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Tolerance of physic nut plants to aluminum activity in nutrient solution

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582 Original Article TOLERANCE OF PHYSIC NUT PLANTS TO ALUMINUM ACTIVITY IN NUTRIENT SOLUTION TOLERÂNCIA DE PLANTAS DE PINHÃO-MANSO À ATIVIDADE DE ALUMÍNIO, EM SOLUÇÃO NUTRITIVA Maria do Carmo LANA1; Fábio STEINER2; Tiago ZOZ2; Rubens FEY3; Jucenei Fernando FRANDOLOSO4 1. Professora Associada, Universidade Estadual do Oeste do Paraná – UNIOESTE, Marechal Cândido Rondon, PR, Brasil. Maria.Lana@unioeste.br ; 2. Doutorando em Agronomia, Universidade Estadual Paulista – UNESP, Botucatu, SP, Brasil. fsteiner@fca.unesp.br; 3. Pós Doutorando, UNIOESTE, Marechal Cândido Rondon, PR, Brasil; 4. Doutorando em Agronomia, UNIOESTE, Marechal Cândido Rondon, PR, Brasil. ABSTRACT: Plants have different levels of tolerance to phytotoxic effects of aluminum and the exploitation of this characteristic is of significant importance to the use of acid soils. This research aimed to evaluate the effect of aluminum activity in nutrient solution on growth of physic nut young plant. After seven days of adaptation, plants were submitted to Al concentrations of 0; 200; 400; 600; 800 and 1,000 mol L–1, corresponding to Al3+ activity solution, of: 14.5, 21.4; 46.6; 75.6; 108.3 e 144.8 mol L–1, respectively. The increased activity of Al3+ decreased linearly the number of leaves, plant height, leaf area, shoot dry matter and root length of physic nut plant. Physic nut young plants are sensitive to high aluminum activity in solution. The root length, number of leaves, shoot dry matter and total dry matter were variables more affected by Al activity in solution, and can be used to discriminate the tolerance levels to aluminum in physic nut plants. The accumulation of aluminum increased in a activity-dependent manner; however, its translocation from root to shoot was low. KEYWORDS: Jatropha curcas L. Exchangeable acidity. Aluminum toxicity. Aluminum absorption. INTRODUCTION The physic nut (Jatropha curcas L.) is a perennial species, monoecious and belonging to the family Euphorbiaceae; the same as castor oil plant (HELLER, 1996). It is a fast growing shrub with deciduous habit that can reach up to 5 m high. Physic nut is distributed over the arid and semiarid areas of South America and in all tropical regions. In the last years, it has received special attention because its high seed oil content and quality. Therefore, physic nut is a crop with importance for biodiesel production, being considered potentially as a universally accepted source of energy (KUMAR; SHARMA, 2008). As interest in the plant as a biofuel source has increased, the demand for technical information on the crop is increasingly required. Physic nut is considered a rustic crop that can grow under diverse soil and climate conditions and thrive in low-fertility soils (ARRUDA et al., 2004). However, to achieve high yield levels, plant requires rich soils and good physical condition (KUMAR; SHARMA, 2008). Thus, the acidity correction and soil fertility are critical for success and profitability in this culture (LAVIOLA; DIAS, 2008; SOUZA et al., 2011; BALOTA et al., 2012). This finding becomes even more relevant because the main producing regions of physic nut in Brazil are located in soils, characterized by low base saturation and high levels of Al3+, sufficient to alter Received: 19/11/11 Accepted: 06/06/12 the normal growth of many species of cultivated plants. Little is known about this plant tolerance to aluminum toxicity in soil so far. Arruda et al. (2004) report that in acid soils with pH below 4.5, roots of physic nut do not grow; being necessary the liming of soil. The aluminum (Al) toxicity is considered one of the main factors limiting plant growth in acid soils of tropical regions, mainly by causing root growth inhibition (GIANNAKOULA et al., 2008). Toxic levels of aluminum are present in 50% of areas with agricultural potential; in addition, the acidity in soil has worsened with the extensive use of ammonia fertilizer (ZHANG et al., 2007). Thus, knowledge and selection of tolerant species to aluminum is an alternative that offers possibility of success for deployment of these crops in these agricultural areas. Several researches have been conducted using nutrient solution in order to determine perennial species’ tolerance to Al. With regard to growth in the presence of aluminum, works performed with citrus (Santos et al., 1999), grapevine (TECCHIO et al., 2006), apple tree (DANTAS et al., 2001; STOLF et al., 2008), coffee (BRACCINI et al., 1998; MATTIELLO et al., 2008), mango (NAING et al., 2009) and physic nut (STEINER et al., 2012), showed that the results obtained in most cases, reveals the harmful effects of aluminum to the development of both shoot and root system of plants. These effects include Biosci. J., Uberlândia, v. 29, n. 3, p. 582-589, May/June 2013 583 Tolerance of physic. LANA, M. C. et al. reductions in dry matter mass, number and length of roots and root area, which often are associated with increases in the average radius and root volume (SIVAGURU et al., 1992). In the shoot, there was reduction in dry matter mass and plant height (DANTAS et al., 2001). Researches with castor beans, a species belonging to the family Euphorbiaceae, reported high sensitivity of this species the presence of exchangeable Al in soil (LIMA et al., 2007). However, physic nut plants for these studies are still incipient and not conclusive. This research was developed aiming to evaluate the effect of aluminum activity in nutrient solution on growth of physic nut young plants. MATERIAL AND METHODS The experiment was carried out under greenhouse conditions, localized in the Universidade Estadual do Oeste do Paraná, in Marechal Cândido Rondon, Paraná, Brazil (24º31' S, 54º01' W, altitude: 420 m), where the environmental conditions were: minimum and maximum air temperatures of 22 and 36 ºC, respectively; mean air relative humidity ranged from 45–80%. Physic nut seeds, collected directly from the treetop of a plant population in Eldorado, Mato Grosso do Sul, Brazil, were placed for germinating in plastic trays (42 × 28 × 6 cm) containing washed sand and were daily irrigated with distillate water. Eight days after germination, the seedlings were withdrawn of sand and selected for homogeneity of root system length and shoot height. The seedlings presented with 150 ± 10 mm mean height and 60 ± 5 mm primary root length. The seedlings were transferred to plastic pots (1.5 L) containing nutrient solution of Hoagland & Arnon (1950) modified with the following concentrations: macronutrients (mmol L– 1 ) NO3 = 7.5; H2PO4- = 0.5; K = 3.0; Ca = 2.5; Mg = 1.0 and SO4 = 1.0 and micronutrients ( mol L–1): B = 23.0; Cu = 0.16; Fe-EDTA = 44.8; Mn = 6.3; Zn = 0.65 e Mo = 0.05. After seven days of adaptation, plants were submitted to Al concentrations of 0; 200; 400; 600; 800 and 1,000 mol L–1, 3+ corresponding to Al activity solution, estimated by the software Visual MINTEQ 3.0 (GUSTAFSSON, 2011) of: 14.5, 21.4; 46.6; 75.6; 108.3 e 144.8 mol L–1, respectively. Aluminum was added in form of AlCl3.6H2O. The solution’s pH (4.15 ± 0.05) was daily monitored and adjusted when necessary using 0.5 mol L–1 NaOH or 0.5 mol L–1 HCl solutions. After 32 days of exposure to Al toxicity, the crop yield was evaluated in terms of dry matter production of shoots (SDM, g plant–1) and roots (RDM, g plant–1). Plants of all treatments were harvested separately, dried for four days at 65 ± 2 ºC, and then weighed. The leaf area (LA, cm2 plant−1) was determined using the following equation proposed by Severino et al. (2007): LA = 0.84 (L × W)0.99, where L and W are leaf length and width, respectively. The root lengths (mean of three longest roots in a plant) were measured (centimeter plant) for every Al treatment. Root volume (RV, cm3 plant−1) was determined by water displacement using a calibrated cylinder. The number of leaves per plant and plant height were also measured. The plant material from shoot and root were ground, digested in nitric-perchloric acid and the Al concentration was determined by spectrophotometry with eriochrome cyanine R as described by Miyazawa et al. (1999). The study of relative importance of growth characteristics evaluated through the eight variables studied was expressed in decrease percentage caused by Al regarding to control plants without Al, according to the following equation: growth reduction (%) = [(growth without Al – growth with Al)/growth without Al] × 100. The experiment was arranged in a completely randomized design with four replicates (an individual pot containing one plant represented one replicate). Data were submitted to analysis of variance (ANOVA); regression analysis was carried out by F test (p < 0.05) for variables that presented significant differences among treatments. The significant equations with the greatest determination coefficients were adjusted. RESULTS AND DISCUSSION The plant shoot growth of physic nut was negatively affected by Al activity in nutrient solution (Figure 1). It was verified linear decrease for all variables evaluated, with decreases of 14 leaf units (Figure 1a), 19 cm in height (Figure 1b), 818 cm2 in leaf area and 8 g of shoot dry matter per plant for each increment of 1 mol L–1 of Al activity in nutrient solution, respectively. A number of studies have reported inhibited plant growth under Al toxicity (MATTIELLO et al., 2008; STOLF et al., 2008; NAING et al., 2009; STEINER et al., 2012). Similarly, in the present study, a sharp decrease in the leaf area, and growth of plants was noted, which is in agreement with the decrease in plant leaf area and root length reported in various other studies (LIMA et al., 2007). On the basis of these results, our findings suggested that an elevated Al activity in solution can inhibit the normal growth and Biosci. J., Uberlândia, v. 29, n. 3, p. 582-589, May/June 2013 584 Tolerance of physic. LANA, M. C. et al. development of physic nut young plants. However, it must be emphasized that in neither of Al activity used were verified symptoms of toxicity by Al in leaves that usually resemble to phosphorus 27 A 8 Plant height (cm) Leaves per plant . 9 deficiency (MALAVOLTA et al., 1997) as verified for coffee (BRACCINI et al., 1998) and apple tree (DANTAS et al., 2001). 7 6 = 8.15 – 0.014**x 2 5 R = 0.84 C.V. (%) = 10.1 4 750 30 60 90 120 25 24 23 = 25.9 – 0.019*x 22 R = 0.89 C.V. (%) = 8.1 2 150 C 0 7 700 650 600 = 699.3 – 0.818*x 2 550 R = 0.84 C.V. (%) = 12.6 500 30 60 90 120 150 120 150 D –1 Shoot dry matter (g plant ) –1 2 26 21 0 Leaf area (cm plant ) B 6 5 = 5.92 – 0.008*x 4 2 R = 0.73 C.V. (%) = 13.8 3 0 30 60 90 120 150 0 30 60 90 –1 Aluminum activity in solution ( mol L ) *, **: significant at 5 and 1 %, respectively, by F test (n = 5). Figure 1. Number of leaves (A), plant height (B), leaf area (C) and shoot dry matter (D) of physic nut young plants as affected by aluminum activity in nutrient solution. In roots, symptoms of toxicity were quite evident manifesting through thickening and yellowing of root tips. Roots of control plants were long and clearer-color. Symptoms of Al toxicity in physic nut visually observed in this study agree with those reported by Braccini et al. (1998) in coffee. Roots’ growth was negatively affected by Al activity, reducing linearly with Al increase (Figure 2a). However, Al activity used did not affect the root volume and dry matter of root (Figure 2b and 2c, respectively). Macedo et al. (2011) found that the root length and fresh matter of physic nut plants were reduced in 25 and 38%, respectively, when exposed for seven days, the concentration of 220 mol L–1 of Al in nutrient solution. According to Epstein e Bloom (2006), nutritional factors often influence growth and morphology of particular organs of plants in specific ways. As the roots are organs in closer contact with nutritional environment of plant, they are especially prone to be affected by this environment. Behavior also observed in the present study. Aluminum effects in roots are well documented in literature and the reduction of root growth rate of sensible species has been considered the main effect of Al toxic influencing in elongation and cell division (FERREIRA et al., 2006). According to Samac e Tesfaye (2003), the primary site of Al toxic action is the distal part of transition zone in root tip, where cells are entering in elongation phase. The inhibition Biosci. J., Uberlândia, v. 29, n. 3, p. 582-589, May/June 2013 585 Tolerance of physic. LANA, M. C. et al. of root growth is the faster visible symptom of Al 9 A 24 –1 Root volume (cm plant ) 22 3 Length of longest roots (cm). 26 toxicity in plants. 20 18 16 = 24.3 – 0.053*x 14 R = 0.91 C.V. (%) = 9.4 2 12 8 7 6 = 6.77 C.V. (%) = 20.4 5 4 0 0,8 30 60 90 120 150 0 8 –1 Total dry matter (g plant ) C –1 Root dry matter (g plant ) B 0,7 0,6 0,5 = 0.60 C.V. (%) = 18.8 0,4 0,3 30 60 90 120 150 120 150 D 7 6 5 = 6.55 – 0.0084*x 2 R = 0.75 C.V. (%) = 17.4 4 3 0 30 60 90 120 150 0 30 60 90 –1 Aluminum activity in solution ( mol L ) *, **: significant at 5 and 1 %, respectively, by F test (n = 5). Figure 2. Length of longest roots (A), root volume (B), root dry matter (C) and total dry matter (D) of physic nut young plants as affected by aluminum activity in nutrient solution. The damage in root structure formation, thickening and permeability decrease of root cells, contributes to accentuate the deleterious effects of Al in root system (BARCELÓ; POSCHENRIEDER, 2002; ILLÉS et al., 2006). Baligar et al. (1993) consider the root growth inhibition as a major Al effect, becoming it short and thick. This feature, incidentally, serves as a best indicator when evaluating the Al tolerance level in nutrient solution for species. The decrease or increase percentage the effect of Al activity in regarding the control is shown in Table 1. The root length, number of leaves, shoot dry matter and total dry matter were variables more affected by Al activity in solution (Table 1), and can be used to discriminate the Al levels tolerance in physic nut plants. The main effect of Al toxicity in the plant shoots is the shortening of internodes, resulting in plants of smaller height (DANTAS et al., 2001). In physic nut young plants was verified that plant height was the less affected shoot variable, with 11.2% decrease compared to plant height in presence of 14.5 and 144.8 mol L–1 Al activity in nutrient solution (Table 1). For the shoot dry matter, number leaves and leaf area such decrease was about 23.9; 23.8 and 16.1%, respectively, if compared to plant in presence of 14.5 and 144.8 mol L–1 Al activity. Biosci. J., Uberlândia, v. 29, n. 3, p. 582-589, May/June 2013 586 Tolerance of physic. LANA, M. C. et al. Table 1. Percentages of reduction or increase the effect of aluminum activity in nutrient solution on number of leaves (NL), plant height (PH), leaf area (LA), shoot dry matter (SDM), root length (RL), root volume (RV), root dry matter (RDM), and total dry matter (TDM) Aluminum NL PH LA SDM RL RV RDM TDM activity mol L–1 of Al3+ 21.4 46.6 75.6 108.3 144.8 ----------------------------------------------- % --------------------------------------------------–11.9 –1.9 –6.2 –14.5 –2.6 –8.3 –1.0 –13.3 –11.9 –4.6 –8.0 –16.9 –7.7 –2.8 –7.7 –16.1 –9.5 –3.5 –12.9 –14.9 –6.0 0.0 +6.7 –13.0 –23.8 –6.6 –16.3 –19.5 –23.1 –8.3 –2.5 –18.0 –23.8 –11.2 –16.1 –23.9 –29.9 –16.7 –15.6 –23.2 about 0.77 mg plant–1 (Figure 3c). The aluminum accumulation in root was adjusted to a quadratic model (Figure 3d), presenting maximum Al accumulation of 4.31 mg plant–1 at 100 mol L–1 Al activity. The Al accumulation value found in control plants, both in shoot and roots is due to the high levels of this element in physic nut plants before experiment deployment which was 0.48 mg plant–1 in shoot and 4.05 mg plant–1 in root system. 0,18 0,16 0,14 0,12 = 0.12 + 0.0003*x 2 R = 0.84 C.V. (%) = 29.0 0,10 0,08 60 90 120 B 8 6 4 = 2.60 + 0.045**x 2 2 R = 0.82 C.V. (%) = 31.5 0 150 –1 30 Al accumulated in root (mg plant ) –1 10 0 0 Al accumulated in shoot (mg plant ) –1 A –1 Al concentratio in shoot (g kg ) 0,20 Al concentration in root (g kg ) The increase of Al activity in nutrient solution provided linear increase in Al concentration, both in shoot and root of physic nut plants, with maximum activity (144.8 mol L–1) concentrations about 0.16 g kg–1 of Al in shoot (Figure 3a) and of 9.12 g kg–1 of Al in root (Figure 3b). Concerning the Al accumulation in shoot of physic nut plants were not affected (p > 0.05) by Al activity in nutrient solution, with average values 1,0 C 0,9 0,8 0,7 0,6 = 0.77 C.V. (%) = 32.9 0,5 0,4 0 30 60 90 120 150 5 30 60 90 120 150 D 4 3 2 2 = 0.04 + 0.079**x – 0.0004**x 2 1 R = 0.91 C.V. (%) = 37.5 0 0 30 60 90 120 150 –1 Aluminum activity in solution ( mol L ) *, **: significant at 5 and 1 %, respectively, by F test (n = 5). Figure 3. Aluminum concentration in shoot (A) and root (B), aluminum accumulated in shoot (C) and root (C) of physic nut young plants as affected by of aluminum activity in nutrient solution. Biosci. J., Uberlândia, v. 29, n. 3, p. 582-589, May/June 2013 587 Tolerance of physic. LANA, M. C. et al. The Al was preferably accumulated in the root of physic nut plants, being small the amount translocated to the shoot (Figure 3). Results also observed and documented in the literature by several authors (BARCELÓ; POSCHENRIEDER, 2002). This fact justified the remarkable effect of this ion on the root development as observed in this study. Aluminum complexation in the roots, preventing its transport to the shoots of the plant, can be an important factor for Al tolerance in plants, because the permanence of the ion in the root can prevent the deleterious effects of this metal in other organs. enfocar la importancia de la producción mediática de los niños en su descubrimiento del mundo, sobre todo utilizando el periódico escolar y la imprenta. Asimismo las asociaciones de profesores trabajaron en esta línea e incluso la enseñanza católica se comprometió desde los años sesenta realizando trabajos originales en el marco de la corriente del Lenguaje Total. Páginas 43-48 45 Comunicar, 28, 2007 En el ámbito de los medios, también desde el principio del siglo XX hay ciertas corrientes de conexión. Pero es a lo largo de los años sesenta cuando se constituyeron asociaciones de periodistas apasionados por sus funciones de mediadores, que fomentaron la importancia ciudadana de los medios como algo cercano a los jóvenes, a los profesores y a las familias. Así se crearon la APIJ (Asociación de Prensa Información para la Juventud), la ARPEJ (Asociación Regional de Prensa y Enseñanza para la Juventud), el CIPE (Comité Interprofesional para la Prensa en la Escuela) o la APE (Asociación de Prensa y Enseñanza), todas ellas para la prensa escrita Estas asociaciones fueron precedidas por movimientos surgidos en mayo de 1968, como el CREPAC que, utilizando películas realizadas por periodistas conocidos, aclaraba temas que habían sido manipulados por una televisión demasiado próxima al poder político y realizaba encuentros con grupos de telespectadores. cipio del siglo XX, y nos han legado textos fundadores muy preciados, importantes trabajos de campo y muchos logros educativos y pedagógicos. La educación en medios ha tenido carácter de oficialidad de múltiples maneras, aunque nunca como una enseñanza global. Así la campaña «Operación Joven Telespectador Activo» (JTA), lanzada al final de los años setenta y financiada de manera interministerial para hacer reflexionar sobre las prácticas televisuales de los jóvenes, la creación del CLEMI (Centro de Educación y Medios de Comunicación) en el seno del Ministerio de Educación Nacional en 1983, la creación de la optativa «Cine-audiovisual» en los bachilleratos de humanidades de los institutos en 1984 (primer bachillerato en 1989) y múltiples referencias a la educación de la imagen, de la prensa, de Internet. La forma más visible y rápida de evaluar el lugar de la educación en medios es valorar el lugar que se le ha reservado en los libros de texto del sistema educa- 2. Construir la educación en los medios sin nombrarla El lugar que ocupa la edu- La denominación «educación en medios», que debería cación en los medios es muy ambiguo, aunque las cosas están cambiando recientemente. entenderse como un concepto integrador que reagrupase todos los medios presentes y futuros, es a menudo percibida En principio, en Francia, co- por los «tradicionalistas de la cultura» como una tendencia mo en muchos otros países, la educación en los medios no es hacia la masificación y la pérdida de la calidad. una disciplina escolar a tiempo completo, sino que se ha ido conformado progresivamente a través de experiencias y reflexiones teóricas que han tivo en Francia. Una inmersión sistemática nos permi- permitido implantar interesantes actividades de carác- te constatar que los textos oficiales acogen numerosos ter puntual. Se ha ganado poco a poco el reconoci- ejemplos, citas, sin delimitarla con precisión. miento de la institución educativa y la comunidad es- colar. Podemos decir que ha conquistado un «lugar», 3. ¿Por qué la escuela ha necesitado casi un siglo en el ámbito de la enseñanza transversal entre las dis- para oficilializar lo que cotidianamente se hacía en ciplinas existentes. ella? Sin embargo, la escuela no está sola en esta aspi- Primero, porque las prácticas de educación en me- ración, porque el trabajo en medios es valorado igual- dios han existido antes de ser nombradas así. Recor- mente por el Ministerio de Cultura (campañas de foto- demos que no fue hasta 1973 cuando aparece este grafía, la llamada «Operación Escuelas», presencia de término y que su definición se debe a los expertos del colegios e institutos en el cine ), así como el Minis- Consejo Internacional del Cine y de la Televisión, que terio de la Juventud y Deportes que ha emprendido en el seno de la UNESCO, definen de esta forma: numerosas iniciativas. «Por educación en medios conviene entender el estu- Así, esta presencia de la educación en los medios dio, la enseñanza, el aprendizaje de los medios moder- no ha sido oficial. ¡La educación de los medios no apa- nos de comunicación y de expresión que forman parte rece oficialmente como tal en los textos de la escuela de un dominio específico y autónomo de conocimien- francesa hasta 2006! tos en la teoría y la práctica pedagógicas, a diferencia Este hecho no nos puede dejar de sorprender ya de su utilización como auxiliar para la enseñanza y el que las experiencias se han multiplicado desde el prin- aprendizaje en otros dominios de conocimientos tales Páginas 43-48 46 Comunicar, 28, 2007 como los de matemáticas, ciencias y geografía». A pe- mente en todas las asignaturas. Incluso los nuevos cu- sar de que esta definición ha servido para otorgarle un rrículos de materias científicas en 2006 para los alum- reconocimiento real, los debates sobre lo que abarca y nos de 11 a 18 años hacen referencia a la necesidad no, no están totalmente extinguidos. de trabajar sobre la información científica y técnica y En segundo lugar, porque si bien a la escuela fran- el uso de las imágenes que nacen de ella. cesa le gusta la innovación, después duda mucho en Desde junio de 2006, aparece oficialmente el tér- reflejar y sancionar estas prácticas innovadoras en sus mino «educación en medios» al publicar el Ministerio textos oficiales. Nos encontramos con una tradición de Educación los nuevos contenidos mínimos y las sólidamente fundada sobre una transmisión de conoci- competencias que deben adquirir los jóvenes al salir mientos muy estructurados, organizados en disciplinas del sistema educativo. escolares que se dedican la mayor parte a transmitir Este documento pretende averiguar cuáles son los conocimientos teóricos. La pedagogía es a menudo se- conocimientos y las competencias indispensables que cundaria, aunque los profesores disfrutan de una ver- deben dominar para terminar con éxito su escolaridad, dadera libertad pedagógica en sus clases. El trabajo seguir su formación y construir su futuro personal y crítico sobre los medios que estaba aún en elaboración profesional. Siete competencias diferentes han sido te- necesitaba este empuje para hacerse oficial. nidas en cuenta y en cada una de ellas, el trabajo con Aunque el trabajo de educación en los medios no los medios es reconocido frecuentemente. Para citar esté reconocido como disciplina, no está ausente de un ejemplo, la competencia sobre el dominio de la len- gua francesa definen las capa- cidades para expresarse oral- La metodología elaborada en el marco de la educación en mente que pueden adquirirse con la utilización de la radio e, medios parece incluso permitir la inclinación de la sociedad incluso, se propone fomentar de la información hacia una sociedad del conocimiento, como defiende la UNESCO. En Francia, se necesitaría unir el interés por la lectura a través de la lectura de la prensa. La educación en los medios las fuerzas dispersas en función de los soportes mediáticos y orientarse más hacia la educación en medios que al dominio adquiere pleno derecho y entidad en la sección sexta titulada «competencias sociales y cívi- técnico de los aparatos. cas» que indica que «los alum- nos deberán ser capaces de juz- gar y tendrán espíritu crítico, lo que supone ser educados en los las programaciones oficiales, ya que, a lo largo de un medios y tener conciencia de su lugar y de su influencia estudio de los textos, los documentalistas del CLEMI en la sociedad». han podido señalar más de una centena de referencias a la educación de los medios en el seno de disciplinas 4. Un entorno positivo como el francés, la historia, la geografía, las lenguas, Si nos atenemos a las cifras, el panorama de la las artes plásticas : trabajos sobre las portadas de educación en medios es muy positivo. Una gran ope- prensa, reflexiones sobre temas mediáticos, análisis de ración de visibilidad como la «Semana de la prensa y publicidad, análisis de imágenes desde todos los ángu- de los medios en la escuela», coordinada por el CLE- los, reflexión sobre las noticias en los países europeos, MI, confirma año tras año, después de 17 convocato- información y opinión rias, el atractivo que ejerce sobre los profesores y los Esta presencia se constata desde la escuela mater- alumnos. Concebida como una gran operación de nal (2 a 6 años) donde, por ejemplo, se le pregunta a complementariedad source of circulating FGF-21. The lack of association between circulating and muscle-expressed FGF-21 also suggests that muscle FGF-21 primarily works in a local manner regulating glucose metabolism in the muscle and/or signals to the adipose tissue in close contact to the muscle. Our study has some limitations. The number of subjects is small and some correlations could have been significant with greater statistical power. Another aspect is that protein levels of FGF-21 were not determined in the muscles extracts, consequently we cannot be sure the increase in FGF-21 mRNA is followed by increased protein expression. In conclusion, we show that FGF-21 mRNA is increased in skeletal muscle in HIV patients and that FGF-21 mRNA in muscle correlates to whole-body (primarily reflecting muscle) insulin resistance. These findings add to the evidence that FGF-21 is a myokine and that muscle FGF-21 might primarily work in an autocrine manner. Acknowledgments We thank the subjects for their participation in this study. Ruth Rousing, Hanne Willumsen, Carsten Nielsen and Flemming Jessen are thanked for excellent technical help. The Danish HIV-Cohort is thanked for providing us HIV-related data. 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Am J Physiol 237: E214–E223. 22. Plomgaard P, Bouzakri K, Krogh-Madsen R, Mittendorfer B, Zierath JR, et al. (2005) Tumor necrosis factor-alpha induces skeletal muscle insulin resistance in healthy human subjects via inhibition of Akt substrate 160 phosphorylation. Diabetes 54: 2939–2945. 23. Thomas JA, Schlender KK, Larner J (1968) A rapid filter paper assay for UDPglucose-glycogen glucosyltransferase, including an improved biosynthesis of UDP-14C-glucose. Anal Biochem 25: 486–499. 24. Haugaard SB, Andersen O, Madsbad S, Frosig C, Iversen J, et al. (2005) Skeletal Muscle Insulin Signaling Defects Downstream of Phosphatidylinositol 3-Kinase at the Level of Akt Are Associated With Impaired Nonoxidative Glucose Disposal in HIV Lipodystrophy. Diabetes 54: 3474–3483. 25. Boden G, Jadali F, White J, Liang Y, Mozzoli M, et al. (1991) Effects of fat on insulin-stimulated carbohydrate metabolism in normal men. J Clin Invest 88: 960–966. 26. Mashili FL, Austin RL, Deshmukh AS, Fritz T, Caidahl K, et al. (2011) Direct effects of FGF21 on glucose uptake in human skeletal muscle: implications for type 2 diabetes and obesity. Diabetes Metab Res Rev 27: 286–297. 27. Torriani M, Thomas BJ, Barlow RB, Librizzi J, Dolan S, et al. (2006) Increased intramyocellular lipid accumulation in HIV-infected women with fat redistribution. J Appl Physiol 100: 609–614. 28. Lee MS, Choi SE, Ha ES, An SY, Kim TH, et al. (2012) Fibroblast growth factor-21 protects human skeletal muscle myotubes from palmitate-induced insulin resistance by inhibiting stress kinase and NF-kappaB. Metabolism . 29. Tyynismaa H, Carroll CJ, Raimundo N, Ahola-Erkkila S, Wenz T, et al. (2010) Mitochondrial myopathy induces a starvation-like response. Hum Mol Genet 19: 3948–3958. 30. Maagaard A, Holberg-Petersen M, Kollberg G, Oldfors A, Sandvik L, et al. (2006) Mitochondrial (mt)DNA changes in tissue may not be reflected by depletion of mtDNA in peripheral blood mononuclear cells in HIV-infected patients. Antivir Ther 11: 601–608. 31. Payne BA, Wilson IJ, Hateley CA, Horvath R, Santibanez-Koref M, et al. (2011) Mitochondrial aging is accelerated by anti-retroviral therapy through the clonal expansion of mtDNA mutations. Nat Genet 43: 806–810. 32. Kliewer SA, Mangelsdorf DJ (2010) Fibroblast growth factor 21: from pharmacology to physiology. Am J Clin Nutr 91: 254S–257S. 33. Gallego-Escuredo JM, Domingo P, Gutierrez MD, Mateo MG, Cabeza MC, et al. (2012) Reduced Levels of Serum FGF19 and Impaired Expression of Receptors for Endocrine FGFs in Adipose Tissue From HIV-Infected Patients. J Acquir Immune Defic Syndr 61: 527–534. 34. Domingo P, Gallego-Escuredo JM, Domingo JC, Gutierrez MM, Mateo MG, et al. (2010) Serum FGF21 levels are elevated in association with lipodystrophy, insulin resistance and biomarkers of liver injury in HIV-1-infected patients. AIDS 24: 2629–2637. PLOS ONE | www.plosone.org 7 March 2013 | Volume 8 | Issue 3 | e55632
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