bluuebunny/crossref_metadata_2025 huggingface dataset:
The S receptor kinase gene determines dominance relationships in stigma expression of self‐incompatibility in Brassica
Authors: Hatakeyama Katsunori , Takasaki Takeshi , Suzuki Go , Nishio Takeshi , Watanabe Masao , Isogai Akira , Hinata Kokichi
Published: March 2003

Self‐incompatibility (SI) in Brassica is sporophytically controlled by the multi‐allelic S locus. SI phenotypes of the stigma and pollen in an S heterozygote are determined by the two S haplotypes it carries; the two haplotypes may be co‐dominant or exhibit a dominant/recessive relationship. Because the S receptor kinase (SRK) gene of the S locus was recently shown to determine the S haplotype specificity of the stigma, we wished to investigate whether SRK also plays a role in the dominance relationships between S haplotypes. We crossed plants carrying an SRK28 transgene with plants homozygous for one of five S haplotypes that are either co‐dominant with, or recessive to, S28 haplotype in the stigma, and analyzed the SI phenotypes of the progeny. In all cases, the SI phenotype of the stigma of plants carrying the SRK28 transgene could be predicted by the known dominance relationships between the S haplotype(s) and the S28 haplotype. Moreover, in the S43 homozygote carrying the SRK28 transgene where the S43 phenotype in the stigma was masked by the presence of the SRK28, the transcript level of SRK28 was found to be much lower than that of SRK43. All these results suggest that the dominance relationships between S haplotypes in the stigma are determined by SRK, but not by virtue of its relative expression level.
Unexpected roles for cryptochrome 2 and phototropin revealed by high‐resolution analysis of blue light‐mediated hypocotyl growth inhibition
Authors: Folta Kevin M. , Spalding Edgar P.
Published: March 2003

Blue light (BL) rapidly and strongly inhibits hypocotyl elongation during the photomorphogenic response known as de‐etiolation, the transformation of a dark‐grown seedling into a pigmented, photoautotrophic organism. In Arabidopsis thaliana, high‐resolution studies of hypocotyl growth accomplished by computer‐assisted electronic image capture and analysis revealed that inhibition occurs in two genetically independent phases, the first beginning within 30 sec of illumination. The present work demonstrates that phototropin (nph1), the photoreceptor responsible for phototropism, is largely responsible for the initial, rapid inhibition. Signaling from phototropin during the curvature response is dependent upon interaction with NPH3, but the results presented here demonstrate that NPH3 is not necessary for phototropin‐dependent growth inhibition. Activation of anion channels, which transiently depolarizes the plasma membrane within seconds of BL, is an early event in the cryptochrome signaling pathway leading to a phase of growth inhibition that replaces the transient phototropin‐dependent phase after approximately 30 min of BL. Surprisingly, cry1 and cry2 were found to contribute equally and non‐redundantly to anion‐channel activation and to growth inhibition between 30 and 120 min of BL. Inspection of the inhibition kinetics displayed by nph1 and nph1cry1 mutants revealed that the cryptochrome phase of inhibition is delayed in seedlings lacking phototropin. This result indicates that BL‐activation of phototropin influences cryptochrome signaling leading to growth inhibition. Mutations in the NPQ1 gene, which inhibit BL‐induced stomatal opening, do not affect any aspect of the growth inhibition within the first 120 min examined here, and NPQ1 does not affect the activation of anion channels.
The auxin signal for protoplast swelling is perceived by extracellular ABP1
Authors: Steffens Bianka , Feckler Christian , Palme Klaus , Christian May , Böttger Michael , Lüthen Hartwig
Published: March 2003

Protoplasts of corn coleoptiles and Arabidopsis hypocotyls respond to the plant hormone auxin with a rapid change in volume. We checked the effect of antibodies directed against epitopes of auxin‐binding protein 1 from Arabidopsis thaliana (AtERabp1) and Zea mays (ZmERabp1), respectively. Antibodies raised against the C‐terminus of AtERabp1 inhibited the response to auxin, while antibodies raised against a part of box a, the putative auxin‐binding domain, induced a swelling response similar to that caused by auxin treatment. Synthetic C‐terminal oligopeptides of ZmERabp1 also caused a swelling response. These effects occurred regardless of whether the experiments were carried out with homologous (anti‐AtERabp1 antibodies on Arabidopsis protoplasts or anti‐ZmERabp1 antibodies in maize protoplasts) or heterologous immunological tools. The results indicate that the auxin signal for protoplast swelling is perceived by extracellular ABP1.
The monarch butterfly controversy: scientific interpretations of a phenomenon
Authors: Shelton Anthony M. , Sears Mark K.
Published: March 2003

The future development and use of agricultural biotechnology has been challenged by two preliminary studies indicating potential risk to monarch butterfly populations by pollen from corn engineered to express proteins from Bacillus thuringiensis. Likewise, these studies have also challenged the way in which science should be performed, published in scientific journals and communicated to the public at large. Herein, we provide a history of the monarch controversy to date. We believe a retrospective view may be useful for providing insights into the proper roles and responsibilities of scientists, the media and public agencies and the consequences when they go awry.
Local expression of enzymatically active class I β‐1, 3‐glucanase enhances symptoms of TMV infection in tobacco
Authors: Bucher Gregor L. , Tarina Corina , Heinlein Manfred , Di Serio Francesco , Meins Fred , Iglesias Victor Alejandro
Published: March 2003

Mutant tobacco plants deficient for class I β‐1,3‐glucanase (GLU I) are decreased in their susceptibility to virus infection. This is correlated with delayed virus spread, a reduction in the size exclusion limit of plasmodesmata and increased cell‐wall deposition of the β‐1,3‐glucan callose. To further investigate a role of GLU I during cell‐to‐cell movement of virus infection, we inserted the GLU I coding sequence into TMV for overexpression in infected cells. Compared with the size of local lesions produced on plants infected with virus expressing either an enzymatically inactive GLU I or a frameshift mutant of the gene, the size of local lesions caused by infection with virus expressing active GLU I was consistently increased. Viruses expressing antisense GLU I constructs led to lesions of decreased size. Similar effects were obtained for virus spread using plants grown at 32°C to block the hypersensitive response. Together, these results indicate that enzymatically active GLU I expressed in cells containing replicating virus can increase cell‐to‐cell movement of virus. This supports the view that GLU I induced locally during infection helps to promote cell‐to‐cell movement of virus by hydrolyzing callose. Moreover, our results provide the first direct evidence that a biological function of a plant β‐1,3‐glucanase depends on its catalytic activity.
Presence of an SAR‐like sequence in junction regions between an introduced transgene and genomic DNA of cultured tobacco cells: its effect on transformation frequency
Authors: Shimizu Katsuya , Takahashi Misa , Goshima Naoki , Kawakami Shigeki , Irifune Kohei , Morikawa Hiromichi
Published: March 2003

A 12.5‐kb DNA fragment with junction regions between the transgene and genomic DNA was cloned from a transgenic tobacco cell line obtained by microprojectile bombardment of plasmid pCaMVNEO. Nucleotide sequence analysis of the fragment (DDBJ accession no. D84238) showed that it carried a 7.7‐kb core sequence (concatemer of a complete pCaMVNEO and a partial pCaMVNEO) and two identical 1.3‐kb junction sequences that flanked both the 5′ and 3′ ends of the core sequence and had inverted orientations. These sequences had topoisomerase II (Topo II) cleavage sites and adenine and thimine‐rich sequences known to be specific to nuclear scaffold‐attachment regions (SARs). An in vitro binding assay showed that a 507‐bp fragment (designated TJ1) from the 1.3‐kb sequence had the ability to bind to nuclear scaffold preparations of cultured tobacco cells, confirmation that the 1.3‐kb sequence is an SAR. Insertion of TJ1at the 5′ and 3′ sides of the expression cassette for the npt II gene increased transformant yields 5‐ to 10‐fold and the NPT II enzyme activity per copy of the gene 5‐fold. TJ1enhances the integration or expression of the transgene, or both. Clearly, TJ1is very useful for producing transgenic plants. This is the first report on an SAR‐like sequence that is located in the transgene locus and enhances transformation efficiency in eukaryotic cells. The possible role of TJ1‐SAR in the molecular evolution of plant genome is discussed.
Constitutive salicylic acid‐dependent signaling in cpr1 and cpr6 mutants requires PAD4
Authors: Jirage Dayadevi , Zhou Nan , Cooper Bret , Clarke Joseph D. , Dong Xinnian , Glazebrook Jane
Published: March 2003

Salicylic acid (SA)‐dependent signaling controls activation of a set of plant defense mechanisms that are important for resistance to a variety of microbial pathogens. Many Arabidopsis mutants that display altered SA‐dependent signaling have been isolated. We used double mutant analysis to determine the relative positions of the pad4, cpr1, cpr5, cpr6, dnd1 and dnd2 mutations in the signal transduction network leading to SA‐dependent activation of defense gene expression and disease resistance. The pad4 mutation causes failure of SA accumulation in response to infection by certain pathogens, while the other mutations cause constitutively high levels of SA, defense gene expression and resistance. The cpr1 pad4, cpr5 pad4, cpr6 pad4, dnd1 pad4 and dnd2 pad4 double mutants were constructed and assayed for stature, presence of spontaneous lesions, resistance to Pseudomonas syringae and Peronospora parasitica, SA levels, expression of PAD4, PR‐1 and PDF1.2, and accumulation of camalexin. We found that the effects of the cpr1 and cpr6 mutations on SA‐dependent gene expression are completely dependent on PAD4 function. In contrast, SA accumulation in the lesion‐mimic mutant cpr5 is partially PAD4‐independent, while in dnd1 and dnd2 mutants it is completely PAD4‐independent. A model describing a possible arrangement of activities in the signal transduction network is presented.
A novel higher plant protein tyrosine phosphatase interacts with SNF1‐related protein kinases via a KIS (kinase interaction sequence) domain
Authors: Fordham‐Skelton Anthony P. , Chilley Paul , Lumbreras Victoria , Reignoux Sabrina , Fenton Tim R. , Dahm Christina C. , Pages Montserrat , Gatehouse John A.
Published: March 2003

A novel protein phosphatase in Arabidopsis thaliana was identified by database searching. This protein, designated AtPTPKIS1, contains a protein tyrosine phosphatase (PTP) catalytic domain and a kinase interaction sequence (KIS) domain. It is predicted to interact with plant SNF1‐related kinases (SnRKs), representing central regulators of metabolic and stress responses. AtPTPKIS1 has close homologues in other plant species, both dicots and monocots, but is not found in other kingdoms. The tomato homologue of AtPTPKIS1 was expressed as a recombinant protein and shown to hydrolyse a generic phosphatase substrate, and phosphotyrosine residues in synthetic peptides. The KIS domain of AtPTPKIS1 was shown to interact with the plant SnRK AKIN11 both in vivo in the yeast two‐hybrid system, and in vitro in a GST‐fusion ‘pull down’ assay. The genomes of Arabidopsis and other plants contain further predicted proteins related to AtPTPKIS1, which could also interact with SnRKs and act in novel regulatory and signalling pathways.
The cycloidea gene can respond to a common dorsoventral prepattern in Antirrhinum
Authors: Clark Jennifer I. , Coen Enrico S.
Published: March 2003

Dorsoventral asymmetry in flowers of Antirrhinum depends on expression of the cycloidea gene in dorsal regions of floral meristems. To determine how cycloidea might be regulated we analysed its expression in several contexts. We show that cycloidea is activated shortly after floral induction, and that in addition to flowers, cycloidea can be asymmetrically expressed in shoots, even though these shoots show no marked dorsoventral asymmetry. Shoots expressing cycloidea include secondary branches lying just below the inflorescence, and shoots of floricaula mutants. Asymmetric cycloidea expression may also be observed within organ primordia, such as the sepals of terminal flowers produced by centroradialis mutants. Later expression of cycloidea within flowers can be modified by mutations in organ identity genes. Taken together, the results suggest that cycloidea can respond to a common dorsoventral pre‐pattern in the apex and that the specific effects of cycloidea on the flower depend on interactions with floral‐specific genes.
Nitric oxide mediates iron‐induced ferritin accumulation in Arabidopsis
Authors: Murgia Irene , Delledonne Massimo , Soave Carlo
Published: March 2003

Nitric oxide (NO) is a signaling molecule that plays a critical role in the activation of innate immune and inflammatory responses in animals. During the last few years, NO has also been detected in several plant species and the increasing number of reports on its function in plants have implicated NO as an important effector of growth, development and defense. Analogously to animals, NO has been recently shown to inhibit tobacco aconitase. This suggests that NO may elevate free iron levels in the cells by converting tobacco cytoplasmic aconitase into a mRNA binding protein that negatively regulates accumulation of ferritin.

    We investigated the possible role of NO as a regulator of ferritin levels in Arabidopsis and found that the NO‐donor sodium nitroprusside (SNP) induces accumulation of ferritin both at mRNA and protein level. Iron is not necessary for this NO‐mediated ferritin transcript accumulation, since SNP is still able to induce the accumulation of ferritin transcript in Arabidopsis suspension cultures pre‐treated with the iron chelants DFO or ferrozine. However, NO is required for iron‐induced ferritin accumulation, as the NO scavenger CPTIO prevents ferritin transcript accumulation in Arabidopsis suspension cultures treated with iron. The pathway is ser/thr phosphatase‐dependent and necessitates protein synthesis; furthermore, NO mediates ferritin regulation through the IDRS sequence of the Atfer1 promoter responsible for transcriptional repression under low iron supply.

    NO, by acting downstream of iron in the induction of ferritin transcript accumulation is therefore a key signaling molecule for regulation of iron homeostasis in plants.
Molecular and biochemical mechanisms associated with dormancy and drought tolerance in the desert legume Retama raetam
Authors: Pnueli Lilach , Hallak‐Herr Elza , Rozenberg Mira , Cohen Mira , Goloubinoff Pierre , Kaplan Aaron , Mittler Ron
Published: March 2003

Dormancy is an important developmental program allowing plants to withstand extended periods of extreme environmental conditions, such as low temperature or drought. Seed dormancy, bud dormancy and desiccation tolerance have been extensively studied, but little is known about the mechanisms involved in the dormancy of drought‐tolerant plants, key to the survival of many plant species in arid and semi‐arid environments. Subtractive PCR cloning of cDNAs from Retama raetam, a C3 drought‐tolerant legume, revealed that dormancy in this plant is accompanied by the accumulation of transcripts encoding a pathogenesis‐related, PR‐10‐like protein; a low temperature‐inducible dehydrin; and a WRKY transcription factor. In contrast, non‐dormant plants subjected to stress conditions contained transcripts encoding a cytosolic small heat‐shock protein, HSP18; an ethylene‐response transcriptional co‐activator; and an early light‐inducible protein. Physiological and biochemical analysis of Rubisco activity and protein in dormant and non‐dormant tissues suggested a novel post‐translational mechanism of regulation that may be controlled by the redox status of cells. Ultrastructural analysis of dormant plants revealed that air spaces of photosynthetic tissues contained an extracellular matrix that may function to prevent water loss. The cytosol of dormant cells appeared to be in a glassy state, limiting metabolic activity. A combination of biochemical, molecular and structural mechanisms, in association with metabolic suppression, may be key to the extreme drought tolerance of R. raetam and its acclimation to the desert ecosystem. These may enable plants to withstand long periods of drought, as well as rapidly to exit dormancy upon rainfall.
Modifying the pollen coat protein composition in Brassica
Authors: Foster Elizabeth , Schneiderman Danielle , Cloutier Michel , Gleddie Stephen , Robert Laurian S.
Published: March 2003

The interactions between pollen and stigma are essential for plant reproduction and are made possible by compounds, such as proteins and lipids, located on their surfaces. The pollen coat is formed in part by compounds synthesized in, and released from, the tapetum, which become transferred to the pollen coat late in pollen development. In the Brassicaceae the predominant proteins of the mature pollen coat are the tapetal oleosin‐like proteins, which are highly expressed in, and ultimately transferred from, the tapetum. Here we report the modification of the protein composition of the pollen coat by the addition of an active enzyme which was synthesized in the tapetum. The marker enzyme β‐glucuronidase (GUS) was successfully targeted to the pollen coat in transgenic Brassica carinata plants expressing GUS translationally fused to a B. napus tapetal oleosin‐like protein (BnOlnB;4). To our knowledge this is the first demonstration of the targeting of an enzyme to the pollen coat.
Role of petunia pMADS3 in determination of floral organ and meristem identity, as revealed by its loss of function
Authors: Kapoor Meenu , Tsuda Shinzo , Tanaka Yoshikazu , Mayama Tomoko , Okuyama Yohei , Tsuchimoto Suguru , Takatsuji Hiroshi
Published: March 2003

pMADS3, a petunia class C gene, is the candidate homologue of Arabidopsis AGAMOUS (AG), which is involved in the specification of stamens and carpels. We report the characterization of loss‐of‐function phenotype of pMADS3 that resulted from silencing of this gene. Silencing of pMADS3 resulted in homeotic conversion of stamens into petaloid structures, whereas the carpels were only weakly affected. Ectopic secondary inflorescences emerged from the interstamenal region in the third whorl, which is unique and has not been reported for any class C gene of other plant species. Third‐order inflorescences emerged at corresponding positions in the third whorl of inner flowers of secondary inflorescences, indicating reiterative conversion of parts of the floral meristem into inflorescence meristem. On the basis of phenotypic analysis of the pMADS3‐silenced plants, we propose that pMADS3 is involved in determination of floral organ and floral meristem identity in petunia. Two hybrid studies in yeast showed that PMADS3 protein interacted specifically with FBP2, a candidate homologue of Arabidopsis SEPALLATA3 (SEP3). The evidence presented here suggest that a complex involving PMADS3 and FBP2 is responsible for specification of organ identity in the third whorl.
CO2 provides an intermediate link in the red light response of guard cells
Authors: Roelfsema M. Rob G. , Hanstein Stefan , Felle Hubert H. , Hedrich Rainer
Published: March 2003

Guard cells in intact leafs display light‐induced membrane potential changes, which alter the direction of K+‐transport across the plasma membrane (Roelfsema et al., 2001). A beam of blue light, but not red light, directed at the impaled guard cell triggers this response, while both light qualities induce opening of stomata. To gain insight into this apparent contradiction, we explored the possible interaction between red light and CO2. Guard cells in the intact plant were impaled with double‐barrelled electrodes and illuminated with red light. Cells that were hyperpolarized in CO2‐free air, depolarized after a switch to air with 700 µl l−1 CO2, in a reversible manner. As a result, K+‐fluxes across the plasma membrane changed direction, to favour K+ extrusion and stomatal closure in the presence of CO2. Concurrent with the depolarization, an inward current across the plasma membrane appeared, most likely due to activation of anion channels. Guard cell responses to CO2 could be recorded in darkness as well as in red light. However, in darkness some cells spontaneously depolarized, these cells hyperpolarized again in red light. Here, red light was projected on a large area of the leaf and decreased the intracellular CO2 concentration by about 250 µl l−1, as measured with a miniature CO2 sensor placed in the substomatal cavity. We conclude, that in intact leaves the red light response of guard cells is mediated through a decrease of the intercellular CO2 concentration.
A chromatin immunoprecipitation (ChIP) approach to isolate genes regulated by AGL15, a MADS domain protein that preferentially accumulates in embryos
Authors: Wang Huai , Tang Weining , Zhu Cong , Perry Sharyn E.
Published: March 2003

AGAMOUS‐like‐15 (AGL15) is a member of the MADS‐domain family of DNA‐binding regulatory factors that accumulates preferentially in tissue developing in an embryonic mode. To better understand how AGL15 functions, we developed a chromatin immunoprecipitation (ChIP) approach to isolate genes regulated directly by AGL15. ChIP allows purification of in vivo protein–DNA complexes. The co‐purified DNA is recovered and used to isolate the putatively regulated gene. Several tests must be performed to show that the putative downstream target gene is truly regulated by the DNA‐binding protein. The DNA‐binding regulatory protein must interact with cis regulatory elements. The downstream gene expression pattern should respond to the level of the trans‐acting regulatory factor. The cis element should be able to confer regulation in response to the trans‐acting factor. We describe, in this report, our ChIP protocol, and discuss in detail, tests to confirm regulation by AGL15 for two targets identified by ChIP. These targets are referred to as Downstream Target of AGL15 (DTA1 and DTA2). Expression of DTA1, which encodes a protein with high similarity to GA‐2 oxidase‐like proteins, is induced by AGL15. DTA2 encodes a novel protein and expression of this target is repressed by AGL15.
Activation tagging of the two closely linked genes LEP and VAS independently affects vascular cell number
Authors: Van Der Graaff Eric , Hooykaas Paul J.J. , Keller Beat
Published: March 2003

The complex dominant Arabidopsis thaliana mutant lettuce (let) shows the conversion of the leaf petiole into a leaf blade caused by an ectopic leaf blade formation. This is the result of the activation tagging of the LEAFY PETIOLE (LEP) gene encoding an AP2/EREBP‐like transcription factor. Here, we report that in addition to this leafy petiole phenotype, the size of the vascular bundles is increased in all aerial organs in let as a result of an increase in the number of xylem, phloem (pro)cambial and pericycle cells. This vascular phenotype is caused by activation tagging of the two genes VASCULAR TISSUE SIZE (VAS) and LEP. These genes are closely linked and arranged in tandem. Activation tagging of LEP only caused a specific increase in the number of xylem cells. This increased xylem cell number, together with the ectopic leaf blade formation, indicates that LEP functions as a cell division‐promoting factor. The activation tagging of VAS only resulted in a specific increase in phloem (pro)cambial and pericycle cells. We conclude that activation tagging of LEP and VAS results in additive phenotypes. Insertional mutants for LEP and VAS display wild‐type vascular development, indicating the relevance of activation tagging for functional analysis of novel genes involved in plant development.
Tomato tos1 mutation identifies a gene essential for osmotic tolerance and abscisic acid sensitivity
Authors: Borsani Omar , Cuartero Jesús , Valpuesta Victoriano , Botella Miguel A.
Published: March 2003

Osmotic stress severely limits plant growth and agricultural productivity. We have used mutagenesis to identify plant genes that are required for osmotic stress tolerance in tomato. As a result, we have isolated a novel mutant in tomato (tos1) caused by a single recessive nuclear mutation that is hypersensitive to general osmotic stress. Growth measurements demonstrated that the tos1 mutant is less sensitive to intracellular abscisic acid (ABA) and this decreased ABA sensitivity of tos1 is a basic cellular trait expressed by the mutant at all developmental stages analysed. It is not caused by a deficiency in the synthesis of ABA because the tos1 seedlings accumulated more ABA than the wild type (WT) after osmotic stress. In contrast, the tss2 tomato mutant, which is also hypersensitive to osmotic stress, is hypersensitive to exogenous ABA. Comparative analysis of tos1 and tss2 indicates that appropriate ABA perception and signalling is essential for osmotic tolerance.
Poplar potassium transporters capable of controlling K+ homeostasis and K+‐dependent xylogenesis
Authors: Langer Katharina , Ache Peter , Geiger Dietmar , Stinzing Andrea , Arend Matthias , Wind Christa , Regan Sharon , Fromm Jörg , Hedrich Rainer
Published: March 2003

The cambial K+ content of poplar increases during the growth period in a K+ supply dependent manner. Upon K+ starvation or application of tetraethylammoniumchloride (TEA+), a K+ channel blocker, the average vessel lumen and expansion zone area were significantly reduced. In search for the molecular basis of potassium‐dependent xylogenesis in poplar, K+ transporters homologous to those of known function in Arabidopis phloem‐ and xylem‐physiology were isolated from a poplar wood EST library. The expression profile of three distinct K+ channel types and one K+ transporter, Populus tremula K+ uptake transporter 1 (PtKUP1), was analysed by quantitative RT‐PCR. Thereby, we found P. tremula outward rectifying K+ channel (PTORK) and P. tremula K+ channel 2 (PTK2) correlated with the seasonal wood production. K+ transporter P. tremula 1 (KPT1) was predominantly found in guard cells. Following the heterologous expression in Xenopus oocytes the biophysical properties of the different channels were determined. PTORK, upon membrane de‐polarization mediates potassium release. PTK2 is almost voltage independent, carrying inward K+ flux at hyperpolarized potential and K+ release upon de‐polarization. PtKUP1 was expressed in a K+ uptake‐deficient Escherichia coli strain, where this K+ transporter rescued K+‐dependent growth. In order to link the different K+ transporters to the cambial activity and wood production, we compared the expression profiles to seasonal changes in the K+ content of the bark as well as xylem vessel diameter. Thereby, we found PTORK and PTK2 transcripts to follow the annual K+ variations in poplar branches. PtKUP1 was expressed at a low level throughout the year, suggesting a housekeeping function. From these data, we conclude that K+ channels are involved in the regulation of K+‐dependent wood production.
The plant multidrug resistance ABC transporter AtMRP5 is involved in guard cell hormonal signalling and water use
Authors: Klein Markus , Perfus‐Barbeoch Laetitia , Frelet Annie , Gaedeke Nicola , Reinhardt Didier , Mueller‐Roeber Bernd , Martinoia Enrico , Forestier Cyrille
Published: March 2003

Carbon dioxide uptake and water release through stomata, controlling the opening and closure of stomatal pore size in the leaf surface, is critical for optimal plant performance. Stomatal movements are regulated by multiple signalling pathways involving guard cell ion channels. Using reverse genetics, we recently isolated a T‐DNA insertion mutant for the Arabidopsis ABC‐transporter AtMRP5 (mrp5‐1). Guard cells from mrp5‐1 mutant plants were found to be insensitive to the sulfonylurea compound glibenclamide, which in the wild type induces stomatal opening in the dark. Here, we report that the knockout in AtMRP5 affects several signalling pathways controlling stomatal movements. Stomatal apertures of mrp5‐1 and wild‐type Ws‐2 were identical in the dark. In contrast, opening of stomata of mrp5‐1 plants was reduced in the light. In the light, stomatal closure of mrp5‐1 was insensitive to external calcium and abscisic acid, a phytohormone responsible for stomatal closure during drought stress. In contrast to Ws‐2, the phytohormone auxin could not stimulate stomatal opening in the mutant in darkness. All stomatal phenotypes were complemented in transgenic mrp5‐1 plants transformed with a cauliflower mosaic virus (CaMV) 35S‐AtMRP5 construct. Both whole‐plant and single‐leaf gas exchange measurements demonstrated a reduced transpiration rate of mrp5‐1 in the light. Excised leaves of mutant plants exhibited reduced water loss, and water uptake was strongly decreased at the whole‐plant level. Finally, if plants were not watered, mrp5‐1 plants survived much longer due to reduced water use. Analysis of CO2 uptake and transpiration showed that mrp5‐1 plants have increased water use efficiency. Mutant plants overexpressing AtMRP5 under the control of the CaMV 35S promoter again exhibited wild‐type characteristics. These results demonstrate that multidrug resistance‐associated proteins (MRPs) are important components of guard cell functioning.
EXORDIUM– a gene expressed in proliferating cells and with a role in meristem function, identified by promoter trapping in Arabidopsis
Authors: Farrar Kerrie , Evans I. Marta , Topping Jennifer F. , Souter Martin A. , Nielsen John E. , Lindsey Keith
Published: March 2003

To identify new genes expressed in meristematic cells, a promoter trap insertional mutagenesis strategy was used in Arabidopsis thaliana. Transgenic line AtEM201 exhibits promoter trap GUS activity in embryos and in the regions of active cell division in the seedling, notably the apical meristems and young leaves. The tagged gene was named EXORDIUM (EXO). AtEM201 contains a single copy of the promoter trap T‐DNA, located in the EXO gene promoter, resulting in a much reduced level of EXO transcription. Seedlings homozygous for the T‐DNA insertion have no obvious mutant phenotype. The EXO gene, which forms part of a small gene family in Arabidopsis, is structurally related to the tobacco PHI‐1 gene, which is re‐activated in cultured cells following release from phosphate starvation‐induced cell cycle arrest. Expression of both the EXO‐GUS and the native EXO genes is downregulated by exogenous cytokinin. Expression studies using semisynchronised cells suggest that EXO mRNA is preferentially abundant during M phase of the cell cycle. Double mutant studies revealed that the exo mutation can suppress the defective root meristem phenotype of the hydra2 mutant, suggesting that EXO may be a component of a negative regulatory system for cell division.
Diverse RNA viruses elicit the expression of common sets of genes in susceptible Arabidopsis thaliana plants
Authors: Whitham Steven A. , Quan Sheng , Chang Hur‐Song , Cooper Bret , Estes Bram , Zhu Tong , Wang Xun , Hou Yu‐Ming
Published: March 2003

Systemic infections of plants by viruses require that viruses modify host cells in order to facilitate infections. These modifications include induction of host factors required for replication, propagation and movement, and suppression of host defense responses, which are likely to be associated with changes in host gene expression. Past studies of the effects of viral infection on gene expression in susceptible hosts have been limited to only a handful of genes. To gain broader insight into the responses elicited by viruses in susceptible hosts, high‐density oligonucleotide probe microarray technology was used. Arabidopsis leaves were either mock inoculated or inoculated with cucumber mosaic cucumovirus, oil seed rape tobamovirus, turnip vein clearing tobamovirus, potato virus X potexvirus, or turnip mosaic potyvirus. Inoculated leaves were collected at 1, 2, 4, and 5 days after inoculation, total RNA was isolated, and samples were hybridized to Arabidopsis GeneChip microarrays (Affymetrix). Microarray hybridization revealed co‐ordinated changes in gene expression in response to infection by diverse viruses. These changes include virus‐general and virus‐specific alterations in the expression of genes associated with distinct defense or stress responses. Analyses of the promoters of these genes further suggest that diverse RNA viruses elicit common responses in susceptible plant hosts through signaling pathways that have not been previously characterized.
Re‐organisation of the cytoskeleton during developmental programmed cell death in Picea abies embryos
Authors: Smertenko Andrei P. , Bozhkov Peter V. , Filonova Lada H. , von Arnold Sara , Hussey Patrick J.
Published: March 2003

Cell and tissue patterning in plant embryo development is well documented. Moreover, it has recently been shown that successful embryogenesis is reliant on programmed cell death (PCD). The cytoskeleton governs cell morphogenesis. However, surprisingly little is known about the role of the cytoskeleton in plant embryogenesis and associated PCD. We have used the gymnosperm, Picea abies, somatic embryogenesis model system to address this question. Formation of the apical–basal embryonic pattern in P. abies proceeds through the establishment of three major cell types: the meristematic cells of the embryonal mass on one pole and the terminally differentiated suspensor cells on the other, separated by the embryonal tube cells. The organisation of microtubules and F‐actin changes successively from the embryonal mass towards the distal end of the embryo suspensor. The microtubule arrays appear normal in the embryonal mass cells, but the microtubule network is partially disorganised in the embryonal tube cells and the microtubules disrupted in the suspensor cells. In the same embryos, the microtubule‐associated protein, MAP‐65, is bound only to organised microtubules. In contrast, in a developmentally arrested cell line, which is incapable of normal embryonic pattern formation, MAP‐65 does not bind the cortical microtubules and we suggest that this is a criterion for proembryogenic masses (PEMs) to passage into early embryogeny. In embryos, the organisation of F‐actin gradually changes from a fine network in the embryonal mass cells to thick cables in the suspensor cells in which the microtubule network is completely degraded. F‐actin de‐polymerisation drugs abolish normal embryonic pattern formation and associated PCD in the suspensor, strongly suggesting that the actin network is vital in this PCD pathway.
Volume‐dependent collection of peripheral blood progenitor cells during large‐volume leukapheresis for patients with solid tumours and haematological malignancies
Authors: Cassens  , Ostkamp‐Ostermann  , Van Der Werf  , Garritsen  , Ostermann  , Sibrowski
Published: March 2003

We investigated the efficacy of peripheral blood progenitor cell (PBPC) collection during large‐volume leukapheresis (LVL) in patients with solid tumours and haematological malignancies (n = 18). The time‐ and volume‐dependent harvest of leucocytes (WBC), mononuclear cells (MNC), CD34+ cells and colony‐forming cells (CFU‐GM) during LVL was analysed in six sequentially filled collection bags processing four times the patient's blood volumes. The amounts of leucocytes (WBC) and the purity of mononuclear cells (MNC%) did not show any significant changes during LVL. The percentage of CD34+ cells remained constant for the first three bags but consecutively decreased from initially 1.71% CD34+ cells in the beginning of LVL to finally 1.34% CD34+ cells (P = 0.02). The mean numbers of colony‐forming cells (CFU‐GM) decreased from 74 μL−1 to 59 μL−1 during LVL (P = 0.16). Furthermore, the comparison of volume‐dependent PBPC collection for patients with high, medium and low total yields of CD34+ cells showed similar kinetics on different levels for the three groups.

We concluded that — relative to the initial total amount of PBPC harvested — comparable numbers of progenitor cells can be collected during all stages of LVL with a slight decreasing trend processing four times the patient's blood volumes.
National audit of the blood transfusion process in the UK
Authors: Murphy M. F. , Wilkinson J. , Lowe D. , Pearson M.
Published: March 2003

. The objectives of this initiative were to produce nationally tested audit tools, to influence the content of national guidelines, and to enable performance indicators to be set for the clinical transfusion process.

Audit tools were developed for blood transfusion practice through a collaboration between Royal Colleges and specialist Societies with an interest in blood transfusion. National audits were carried out involving 50 hospitals in the first audit and 23 of the same hospitals in the second.

Over 20% of participating hospitals did not have Hospital Transfusion Committees. Most hospitals had written policies for the taking of blood samples for grouping and compatibility testing. Formal training for the phlebotomists and nurses who took blood samples was almost universal, but only one‐third gave training to doctors. The audits of transfusion practice demonstrated considerable variation in the performance of standard procedures in relation to the administration of blood, and little change in practice between the two audits.

The first two objectives have been met in that audit tools were developed and published, and information from the first audits was used in the development of national guidelines for the administration of blood. A significant shortfall in the systems for monitoring and delivering transfusions is present in many hospitals. This justifies pursuing the third objective but this will require a new initiative. The type of analysis and the method used for the presentation of audit data developed in this study may be useful for setting performance indicators for the clinical transfusion process.
Gene frequencies of human platelet antigens 1–5 in indigenous Australians in Western Australia
Authors: Bennett J. A. , Palmer L. J. , Musk A. W. , Erber W. N.
Published: March 2003

Summary  The frequencies of human platelet antigen (HPA) systems vary between different racial groups; however, HPA frequency data for some racial groups are still incomplete. We report the distribution of HPA 1–5 systems in Australian Aborigines from a remote community in the north‐west of Australia and compare our findings with HPA observed in a Western Australian blood donor population. Using a polymerase chain reaction (PCR) with sequence‐specific primers, 185 indigenous Australians and 1000 Western Australian blood donors were genotyped for each of the HPA 1–5 systems. Comparison of gene frequencies of alleles from HPA‐1, ‐2, ‐3 and ‐5 systems showed significant differences between Aboriginal people and Western Australian blood donors (P < 0·001). In particular, the frequency of HPA‐3b (0·068) in the Australian Aboriginals, from this study, was one of the lowest reported, whilst the frequency of HPA‐5b (0·246) was one of the highest for this allele. Gene frequencies were similar to those reported for central Australian Aborigines but with no other ethnic group. In conclusion, this study confirms significant differences in HPA distributions between indigenous Australians, Australian blood donors and other racial groups. These results indicate a higher potential risk of alloimmunization to HPA‐1, ‐2 and ‐3 in Australian Aborigines receiving transfusion therapy from a Caucasian blood donor population, thereby having practical implications for transfusion and pregnancy risks in people of Aboriginal origin.
A comparison of oral fluid and serum for the detection of rubella‐specific antibodies in a community study in Addis Ababa, Ethiopia
Authors: Nokes D. James , Nigatu Wondatir , Abebe Almaz , Messele Tsehaynesh , Dejene Amare , Enquselassie Fikre , Vyse Andrew , Brown David , Cutts Felicity T.
Published: March 2003

objective To assess the utility of oral fluid compared with serum for the determination of age‐prevalence of rubella‐specific antibodies in an urban African community setting.

method Paired serum and oral fluid samples were collected from 439 individuals aged 0–49 years in Addis Ababa, Ethiopia, as part of a larger seroepidemiological survey in 1994. Oral fluid was sampled using a simple sponge device that was well accepted by subjects of all ages; venous blood was collected by Vacutainer system. We measured rubella‐specific antibodies in serum by the Radial Haemolysis (RH) test, supported by two confirmatory assays, and in oral fluid by IgG antibody‐capture radioimmunoassay (GACRIA).

results Sensitivity and specificity of oral fluid results compared to serum were 89% and 76%, respectively. Sensitivity declined from 96% in age group 0–19 years to 90% in age group 20–29 and 78% in age group 30–49. Specificity was 86% in 0–9 year olds contrasting with 61% in older groups (10–49 years). The positive predictive value of an oral fluid sample was high in all age groups (range 92–100%), while the negative predictive value declined from ≥80% in those aged <10 years to <10% in those aged ≥30 years. Serum confirmatory tests suggested a proportion of false serum RH negatives, increasing with age, indicating a need to standardize serum as well as oral fluid tests.

conclusion In the community setting of a developing country, oral fluid surveys could be useful to estimate age‐prevalence of rubella immunity and identify rubella‐susceptible children for follow‐up. Further work is required to simplify assays and sample processing, improve assay sensitivity and estimate assay specificity more precisely, and compare and standardise collection methods suitable for surveillance of a variety of childhood viral infections.
Voluntary health insurance in Bwamanda, Democratic Republic of Congo. An exploration of its meanings to the community
Authors: Criel B. , Van Dormael M. , Lefèvre P. , Menase U. , Van Lerberghe W.
Published: March 2003

An insurance scheme covering hospital care in the rural district of Bwamanda in the North‐west of the Democratic Republic of Congo, which locally is called the mutuelle, was conceived and developed in 1986 on the initiative of Belgian doctors working in the district under the arrangements for bilateral Belgian aid. After more than 10 years of operation the Bwamanda scheme has achieved a high rate of coverage, contributed to a significant improvement in access to hospital‐based in‐patient care, and constitutes a stable source of revenue for the operation of the hospital. We present an investigation conducted through focus groups in 1996 of the population's social perceptions of this risk‐sharing scheme to identify ways to improve it. The findings pertain to the reasons for people to subscribe to the scheme; to the perception of its redistribution effects; to people's frustrations and questions; and finally to the relationships between the insurance scheme and traditional mutual aid arrangements. The difference between a hospital insurance scheme (a logic of contract) and the traditional systems of mutual aid (a logic of alliance) is highlighted, and the impact of the hospital insurance scheme on social inequalities is discussed. The implications of this study on the management of the Bwamanda health insurance scheme are reviewed, and this study may be useful to health managers working in similar contexts.
Origin and prevention of airport malaria in France
Authors: Guillet  , Germain  , Giacomini  , Chandre  , Akogbeto  , Faye  , Kone  , Manga  , Mouchet
Published: March 2003

Summary Since 1969, 63 cases of airport malaria have been reported in Western Europe, 24 of which occurred in France. Most were due to Plasmodium falciparum. In 1994, 7 cases occurred in and around Roissy Charles de Gaulle airport (CDG), showing 4 types of contamination: among employees working on airstrips or opening containers, among residents living near the airport, among people living at some distance from the airport after a secondary transport of vectors, and by vectors transported in luggage. In‐flight or stop‐over infection is not considered as airport malaria. The infective anophelines originated from airports where malaria transmission occurs, mostly in subsaharan Africa. A tentative list is given taking into account aerial traffic with France. Surveys in the airports of Dakar (Senegal), Cotonou (Benin), Abidjan (Cote d'Ivoire) and Yaoundé (Cameroun) found potential vectors in all of these from July to September. After 1994, the Contrôle Sanitaire aux Frontières (CSF) in charge at CDG concentrated its efforts on the flights at risk, as well as information and sensitization of airline companies, which resulted in 73% and 87% of the flights at risk being properly disinsected in 1995 and 1996. Despite pyrethroid resistance in Anopheles gambiae s.s. in West Africa, the efficacy of aircraft spraying with permethrin aerosols is still acceptable. However, surveillance of resistance should be improved and search for nonpyrethroid insecticides suitable for aircraft strongly encouraged.
Diagnostic significance of Schistosoma mansoni proteins Sm31 and Sm32 in human schistosomiasis in an endemic area in Egypt
Authors: El‐Sayed Laila H. , Ghoneim  , Demian  , El‐Sayed  , Tawfik  , Sakr  , Abou‐Basha  , Renganathan  , Klinkert  , Abou‐Rawash
Published: March 2003

Summary We performed a series of ELISAs to evaluate the diagnostic significance of two Schistosoma mansoni proteins, Sm31 (cysteine proteinase, cathepsin B) and Sm32 (asparaginyl endopeptidase). Our study populations were chosen from two villages in an endemic area close to Alexandria. Using fusion proteins MS2‐Sm31 and MS2‐Sm32 as antigens, 70% and 78.9%, respectively, of patient sera from 134 parasitologically confirmed cases reacted positively. The percentage of seropositivity increased to 84.5% when parasite‐derived proteins Sm31 and Sm32 were used. The serum levels of antibodies to these two proteins in recombinant or native forms do not correlate with intensity of infection and hence are detected even when egg counts are low, which makes proteins Sm31 and Sm32 useful antigens in the identification of S. mansoni infected cases, particularly in endemic areas in Egypt.
Five year impact of chemotherapy on morbidity attributable to Schistosoma japonicum infection in the Dongting Lake region
Authors: Ross Allen G. P. , Ross Allen G. P. , Li Yuesheng , Li Yuesheng , Booth Mark , Sleigh Adrian C. , Williams Gail M. , McManus Donald P.
Published: March 2003

Objective To determine changes in the last 5 years of the fraction of acute and chronic symptoms attributable to schistosomiasis japonica in fishing communities with moderate endemicity in the Dongting Lake region of China.

Method Complete medical histories, physical examinations, and stool samples were obtained from 1909 individuals (53% male) ranging in age from 4 to 81 years. Age, sex, occupation, frequency of water contact, number of times treated for schistosomiasis, and last year of treatment were tested as potential effect modifiers and confounders.

Results Overall, there were very few infected cases and very little variation in any prevalence ratio with infection intensity, sex, age, year of last treatment, number of times treated or frequency of water contact. The attributable fraction of liver enlargement in one village was estimated at 0.114 (11.4%), although this was not significantly > 0 (95% CI; − 0.008–0.237).

Conclusion The chemotherapy‐based schistosomiasis control programme in this locality has succeeded in reducing attributable morbidity to undetectable levels, but many uncertainties remain about sustaining control efforts in the future. Both old and new control strategies will have to be examined if the health and well‐being of these people are to be maintained into the next millennium, given that periodic chemotherapy will not be accepted indefinitely.