mg/kg/day: P = 0.016; 20 mg/kg/day: P = 0.034). Levels in the cysts were not significantly different probably due to the sample size; nevertheless a lineal relation between the values obtained in serum and inside the cysts could be discerned in the patients treated with the combined medication. conclusion Albendazole plus praziquantel is more effective than monotherapy with albendazole in the preoperative treatment of intra‐abdominal hydatidosis.
Little effect of praziquantel or artemisinin on clonorchiasis in northern Vietnam. A pilot study
Authors: Tinga Niels , Van De Nguyen , Vien Ha Viet , Van Chau Le , Toan Nguyen Duy , Kager Piet A. , de Vries Peter J. 
Published: March 2003

Summary The first choice for treatment of Clonorchis sinensis infections is praziquantel. Experimental data suggest that artemisinin derivatives are active against C. sinensis.The efficacy of both drugs against clonorchiasis was evaluated in a pilot study in clonorchiasis patients in an endemic area in the North of Vietnam. Twenty‐one patients received praziquantel 25 mg/kg o.d. for three days, the regular regimen in that area, and 21 patients were treated with artemisinin 500 mg b.i.d. for 5 days. Faecal egg counts were performed before as well as 6 days and 5 weeks after treatment. In the praziquantel group the faecal egg count decreased significantly from a mean value of 1632 eggs per gram faeces (epg) to 37 epg 5 weeks after treatment (P < 0.01) but, surprisingly, the eradication rate (95% confidence limit) at week 5 was only 29% (11–52%). In the artemisinin‐treated group the reduction of the egg count was insignificant: from 1103 to 542 epg (P > 0.05). The proportion of patients (95% c.l.) with C. sinensis eggs in their stool on week 5 was 90% (70–99%) in the artemisinin group and 71% (48–89%) in the praziquantel group (P > 0.05) and the eradication rate (95% c.l.) at week 5 was only 10% (1–30%). With a sensitivity of detection of eggs in stool > 0.89, this implies a statistically significant but clinically unsatisfactory reduction for treatment with praziquantel. Sensitivity is probably less. For artemisinin there was no significant reduction. In conclusion, for human clonorchiasis in the North of Vietnam, the efficacy of praziquantel 25 mg/kg o.d. for 3 days was unsatisfactory and artemisinin for 5 days is not an effective alternative.