Using Arabidopsis plants transformed with a redox-sensing green fluorescent protein targeted to the cytosol (c-roGFP1), we have demonstrated, in real time, measurements of reversible changes of redox status in the cytosol of plants subjected to a gradual water-stress, followed by re-watering. Plants sensed water stress, and changed the redox potential of their cytosol to a more oxidized value after a gradually-imposed water stress. Small variations in the cytosol redox potential and ascorbate (AA) values suggest that this parameter was tightly regulated. The re-watering was paralleled by a return of water stress, redox potential and ascorbate to initial values, showing the reversibility of water stress and its consequences.
Arabidopsis/physiology , Cytosol/metabolism , Dehydration/metabolism , Green Fluorescent Proteins/metabolism , Arabidopsis/metabolism , Ascorbic Acid/metabolism , Dehydroascorbic Acid/metabolism , Gene Expression Regulation, Plant/physiology , Oxidation-Reduction , Reactive Oxygen Species
Many interventional treatments have been proposed for intrastent stenosis, in particular by drug-eluting stents, with encouraging results. The aim of this study was to assess the clinical outcome of patients with restenosis of an ordinary uncovered stent treated by a drug eluting stent in a prospective series. The register included 43 patients (50 intrastent restenoses) treated by a drug eluting stent (Cypher or Taxus). The restenosis lesion was focal in 32% of cases with an average length of 14.8 +/- 8 mm and diameter inferior to 2.5 mm in 48% of cases. A Cypher stent was implanted in 44% of cases and a Taxus stent in 56% of cases. After an average follow-up of 6.7 +/- 1.3 months, the major adverse cardiac event rate was 9.3%. It included one transmural infarct in a patient, due to stent thrombosis, and symptomatic restenoses in 3 patients (clinical restenosis rate: 7%). An angiographic control was performed in 15 patients (35%) identifying focal restenosis at the exit of the stent in the 3 symptomatic patients. As in previously reported studies, these results show that with well conducted platelet antiaggregant therapy, the treatment of intrastent restenosis with a drug eluting stent is effective with a low rate of adverse cardiovascular events which compares favourably with previously proposed techniques of management.
Coronary Restenosis/therapy , Stents , Adult , Aged , Aged, 80 and over , Angina Pectoris/etiology , Aspirin/therapeutic use , Clopidogrel , Coronary Angiography , Coronary Thrombosis/etiology , Equipment Design , Female , Follow-Up Studies , Humans , Male , Middle Aged , Myocardial Infarction/etiology , Myocardial Ischemia/etiology , Paclitaxel/administration & dosage , Paclitaxel/therapeutic use , Platelet Aggregation Inhibitors/therapeutic use , Prospective Studies , Sirolimus/administration & dosage , Sirolimus/therapeutic use , Surface Properties , Ticlopidine/analogs & derivatives , Ticlopidine/therapeutic use , Treatment Outcome
BACKGROUND: Fractional flow reserve (FFR) is correlated with angiographic and intravascular ultrasound assessments of stent placement. Post-stenting FFR has been described as a good predictor of clinical events after 6 months. OBJECTIVE: To evaluate the feasibility and clinical impact of targeting an FFR > 0.95 via incremental in-stent inflation pressures. METHODS: In this multicenter prospective study, 100 consecutive patients underwent FFR measurement at baseline, after balloon predilatation, and after stenting with 4-atm inflation pressure increments from 8 to 20 atmospheres. Inflations were stopped when FFR increased above 0.95 and angiographic stenosis was less than 20%. RESULTS: FFR > 0.95 was achieved in 81% of cases; this FFR target was reached at 8 atm in 47% of patients, 12 atm in 16 %, 16 atm in 15%, and 20 atm in 3%. Fifty percent of patients with adequate angiographic result had an FFR less than 0.95 and needed further higher inflations. FFR was correlated with residual stenosis when the total procedure was evaluated, and this correlation persisted when in-stent inflations alone were considered. Final FFR was significantly correlated with anginal status after 6 months. CONCLUSIONS: Angiography guided PCI does not allow optimization of FFR. Since optimal post stenting FFR is correlated to better anginal status at 6-months, this suggests that FFR guided PCI is required to achieve optimal functional results of PCI.
The impact of the progress of interventional cardiology on the improved prognosis of myocardial infarction due to occlusion of a saphenous vein bypass graft is not well known. The aim of this study was to report the modalities and results at short and medium term of revascularisation by angioplasty of venous grafts in the acute phase of myocardial infarction. Out of a total of 870 consecutive patients treated by angioplasty in the first 6 hours of myocardial infarction with persistent ST elevation between 1990 and 2002, 16 (2%) had acute occlusion of a saphenous vein graft. Twelve of the 16 patients had previous myocardial infarction; perfusion was obtained in 7 patients. The attempt failed in 9 patients because of "no-reflow" (n=5), the extensive nature of the thrombosis (n=2) and technical failure (n=2). Three patients died in hospital, all after failed angioplasty. At 6 months, of the 13 survivors of the hospital period, 2 had been readmitted for a revascularisation procedure. At 2 years, 3 patients had died, 2 were readmitted for recurrent myocardial infarction and 8 patients remained free of a major cardiovascular event. Reperfusion by angioplasty of an occluded saphenous vein graft in the acute phase of myocardial infarction remains imperfect and the prognosis at short and medium term is poor.
Angioplasty, Balloon, Coronary , Graft Occlusion, Vascular/therapy , Myocardial Infarction/therapy , Myocardial Revascularization , Aged , Electrocardiography , Female , Graft Occlusion, Vascular/mortality , Humans , Male , Myocardial Infarction/mortality , Prospective Studies , Saphenous Vein/transplantation , Treatment Outcome
Stents are the main technique of coronary revascularization in France and western countries. However, a better understanding of the pathophysiology of in-stent restenosis and the well-recognized roles played by inflammation and cell proliferation led to the development of drug-eluting stents, which have nearly eliminated the risk of restenosis. In this context, the success of gene therapy will depend on our ability to simplify and optimize current protocols of arterial gene transfer. For the time being, arterial gene therapy remains a powerful tool for deciphering the complex pathophysiology of restenosis and will certainly have far-reaching implications in the fields of vascular biology and therapeutics.
Arteriosclerosis/therapy , Coronary Restenosis/therapy , Genetic Therapy , Adenoviridae/genetics , Coronary Restenosis/physiopathology , Gene Transfer Techniques , Genetic Vectors , Humans , Retroviridae/genetics , Stents
The objective of this study was to evaluate the evolution of therapeutic strategies in the course of myocardial infarction. Two successive periods were studied: 1988/96 (700 patients) and 1996/2001 (700 patients). The following parameters were compared: patient characteristics, management methods, and results on the hospital morbidity and mortality. The patient characteristics were little changed, in terms of age and sex, with a drop in the frequency of anterior infarcts during the second period (46 vs 51%, p = 0.0001). The average delay to admission remained stable over both periods, 186 vs 189 min. During the second period, primary angioplasty was favoured (66 versus 44%, p = 0.0001), associated with a wider use of stents (47 against 4%, p = 0.0001) and anti GP IIb/IIIa (24 against 0.5%, p = 0.0001). In the acute phase, TIMI3 reperfusion was obtained in 81% of cases (88/96 period) against 88% during the second period (p = 0.02). The hospital mortality was reduced by 1.2% (8.9 against 7.7%, NS). Without cardiogenic shock, the mortality was comparable between the two groups (5%), whereas it diminished in the small group of patients (5%) in cardiogenic shock, from 76 to 66% (NS). Haemorrhagic complications were reduced, but the rate of symptomatic reocclusion remained stable (2.5%). With multivariate analysis, the independent predictive mortality factors were identical in the two groups: age and cardiogenic shock on admission. Currently, TIMI3 reperfusion is possible in close to 90% of patients in the acute phase of infarction. Our efforts should focus on earlier management, especially for older patients, too often excluded without reason, and for those in cardiogenic shock, which constitutes a therapeutic quest for the future. The theory of angioplasty facilitated by anti GP IIb/IIIa and/or prehospital thrombolysis must be evaluated scientifically with the goal of early and efficient reperfusion for the greatest number of patients.
Myocardial Infarction/therapy , Myocardial Reperfusion/methods , Aged , Cohort Studies , Female , Hospitalization , Humans , Male , Middle Aged , Myocardial Reperfusion/adverse effects , Myocardial Reperfusion/trends , Postoperative Complications/epidemiology
UNLABELLED: Early retraction of the arterial introducer facilitates patient management after coronary angioplasty. Closure systems permit rapid haemostasis, but are costly and do not avoid all serious vascular complications. Moderate doses of heparin, used often at the moment, could allow immediate retraction of the introducer with rapid and safe haemostasis by manual compression. METHODS: We evaluated prospectively in 350 consecutive patients the safety and efficacy of immediate retraction of the 6F introducer after coronary angioplasty performed by the femoral route with a moderate dose of heparin (70 IU. kg-1). Only procedures during acute infarction or using abciximab electively were excluded. RESULTS: Retraction of the introducer was immediate in 340 patients (97%). The dose of heparin administered was 5300 +/- 800 IU and the compression time was 11 +/- 4 minutes. The activated clotting time at retraction of the introducer was 254 +/- 46 s. Six (1.7%) serious vascular complications (4 significant haematomas and 2 false aneurysms) were noted during the hospital phase. A single patient (0.6%) was transfused and no vascular surgical procedure was necessary. The average duration of stay after angioplasty was 2.6 +/- 2.2 days and 73% of patients left before 48 hours. CONCLUSION: Immediate retraction of the arterial introducer is possible with simple manual compression, after coronary angioplasty performed with a moderate dose of heparin.
Angioplasty , Anticoagulants/administration & dosage , Coronary Disease/surgery , Femoral Artery , Hemostatic Techniques , Heparin/administration & dosage , Feasibility Studies , Humans , Middle Aged , Postoperative Care , Prospective Studies , Time Factors
Coronary flow reserve is the ability of coronary flow to increase above its basal value when the coronary vascular bed is maximally dilated. It is a global parameter of coronary flow, which is early altered in the presence of epicardial coronary artery stenosis or a coronary microcirculation disorder. Until now, clinical use of coronary flow reserve has been hampered by the lack of an easy, reliable and non-invasive method. Recently developed high-frequency transthoracic Doppler echocardiography now allows non-invasive assessment of coronary flow reserve. After an initial learning curve, it is possible to study coronary flow, essentially in the left anterior descending artery. Coronary flow reserve is expressed as the ratio of maximal hyperaemic to basal mean coronary velocity. Maximal hyperaemic flow is obtained with adenosine. Clinical applications of coronary flow reserve are numerous. Coronary flow reserve enables the assessment of hemodynamic relevance of a moderate coronary stenosis. Detection of coronary restenosis is also possible by repeated non-invasive measurement of coronary flow reserve. Moreover, evaluation of the microcirculation is of crucial importance in order to appreciate myocardial reperfusion following successful recanalisation on the infarct-related artery. Transthoracic Doppler echocardiography could allow identification of "no-reflow" by analysis of coronary flow pattern and coronary flow reserve. Furthermore, transthoracic Doppler echocardiography constitutes one of the only available and simple means to evaluate microcirculatory disorders (hypertension, diabetes,...). Finally, the possibility of non-invasive follow-up of arterial bypasses constitutes a major advantage of this technique.
Coronary Stenosis/diagnostic imaging , Coronary Vessels/diagnostic imaging , Coronary Vessels/pathology , Echocardiography, Doppler/methods , Hemodynamics , Humans , Microcirculation , Regional Blood Flow
BACKGROUND: It has been suggested that patients undergoing acute intervention for coronary syndromes may not receive adequate secondary prevention. OBJECTIVE: To analyse the impact of availability and use of coronary interventions on the prescription of secondary prevention after acute coronary syndromes. DESIGN: Analysis of a prospective multicentre register of patients admitted to hospital for acute coronary syndromes. SETTING: A 1999 pan-European survey in 390 hospitals. PATIENTS: 3092 patients admitted to hospital with acute coronary syndromes (including 777 for ST elevation myocardial infarction within 12 hours of onset). MAIN OUTCOME MEASURES: Rates of prescription of aspirin and lipid lowering agents. RESULTS: Performance of coronary angiography and percutaneous coronary interventions (PCI) during the hospital stay were independent predictors of prescription of aspirin at discharge (odds ratio (OR) 1.29 and 1.89, p = 0.053 and p < 0.0001, respectively). Lipid lowering agents were prescribed more often on discharge in patients admitted to hospitals with catheterisation laboratories than without (for infarction with ST elevation, 45% v 40% (NS); for other acute coronary syndromes, 46% v 36%; p < 0.05). Prescription rates were higher among patients undergoing coronary angiography or PCI than in those treated conservatively (for infarction with ST elevation, 49%, 53%, and 39%, p < 0.05; for other acute coronary syndromes, 50%, 54%, and 34%, p < 0.05). Logistic regression analysis showed that PCI was an independent predictor of prescription of lipid lowering agents at discharge (OR 1.48, p < 0.0002). CONCLUSIONS: Contrary to expectations, invasive procedures for acute coronary syndromes are associated with higher rates of prescription of pharmacological secondary prevention.
Aspirin/therapeutic use , Coronary Disease/prevention & control , Fibrinolytic Agents/therapeutic use , Hypolipidemic Agents/therapeutic use , Adrenergic beta-Antagonists/therapeutic use , Aged , Angioplasty, Balloon, Coronary/statistics & numerical data , Angiotensin-Converting Enzyme Inhibitors/therapeutic use , Coronary Angiography/statistics & numerical data , Female , Hospitalization , Humans , Logistic Models , Male , Middle Aged , Patient Discharge/statistics & numerical data , Prospective Studies , Registries , Regression Analysis
This is the first report on using green fluorescent protein (GFP) as a pH reporter in plants. Proton fluxes and pH regulation play important roles in plant cellular activity and therefore, it would be extremely helpful to have a plant gene reporter system for rapid, non-invasive visualization of intracellular pH changes. In order to develop such a system, we constructed three vectors for transient and stable transformation of plant cells with a pH-sensitive derivative of green fluorescent protein. Using these vectors, transgenic Arabidopsis thaliana and tobacco plants were produced. Here the application of pH-sensitive GFP technology in plants is described and, for the first time, the visualization of pH gradients between different developmental compartments in intact whole-root tissues of A. thaliana is reported. The utility of pH-sensitive GFP in revealing rapid, environmentally induced changes in cytoplasmic pH in roots is also demonstrated.
Arabidopsis/genetics , Cytoplasm/chemistry , Luminescent Proteins/genetics , Plant Roots/cytology , Protons , Arabidopsis/chemistry , Arabidopsis/cytology , Gene Expression Regulation, Plant , Genes, Plant , Genes, Reporter/genetics , Green Fluorescent Proteins , Hydrogen-Ion Concentration , Microscopy, Fluorescence , Plant Roots/chemistry , Plant Roots/genetics , Plants, Genetically Modified , Plasmids/genetics , Nicotiana/genetics
BACKGROUND: Intimal hyperplasia is the principal mechanism of in-stent restenosis. Matrix metalloproteinases (MMPs) play a key role in intimal growth after balloon angioplasty (BA). Little is known, however, about MMP expression after stent implantation (ST). We investigated whether MMP9 and MMP2 are differentially expressed after ST and BA. METHODS AND RESULTS: Hypercholesterolemic rabbits underwent ST and BA in the right and left iliac arteries, respectively. The expression of MMPs and their inhibitors (TIMPs) was studied at various time points in the injured arteries by use of zymography, reverse transcription-polymerase chain reaction, and immunohistochemistry. MMP2, but not MMP9, was constitutively expressed in uninjured arteries. MMP9 expression was rapidly induced after injury, whereas the increase in MMP2 expression was delayed. At all time points, pro-MMP9 activity and MMP9 mRNA levels were >/=2-fold (ANOVA, P=0.002) and >/=3-fold (P<0.0001) higher after ST than after BA, respectively. Active MMP9 was detected only after ST. Although the increases in MMP2 mRNA levels were of similar magnitudes after ST and BA, pro-MMP2 activity was slightly higher 7 and 30 days after ST, and MMP2 activity was >/=2-fold higher 7 to 60 days after ST (P=0.002). No difference in TIMP expression was observed between stented and balloon-injured arteries. Cellular distributions of MMPs and TIMP1 were similar after ST and BA. Early inflammatory cell recruitment and 30-day intimal growth were more severe after ST. CONCLUSIONS: Stent implantation results in more intense and sustained expression of MMP9 and activation of MMP2 than balloon angioplasty.
Angioplasty, Balloon , Hypercholesterolemia/metabolism , Matrix Metalloproteinases/genetics , Stents , Animals , Gene Expression Regulation, Enzymologic , Iliac Artery/metabolism , Iliac Artery/pathology , Immunohistochemistry , Matrix Metalloproteinase 2/genetics , Matrix Metalloproteinase 2/metabolism , Matrix Metalloproteinase 9/genetics , Matrix Metalloproteinase 9/metabolism , Matrix Metalloproteinases/biosynthesis , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rabbits , Reverse Transcriptase Polymerase Chain Reaction , Tissue Inhibitor of Metalloproteinase-1/genetics , Tissue Inhibitor of Metalloproteinase-1/metabolism , Tissue Inhibitor of Metalloproteinase-2/genetics , Tissue Inhibitor of Metalloproteinase-2/metabolism , Tunica Intima/metabolism , Tunica Intima/pathology
In order to determine the reasons for the low mortality after myocardial infarction in smokers compared with non-smokers (the smoker's paradox), the authors analysed the initial clinical data, the therapeutic interventions and hospital mortality in 790 consecutive patients (555 smokers, 235 non-smokers) admitted to hospital within 6 hours of the first symptoms of acute myocardial infarction and treated by intravenous thrombolytic agents and/or coronary angioplasty. Multivariate analysis with linear regression was used to identify the predictive factors of hospital mortality. The main differences between smokers and non-smokers were age (56 vs 67 years, p < 0.0001), gender (male, 90 vs 60%, p < 0.01), cardiogenic shock on admission (3 vs 8%, p < 0.01). TIMI 3 flow was obtained in the culprit artery in 84% of smokers and 79% of non-smokers (NS). Hospital mortality was 5% in the smoking population and 16% in non-smokers (p < 0.0001). In multivariate analysis, the variables of cardiogenic shock, age, gender and hypertension provided most of the prognostic information and tobacco consumption did not appear to have a protective effect. In patients admitted to hospital with acute myocardial infarction, identical incidences of early reperfusion are obtained in smokers and in non-smokers. However, mortality is higher in the non-smoking group due to more severe clinical characteristics on admission. Tobacco consumption is not a protective factor in the immediate period after acute myocardial infarction.
Myocardial Infarction/mortality , Smoking/adverse effects , Aged , Female , Humans , Male , Middle Aged , Myocardial Infarction/pathology , Prognosis , Regression Analysis , Reperfusion Injury/pathology , Retrospective Studies , Risk Factors , Severity of Illness Index , Shock, Cardiogenic
OBJECTIVE: Monocyte adhesion to endothelial cells and subsequent secretion of matrix metalloproteinases (MMPs) by activated macrophages are key events in arteriosclerosis and restenosis. We tested the hypothesis that interleukin-10 (IL-10), a potent anti-inflammatory cytokine, inhibits monocyte-endothelial cell interactions. METHODS: The effect of IL-10 on monocyte/endothelial cell adhesion, as well as on the expression of MMP-9 and the tissue inhibitor of MMP-9, TIMP-1, were first tested in vitro in coculture systems. In addition, we used an ex vivo binding assay to study the inhibitory effect of IL-10 on monocyte adhesion to carotid arteries obtained from either normal, or L-nitro arginine-methyl ester (L-NAME)-treated rats. The effect of IL-10 on the expression of monocyte adhesion molecules (CD18 and CD62-L) was studied by flow cytometry. RESULTS: IL-10 (150 ng/ml) inhibits monocyte adhesion to endothelial cells (by 35%) and to carotid arteries (by 40 and 50%, in normal and L-NAME-treated rats, respectively), via direct modulation of the expression of CD18 and CD62-L. Moreover, IL-10 dose-dependently decreases MMP-9 activity and increases TIMP-1 levels in coculture systems, both at the transcriptional level. CONCLUSIONS: Our results suggest that IL-10 is an important modulator of monocyte-endothelial cell interactions.
Endothelium, Vascular/metabolism , Interleukin-10/pharmacology , Matrix Metalloproteinase 9/metabolism , Monocytes/metabolism , Tissue Inhibitor of Metalloproteinase-1/metabolism , Analysis of Variance , Blotting, Western , Cell Adhesion/drug effects , Coculture Techniques , Dose-Response Relationship, Drug , Electrophoresis, Polyacrylamide Gel , Enzyme-Linked Immunosorbent Assay , Humans
A calmodulin-dependent protein kinase (MCK1) appeared important in regulating flowering in tobacco. The expression of modified MCK1 that lacks the C-terminal including calmodulin-binding domain upsets the flowering developmental program, leading to the abortion of flower primordia initiated on the main axis of the plant and, as well, caused the prolongation of the vegetative phase in axillary buds. The abortion process of flowers began first in the developing anthers and subsequently the entire flower senesces. In axillary buds the prolonged vegetative phase was characterized by atypical elongated, narrow, twisted leaves. These results suggested a role for calmodulin-dependent protein kinase homologs in mediating flowering.
OBJECTIVES: We sought to make a prospective comparison of systematic stenting with provisional stenting guided by Doppler measurements of coronary velocity reserve and quantitative coronary angiography. BACKGROUND: Despite the increasing use of stents during percutaneous transluminal coronary angioplasty, it is unclear whether systematic stenting is superior to a strategy of provisional stenting in which stents are placed only in patients with unsatisfactory results or as a bail-out procedure. METHODS: Two hundred fifty-one patients undergoing elective coronary angioplasty were randomly assigned either to provisional stenting (group 1, in which stenting was performed if postangioplasty coronary velocity reserve was <2.2 and/or residual stenosis > or =35% or as bail-out) or to systematic stenting (group 2). The primary end point was the six-month angiographic minimal lumen diameter (MLD). Major adverse cardiac events were secondary end points (death, acute myocardial infarction and target lesion revascularization). RESULTS: Stenting was performed in 48.4% of patients in group 1 and 100% of patients in group 2 (p<0.01). Six months after angioplasty, the MLD did not differ between groups (1.90+/-0.79 mm vs. 1.99+/-0.70 mm, p = 0.39), as was the rate of binary restenosis (27.1% vs. 21.4%, p = 0.37). Among patients with restenosis, 13/32 (40.6%) in group 1 but 100% (25/25) in group 2 had in-stent restenosis (p<0.01). Target lesion revascularization (15.1% vs. 14.4% in groups 1 and 2 respectively, p = 0.89) and major adverse cardiac events (15.1% vs. 16.0%, p = 0.85) were not significantly different. CONCLUSIONS: Systematic stenting does not provide superior angiographic results at six months as compared with provisional stenting.
Angioplasty, Balloon, Coronary , Coronary Disease/therapy , Stents , Aged , Coronary Angiography , Coronary Vessels/pathology , Echocardiography, Doppler , Humans , Middle Aged , Prospective Studies
The quiescent center is viewed as an architectural template in the root apical meristem of all angiosperm and gymnosperm root tips. In roots of Arabidopsis thaliana (L.) Heynh., the quiescent center inhibits differentiation of contacting initial cells and maintains the surrounding initial cells as stem cells. Here, the role of the quiescent center in the development of the maize (Zeca mays L.) root cap has been further explored. Three maize root-specific genes were identified. Two of these were exclusively expressed in the root cap and one of them encoded a GDP-mannose-4,6-dehydratase. Most likely these two genes are structural, tissue-specific markers of the cap. The third gene, a putative glycine-rich cell wall protein, was expressed in the cap and in the root epidermis and, conceivably is a positional marker of the cap. Microsurgical and molecular data indicate that the quiescent center and cap initials may regulate the positional and structural expression of these genes in the cap and thereby control root cap development.
Genes, Plant/genetics , Plant Root Cap/genetics , Zea mays/genetics , Amino Acid Sequence , Gene Expression Regulation, Plant/genetics , Gene Expression Regulation, Plant/physiology , Genes, Plant/physiology , Hydro-Lyases/genetics , Hydro-Lyases/physiology , Plant Root Cap/growth & development , Zea mays/growth & development
The phytohormone auxin has wide-ranging effects on growth and development. Genetic and physiological approaches implicate auxin flux in determination of floral organ number and patterning. This study uses a novel technique of transiently applying a polar auxin transport inhibitor, N-1-naphthylphthalamic acid (NPA), to developing Arabidopsis flowers to further characterize the role of auxin in organogenesis. NPA has marked effects on floral organ number as well as on regional specification in wild-type gynoecia, as defined by morphological and histological landmarks for regional boundaries, as well as tissue-specific reporter lines. NPA's effects on gynoecium patterning mimic the phenotype of mutations in ETTIN, a member of the auxin response factor family of transcription factors. In addition, application of different concentrations of NPA reveal an increased sensitivity of weak ettin alleles to disruptions in polar auxin transport. In contrast, the defects found in spatula gynoecia are partially rescued by treatment with NPA. A model is proposed suggesting an apical-basal gradient of auxin during gynoecium development. This model provides a mechanism linking ETTIN's putative transcriptional regulation of auxin-responsive genes to the establishment or elaboration of tissue patterning during gynoecial development.
Arabidopsis Proteins , Arabidopsis/growth & development , DNA-Binding Proteins/metabolism , Indoleacetic Acids/metabolism , Nuclear Proteins/metabolism , Alleles , Arabidopsis/drug effects , Arabidopsis/genetics , Arabidopsis/ultrastructure , Biological Transport/drug effects , DNA-Binding Proteins/genetics , Gene Expression Regulation, Developmental/drug effects , Gene Expression Regulation, Plant/drug effects , Genes, Plant/genetics , Indoleacetic Acids/antagonists & inhibitors , Microscopy, Electron, Scanning , Morphogenesis/drug effects , Mutation , Nuclear Proteins/genetics , Organ Specificity , Phenotype , Phthalimides/pharmacology , Plant Proteins/metabolism
The alternate (zigzag) configuration of the chromosome ring in oenotheras fulfills the requirement of high tension across kinetochores for stability of the configuration and the progression to anaphase. However, also semialternate configurations (two pairs of adjacent kinetochores interspaced among the zigzag) fulfill the requirement of high tension across kinetochores. If only the magnitude of tensile force acting on a kinetochore pair governs the stability of microtubule attachments, the probability of occurrence of the semialternate configurations would be higher than that of fully alternate configurations. Yet the percentage of irregularity in the zigzag configuration is surprisingly low, which means that the semialternate configurations are corrected. The only difference which distinguishes the fully alternate and the semialternate configurations with respect to the tension across kinetochores is that the tension across a kinetochore alternating with its neighbors is rather uniformly distributed over the kinetochore, while there is a gradient of the tension in the kinetochore having a non-alternating neighbor, with low tension on the side of this neighbor. Apparently, a low tension across a part of a kinetochore brings about correction of its attachment to microtubules. This hypothesis fits with the repeat subunit model of the kinetochore; apparently, each subunit can function autonomously in the tension-governed mechanisms, stabilizing its attachment and controlling the metaphase-to-anaphase transition.
Chromosome Segregation , Kinetochores , Rosales/genetics , Heterozygote , Metaphase , Models, Genetic , Translocation, Genetic
