Contribución del retículo endoplasmático a la onda de calcio en epitelio pigmentario de la retina.

Las células del epitelio pigmentario tienen una función clave como reguladoras de la homeostasis retiniana y constitución de la barrera hemato-retiniana. Se ha descrito previamente en la literatura que estas células presentan ondas de calcio intracelulares implicadas en los procesos fisiológicos retinianos. Aunque se supone que en la génesis y extensión de la onda de calcio están implicados tanto factores intracelulares como paracrinos, los datos existentes en la literatura no son concluyentes. Por otro lado, la supuesta participación de los depósitos de calcio intracelulares (retículo endoplasmático) en la extensión de la onda se ha estudiado sólo de modo indirecto, por lo que, para esclarecer los mecanismos implicados en el origen y propagación de la onda de calcio, se elaboró este trabajo en el que se realizaron mediciones de calcio directas y simultáneas en citosol y en retículo endoplasmático mediante los sensores fluorescentes de calcio Fura-2 y erGAP3. Se transfectó la línea ARPE-19 para conseguir un clon estable cuya característica fuera la expresión en retículo endoplasmático de la sonda de calcio fluorescente erGAP3. Se llevaron a cabo los experimentos en un microscopio de epifluorescencia con el cultivo de las células en monocapa, con estimulación mecánica. Para demostrar la implicación de los distintos receptores y canales celulares se utilizaron diversos fármacos y condiciones. Los resultados obtenidos parecen indicar que el inicio de la onda de calcio se produce a través de la liberación de ATP desencadenada por la estimulación mecánica, por lo que, con la inhibición de los receptores purinérgicos con suramina y la degradación de ATP por la apirasa, se obtiene una disminución de intensidad de la onda y de su propagación. La implicación de las conexinas se estudió mediante células no confluentes y con el bloqueo mediante carbenoxolona; se obtuvo como resultado la onda de calcio sin aportación de calcio desde el retículo. Podemos concluir que en las células ARPE-19/erGAP3 la propagación de la onda en las capas más proximales depende de las conexinas y en las capas más distales de la activación de los receptores purinérgicos mediante el ATP extracelular.Grado en Medicin

Changes in growth rate, root morphology and water use efficiency of potted Callistemon citrinus plants in response to different levels of water deficit

Callistemon is widely used as a flowering shrub in gardening and landscaping in the Mediterranean area. However, prolonged or severe water stress may alter its physiological and morphological behaviour. Callistemon citrinus plants were grown in nursery conditions and subjected to three irrigation treatments: a control (watered to container capacity) and two water deficit treatments of 50 and 25% of the amount of water supplied in the control treatment (moderate and severe deficit irrigation, respectively). After 53 weeks, the moderate deficit irrigation plants showed a lower relative growth rate but increased root/shoot ratio, improved the root system and increased water use efficiency, while flowering and leaf colour were unaffected. However, severe deficit irrigation reduced flowering and affected leaf colour. Both deficit irrigation treatments reduced stomatal conductance, suggesting an efficient and adaptive stomatal control in this species. These reductions were marked after longer periods in plants submitted to severe deficit irrigation, which decreased photosynthesis and could delay plant recovery and cause permanent damage. Differences between stem and leaf water potential values have seen to be a good indicator of instantaneous shoot transpiration. Water consumption was influenced by the active periods of growth and inflorescence formation. It is concluded that moderate deficit irrigation can be used successfully in C. citrinus plant production to reduce water consumption while maintaining good overall quality. © 2013 Elsevier B.V.This work was supported by the Spanish Ministry of Science and Innovation (AGL 2008-05258-C02-1-2, AGL 2011-30022-C02-01) and Fundación Séneca (15356/PI/10).Peer Reviewe

Comparison of individual and combined effects of salinity and deficit irrigation on physiological, nutritional and ornamental aspects of tolerance in Callistemon laevis plants

The effect of water deficit, salinity and both applied simultaneously on several physiological and morphological parameters in the ornamental plant Callistemon laevis was studied to identify the tolerance mechanisms developed by this species to these sources of stress and to evaluate their adaptability to such conditions. C. laevis plants were grown in pots outdoors and subjected to four irrigation treatments lasting ten months: control (0.8dSm-1, 100% water holding capacity), water deficit (0.8dSm-1, 50% of the amount of water supplied in control), saline (4.0dSm-1, same amount of water supplied as control) and saline water deficit (4.0dSm-1, 50% of the water supplied in the control). Water and saline stress, when applied individually, led to a reduction of 12% and 39% of total biomass, respectively, while overall plant quality (leaf color and flowering) was unaffected. However, saline water deficit affected leaf color and flowering and induced an excessive decrease of growth (68%) due to leaf tissue dehydration and a high leaf Cl and Na concentration. Biomass partitioning depended not only on the amount of water applied, but also on the electrical conductivity of the water. Water stress induced active osmotic adjustment and decreased leaf tissue elasticity. Although both Na and Cl concentrations in the plant tissues increased with salinity, Cl entry through the roots was more restricted. In plants submitted to salinity individually, Na tended to remain in the roots and stems, and little reached the leaves. However, plants simultaneously submitted to water and saline stress were not able to retain this ion in the woody parts. The decrease in stomatal conductance and photosynthesis was more marked in the plants submitted to both stresses, the effect of which decreased photosynthesis, and this together with membrane damage delayed plant recovery. The results show that the combination of deficit irrigation and salinity in C. laevis is not recommended since it magnifies the adverse effects of either when applied individually. © 2015 Elsevier GmbH.This work was supported by the Spanish Ministry of Economy and Competitiveness (project CICYT AGL 2011-30022-C02-01-02) and Fundación Séneca-Agencia de Ciencia y Tecnología de la Región de Murcia (15356/PI/10).Peer Reviewe

Long-term effect of salinity on plant quality, water relations, photosynthetic parameters and ion distribution in Callistemon citrinus

The effect of saline stress on physiological and morphological parameters in Callistemon citrinus plants was studied to evaluate their adaptability to irrigation with saline water. C. citrinus plants, grown under greenhouse conditions, were subjected to two irrigation treatments lasting 56 weeks: control (0.8 dS·m-1) and saline (4 dS·m-1). The use of saline water in C. citrinus plants decreased aerial growth, increased the root/shoot ratio and improved the root system (increased root diameter and root density), but flowering and leaf colour were not affected. Salinity caused a decrease in stomatal conductance and evapotranspiration, which may prevent toxic levels being reached in the shoot. Net photosynthesis was reduced in plants subjected to salinity, although this response was evident much later than the decrease in stomatal conductance. Stem water potential was a good indicator of salt stress in C. citrinus. The relative salt tolerance of Callistemon was related to storage of higher levels of Na+ and Cl- in the roots compared with the leaves, especially in the case of Na+, which could have helped to maintain the quality of plants. The results show that saline water (around 4 dS·m-1) could be used for growing C. citrinus commercially. However, the cumulative effect of irrigating with saline water for 11 months was a decrease in photosynthesis and intrinsic water use efficiency, meaning that the interaction of the salinity level and the time of exposure to the salt stress should be considered important in this species. © 2014 German Botanical Society and Royal Botanical Society of the Netherlands.This work was supported by the Spanish Ministry of Science and Innovation (AGL 2011-30022-C02-01-02) and Fundación Séneca (15356/PI/10).Peer Reviewe

Regulated deficit irrigation in different phenological stages of potted geranium plants: Water consumption, water relations and ornamental quality

The irrigation water requirements and sensitivity to water deficits of ornamental plants is of great interest to horticultural producers for planning irrigation strategies. The effect of different deficit irrigation strategies on physiological and morphological parameters in geranium plants was studied in different growth phases to evaluate how such strategies can be safely used and to ascertain whether the flowering phase is sensitive to deficit irrigation. Pelargonium × hortorum L. H. Bailey plants, grown in a controlled growth chamber, were subjected to four irrigation treatments: control (100 % water field capacity throughout the experiment), sustainable deficit irrigation (75 % water field capacity throughout the experiment), and two regulated deficit irrigation treatments that included water stress during the vegetative growth phase or during the flowering development phase. Although the total amount of irrigation water was similar in the three deficit irrigation treatments (around 80 % of the control value), the lowest values for both height and flowering were found when deficit irrigation was applied during flowering. This indicates that plant quality does not only depend on the amount of water applied but also on the time when the reduction is applied, and that flowering is the most sensitive phase to water stress. Evapotranspiration was related to the formation of inflorescences and to increased plant height. When the irrigation strategy was changed, plants increased or decreased their water consumption and stomatal conductance to adjust to the new conditions by regulating stomatal opening, although, in general, the values of both parameters remained below those observed in the control plants. © 2012 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.This work was supported by the Spanish Ministry of Science and Innovation (AGL 2008-05258-C02-1-2, AGL 2011-30022-C02-01) and Fundación Séneca (15356/PI/10).Peer Reviewe

Regulated deficit irrigation in potted Dianthus plants: Effects of severe and moderate water stress on growth and physiological responses

The purpose of this study was to analyze the physiological and morphological response of carnation plants to different levels of irrigation and to evaluate regulated deficit irrigation as a possible technique for saving water through the application of controlled drought stress. Carnations, Dianthus caryophyllus L. cultivar, were pot-grown in an unheated greenhouse and submitted to two experiments. In the first experiment, the plants were exposed to three irrigation treatments: (control); 70% of the control (moderate deficit irrigation, MDI) and 35% of the control (severe deficit irrigation, SDI). In the second experiment, the plants were submitted to a control treatment, deficit irrigation (DI, 50% of the control) and regulated deficit irrigation (RDI). After 15 weeks, MDI plants showed a slightly reduced total dry weight, plant height and leaf area, while SDI had clearly reduced all the plant size parameters. RDI plants had similar leaf area and total dry weight to the control treatment during the blooming phase. MDI did not affect the number of flowers and no great differences in the colour parameters were observed. RDI plants had higher flower dry weight, while plant quality was affected by the SDI (lower number of shoots and flowers, lower relative chlorophyll content). Leaf osmotic potential decreased with deficit irrigation, but more markedly in SDI, which induced higher values of leaf pressure. Stomatal conductance (gs) decreased in drought conditions more than the photosynthetic rate (Pn). Osmotic adjustment of 0.3 MPa accompanied by decreases in elasticity in response to drought resulted in turgor less at lower leaf water potentials and prevented turgor loss during drought periods. © 2009 Elsevier B.V. All rights reserved.This work was supported by CICYT projects AGL 2005-05588-C02-1 and AGL 2005-05588-C02-2 and by the Consejería de Agricultura y Agua de la Región de Murcia, programme (UPCT-CEBAS-IMIDA.2005).Peer Reviewe

Genetic Response of Common Bean to the Inoculation with Indigenous Fusarium Isolates

[EN] Fungal species from the genus Fusarium are important soil-borne pathogens worldwide, causing significant economic losses in diverse crops. The need to find sustainable solutions against this disease has led to the development of new strategies—for instance, the use of biocontrol agents. In this regard, non-pathogenic Fusarium isolates have demonstrated their ability to help other plants withstand subsequent pathogen attacks. In the present work, several Fusarium isolates were evaluated in climatic chambers to identify those presenting low or non-pathogenic behavior. The inoculation with a low-pathogenic isolate of the fungus did not affect the development of the plant, contrary to the results observed in plants inoculated with pathogenic isolates. The expression of defense-related genes was evaluated and compared between plants inoculated with pathogenic and low-pathogenic Fusarium isolates. Low-pathogenic isolates caused a general downregulation of several plant defense-related genes, while pathogenic ones produced an upregulation of these genes. This kind of response to low-pathogenic fungal isolates has been already described for other plant species and fungal pathogens, being related to enhanced tolerance to later pathogen attacks. The results here presented suggest that low-pathogenic F. oxysporum and F. solani isolates may have potential biocontrol activity against bean pathogens via induced and systemic responses in the plantSIThis research was funded by Junta de Castilla y León, Consejería de Educación for the project “Application of Trichoderma strains in sustainable quality bean production” (LE251P18), the grant to SA-G of the Junta de Castilla y León according to ORDER EDU/529/2017, of June 26, co-financed by the European Social Fund, and the grant to AP-A (FPU19/03650) of Ministerio de Ciencia, Innovacion y Universidades (Spain)

Transpiration, photosynthetic responses, tissue water relations and dry mass partitioning in Callistemon plants during drought conditions

Callistemon is an Australian species used as ornamental plant in Mediterranean regions. The objective of this research was to analyse the ability of Callistemon to overcome water deficit in terms of adjusting its physiology and morphology. Potted Callistemon laevis Anon plants were grown in controlled environment and subjected to drought stress by reducing irrigation water by 40% compared to the control (irrigated to container capacity). The drought stress produced the smallest plants throughout the experiment. After three months of drought, the leaf area, number of leaves and root volume decreased, while root/shoot ratio and root density increased. The higher root hydraulic resistance in stressed plants caused decreases in leaf and stem water potentials resulting in lower stomatal conductance and indicating that water flow through the roots is a factor that strongly influences shoot water relations. The water stress affected transpiration (63% reduction compared with the control). The consistent decrease in gs suggested an adaptative efficient stomatal control of transpiration by this species, resulting in a higher intrinsic water use efficiency (Pn/gs) in drought conditions, increasing as the experimental time progressed. This was accompanied by an improvement in water use efficiency of production to maintain the leaf water status. In addition, water stress induced an active osmotic adjustment and led to decreases in leaf tissue elasticity in order to maintain turgor. Therefore, the water deficit produced changes in plant water relations, gas exchange and growth in an adaptation process which could promote the faster establishment of this species in gardens or landscaping projects in Mediterranean conditions.This work was supported by the projects: CICYT (AGL 2008-05258-C02-1-2), CDTI (IDI-20070868) and Fundación Seneca (05660/PI/07).Peer Reviewe

Growth, water relations and ion accumulation in Phlomis purpurea plants under water deficit and salinity

The effect of different levels of water deficit and salinity on physiological and morphological alterations in Phlomis purpurea plants was studied to evaluate their adaptability to such conditions. P. purpurea plants growing under greenhouse conditions were subjected to four irrigation treatments between November and May 2008: control (C, 1 dS m-1), moderate water deficit (MWD, 1dS m-1, 60% of the control), severe water deficit (SWD, 1 dS m-1, 40% of the control) and saline (S, 4 dS m-1). Aerial dry weight decreased with salinity, response that was more marked in the water deficit treatments, especially SWD. Stem diameter and leaf number were similarly reduced in both water deficit treatments, while leaf area also decreased in saline treated plants. Throughout the experiment, plant height was similar in both control and saline treated plants and was inhibited 10 weeks after application of the deficit irrigation onwards. Only at the end of the experiment were there significant differences in plant height between all treatments. Plants irrigated with saline water had higher Na+ concentrations in their leaves than in their roots and shoots, while Cl- concentrations were similar in leaves and roots, suggesting some resistance to the movement of the latter ions from root to shoots. The accumulation of salt in the leaves was associated with osmotic adjustment, which maintained midday leaf turgor in saline treated plants. However, no osmotic adjustment was observed in plants submitted to water stress. The results indicate that the effect of osmotic stress due to water deficit was more severe than the toxic effect of salt.This work was supported by the projects: CICYT (AGL 2008-05258-C02-1-2), CDTI (IDI-20070868) and Convenio de la Consejería de Agricultura y Agua de la Región de Murcia-UPCT-CEBAS, 2008.Peer Reviewe

Prevalence of convergence insufficiency among Spanish school children aged 6 to 14 years

Clinical relevance: Convergence insufficiency (CI) at an early age can lead to learning difficulties affecting school performance. The aim of this study was to examine the prevalence of CI in a non-clinical population of Spanish children using well defined clinical criteria and to determine whether sex is a risk factor. Methods: Visual acuity and binocular vision tests were performed in 628 children aged 6-14 years (mean age 9.6 ± 1.3 years) at three schools in the Madrid Community, Spain. To assess CI prevalence we used CITT (Convergence Insufficiency Treatment Trial) criteria. The three signs considered were: i) exophoria at least 4∆ greater at near than at far; ii) near break point of convergence (NPC) ≥ 6 cm; and iii) reduced positive fusional vergence (PFV) at near (≤ 15∆ base-out break or failed Sheard's criterion). Results: The CI prevalence detected was 5.30% (33 children). Proportions of children with one or two signs of CI were 23.76% (148 children) and 12.20% (76 children), respectively. No differences in these CI rates by sex were detected. Conclusion: The clinically significant CI prevalence observed here suggests the need for more binocular vision screening programmes in school settings.Depto. de Optometría y VisiónFac. de Óptica y OptometríaTRUEpu