bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hypericum perforatum L (St John's wort) preferentially increases extracellular dopamine levels in the rat prefrontal cortex
Authors: Yoshitake Takashi , Iizuka Ryuji , Yoshitake Shimako , Weikop Pia , Müller Walter E , Ögren Sven Ove , Kehr Jan 
Published: June 2004

The effects of hydro‐alcoholic extracts of Hypericum perforatum L on extracellular serotonin (5‐HT), noradrenaline (NA) and dopamine (DA) levels and the acidic metabolites (3,4‐dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5‐hydroxy‐3‐indoleacetic acid (5‐HIAA)) were examined by in vivo microdialysis in the prefrontal cortex of awake rats. Thus, a single dose (60 mg kg−1 i.p. or 300 mg kg−1 p.o.) of H. perforatum increased DA concentrations to 165 and 140% of control values, respectively, and increased locomotor activity in nonhabituated rats. DOPAC and HVA levels were markedly reduced. 5‐HT concentrations were elevated only moderately, while the NA levels were not affected by any treatment. The whole‐tissue analysis revealed that hypericum increased, whereas the monoamine oxidase (MAO) A/B inhibitor phenelzine decreased DA and 5‐HT turnover. The present data indicate that the mechanism of action of hypericum extract in vivo is more complex than the inhibition of monoamine reuptake or metabolism observed in vitro. The finding of preferential enhancement of DA transmission is in agreement with human studies measuring DA‐mediated neuroendocrine responses.British Journal of Pharmacology (2004) 142, 414–418. doi:10.1038/sj.bjp.0705822
Vasoactive properties of CORM‐3, a novel water‐soluble carbon monoxide‐releasing molecule
Authors: Foresti Roberta , Hammad Jehad , Clark James E , Johnson Tony R , Mann Brian E , Friebe Andreas , Green Colin J , Motterlini Roberto 
Published: June 2004

Carbon monoxide (CO), one of the end products of heme catabolism by heme oxygenase, possesses antihypertensive and vasodilatory characteristics. We have recently discovered that certain transition metal carbonyls are capable of releasing CO in biological fluids and modulate physiological functions via the delivery of CO. Because the initial compounds identified were not water soluble, we have synthesized new CO‐releasing molecules that are chemically modified to allow solubility in water. The aim of this study was to assess the vasoactive properties of tricarbonylchloro(glycinato)ruthenium(II) (CORM‐3) in vitro and in vivo.
CORM‐3 produced a concentration‐dependent relaxation in vessels precontracted with phenylephrine, exerting significant vasodilatation starting at concentrations of 25–50 μM. Inactive CORM‐3, which does not release CO, did not affect vascular tone.
Blockers of ATP‐dependent potassium channels (glibenclamide) or guanylate cyclase activity (ODQ) considerably reduced CORM‐3‐dependent relaxation, confirming that potassium channels activation and cGMP partly mediate the vasoactive properties of CO. In fact, increased levels of cGMP were detected in aortas following CORM‐3 stimulation.
The in vitro and in vivo vasorelaxant activities of CORM‐3 were further enhanced in the presence of YC‐1, a benzylindazole derivative which is known to sensitize guanylate cyclase to activation by CO. Interestingly, inhibiting nitric oxide production or removing the endothelium significantly decreased vasodilatation by CORM‐3, suggesting that factors produced by the endothelium influence CORM‐3 vascular activities.
These results, together with our previous findings on the cardioprotective functions of CORM‐3, indicate that this molecule is an excellent prototype of water‐soluble CO carriers for studying the pharmacological and biological features of CO.

British Journal of Pharmacology (2004) 142, 453–460. doi:10.1038/sj.bjp.0705825
Water‐soluble carbon monoxide‐releasing molecules: helping to elucidate the vascular activity of the ‘silent killer’
Authors: Chatterjee Prabal Kumar 
Published: June 2004

Carbon monoxide (CO) is formed during the degradation of haeme by haeme oxygenase (HO). As well as being an important signalling molecule and vasodilator, CO also possesses antihypertensive, anti‐inflammatory and antiapoptotic qualities and protects against ischaemic tissue injury. Several approaches have been used to investigate the therapeutic potential of CO, ranging from direct administration of CO gas to the use of prodrugs, which generate CO upon metabolism. A novel approach involves the use of specific CO carriers, which will release measurable, controllable and effective amounts of CO into biological systems. Transitional metal carbonyls based around iron, manganese or ruthenium have recently been developed as CO‐releasing molecules (CO‐RMs) that, under appropriate conditions, will release CO. Such molecules have been shown to provide cardioprotection in both ex vivo and in vivo experiments. To date, CO‐RMs have been largely incompatible with biological systems in that they are only soluble in organic solvents or have to be preactivated either by physical or chemical stimuli. However, the recent development of water‐soluble CO‐RMs has provided new opportunities to investigate the pharmacological and biological features of CO without such confounding influences. CORM‐3, a novel water‐soluble CO‐RM, has recently been used to confirm the cardioprotective actions of CO. In this issue of British Journal of Pharmacology, Foresti and co‐workers report that CORM‐3 delivers CO, produces aortic vasodilation ex vivo and reduces blood pressure in vivo via modulation of the same cGMP and potassium channels utilised by endogenous and exogenous CO. These findings suggest that CORM‐3 has the potential for use as a modulator of vascular function and hypertension. However, the use of water‐soluble CO‐RMs raises several questions of their own which will need to be addressed if CO‐RMs are to be of future use therapeutically.British Journal of Pharmacology (2004) 142, 391–393. doi:10.1038/sj.bjp.0705826
4‐Chloro‐benzo[F]isoquinoline (CBIQ) activates CFTR chloride channels and KCNN4 potassium channels in Calu‐3 human airway epithelial cells
Authors: Szkotak A J , Murthy M , MacVinish L J , Duszyk M , Cuthbert A W 
Published: June 2004

Calu‐3 cells have been used to investigate the actions of 4‐chloro‐benzo[F]isoquinoline (CBIQ) on short‐circuit current (SCC) in monolayers, whole‐cell recording from single cells and by patch clamping.
CBIQ caused a sustained, reversible and repeatable increase in SCC in Calu‐3 monolayers with an EC50 of 4.0 μM. Simultaneous measurements of SCC and isotopic fluxes of 36Cl− showed that CBIQ caused electrogenic chloride secretion.
Apical membrane permeabilisation to allow recording of basolateral membrane conductance in the presence of a K+ gradient suggested that CBIQ activated the intermediate‐conductance calcium‐sensitive K+‐channel (KCNN4). Permeabilisation of the basolateral membranes of epithelial monolayers in the presence of a Cl− gradient suggested that CBIQ activated the Cl−‐channel CFTR in the apical membrane.
Whole‐cell recording in the absence of ATP/GTP of Calu‐3 cells showed that CBIQ generated an inwardly rectifying current sensitive to clotrimazole. In the presence of the nucleotides, a more complex I/V relation was found that was partially sensitive to glibenclamide. The data are consistent with the presence of both KCNN4 and CFTR in Calu‐3.
Isolated inside‐out patches from Calu‐3 cells revealed clotrimazole‐sensitive channels with a conductance of 12 pS at positive potentials after activation with CBIQ and demonstrating inwardly rectifying properties, consistent with the known properties of KCNN4. Cell‐attached patches showed single channel events with a conductance of 7 pS and a linear I/V relation that were further activated by CBIQ by an increase in open state probability, consistent with known properties of CFTR. It is concluded that CBIQ activates CFTR and KCNN4 ion channels in Calu‐3 cells.

British Journal of Pharmacology (2004) 142, 531–542. doi:10.1038/sj.bjp.0705846
Ambiguous Figures: Living versus Nonliving Objects
Authors: Verstijnen Use M , Wagemans Johan 
Published: June 2004

Eleven series of figures were studied, each series ranging from one extreme interpretation via five ambiguous intermediates to a second extreme interpretation. Triplets consisting of an ambiguous exemplar in the middle flanked on the left and right by its two extreme interpretations were presented to large groups of subjects. The initial aim was to establish the levels of perceptual ambiguity of each exemplar in a series, and normative data on the ambiguous figures are provided for future reference and use. However, several biases were encountered and these were examined in more detail. In experiment 1 the subject's task was to compare the middle figure with the flankers and draw an arrow from the middle figure towards the flanking extreme they judged the most similar. Here, an overall preference for the left extreme was found. Therefore the instructions were reversed in experiment 2; flankers had to be compared with the middle figure. The preference for the left extreme remained for figures of living objects, but for nonliving objects the preference switched to the right extreme. To do away with any effect of the arrows, in experiment 3 subjects were divided into two groups each receiving different instructions and were asked to circle one of the extremes. However, the pattern of biases remained the same. The bias found with figures of living objects may be explained on the basis of top–down processes. For nonliving figures, an hypothesis based on bottom–up processes like neural fatigue was considered but rejected.
Distance Estimation in a Dynamic Simulated Environment: A Visual Field Dependence Problem?
Authors: Vianin Pascal , Baumberger Bernard , Flückiger Michelangelo 
Published: June 2004

Egocentric distance estimation implies that the subject perceives his own location in the environment. In a simulated environment, subjects have to transpose perceptively their own observation point in order to assume their virtual body position. As only visual information specifies this position, their ability to perceive the camera viewpoint should be linked to the field dependence – independence factor (FDI). Field-independent subjects underestimated the mid-distance between their own virtual body position and a far-located target; their bisection was located between the projective (2-D) and the simulated (3-D) mid-distance which indicates their difficulty in considering the in-depth simulated spatial references. High correlations between the vertical estimation in the rod-and-frame test and the egocentric-distance-estimation task (with shifted camera) suggest a similar perceptive process in both tasks. This result is confirmed by the better performances of the field-dependent subjects in this condition. In conclusion, we discuss the relationship between FDI and the sense of presence in virtual environments.
Ectopic Expression of the Petunia MADS Box GeneUNSHAVENAccelerates Flowering and Confers Leaf-Like Characteristics to Floral Organs in a Dominant-Negative Manner[W]
Authors: Ferrario Silvia , Busscher Jacqueline , Franken John , Gerats Tom , Vandenbussche Michiel , Angenent Gerco C. , Immink Richard G.H. 
Published: June 2004

AbstractSeveral genes belonging to the MADS box transcription factor family have been shown to be involved in the transition from vegetative to reproductive growth. The Petunia hybrida MADS box gene UNSHAVEN (UNS) shares sequence similarity with the Arabidopsis thaliana flowering gene SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1, is expressed in vegetative tissues, and is downregulated upon floral initiation and the formation of floral meristems. To understand the role of UNS in the flowering process, knockout mutants were identified and UNS was expressed ectopically in petunia and Arabidopsis. No phenotype was observed in petunia plants in which UNS was disrupted by transposon insertion, indicating that its function is redundant. Constitutive expression of UNS leads to an acceleration of flowering and to the unshaven floral phenotype, which is characterized by ectopic trichome formation on floral organs and conversion of petals into organs with leaf-like features. The same floral phenotype, accompanied by a delay in flowering, was obtained when a truncated version of UNS, lacking the MADS box domain, was introduced. We demonstrated that the truncated protein is not translocated to the nucleus. Using the overexpression approach with both the full-length and the nonfunctional truncated UNS protein, we could distinguish between phenotypic alterations because of a dominant-negative action of the protein and because of its native function in promoting floral transition.
Tomato Heat Stress Transcription Factor HsfB1 Represents a Novel Type of General Transcription Coactivator with a Histone-Like Motif Interacting with the Plant CREB Binding Protein Ortholog HAC1[W]
Authors: Bharti Kapil , von Koskull-Döring Pascal , Bharti Sanita , Kumar Pravir , Tintschl-Körbitzer Angelika , Treuter Eckardt , Nover Lutz 
Published: June 2004

AbstractIn contrast with the class A heat stress transcription factors (HSFs) of plants, a considerable number of HSFs assigned to classes B and C have no evident function as transcription activators on their own. However, in the following article, we provide evidence that tomato (Lycopersicon peruvianum) HsfB1 represents a novel type of coactivator cooperating with class A HSFs (e.g., with tomato HsfA1). Provided the appropriate promoter architecture, the two HSFs assemble into an enhanceosome-like complex, resulting in strong synergistic activation of reporter gene expression. Moreover, HsfB1 also cooperates in a similar manner with other activators, for example, with the ASF1/2 enhancer binding proteins of the 35S promoter of Cauliflower mosaic virus or with yet unidentified activators controlling housekeeping gene expression. By these effects, HsfB1 may help to maintain and/or restore expression of certain viral or housekeeping genes during ongoing heat stress. The coactivator function of HsfB1 depends on a histone-like motif in its C-terminal domain with an indispensable Lys residue in the center (GRGKMMK). This motif is required for recruitment of the plant CREB binding protein (CBP) ortholog HAC1. HsfA1, HsfB1, and HAC1/CBP form ternary complexes in vitro and in vivo with markedly enhanced efficiency in promoter recognition and transcription activation in plant and mammalian (COS7) cells. Using small interfering RNA–mediated knock down of HAC1 expression in Arabidopsis thaliana mesophyll protoplasts, the crucial role for the coactivator function of HsfB1 was confirmed.
Silencing of Hydroxycinnamoyl-Coenzyme A Shikimate/Quinate Hydroxycinnamoyltransferase Affects Phenylpropanoid Biosynthesis[W]
Authors: Hoffmann Laurent , Besseau Seébastien , Geoffroy Pierrette , Ritzenthaler Christophe , Meyer Denise , Lapierre Catherine , Pollet Brigitte , Legrand Michel 
Published: June 2004

AbstractThe hydroxyl group in the 3-position of the phenylpropanoid compounds is introduced at the level of coumarate shikimate/quinate esters, whose synthesis implicates an acyltransferase activity. Specific antibodies raised against the recombinant tobacco (Nicotiana tabacum) acyltransferase revealed the accumulation of the enzyme in stem vascular tissues of tobacco, in accordance with a putative role in lignification. For functional analysis, the acyltransferase gene was silenced in Arabidopsis thaliana and N. benthamiana by RNA-mediated posttranscriptional gene silencing. In Arabidopsis, gene silencing resulted in a dwarf phenotype and changes in lignin composition as indicated by histochemical staining. An in-depth study of silenced N. benthamiana plants by immunological, histochemical, and chemical methods revealed the impact of acyltransferase silencing on soluble phenylpropanoids and lignin content and composition. In particular, a decrease in syringyl units and an increase in p-hydroxyphenyl units were recorded. Enzyme immunolocalization by confocal microscopy showed a correlation between enzyme accumulation levels and lignin composition in vascular cells. These results demonstrate the function of the acyltransferase in phenylpropanoid biosynthesis.
The ArabidopsisSKU6/SPIRAL1Gene Encodes a Plus End–Localized Microtubule-Interacting Protein Involved in Directional Cell Expansion[W]
Authors: Sedbrook John C. , Ehrhardt David W. , Fisher Sarah E. , Scheible Wolf-Rüdiger , Somerville Chris R. 
Published: June 2004

AbstractThe sku6-1 mutant of Arabidopsis thaliana exhibits altered patterns of root and organ growth. sku6 roots, etiolated hypocotyls, and leaf petioles exhibit right-handed axial twisting, and root growth on inclined agar media is strongly right skewed. The touch-dependent sku6 root skewing phenotype is suppressed by the antimicrotubule drugs propyzamide and oryzalin, and right skewing is exacerbated by cold treatment. Cloning revealed that sku6-1 is allelic to spiral1-1 (spr1-1). However, modifiers in the Columbia (Col) and Landsberg erecta (Ler) ecotype backgrounds mask noncomplementation in sku6-1 (Col)/spr1-1 (Ler) F1 plants. The SPR1 gene encodes a plant-specific 12-kD protein that is ubiquitously expressed and belongs to a six-member gene family in Arabidopsis. An SPR1:green fluorescent protein (GFP) fusion expressed in transgenic seedlings localized to microtubules within the cortical array, preprophase band, phragmoplast, and mitotic spindle. SPR1:GFP was concentrated at the growing ends of cortical microtubules and was dependent on polymer growth state; the microtubule-related fluorescence dissipated upon polymer shortening. The protein has a repeated motif at both ends, separated by a predicted rod-like domain, suggesting that it may act as an intermolecular linker. These observations suggest that SPR1 is involved in microtubule polymerization dynamics and/or guidance, which in turn influences touch-induced directional cell expansion and axial twisting.
The Arabidopsis F-Box Protein SLEEPY1 Targets Gibberellin Signaling Repressors for Gibberellin-Induced Degradation[W]
Authors: Dill Alyssa , Thomas Stephen G. , Hu Jianhong , Steber Camille M. , Sun Tai-ping 
Published: June 2004

AbstractThe nuclear DELLA proteins are highly conserved repressors of hormone gibberellin (GA) signaling in plants. In Arabidopsis thaliana, GA derepresses its signaling pathway by inducing proteolysis of the DELLA protein REPRESSOR OF ga1-3 (RGA). SLEEPY1 (SLY1) encodes an F-box–containing protein, and the loss-of-function sly1 mutant has a GA-insensitive dwarf phenotype and accumulates a high level of RGA. These findings suggested that SLY1 recruits RGA to the SCFSLY1 E3 ligase complex for ubiquitination and subsequent degradation by the 26S proteasome. In this report, we provide new insight into the molecular mechanism of how SLY1 interacts with the DELLA proteins for controlling GA response. By yeast two-hybrid and in vitro pull-down assays, we demonstrated that SLY1 interacts directly with RGA and GA INSENSITIVE (GAI, a closely related DELLA protein) via their C-terminal GRAS domain. The rga and gai null mutations additively suppressed the recessive sly1 mutant phenotype, further supporting the model that SCFSLY1 targets both RGA and GAI for degradation. The N-terminal DELLA domain of RGA previously was shown to be essential for GA-induced degradation. However, we found that this DELLA domain is not required for protein–protein interaction with SLY1 in yeast (Saccharomyces cerevisiae), suggesting that its role is in a GA-triggered conformational change of the DELLA proteins. We also identified a novel gain-of-function sly1-d mutation that increased GA signaling by reducing the levels of the DELLA protein in plants. This effect of sly1-d appears to be caused by an enhanced interaction between sly1-d and the DELLA proteins.
The Novel Myb Transcription Factor LCR1 Regulates the CO2-Responsive GeneCah1, Encoding a Periplasmic Carbonic Anhydrase inChlamydomonas reinhardtii [W]
Authors: Yoshioka Satoshi , Taniguchi Fumiya , Miura Kenji , Inoue Takeshi , Yamano Takashi , Fukuzawa Hideya 
Published: June 2004

AbstractChlamydomonas reinhardtii acclimates to CO2-limiting stress by inducing a set of genes for a carbon-concentrating mechanism (CCM). This set includes the gene Cah1, which encodes a periplasmic carbonic anhydrase. Although physiological aspects of CO2 response have been extensively studied, regulatory components, such as transcription factors involved in the acclimation, have not been well described in eukaryotic microalgae. Using an arylsulfatase gene driven by the Cah1 promoter, a regulatory mutant of Cah1 was isolated and named lcr1 (for low-CO2 stress response). The photosynthetic affinity for inorganic carbon of lcr1 was reduced compared with that of wild-type cells. Expression of three low-CO2-inducible genes, Cah1, Lci1, and Lci6, were regulated by LCR1 as shown by cDNA array and RNA gel blot analyses. The Lcr1 gene encodes a protein of 602 amino acids containing a single Myb domain, which binds to the Cah1-promoter region. Expression of Lcr1 was induced by lowering CO2 levels and controlled by the regulatory factor CCM1. These results suggest that LCR1 transmits the low CO2 signal to at least three CO2-responsive genes and then fully induces CCM.
CENTRIN2 Modulates Homologous Recombination and Nucleotide Excision Repair in Arabidopsis[W]
Authors: Molinier Jean , Ramos Cynthia , Fritsch Olivier , Hohn Barbara 
Published: June 2004

Abstract
A genetic screen of a population of Arabidopsis thaliana lines exhibiting enhanced somatic homologous recombination yielded a mutant affected in expression of a gene encoding a caltractin-like protein (centrin). The hyperrecombinogenic phenotype could be reproduced using RNA interference (RNAi) technology. Both the original mutant and the RNAi plants exhibited a moderate UV-C sensitivity as well as a reduced efficiency of in vitro repair of UV-damaged DNA. Transcription profiling of the mutant showed that expression of components of the nucleotide excision repair (NER) pathway and of factors involved in other DNA repair processes were significantly changed. Our data suggest an indirect involvement of centrin in recombinational DNA repair via the modulation of the NER pathway. These findings thus point to a novel interconnection between an early step of NER and homologous recombination, which may play a critical role in plant DNA repair.
The Arabidopsis Mutant sleepy1gar2-1 Protein Promotes Plant Growth by Increasing the Affinity of the SCFSLY1 E3 Ubiquitin Ligase for DELLA Protein Substrates[W]
Authors: Fu Xiangdong , Richards Donald E. , Fleck Barbara , Xie Daoxin , Burton Nicolas , Harberd Nicholas P. 
Published: June 2004

AbstractDELLA proteins restrain the cell proliferation and enlargement that characterizes the growth of plant organs. Gibberellin stimulates growth via 26S proteasome–dependent destruction of DELLAs, thus relieving DELLA-mediated growth restraint. Here, we show that the Arabidopsis thaliana sleepy1gar2-1 (sly1gar2-1) mutant allele encodes a mutant subunit (sly1gar2-1) of an SCFSLY1 E3 ubiquitin ligase complex. SLY1 (the wild-type form) and sly1gar2-1 both confer substrate specificity on this complex via specific binding to the DELLA proteins. However, sly1gar2-1 interacts more strongly with the DELLA target than does SLY1. In addition, the strength of the SCFSLY1–DELLA interaction is increased by target phosphorylation. Growth-promoting DELLA destruction is dependent on SLY1 availability, on the strength of the interaction between SLY1 and the DELLA target, and on promotion of the SCFSLY1–DELLA interaction by DELLA phosphorylation.