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Over 18 million people worldwide were diagnosed with cancer in 2020, including over 150,000 people in Australia. Although improved early detection and treatment have increased the survival rates, cardiotoxic treatment and inadequate management of cardiovascular risk factors have resulted in cardiovascular disease (CVD) being one of the leading causes of non-cancer-related death and disability among cancer survivors. International guidelines outline the standards of care for CVD risk surveillance and management. However, Australian cardio-oncology policies and clinical guidelines are limited. There is increasing growth of cardio-oncology research in Australia and support from leading Australian professional bodies and advocacy and research networks, including the Cardiac Society of Australia and New Zealand, the Clinical Oncology Society of Australia, the National Heart Foundation of Australia, and the Australian Cardiovascular Alliance (ACvA). Thus, opportunities to drive multidisciplinary cardio-oncology initiatives are growing, including grant funding, position statements, and novel research to inform new policies. The ACvA has a unique flagship structure that spans the translational research pipeline from drug discovery to implementation science. This article aims to highlight how multidisciplinary cardio-oncology innovations could intersect with the seven ACvA flagships, and to showcase Australian achievements in cardio-oncology thus far. We summarise eight key priority areas for future cardio-oncology research that emerged. These strategies will strengthen cardio-oncology research and care in Australia, and drive new guidelines, policies, and government initiatives to ensure equity in health outcomes for all cardio-oncology patients.
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Cardiología , Enfermedades Cardiovasculares , Oncología Médica , Humanos , Australia/epidemiología , Enfermedades Cardiovasculares/terapia , Enfermedades Cardiovasculares/epidemiología , Oncología Médica/organización & administración , Oncología Médica/normas , Cardiología/normas , Neoplasias/terapia , Neoplasias/complicaciones , Investigación Biomédica , CardiooncologíaRESUMEN
Background: Cardiovascular disease (CVD) and cancer are leading causes of death and people with cancer are at higher risk of developing CVD than the general population. Many cancer medicines have cardiotoxic effects but the size of the population exposed to these potentially cardiotoxic medicines is not known. We aimed to determine the prevalence of exposure to potentially cardiotoxic cancer medicines in Australia. Methods: We identified potentially cardiotoxic systemic cancer medicines through searching the literature and registered product information documents. We conducted a retrospective cohort study of Australians dispensed potentially cardiotoxic cancer medicines between 2005 and 2021, calculating age-standardised annual prevalence rates of people alive with exposure to a potentially cardiotoxic medicine during or prior to each year of the study period. Findings: We identified 108,175 people dispensed at least one potentially cardiotoxic cancer medicine; median age, 64 (IQR: 52-74); 57% female. Overall prevalence increased from 49 (95%CI: 48.7-49.3)/10,000 to 232 (95%CI: 231.4-232.6)/10,000 over the study period; 61 (95%CI: 60.5-61.5)/10,000 to 293 (95%CI: 292.1-293.9)/10,000 for females; and 39 (95%CI: 38.6-39.4)/10,000 to 169 (95%CI: 168.3-169.7)/10,000 for males. People alive five years following first exposure increased from 29 (95%CI: 28.8-29.2)/10,000 to 134 (95%CI: 133.6-134.4)/10,000; and from 22 (95%CI: 21.8-22.2)/10,000 to 76 (95%CI: 75.7-76.3)/10,000 for those alive at least 10 years following first exposure. Most people were exposed to only one potentially cardiotoxic medicine, rates of which increased from 39 (95%CI: 38.7-39.3)/10,000 in 2005 to 131 (95%CI: 130.6-131.4)/10,000 in 2021. Interpretation: The number of people exposed to efficacious yet potentially cardiotoxic cancer medicines in Australia is growing. Our findings can support the development of service planning and create awareness about the magnitude of cancer treatment-related cardiotoxicities. Funding: NHMRC Centre for Research Excellence in Medicines Intelligence, Cancer Institute NSW Early Career Fellowship.
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PURPOSE: To qualitatively explore Australian healthcare professionals' perspectives on how to improve the care and management of cancer-related financial toxicity, including relevant practices, services, and unmet needs. METHODS: We invited healthcare professionals (HCP) who currently provide care to people with cancer within their role to complete an online survey, which was distributed via the networks of Australian clinical oncology professional associations/organisations. The survey was developed by the Clinical Oncology Society of Australia's Financial Toxicity Working Group and contained 12 open-ended items which we analysed using descriptive content analysis and NVivo software. RESULTS: HCPs (n = 277) believed that identifying and addressing financial concerns within routine cancer care was important and most believed this to be the responsibility of all HCP involved in the patient's care. However, financial toxicity was viewed as a "blind spot" within a medical model of healthcare, with a lack of services, resources, and training identified as barriers to care. Social workers reported assessment and advocacy were part of their role, but many reported lacking formal training and understanding of financial complexities/laws. HCPs reported positive attitudes towards transparent discussions of costs and actioning cost-reduction strategies within their control, but feelings of helplessness when they perceived no solution was available. CONCLUSION: Identifying financial needs and providing transparent information about cancer-related costs was viewed as a cross-disciplinary responsibility, however, a lack of training and services limited the provision of support. Increased cancer-specific financial counselling and advocacy, via dedicated roles or developing HCPs' skills, is urgently needed within the healthcare system.
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Estrés Financiero , Neoplasias , Humanos , Australia , Personal de Salud/educación , Neoplasias/terapia , Oncología Médica/educaciónRESUMEN
Cancer and cardiovascular disease (CVD) commonly coexist, with increasing evidence that long-term cancer survivors are more likely to die from CVD than the general population. Effective management of CVD and its risk factors requires identification of patients at increased risk who may benefit from early intervention and their appropriate monitoring across the disease trajectory. Improving outcomes requires new models of multidisciplinary cancer care supported by care pathways. Such pathways require a clear delineation of the roles and responsibilities of all team members and provision of appropriate enablers for their delivery. These include accessible point-of-care tools/risk calculators, patient resources, and the provision of tailored training opportunities for health care providers.
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AIM: To understand the opinions and current practices of health professionals on the topic of addressing cancer-related financial toxicity among patients. METHODS: A cross-sectional online survey was distributed through Australian clinical oncology professional organizations/networks. The multidisciplinary Clinical Oncology Society of Australia Financial Toxicity Working Group developed 25 questions relating to the frequency and comfort levels of patient-clinician discussions, opinions about their role, strategies used, and barriers to providing solutions for patients. Descriptive statistics were used and subgroup analyses were undertaken by occupational groups. RESULTS: Two hundred and seventy-seven health professionals completed the survey. The majority were female (n = 213, 77%), worked in public facilities (200, 72%), and treated patients with varied cancer types across all of Australia. Most participants agreed that it was appropriate in their clinical role to discuss financial concerns and 231 (88%) believed that these discussions were an important part of high-quality care. However, 73 (28%) stated that they did not have the appropriate information on support services or resources to facilitate such conversations, differing by occupation group; 7 (11%) social workers, 34 (44%) medical specialists, 18 (25%) nurses, and 14 (27%) of other occupations. Hindrances to discussing financial concerns were insufficient resources or support systems to refer to, followed by lack of time in a typical consultation. CONCLUSION: Health professionals in cancer care commonly address the financial concerns of their patients but attitudes differed across occupations about their role, and frustrations were raised about available solutions. Resources supporting financial-related discussions for all health professionals are urgently needed to advance action in this field.
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Personal de Salud , Neoplasias , Humanos , Masculino , Femenino , Australia , Estudios Transversales , Encuestas y Cuestionarios , Neoplasias/terapiaRESUMEN
The aim of the study was to determine the feasibility of complexation between the antioxidant trans-resveratrol (RSV) and underivatized cyclodextrins (CDs) using a variety of preparative methods, including physical mixing, kneading, microwave irradiation, co-evaporation, and co-precipitation techniques. Products were characterized using differential scanning calorimetry (DSC), simultaneous thermogravimetric/DSC analysis (TGA/DSC), Fourier transform infrared (FT-IR) spectroscopy, and powder X-ray diffraction (PXRD). With α-CD and RSV, sample amorphization was revealed by PXRD and FT-IR, but no definitive inclusion complexation was evident. Similar results were obtained in attempts to complex RSV with ß-CD. However, complex formation between γ-CD and RSV was evident from observation of an endo-/exothermic effect appearing in the DSC trace of the product from kneading and was further corroborated by FT-IR and PXRD methods. The latter technique indicated complexation unequivocally as the diffraction peak profile for the product matched that for known isostructural γ-CD complexes. Single crystal X-ray analysis followed, confirming the predicted complex between γ-CD and RSV. A combination of 1H NMR and TGA data yielded the complex formula (γ-CD)3·(RSV)4·(H2O)62. However, severe disorder of the RSV molecules prevented their modeling. In contrast, our previous studies of the inclusion of RSV in methylated CDs yielded crystals with only minor guest disorder.
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Ciclodextrinas/química , Resveratrol/química , Sesquiterpenos/química , Cristalografía por Rayos X , Humanos , Microondas , Estereoisomerismo , Termodinámica , Difracción de Rayos X , FitoalexinasRESUMEN
BACKGROUND: Several targeted therapies for cancer have been associated with cardiovascular toxicity. The evidence for this association has not been synthesized systematically nor has the quality of evidence been considered. We synthesized systematic review evidence of cardiovascular toxicity of individual targeted agents. METHODS: We searched MEDLINE, Embase, and the Cochrane Database of Systematic Reviews for systematic reviews with meta-analyses of cardiovascular outcomes for individual agents published to May 2020. We selected reviews according to prespecified eligibility criteria (International Prospective Register of Systematic Reviews CRD42017080014). We classified evidence of cardiovascular toxicity as sufficient, probable, possible, or indeterminate for specific cardiovascular outcomes based on statistical significance, study quality, and size. RESULTS: From 113 systematic reviews, we found at least probable systematic review evidence of cardiovascular toxicity for 18 agents, including high- and all-grade hypertension for bevacizumab, ramucirumab, axitinib, cediranib, pazopanib, sorafenib, sunitinib, vandetanib, aflibercept, abiraterone, and enzalutamide, and all-grade hypertension for nintedanib; high- and all-grade arterial thromboembolism (includes cardiac and/or cerebral events) for bevacizumab and abiraterone, high-grade arterial thromboembolism for trastuzumab, and all-grade arterial thromboembolism for sorafenib and tamoxifen; high- and all-grade venous thromboembolism (VTE) for lenalidomide and thalidomide, high-grade VTE for cetuximab and panitumumab, and all-grade VTE for bevacizumab; high- and all-grade left ventricular ejection fraction decline or congestive heart failure for bevacizumab and trastuzumab, and all-grade left ventricular ejection fraction decline/congestive heart failure for pazopanib and sunitinib; and all-grade corrected QT interval prolongation for vandetanib. CONCLUSIONS: Our review provides an accessible summary of the cardiovascular toxicity of targeted therapy to assist clinicians and patients when managing cardiovascular health.
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There is ongoing interest in exploiting the antioxidant activity and other medicinal properties of natural monophenolic/polyphenolic compounds, but their generally low aqueous solubility limits their applications. Numerous studies have been undertaken to solubilize such compounds via supramolecular derivatization with co-crystal formation with biocompatible coformer molecules and cyclodextrin (CD) complexation being two successful approaches. In this study, eight new crystalline products obtained by complexation between methylated cyclodextrins and the bioactive phenolic acids (ferulic, hydroferulic, caffeic, and p-coumaric acids) were investigated using thermal analysis (hot stage microscopy, thermogravimetry, differential scanning calorimetry) and X-ray diffraction. All of the complexes crystallized as ternary systems containing the host CD, a phenolic acid guest, and water. On heating each complex, the primary thermal events were dehydration and liberation of the respective phenolic acid component, the mass loss for the latter step enabling determination of the host-guest stoichiometry. Systematic examination of the X-ray crystal structures of the eight complexes enabled their classification according to the extent of inclusion of each guest molecule within the cavity of its respective CD molecule. This revealed three CD inclusion compounds with full guest encapsulation, three with partial guest inclusion, and two that belong to the rare class of 'non-inclusion' compounds.
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Ácidos Cumáricos/química , Ciclodextrinas/química , Hidroxibenzoatos/química , Agua/química , Materiales Biocompatibles/química , Cristalografía por Rayos X , SolubilidadRESUMEN
Wheat is a staple crop, frequently cultivated in water-restricted environments. Improving crop water-use efficiency would be desirable if grain yield can be maintained. We investigated whether a decrease in wheat stomatal density via the manipulation of epidermal patterning factor (EPF) gene expression could improve water-use efficiency. Our results show that severe reductions in stomatal density in EPF-overexpressing wheat plants have a detrimental outcome on yields. However, wheat plants with a more moderate reduction in stomatal density (i.e. <50% reduction in stomatal density on leaves prior to tillering) had yields indistinguishable from controls, coupled with an increase in intrinsic water-use efficiency. Yields of these moderately reduced stomatal density plants were also comparable with those of control plants under conditions of drought and elevated CO2. Our data demonstrate that EPF-mediated control of wheat stomatal development follows that observed in other grasses, and we identify the potential of stomatal density as a tool for breeding wheat plants that are better able to withstand water-restricted environments without yield loss.
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Sequías , Estomas de Plantas/metabolismo , Triticum/metabolismo , Agua/metabolismo , Estomas de Plantas/genética , Estomas de Plantas/crecimiento & desarrollo , Triticum/genética , Triticum/crecimiento & desarrolloRESUMEN
The formation of stomata and leaf mesophyll airspace must be coordinated to establish an efficient and robust network that facilitates gas exchange for photosynthesis, however the mechanism by which this coordinated development occurs remains unclear. Here, we combine microCT and gas exchange analyses with measures of stomatal size and patterning in a range of wild, domesticated and transgenic lines of wheat and Arabidopsis to show that mesophyll airspace formation is linked to stomatal function in both monocots and eudicots. Our results support the hypothesis that gas flux via stomatal pores influences the degree and spatial patterning of mesophyll airspace formation, and indicate that this relationship has been selected for during the evolution of modern wheat. We propose that the coordination of stomata and mesophyll airspace pattern underpins water use efficiency in crops, providing a target for future improvement.
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Células del Mesófilo/química , Células del Mesófilo/metabolismo , Estomas de Plantas/química , Estomas de Plantas/metabolismo , Arabidopsis/química , Arabidopsis/metabolismo , Gases/metabolismo , Porosidad , Triticum/química , Triticum/metabolismo , Agua/metabolismoRESUMEN
Many plant pathogens gain entry to their host via stomata. On sensing attack, plants close these pores to restrict pathogen entry. Here, we show that plants exhibit a second longer term stomatal response to pathogens. Following infection, the subsequent development of leaves is altered via a systemic signal. This reduces the density of stomata formed, thus providing fewer entry points for pathogens on new leaves. Arabidopsis thaliana leaves produced after infection by a bacterial pathogen that infects through the stomata (Pseudomonas syringae) developed larger epidermal pavement cells and stomata and consequently had up to 20% reductions in stomatal density. The bacterial peptide flg22 or the phytohormone salicylic acid induced similar systemic reductions in stomatal density suggesting that they might mediate this effect. In addition, flagellin receptors, salicylic acid accumulation, and the lipid transfer protein AZI1 were all required for this developmental response. Furthermore, manipulation of stomatal density affected the level of bacterial colonization, and plants with reduced stomatal density showed slower disease progression. We propose that following infection, development of new leaves is altered by a signalling pathway with some commonalities to systemic acquired resistance. This acts to reduce the potential for future infection by providing fewer stomatal openings.
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Arabidopsis/microbiología , Estomas de Plantas/microbiología , Pseudomonas syringae/fisiología , Ácido Abscísico/metabolismo , Arabidopsis/citología , Arabidopsis/inmunología , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/fisiología , Proteínas de Unión a Ácidos Grasos/genética , Proteínas de Unión a Ácidos Grasos/metabolismo , Proteínas de Unión a Ácidos Grasos/fisiología , Interacciones Huésped-Patógeno , Peronospora/fisiología , Ácidos Pipecólicos/metabolismo , Enfermedades de las Plantas/inmunología , Enfermedades de las Plantas/microbiología , Hojas de la Planta/citología , Hojas de la Planta/inmunología , Hojas de la Planta/microbiologíaRESUMEN
INTRODUCTION: The introduction of targeted therapies for cancer has contributed to dramatic improvements in patient survival. Nevertheless, several targeted therapies have been associated with 'off-target' adverse effects, based on varying levels of evidence. To date, this evidence has not been systematically synthesised. We will synthesise published systematic review evidence of cardiovascular toxicity associated with targeted cancer therapies. METHODS AND ANALYSIS: We will include systematic reviews of randomised controlled trials and observational studies that report on cardiovascular outcomes for individual agents. We will identify systematic reviews by applying predeveloped, standardised search strategies within Embase, Medline and Cochrane Central. Two independent reviewers will identify reviews published up to 31 December 2016 using predefined eligibility criteria. They will resolve ambiguous cases through consensus, arbitrated by a third reviewer if required. The reviewers will extract and report data according to methodological guidelines for overviews provided by the Cochrane Collaboration, Joanna Briggs Institute and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols. They will assess the quality of included reviews by applying the Assessment of Multiple Systematic Reviews tool. They will judge the quality of evidence in included reviews based on their assessment of bias and incorporation into the interpretation of findings. In synthesising the evidence, we will classify agents based on systematic review evidence of toxicity (sufficient, probable, possible or indeterminate) for specific cardiovascular outcomes (congestive heart failure, myocardial infarction, ischaemic heart disease, left ventricular ejection fraction decline, cerebrovascular disease, pulmonary embolism, thrombosis and hypertension). This will provide clinicians and patients with an accessible synthesis based on robust methodology. ETHICS AND DISSEMINATION: Ethics approval is not required for overviews. We will conduct the study in collaboration with consumer representatives. We will submit results for peer-review publication, and disseminate them through established clinical and consumer networks. PROSPERO REGISTRATION NUMBER: CRD42017080014.
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Antineoplásicos/efectos adversos , Cardiotoxicidad , Enfermedades Cardiovasculares/inducido químicamente , Terapia Molecular Dirigida/efectos adversos , Neoplasias/tratamiento farmacológico , Humanos , Estudios Observacionales como Asunto , Ensayos Clínicos Controlados Aleatorios como Asunto , Proyectos de Investigación , Revisiones Sistemáticas como AsuntoRESUMEN
The epidermal patterning factor (EPF) family of secreted signaling peptides regulate the frequency of stomatal development in model dicot and basal land plant species. Here, we identify and manipulate the expression of a barley (Hordeum vulgare) ortholog and demonstrate that when overexpressed HvEPF1 limits entry to, and progression through, the stomatal development pathway. Despite substantial reductions in leaf gas exchange, barley plants with significantly reduced stomatal density show no reductions in grain yield. In addition, HvEPF1OE barley lines exhibit significantly enhanced water use efficiency, drought tolerance, and soil water conservation properties. Our results demonstrate the potential of manipulating stomatal frequency for the protection and optimization of cereal crop yields under future drier environments.
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Sequías , Hordeum/fisiología , Proteínas de Plantas/genética , Estomas de Plantas/fisiología , Deshidratación , Regulación de la Expresión Génica de las Plantas , Hordeum/genética , Hordeum/crecimiento & desarrollo , Proteínas de Plantas/metabolismo , Plantas Modificadas GenéticamenteRESUMEN
Stomata are formed by a pair of guard cells which have thickened, elastic cell walls to withstand the large increases in turgor pressure that have to be generated to open the pore that they surround. We have characterized FOCL1, a guard cell-expressed, secreted protein with homology to Hyp-rich cell wall proteins. FOCL1-GFP localizes to the guard cell outer cuticular ledge and plants lacking FOCL1 produce stomata without a cuticular ledge. Instead the majority of stomatal pores are entirely covered over by a continuous fusion of the cuticle, and consequently plants have decreased levels of transpiration and display drought tolerance. The focl1 guard cells are larger and less able to reduce the aperture of their stomatal pore in response to closure signals suggesting that the flexibility of guard cell walls is impaired. FOCL1 is also expressed in lateral root initials where it aids lateral root emergence. We propose that FOCL1 acts in these highly specialized cells of the stomata and root to impart cell wall strength at high turgor and/or to facilitate interactions between the cell wall and the cuticle.
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Proteínas de Arabidopsis/metabolismo , Células Vegetales/metabolismo , Estomas de Plantas/citología , Estomas de Plantas/fisiología , Proteínas de Arabidopsis/genética , Regulación de la Expresión Génica de las Plantas , Raíces de Plantas/citología , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Transpiración de Plantas/genética , ProlinaRESUMEN
Stomatal opening and closure depends on changes in turgor pressure acting within guard cells to alter cell shape [1]. The extent of these shape changes is limited by the mechanical properties of the cells, which will be largely dependent on the structure of the cell walls. Although it has long been observed that guard cells are anisotropic due to differential thickening and the orientation of cellulose microfibrils [2], our understanding of the composition of the cell wall that allows them to undergo repeated swelling and deflation remains surprisingly poor. Here, we show that the walls of guard cells are rich in un-esterified pectins. We identify a pectin methylesterase gene, PME6, which is highly expressed in guard cells and required for stomatal function. pme6-1 mutant guard cells have walls enriched in methyl-esterified pectin and show a decreased dynamic range in response to triggers of stomatal opening/closure, including elevated osmoticum, suggesting that abrogation of stomatal function reflects a mechanical change in the guard cell wall. Altered stomatal function leads to increased conductance and evaporative cooling, as well as decreased plant growth. The growth defect of the pme6-1 mutant is rescued by maintaining the plants in elevated CO2, substantiating gas exchange analyses, indicating that the mutant stomata can bestow an improved assimilation rate. Restoration of PME6 rescues guard cell wall pectin methyl-esterification status, stomatal function, and plant growth. Our results establish a link between gene expression in guard cells and their cell wall properties, with a corresponding effect on stomatal function and plant physiology.
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Proteínas de Arabidopsis/genética , Arabidopsis/genética , Regulación de la Expresión Génica de las Plantas , Pectinas/metabolismo , Estomas de Plantas/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Pared Celular/metabolismo , Desmetilación , EsterificaciónRESUMEN
Manipulation of stomatal density was investigated as a potential tool for enhancing drought tolerance or nutrient uptake. Drought tolerance and soil water retention were assessed using Arabidopsis epidermal patterning factor mutants manipulated to have increased or decreased stomatal density. Root nutrient uptake via mass flow was monitored under differing plant watering regimes using nitrogen-15 ((15) N) isotope and mass spectrometry. Plants with less than half of their normal complement of stomata, and correspondingly reduced levels of transpiration, conserve soil moisture and are highly drought tolerant but show little or no reduction in shoot nitrogen concentrations especially when water availability is restricted. By contrast, plants with over twice the normal density of stomata have a greater capacity for nitrogen uptake, except when water availability is restricted. We demonstrate the possibility of producing plants with reduced transpiration which have increased drought tolerance, with little or no loss of nutrient uptake. We demonstrate that increasing transpiration can enhance nutrient uptake when water is plentiful.
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Adaptación Fisiológica , Sequías , Nitrógeno/metabolismo , Fósforo/metabolismo , Estomas de Plantas/fisiología , Arabidopsis/fisiología , Isótopos de Carbono , Humedad , Isótopos de Nitrógeno , SueloRESUMEN
Guard cells allow land plants to survive under restricted or fluctuating water availability. They control the exchange of gases between the external environment and the interior of the plant by regulating the aperture of stomatal pores in response to environmental stimuli such as light intensity, and are important regulators of plant productivity. Their turgor driven movements are under the control of a signalling network that is not yet fully characterised. A reporter gene fusion confirmed that the Arabidopsis APK1b protein kinase gene is predominantly expressed in guard cells. Infrared gas analysis and stomatal aperture measurements indicated that plants lacking APK1b are impaired in their ability to open their stomata on exposure to light, but retain the ability to adjust their stomatal apertures in response to darkness, abscisic acid or lack of carbon dioxide. Stomatal opening was not specifically impaired in response to either red or blue light as both of these stimuli caused some increase in stomatal conductance. Consistent with the reduction in maximum stomatal conductance, the relative water content of plants lacking APK1b was significantly increased under both well-watered and drought conditions. We conclude that APK1b is required for full stomatal opening in the light but is not required for stomatal closure.
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Proteínas de Arabidopsis/metabolismo , Estomas de Plantas/metabolismo , Estomas de Plantas/fisiología , Proteínas Quinasas/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Tirosina Quinasas/metabolismo , Ácido Abscísico/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/fisiología , Proteínas de Arabidopsis/genética , Dióxido de Carbono/metabolismo , Oscuridad , Sequías , Regulación de la Expresión Génica de las Plantas/genética , Luz , Fotosíntesis/genética , Fotosíntesis/fisiología , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Hojas de la Planta/fisiología , Estomas de Plantas/genética , Proteínas Quinasas/genética , Proteínas Serina-Treonina Quinasas/genética , Proteínas Tirosina Quinasas/genética , Agua/metabolismoRESUMEN
To investigate the impact of manipulating stomatal density, a collection of Arabidopsis epidermal patterning factor (EPF) mutants with an approximately 16-fold range of stomatal densities (approx. 20-325% of that of control plants) were grown at three atmospheric carbon dioxide (CO(2)) concentrations (200, 450 and 1000 ppm), and 30 per cent or 70 per cent soil water content. A strong negative correlation between stomatal size (S) and stomatal density (D) was observed, suggesting that factors that control D also affect S. Under some but not all conditions, mutant plants exhibited abnormal stomatal density responses to CO(2) concentration, suggesting that the EPF signalling pathway may play a role in the environmental adjustment of D. In response to reduced water availability, maximal stomatal conductance was adjusted through reductions in S, rather than D. Plant size negatively correlated with D. For example, at 450 ppm CO(2) EPF2-overexpressing plants, with reduced D, had larger leaves and increased dry weight in comparison with controls. The growth of these plants was also less adversely affected by reduced water availability than plants with higher D, indicating that plants with low D may be well suited to growth under predicted future atmospheric CO(2) environments and/or water-scarce environments.
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Proteínas de Arabidopsis/química , Arabidopsis/genética , Dióxido de Carbono/química , Proteínas de Unión al ADN/química , Estomas de Plantas/crecimiento & desarrollo , Factores de Transcripción/química , Adaptación Fisiológica , Arabidopsis/química , Arabidopsis/crecimiento & desarrollo , Proteínas de Arabidopsis/genética , Proteínas de Unión al ADN/genética , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Ingeniería Genética , Epidermis de la Planta/química , Epidermis de la Planta/genética , Hojas de la Planta/química , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Estomas de Plantas/química , Estomas de Plantas/genética , Transpiración de Plantas , Plantas Modificadas Genéticamente/química , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/crecimiento & desarrollo , Transducción de Señal , Suelo/química , Temperatura , Factores de Transcripción/genética , Agua/químicaRESUMEN
Understanding the relationship of the size and shape of an organism to the size, shape, and number of its constituent cells is a basic problem in biology; however, numerous studies indicate that the relationship is complex and often nonintuitive. To investigate this problem, we used a system for the inducible expression of genes involved in the G1/S transition of the plant cell cycle and analyzed the outcome on leaf shape. By combining a careful developmental staging with a quantitative analysis of the temporal and spatial response of cell division pattern and leaf shape to these manipulations, we found that changes in cell division frequency occurred much later than the observed changes in leaf shape. These data indicate that altered cell division frequency cannot be causally involved in the observed change of shape. Rather, a shift to a smaller cell size as a result of the genetic manipulations performed correlated with the formation of a smoother leaf perimeter, i.e. appeared to be the primary cellular driver influencing form. These data are discussed in the context of the relationship of cell division, growth, and leaf size and shape.