bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrophysiological Characterization of the Arabidopsis avrRpt2-Specific Hypersensitive Response in the Absence of Other Bacterial Signals
Authors: Pike Sharon M. , Zhang Xue-Cheng , Gassmann Walter 
Published: May 2005

Abstract
The hypersensitive response (HR) is defined as rapid cell collapse at the infection site and often accompanies plant resistance. The physiological processes leading to HR are not well understood. Here, we report an electrophysiological characterization of bacterial HR caused by a single avirulence gene in the absence of other bacterial signals. We used dexamethasone (dex)-inducible transgenic Arabidopsis (Arabidopsis thaliana) plants containing the avrRpt2 gene from Pseudomonas syringae pv tomato. Membrane depolarization in these plants began 1 to 1.5 h after dex application, hours before electrolyte leakage. Progressive depolarization was a sensitive early indicator of HR that occurred only in Arabidopsis leaf cells expressing both avrRpt2 and a functional RPS2 gene. Hyperpolarization of fully depolarized membranes by fusicoccin, a fungal toxin that activates the H+-ATPase, indicates that depolarization did not result from a nonfunctional pump or leaky membranes. Depolarization and electrolyte leakage were inhibited in RPS2 plants by the calcium channel blocker LaCl3, highly correlating these events and suggesting that Ca2+ entry into cells is required for both. Also correlated were inhibition of depolarization, electrolyte leakage, and HR following salicylic acid pretreatment. In salicylic acid-pretreated RPS2 seedlings, avrRpt2 transcript was produced after dex treatment. However, AvrRpt2 protein accumulation was greatly reduced, suggesting a possible mechanism for inhibition of HR in plants with induced resistance. This experimental system is a very sensitive assay that lends itself to the dissection of physiological processes leading to HR in plants, and provides a baseline for future research within a genetic framework.
Root Border-Like Cells of Arabidopsis. Microscopical Characterization and Role in the Interaction with Rhizobacteria
Authors: Vicré Maïté , Santaella Catherine , Blanchet Sandrine , Gateau Aurélien , Driouich Azeddine 
Published: May 2005

Abstract
Plant roots of many species produce thousands of cells that are released daily into the rhizosphere. These cells are commonly termed border cells because of their major role in constituting a biotic boundary layer between the root surface and the soil. In this study, we investigated the occurrence and ultrastructure of such cells in Arabidopsis (Arabidopsis thaliana) using light and electron microscopy coupled to high-pressure freezing. The secretion of cell wall molecules including pectic polysaccharides and arabinogalactan-proteins (AGPs) was examined also using immunofluorescence microscopy and a set of anticarbohydrate antibodies. We show that root tips of Arabidopsis seedlings released cell layers in an organized pattern that differs from the rather randomly dispersed release observed in other plant species studied to date. Therefore, we termed such cells border-like cells (BLC). Electron microscopical results revealed that BLC are rich in mitochondria, Golgi stacks, and Golgi-derived vesicles, suggesting that these cells are actively engaged in secretion of materials to their cell walls. Immunocytochemical data demonstrated that pectins as well as AGPs are among secreted material as revealed by the high level of expression of AGP-epitopes. In particular, the JIM13-AGP epitope was found exclusively associated with BLC and peripheral cells in the root cap region. In addition, we investigated the function of BLC and root cap cell AGPs in the interaction with rhizobacteria using AGP-disrupting agents and a strain of Rhizobium sp. expressing a green fluorescent protein. Our findings demonstrate that alteration of AGPs significantly inhibits the attachment of the bacteria to the surface of BLC and root tip.
Loss-of-Function Mutations of ROOT HAIR DEFECTIVE3 Suppress Root Waving, Skewing, and Epidermal Cell File Rotation in Arabidopsis
Authors: Yuen Christen Y.L. , Sedbrook John C. , Perrin Robyn M. , Carroll Kathleen L. , Masson Patrick H. 
Published: May 2005

Abstract
Wild-type Arabidopsis (Arabidopsis thaliana L. Heynh.) roots growing on a tilted surface of impenetrable hard-agar media adopt a wave-like pattern and tend to skew to the right of the gravity vector (when viewed from the back of the plate through the medium). Reversible root-tip rotation often accompanies the clockwise and counterclockwise curves that form each wave. These rotations are manifested by epidermal cell file rotation (CFR) along the root. Loss-of-function alleles of ROOT HAIR DEFECTIVE3 (RHD3), a gene previously implicated in the control of vesicle trafficking between the endoplasmic reticulum and the Golgi compartments, resulted in an almost complete suppression of epidermal CFR, root skewing, and waving on hard-agar surfaces. Several other root hair defective mutants (rhd2-1, rhd4-1, and rhd6-1) did not exhibit dramatic alterations in these root growth behaviors, suggesting that a generalized defect in root hair formation is not responsible for the surface-dependent phenotypes of rhd3. However, similar alterations in root growth behavior were observed in a variety of mutants characterized by defects in cell expansion (cob-1, cob-2, eto1-1, eto2-1, erh2-1, and erh3-1). The erh2-1 and rhd3-1 mutants differed from other anisotropic cell expansion mutants, though, by an inability to respond to low doses of the microtubule-binding drug propyzamide, which normally causes enhanced left-handed CFR and right skewing. We hypothesize that RHD3 may control epidermal CFR, root skewing, and waving on hard-agar surfaces by regulating the traffic of wall- or plasma membrane-associated determinants of anisotropic cell expansion.
Mutations Affecting Starch Synthase III in Arabidopsis Alter Leaf Starch Structure and Increase the Rate of Starch Synthesis
Authors: Zhang Xiaoli , Myers Alan M. , James Martha G. 
Published: May 2005

Abstract
The role of starch synthase (SS) III (SSIII) in the synthesis of transient starch in Arabidopsis (Arabidopsis thaliana) was investigated by characterizing the effects of two insertion mutations at the AtSS3 gene locus. Both mutations, termed Atss3-1 and Atss3-2, condition complete loss of SSIII activity and prevent normal gene expression at both the mRNA and protein levels. The mutations cause a starch excess phenotype in leaves during the light period of the growth cycle due to an apparent increase in the rate of starch synthesis. In addition, both mutations alter the physical structure of leaf starch. Significant increases were noted in the mutants in the frequency of linear chains in amylopectin with a degree of polymerization greater than approximately 60, and relatively small changes were observed in chains of degree of polymerization 4 to 50. Furthermore, starch in the Atss3-1 and Atss3-2 mutants has a higher phosphate content, approximately two times that of wild-type leaf starch. Total SS activity is increased in both Atss3 mutants and a specific SS activity appears to be up-regulated. The data indicate that, in addition to its expected direct role in starch assembly, SSIII also has a negative regulatory function in the biosynthesis of transient starch in Arabidopsis.
Involvement of Phycobilisome Diffusion in Energy Quenching in Cyanobacteria
Authors: Joshua Sarah , Bailey Shaun , Mann Nicholas H. , Mullineaux Conrad W. 
Published: May 2005

Abstract
Nonphotochemical quenching (NPQ) of excitation energy is a well-established phenomenon in green plants, where it serves to protect the photosynthetic apparatus from photodamage under excess illumination. The induction of NPQ involves a change in the function of the light-harvesting apparatus, with the formation of quenching centers that convert excitation energy into heat. Recently, a comparable phenomenon was demonstrated in cyanobacteria grown under iron-starvation. Under these conditions, an additional integral membrane chlorophyll-protein, IsiA, is synthesized, and it is therefore likely that IsiA is required for NPQ in cyanobacteria. We have previously used fluorescence recovery after photobleaching to show that phycobilisomes diffuse rapidly on the membrane surface, but are immobilized when cells are immersed in high-osmotic strength buffers, apparently because the interaction between phycobilisomes and reaction centers is stabilized. Here, we show that when cells of the cyanobacterium Synechocystis sp. PCC 6803 subjected to prolonged iron-deprivation are immersed in 1 m phosphate buffer, NPQ can still be induced as normal by high light. However, the formation of the quenched state is irreversible under these conditions, suggesting that it involves the coupling of free phycobilisomes to an integral-membrane complex, an interaction that is stabilized by 1 m phosphate. Fluorescence spectra are consistent with this idea. Fluorescence recovery after photobleaching measurements confirm that the induction of NPQ in the presence of 1 m phosphate is accompanied by immobilization of the phycobilisomes. We propose as a working hypothesis that a major component of the fluorescence quenching observed in iron-starved cyanobacteria arises from the coupling of free phycobilisomes to IsiA.
Rapid Array Mapping of Circadian Clock and Developmental Mutations in Arabidopsis
Authors: Hazen Samuel P. , Borevitz Justin O. , Harmon Frank G. , Pruneda-Paz Jose L. , Schultz Thomas F. , Yanovsky Marcelo J. , Liljegren Sarah J. , Ecker Joseph R. , Kay Steve A. 
Published: May 2005

Abstract
Classical forward genetics, the identification of genes responsible for mutant phenotypes, remains an important part of functional characterization of the genome. With the advent of extensive genome sequence, phenotyping and genotyping remain the critical limiting variables in the process of map-based cloning. Here, we reduce the genotyping problem by hybridizing labeled genomic DNA to the Affymetrix Arabidopsis (Arabidopsis thaliana) ATH1 GeneChip. Genotyping was carried out on the scale of detecting greater than 8,000 single feature polymorphisms from over 200,000 loci in a single assay. By combining this technique with bulk segregant analysis, several high heritability development and circadian clock traits were mapped. The mapping accuracy using bulk pools of 26 to 100 F2 individuals ranged from 0.22 to 1.96 Mb of the mutations revealing mutant alleles of EARLY FLOWERING 3, EARLY FLOWERING 4, TIMING OF CAB EXPRESSION 1, and ASYMMETRIC LEAVES 1. While direct detection of small mutations, such as an ethyl-methane sulfonate derived single base substitutions, is limited by array coverage and sensitivity, large deletions such as those that can be caused by fast neutrons are easily detected. We demonstrate this by resolving two deletions, the 77-kb flavin-binding, kelch repeat, f-box 1 and the 7-kb cryptochrome2-1 deletions, via direct hybridization of mutant DNA to ATH1 expression arrays.
A Molecular-Genetic Study of the Arabidopsis Toc75 Gene Family
Authors: Baldwin Amy , Wardle Anthony , Patel Ramesh , Dudley Penny , Park Soon Ki , Twell David , Inoue Kentaro , Jarvis Paul 
Published: May 2005

Abstract
Toc75 (translocon at the outer envelope membrane of chloroplasts, 75 kD) is the protein translocation channel at the outer envelope membrane of plastids and was first identified in pea (Pisum sativum) using biochemical approaches. The Arabidopsis (Arabidopsis thaliana) genome contains three Toc75-related sequences, termed atTOC75-I, atTOC75-III, and atTOC75-IV, which we studied using a range of molecular, genetic, and biochemical techniques. Expression of atTOC75-III is strongly regulated and at its highest level in young, rapidly expanding tissues. By contrast, atTOC75-IV is expressed uniformly throughout development and at a much lower level than atTOC75-III. The third sequence, atTOC75-I, is a pseudogene that is not expressed due to a gypsy/Ty3 transposon insertion in exon 1, and numerous nonsense, frame-shift, and splice-junction mutations. The expressed genes, atTOC75-III and atTOC75-IV, both encode integral envelope membrane proteins. Unlike atToc75-III, the smaller atToc75-IV protein is not processed upon targeting to the envelope, and its insertion does not require ATP at high concentrations. The atTOC75-III gene is essential for viability, since homozygous atToc75-III knockout mutants (termed toc75-III) could not be identified, and aborted seeds were observed at a frequency of approximately 25% in the siliques of self-pollinated toc75-III heterozygotes. Homozygous toc75-III embryos were found to abort at the two-cell stage. Homozygous atToc75-IV knockout plants (termed toc75-IV) displayed no obvious visible phenotypes. However, structural abnormalities were observed in the etioplasts of toc75-IV seedlings and atTOC75-IV overexpressing lines, and toc75-IV plants were less efficient at deetiolation than wild type. These results suggest some role for atToc75-IV during growth in the dark.
Designing cigarettes for women: new findings from the tobacco industry documents
Authors: Carpenter Carrie Murray , Wayne Geoffrey Ferris , Connolly Gregory N. 
Published: May 2005

ABSTRACTAims  To examine internal tobacco industry research on female smoking patterns and product preferences, and how this research has informed the design of female‐targeted cigarettes and impacted smoking behavior among this target population.Design  Research was conducted through a systematic web‐based search of previously secret industry documents made publicly available through the 1998 Master Settlement Agreement.Findings  This study provides evidence that the tobacco industry has conducted extensive research on female smoking patterns, needs and product preferences, and has intentionally modified product design for promotion of cigarette smoking among women. Cigarette manufacturers responded to changing female trends by focusing on social and health concerns as well as promoting dual‐sex brands that also featured traditional female style characteristics.Conclusions  Product features responsive to female‐identified needs and preferences may contribute to differences in female smoking patterns. Assessment of female‐targeted product differences should inform smoking cessation and prevention programs tailored to women. Overall, these findings underscore the need for further investigation of effects of targeting on smoking behavior, health outcomes and regulation of tobacco products by public health agencies.
Pain and use of alcohol to manage pain: prevalence and 3‐year outcomes among older problem and non‐problem drinkers
Authors: Brennan Penny L. , Schutte Kathleen K. , Moos Rudolf H. 
Published: May 2005

ABSTRACTAims  Most older adults report having recently experienced pain, and many older adults have late‐life drinking problems. However, to our knowledge, the intersection of pain and alcohol misuse by older adults has not been studied. This research focuses on the implications of pain for older individuals who have problems with alcohol.Design  Longitudinal survey.Setting, participants and measurement  Older community‐residing adults (n = 401) were classified as problem and non‐problem drinkers. At baseline and 3 years later they were asked to provide information about their pain, use of alcohol to manage pain, drinking behavior, chronic health problems and recent serious injury.Findings  At baseline, older problem drinkers reported more severe pain, more disruption of daily activities due to pain and more frequent use of alcohol to manage pain than did older non‐problem drinkers. More pain was associated with more use of alcohol to manage pain; this relationship was stronger among older adults with drinking problems than among those without drinking problems. Among older men, more baseline drinking problems interacted with use of alcohol to manage pain to predict more health problems and serious injury 3 years later. Among older women, more baseline drinking problems interacted with use of alcohol to manage pain to predict more drinking problems 3 years later.Conclusions  The results highlight the importance of monitoring the drinking behavior of older patients who present with pain complaints, especially patients who have pre‐existing problems with alcohol.
Menstrual cycle length during methadone maintenance
Authors: Schmittner John , Schroeder Jennifer R. , Epstein David H. , Preston Kenzie L. 
Published: May 2005

ABSTRACTAims  While the menstrual disruption of heroin has been demonstrated, there are few published data concerning methadone maintenance and menstrual function. This study was conducted to evaluate whether cycle length was more regular during methadone maintenance.Settings  An out‐patient research treatment program in Baltimore, Maryland, USA.Participants  A total of 191 heroin and cocaine‐using women from two clinical trials, lasting 25–29 weeks; each woman was maintained on 70–100 mg of methadone.Measurements  Start/end dates of each menses were collected.Design  Menstrual patterns were classified as regular, irregular, transient amenorrhea, persistent amenorrhea or cycle restart. Repeated‐measures regression modeling determined correlates of cycle length and predictors of long cycles (> 40 days) and short cycles (< 20 days). Bleeding episodes were defined as 1 or more bleeding days, bound by at least 2 non‐bleeding days. Correlates/predictors examined were body mass index, drug use, methadone dose and race.Findings  In the 133 women for whom menstrual patterns could be determined, cycle‐length irregularity was common: irregular, 62 (46.7%); regular, 37 (27.8%); cycle restart, 16 (12%); persistent amenorrhea, 11 (8.3%); transient amenorrhea, seven (5.3%). Each additional week on methadone maintenance was associated with decreased risk of long (OR = 0.96, P < 0.01 and short (OR = 0.92, P < 0.01) cycles. Of 27 women with secondary amenorrhea pre‐study, 16 (59%) restarted menses. Positivity for opioids or cocaine was not significantly associated with short or long cycles.Conclusions  Cycle length begins to normalize during methadone maintenance. Menses resumption may occur. Methadone maintenance, despite interfering with menstrual function in an absolute sense, may interfere less than illicit heroin abuse.
Reduced activity of 11β‐hydroxysteroid dehydrogenase type 2 is not responsible for sodium retention in nephrotic rats
Authors: Bistrup C. , Thiesson H. C. , Jensen B. L. , Skøtt O. 
Published: May 2005

AbstractAim:  In mineralocorticoid target cells 11‐beta‐hydroxysteroid dehydrogenase type 2 (11βHSD2) converts glucocorticoids into non‐active metabolites thereby protecting the mineralocorticoid receptor (MR) from stimulation by glucocorticoids. In nephrotic syndrome, a decreased activity of 11βHSD2 has been suggested to allow glucocorticoids to stimulate MR, thereby contributing to sodium retention. We tested this hypothesis in the puromycin aminonucleoside model of nephrotic syndrome in rats.Methods:  Complete sodium and potassium intakes and excretions (faeces and urine) were measured in rats in metabolic cages. RNase protection assay of mRNA and Western blotting of protein were used to estimate renocortical expression of 11βHSD2 and of the MR downstream effector serum and glucocorticoid induced kinase (SGK). In an intervention series, dexamethasone was given [10 μg (100 g bw)−1] to suppress endogenous glucocorticoids in the proteinuric stage during active sodium retention.Results:  Nephrotic rats developed proteinuria, positive sodium balance, decreased plasma aldosterone concentration, and decreased urinary Na+/K+ ratio. 11βHSD2 mRNA expression was down‐regulated but protein expression was unchanged. SGK mRNA and phosphorylated SGK protein were up‐regulated while total SGK protein expression was unchanged. Dexamethasone treatment, which suppressed plasma corticosterone concentration, did not correct sodium balance or fluid retention in nephrotic rats.Conclusion:  Our results do not support the hypothesis that stimulation of the MR by endogenous glucocorticoids induces sodium and fluid retention in experimental nephrotic syndrome in rats.
Expression of oestrogen receptor α and β is higher in skeletal muscle of highly endurance‐trained than of moderately active men
Authors: Wiik A. , Gustafsson T. , Esbjörnsson M. , Johansson O. , Ekman M. , Sundberg C. J. , Jansson E. 
Published: May 2005

AbstractAim:  Two known oestrogen receptors (ERs), ERα and the recently cloned ERβ, are expressed in the human skeletal muscle of both males and females. The effects of oestrogen and the role of ERs in skeletal muscle tissue are not well known. Oestrogen receptors and some of their target genes are involved in angiogenic processes. It was hypothesized that ERs are expressed at a higher level in a group with higher oxidative capacity, and that such an enhanced expression would parallel expression of the angiogenic factor – vascular endothelial growth factor (VEGF).Method:  Muscle biopsies were taken from vastus lateralis in 10 highly endurance‐trained males and 10 moderately active males and analysed for the expression of ERs and VEGF.Results:  The major findings in the present study were the higher mRNA levels of ERα, ERβ and VEGF in the highly endurance‐trained than in the moderately active group.Conclusion:  These data suggest that the greater mRNA expression of ERα and ERβ and the oestrogen‐associated angiogenic factor VEGF support the hypothesis of an involvement of ERs in the adaptation of skeletal muscle to endurance training.
An in vivo model for gastric physiological and pathophysiological studies in the mouse
Authors: Henriksnäs J. , Phillipson M. , Petersson J. , Engstrand L. , Holm L. 
Published: May 2005

AbstractAim:  In vivo models for studying gastrointestinal physiology and pathophysiology are well established in rats. Since a number of genetically modified mice are available there is a need for reliable mouse models. The aim of this project was to develop an in vivo mouse model for gastrointestinal studies.Methods:  C57bl/6, NMRI and transgenic FVB/N (expressing human α‐1,3/4‐fucosyltransferase) mice were anaesthetized with isoflurane and the gastric mucosa exteriorized for intravital microscopy. Acid–base status and acid secretion were measured and blood pressure was continuously monitored. Gastric mucosal blood flow was recorded by laser‐Doppler flowmetry. Mucus thickness and accumulation rate were measured with micropipettes.Results:  We have developed an in vivo mouse model for studies of the gastric mucosa. With isoflurane anaesthesia the preparation can be studied for up to 5 h with stable blood pressure and mucosal blood flow. Acid–base status agrees with results from other laboratories. Blood flow increased in both C57bl/6 and α1.3/4‐FT mice in response to luminal HCl, and the mucus gel could be divided into a firmly and a loosely adherent layer, all comparable with results in the rat. However, the firmly adherent mucus layer was thinner (45 ± 2 μm), and the mucus accumulation rate lower, than in the rat. Furthermore, both basal and stimulated acid secretion showed lower outputs than in the rat.Conclusions:  This model has great potential for investigations of gastrointestinal physiology and pathophysiology and can be applied for Helicobacter pylori infection studies.