Perfectionism and binge eating association: a systematic review and meta-analysis.

BACKGROUND: Perfectionism is considered a vulnerability factor for eating disorders. However, the role of perfectionism in binge eating needs clarification due to notably inconsistencies between studies. The purpose to this study was to conduct a systematic review and meta-analysis to estimate the perfectionism-binge eating association. METHOD: Systematic review was performed according to the PRISMA 2020 statement. Four databases (Web of Science, Scopus, PsycINFO and Psicodoc) were searched to identify studies published until September 2022. The literature search yielded 30 published articles (N = 9392) that provided 33 independent estimations of the correlation between the two variables. RESULTS: Random-effects meta-analysis revealed a small-to-moderate positive average effect size between general perfectionism and binge eating (r+ = .17) with a large heterogeneity. Perfectionistic Concerns showed a significant small-to-moderate relationship with binge eating (r+ = .27), whereas Perfectionistic Strivings presented a negligible relationship with binge eating (r+ = .07). Moderator analyses showed that the age, the type of the sample, the study design, and the tools for assessing both variables were statistically associated with the perfectionism-binge eating effect sizes. CONCLUSIONS: Our findings suggest that Perfectionism Concerns are closely associated with binge eating symptomatology. This relationship might be moderated by certain variables, especially by the clinical or non-clinical nature of the sample and the instrument employed to assess binge eating.

Perfectionism is a trait of personality comprising two facets, Perfectionistic Strivings (entails the desire to reach perfection and to pursue unrealistically high standards) and Perfectionistic Concerns (involves self-criticism, concerns over making mistakes, fears about social negative evaluation and lack of satisfaction with achievements). Perfectionist individuals have an increased risk for developing eating disorders. However, whether perfectionism or any of its facets is associated with binge eating (an episode of overeating together with a feeling of loss of control) is an unanswered question. The purpose of this systematic review and meta-analysis was to clarify this question. Our results evidenced that overall perfectionism is associated with binge eating. It means that perfectionist people are more vulnerable to developing binge eating symptomatology, although Perfectionistic Concerns entails a higher risk in comparison with Perfectionistic Strivings. Our study also provides valuable information on the aspects that might explain the variations in the results of previous studies that have analyzed the perfectionism-binge eating association.

Efectividad de la aplicación del programa Echomantra en una adolescente con anorexia nerviosa y su familiar: Un estudio de caso / Effectiveness of the application of the Echomantra in an adolescent girl with anorexia nervosa and her caregiver: A case study

El programa ECHOMANTRA tiene como finalidad facilitar la transición de las pacientes con un trastorno de la conducta alimentaria desde el ingreso hospitalario a su vida cotidiana. Consta de una intervención para los/las familiares (ECHO; Treasure et al., 2015) y otra para las pacientes (MANTRA, Schmidt, et al, 2014). El objetivo de este estudio fue evaluar la efectividad del programa ECHOMANTRA, aplicado junto al tratamiento usual, en una adolescente de 15 años con anorexia nerviosa (AN) y su madre. Se utilizó un diseño de caso único y medidas pre-post, con seguimiento a los 3 y 6 meses. En la paciente se evaluó: patología alimentaria (EDE-Q), estado emocional (DASS-21), ajuste psicosocial (EQ-5D-5L y el CIA 3.0) y motivación al cambio; y en la madre: emoción expresada (FQ), impacto de los síntomas (EDSIS), acomodación a la enfermedad (EAISA), estado emocional (DASS-21) y habilidades de cuidadora (CSS). Ambos programas constaban de 8 sesiones online individuales y semanales. Los resultados mostraron una reducción en la sintomatología de AN, aumento del IMC, mejora del estado emocional, motivación al cambio y ajuste psicosocial; y en la madre, mejoró el estado emocional y las habilidades de cuidado, y disminuyó la acomodación a la enfermedad, la emoción expresada y el impacto de los síntomas. Estos cambios se mantuvieron en el seguimiento. Ambas valoraron el programa como satisfactorio. La aceptabilidad y la eficiencia del tratamiento de la AN puede mejorarse utilizando el ECHOMANTRA para preparar la transición de la atención hospitalaria, apoyando a las pacientes y familiares. (AU)

The aim of the ECHOMANTRA program is to facilitate the transition from hospital back into the community. ECHOMANTRA is based on interventions for carers (Experienced Carers Helping Others, ECHO; Treasure et al. 2016) and patients (Maudsley Model of Anorexia Nervosa Treatment for Adults, MANTRA; Schmidt, et al., 2014). The aim of this study was to evaluate the effectiveness of the ECHOMANTRA program, applied together with the usual treatment, in a 15-yearold adolescent girl with anorexia nervosa (AN) and her mother. A single case design and pre-post measures were used, as well as follow-up at 3 and 6 months. The patient was assessed for: eating pathology (EDE-Q), emotional state (DASS-21), psychosocial adjustment (EQ-5D-5L and CIA 3.0) and motivation to change. In the mother: expressed emotion (FQ), symptom impact (EDSIS), accommodation to illness (EAISA), emotional state (DASS-21) and her caregiver skills (CSS) were assessed. Both programs consisted of 8 on-line sessions, which were conducted individually and on a weekly basis. The results showed a reduction in AN symptomatology, increased BMI, improved emotional state, motivation to change and psychosocial adjustment; and in the mother, improved emotional state and caregiving skills, and reduced accommodation to illness, expressed emotion and the impact of symptoms. These changes were maintained at follow-up. Both patient and family valued the program as satisfactory. Both the acceptability and efficiency of treatment for AN may be improved by using ECHOMANATRA to prepare for transition from inpatient care, by giving support to both patients and their carers. (AU)

Humoral and cellular immune responses to Pfizer-BioNTech BNT162b2 SARS-CoV-2 vaccine in adolescents with liver transplantation: Single center experience.

Background: Immune responses to vaccines against severe acute respiratory syndrome (SARS)-coronavirus (CoV)-2 are variable. In the absence of disease, youngsters are expected to better react to vaccines than adults. Nevertheless, chronic immunosuppression in transplant recipients may impair their capability to generate protection. We aim to explore immune responses after BNT162b2 SARS-CoV-2 vaccination in our cohort of young liver-transplanted patients. Methods: A prospective study of adolescent liver-transplanted patients (n=33) in the long-term follow-up was performed. Immune responses after receiving Pfizer-BioNTech BNT162b2 vaccine were analyzed at two time-points: baseline and 30 days after the second dose. Humoral responses were measured by fluoroenzyme-immunoassay and T-cell responses by interferon-γ-release assay. Post-vaccine coronavirus disease (COVID-19) events were recorded by a survey. Results: Pre-vaccine SARS-CoV-2-specific antibodies were undetectable in 27/32 (84.4%), negative/indeterminate in 3/32 (9.4%) and positive in 2/32 (6.3%) patients. Cellular responses at baseline were negative in 12/18 (66.6%), positive in 3/18 (16.6%) and indeterminate in 3/18 (16.6%) recipients. None of the baseline positives recalled any symptoms. Post-vaccine antibodies were detected in all patients and 92.6% showed levels >816 BAU/mL. Twenty (71.4%) recipients had positive T-cell responses. Regarding post-vaccine SARS-Cov-2 infection, 10 (30.3%) patients reported COVID-19 without hospitalization and 21 (63.6%) did not notify any infection. Negative and positive cell-response groups after vaccination showed statistically significant differences regarding COVID-19 cases (62.5% vs 22.2%, respectively; p=0.046). Conclusions: Adolescents and young adults with liver transplantation responded to SARS-Cov-2 vaccine, generating both humoral and cellular responses. Recipients developing cellular responses after vaccination had a lower incidence of COVID-19.

Intervención psicológica basada en la terapia de aceptación y compromiso para el sobrepeso y la obesidad: un estudio piloto / Psychological intervention based on acceptance and commitment therapy for overweight and obesity: a pilot study

En la actualidad, las intervenciones conductuales para pérdida de peso en sobrepeso y obesidad presentan problemas para mantener los resultados de pérdida de peso a largo plazo. La terapia de aceptación y compromiso (ACT) podría ser un enfoque adecuado para favorecer la pérdida de peso a largo plazo. El objetivo de este estudio piloto es evaluar la eficacia de una intervención basada en ACT en el cambio del peso corporal al finalizar la intervención y en el seguimiento a los 9 meses, además de analizar los efectos de la intervención en diversas variables de interés. Nueve mujeres (edad: M= 44,11 años; DT= 5,82) participaron en una intervención grupal de 10 diez sesiones semanales, abordando contenidos de hábitos alimentarios, actividad física y ACT. Al finalizar la intervención, la pérdida de peso promedio fue de 2,8%, y en el seguimiento a los 9 meses, fue de 3,9%. A tenor de los resultados, podemos afirmar que el estudio ofrece datos a favor de ACT en las intervenciones de pérdida de peso. (AU)

Current behavioral interventions for weight loss in overweight and obesity present problems in maintaining long-term weight loss results. Acceptance andcommitment therapy (ACT) could be a suitable approach to promote long-term weight loss. The aim of this pilot study is to evaluate the efficacy of an ACT-based intervention on body weight change at the end of the intervention and after a 9-month follow-up, in addition to analyzing the effects of the intervention on several variables of interest. Nine women (Mage= 44.11 years; SD= 5.82) attended a group intervention of 10 weekly sessions, addressing contents of eating habits, physical activity, and ACT. At the end of the intervention, the average weight loss was 2.8%, and after a 9-month follow-up, it was 3.9%. Based on the results, it can be concluded that the study provides evidence in favor of the suitability of ACT to help promote weight loss. (AU)

Adaptation and Implementation of an Intervention Programme on Spanish Carers and Adolescent Patients With an Eating Disorder: Study Protocol of a Randomized Controlled Trial.

Introduction: One of the major problems with inpatient treatment of adolescent girls with an eating disorder (ED) is that the strategies learned during their hospital stay are not easily applied or maintained in their daily lives, and this has been related to high rates of relapse and readmission. The ECHOMANTRA programme was developed to optimize outcomes during and following inpatient or day-patient treatment. ECHOMANTRA is based on interventions for carers (Experienced Carers Helping Others, ECHO) and patients (Maudsley Model of Anorexia Nervosa Treatment for Adults, MANTRA) and is developed from the cognitive interpersonal model of anorexia (Schmidt and Treasure, 2006; Treasure and Schmidt, 2013). This study aims to describe the study protocol of a randomized controlled trial (RCT) for evaluating the efficacy of an adaptation of a novel intervention for patients and carers (ECHOMANTRA) to be implemented as an add-on to treatment-as-usual (TAU). Method: In a multi-center pilot RCT, 80 female adolescent patients with a DSM-5 diagnosis of an ED and their carers will be invited to participate in the study. They will then be randomized to receive either the ECHOMANTRA intervention as an add-on to TAU or TAU alone. A repeated measures design will be conducted across four time points. Primary outcomes will be patient psychological well-being and eating disorder symptoms, and secondary outcomes will include body mass index, obsessive-compulsive symptoms, perfectionism, motivation to change and psychosocial adjustment. For carers, outcome variables will include psychological well-being, expressed emotion, accommodation and enabling behaviors, burden, and care skills. Discussion: The results from this trial will establish the effectiveness of ECHOMANTRA and may reveal whether and to what extent this novel intervention can optimize outcomes during and following inpatient treatment. This study will also provide the adaptation of the ECHOMANTRA in the Spanish context for inpatient/day-care treatment.

Positive and Negative Emotional Eating Are Not the Same-The Spanish Version of the Positive-Negative Emotional Eating Scale (PNEES).

The literature points to the importance of distinguishing between positive and negative emotional eating in relation to overeating and binge eating. The aim of this study was to evaluate the Spanish version of the Positive-Negative Emotional Eating Scale (PNEES) in a Spanish community sample. The sample consisted of 628 participants. The mean age was 27.5 (SD = 12.7) and 70.1% of them were women. The participants completed the PNEES, and measures of anxiety and depression (HADS), and eating disorder-related scales (TFEQ-R18, BULIT-R, and EAT-26) that were selected to examine convergent validity. A confirmatory factor analysis was conducted, replicating the original two-factor solution, consisting of Negative Emotional Eating (PNEES-N) and Positive Emotional Eating (PNEES-P). The results showed an acceptable fit of the model (CFI = 0.986; TLI = 0.984, RMSEA = 0.055). Internal consistency ranged from ω = 0.92 to ω = 0.96 for both subscales and the total score. PNEES-P correlations with other variables were lower with respect to the PNEES-N, showing that they are different constructs. A mediation analysis was conducted, in which PNEES-P significantly predicted binge eating and PNEES-N was a partially mediator variable. The results showed that the adaptation process was successful.

Corrigendum: Paracetamol vs. Ibuprofen in Preterm Infants With Hemodynamically Significant Patent Ductus Arteriosus: A Non-inferiority Randomized Clinical Trial Protocol.

[This corrects the article DOI: 10.3389/fped.2020.00372.].

Illness Perception in Adolescent Patients With Anorexia: Does It Play a Role in socio-Emotional and Academic Adjustment?

People's beliefs about their illness have been shown to affect their adjustment. The aim of this study was to describe illness perception in adolescent patients with anorexia nervosa (AN) and assess its relationship with socio-emotional and academic adjustment following Leventhal's Self-Regulation Model. Thirty-four female AN patients, with a mean age of 15.76 (SD = 2.00), completed the Revised Illness Perception Questionnaire (IPQ-R), the Psychosocial Adjustment to Illness Scale (PAIS) and the Hospital Anxiety and Depression Scale (HAD). Adolescent anorexia patients perceived that they had control over their illness and treatment would improve their condition. However, they also believed that it was highly distressing, going to last a long time and would have serious consequences. As for the causes of the disorder, they were attributed primarily to a specific eating disorder and psychological factors. The results showed that anorexia patients' illness perceptions were related to socio-emotional and academic adjustment. In this sense, identity with the illness was associated with a worse academic adjustment, while emotional representation was associated with a worse emotional and social adjustment. These findings highlight how important it is for patients' beliefs about their disease to be considered in the treatment of anorexia. In this respect, clinicians treating these patients should consider how certain beliefs affect their academic and socio-emotional adjustment. It would be interesting for patients to become aware of how these beliefs influence the strategies they use to cope with their disease as well as their adjustment to it.

Paracetamol vs. Ibuprofen in Preterm Infants With Hemodynamically Significant Patent Ductus Arteriosus: A Non-inferiority Randomized Clinical Trial Protocol.

Background: Currently, the first line treatment of persistent ductus arteriosus (PDA) is either indomethacin or ibuprofen. However, the potentially life-threatening side effects associated to their use have prompted physicians to look for alternative options. The incorporation of paracetamol as an alternative to ibuprofen in the management of PDA is still based on insufficient clinical evidence. Hence, more clinical trials are needed to establish a therapeutic role for paracetamol in the management of PDA that take into consideration short- and long-term safety and efficacy outcomes. Study Design: This is a non-inferiority, randomized, multicenter, double-blinded study to evaluate the efficacy, and safety of intravenous (IV) paracetamol vs. IV ibuprofen (standard treatment) for PDA in preterm patients with a gestational age ≤ 30 weeks. At baseline, patients will be randomized (1:1) to treatment with paracetamol or ibuprofen. The primary endpoint is closure of the ductus after the first treatment course. Secondary endpoints are related to effectiveness (need for a second treatment course, rescue treatment, reopening rate, time to definitive closure, need for surgical ligation), safety (early and long-term complications), pharmacokinetics, and pharmacodynamics, pharmacogenetics, pharmacoeconomics, and genotoxicity. Long-term follow-up to 24 months of corrected postnatal age will be performed using Bayley III neurodevelopmental scale. Trial Registration: ClinicalTrials.gov Identifier: NCT04037514. EudraCT: 2015-003177-14.

Aplicación de la terapia centrada en la compasión en pacientes con un trastorno de la conducta alimentaria: un estudio piloto / Compassion-focused therapy in patients with eating disorders: A pilot study

La terapia centrada en la compasión (CFT) se ha desarrollado como una terapia multimodal que integra diferentes estrategias cognitivo conductuales, y recientemente ha empezado a ser aplicada en el ámbito de los trastornos de la conducta alimentaria (TCA). El objetivo de este trabajo ha sido desarrollar y aplicar un programa de intervención basado en la CFT en un grupo de pacientes con un TCA. La muestra estuvo compuesta por 10 personas diagnosticadas de un TCA. La media de edad fue de 20,2 años (DT= 8,06). se obtuvieron medidas de autocompasión, atención plena, actitudes hacia la comida, depresión, ansiedad, imagen corporal y autoestima. Los resultados mostraron un cambio significativo en autocompasión, actitudes hacia la comida, imagen corporal y autoestima. Estos resultados apoyan la aplicación de la CFT a estos pacientes

Compassion-focused therapy (CFT) has been developed as a multimodal therapy that integrates different cognitive-behavioral strategies and has begun to be applied in the field of eating disorders recently. The aim of this work has been to develop and apply an intervention program based on CFT in a group of patients with eating disorders. The sample consisted of 10 participants diagnosed with an eating disorder. The mean age was 20.2 years (SD= 8.06). The following instruments were applied: measures of self-pity, mindfulness, attitudes toward food, depression, anxiety, body image and self-esteem. The results showed a significant change in self-pity, attitudes toward food, body image and selfesteem. These results support the application of CFT to these patients

Chilling stress and hydrogen peroxide accumulation in Chrysanthemum morifolium and Spathiphyllum lanceifolium. Involvement of chlororespiration.

Plants of Chrysanthemum morifolium (sun species) and Spathiphyllum lanceifolium (shade species) were used to study the effects of chilling stems under high illumination. The stress conditions resulted in a greater accumulation of H2O2 in C. morifolium than in S. lanceifolium, and in the down-regulation of photosynthetic linear electron transport in both species. However, only a slight decrease in the maximal quantum yield of PSII was observed under unfavorable conditions in both species, suggesting that mechanisms exist in the chloroplasts that dissipate excess excitation energy and prevent damage to the photosynthetic apparatus. Additionally, changes were observed in the PGR5 polypeptide involved in cyclic electron flow around PSI and in chlororespiratory enzymes (plastidial NDH complex and PTOX). The level of PGR5 increased significantly only in chilled plants of C. morifolium, whereas the levels of the PTOX and NDH-H polypeptide of the plastidial NDH complex and the NDH activity increased significantly only in chilled plants of S. lanceifolium. These findings suggest that the cyclic electron flow involving PGR5 is more active in C. morifolium, while in S. lanceifolium, other mechanisms involving chlororespiratory enzymes are stimulated in response to chilling and high light, resulting in less H2O2 being accumulated in leaves.

Papel del paracetamol en el cierre del conducto arterioso permeable. ¿Una alternativa? / The role of paracetamol for closing patent ductus arteriosus. a challenging alternative for ductal closure?

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The Effects of Cold Stress on Photosynthesis in Hibiscus Plants.

The present work studies the effects of cold on photosynthesis, as well as the involvement in the chilling stress of chlororespiratory enzymes and ferredoxin-mediated cyclic electron flow, in illuminated plants of Hibiscus rosa-sinensis. Plants were sensitive to cold stress, as indicated by a reduction in the photochemistry efficiency of PSII and in the capacity for electron transport. However, the susceptibility of leaves to cold may be modified by root temperature. When the stem, but not roots, was chilled, the quantum yield of PSII and the relative electron transport rates were much lower than when the whole plant, root and stem, was chilled at 10°C. Additionally, when the whole plant was cooled, both the activity of electron donation by NADPH and ferredoxin to plastoquinone and the amount of PGR5 polypeptide, an essential component of the cyclic electron flow around PSI, increased, suggesting that in these conditions cyclic electron flow helps protect photosystems. However, when the stem, but not the root, was cooled cyclic electron flow did not increase and PSII was damaged as a result of insufficient dissipation of the excess light energy. In contrast, the chlororespiratory enzymes (NDH complex and PTOX) remained similar to control when the whole plant was cooled, but increased when only the stem was cooled, suggesting the involvement of chlororespiration in the response to chilling stress when other pathways, such as cyclic electron flow around PSI, are insufficient to protect PSII.

Aplicando la Teoría de la Conducta Planeada: ¿qué factores influyen en la realización de ejercicio físico? / Applying the Theory of Planned Behavior: Which factors influence on doing physical exercise?

OBJETIVO: El propósito de este estudio fue analizar las diferencias entre las actitudes, la norma subjetiva y la percepción de control comportamental entre los grupos de individuos que hacían ejercicio físico y los que no. DISEÑO: Estudio transversal, observacional. Emplazamiento: Se aplicó el cuestionario a la población general en la provincia de Alicante. PARTICIPANTES: Seiscientos setenta y nueve personas que practicaban regularmente ejercicio físico de la provincia de Alicante. MEDICIONES PRINCIPALES: Se administró el cuestionario que evaluaba los componentes del modelo de la Teoría de la Conducta Planeada (TCP). RESULTADOS: Los resultados mostraron que las variables del modelo (TCP) presentaron un buen ajuste a los datos. Además, la norma subjetiva y la percepción de control comportamental influyeron significativamente en la intención y las 3 variables explicaron el 61% de su varianza. CONCLUSIÓN: Los resultados apoyan el importante papel de la TCP en el contexto del ejercicio físico. En ambos grupos, la percepción de control comportamental fue el predictor más potente de la intención de practicar ejercicio físico. Se presenta una propuesta para incluir estas variables en los programas para potenciar la práctica del ejercicio físico

OBJECTIVES: The purpose of this study was analyzed the influence of attitude, subjective norm, and Perceived behavioral control (PBC) on intention of doing physical exercise in a group of people. DESIGN: Cross-sectional and observational study. LOCATION: Questionnaire was applied to general population in the province of Alicante. PARTICIPANTS: 679 people who practiced physical exercise in the province of Alicante. MAIN MEASUREMENTS: It was applied a questionnaire measuring the components of the Theory of Plan Behavior model (TPB). RESULTS: Results showed that variables of the model (TPB) had good fit to the data. Moreover, subjective norm and perceived behavioural control had a significant impact on intention and the three variables explained 61% of its variance. CONCLUSIONS: Findings supported the important role of TPB in the context of physical exercise. Perceived behavioral control was the strongest predictor of intention to practice physical exercise. A possible intervention might lead to implement programs focused in increasing control perception of people to engage in physical exercise

[Applying the Theory of Planned Behavior: Which factors influence on doing physical exercise?]. / Aplicando la Teoría de la Conducta Planeada: ¿qué factores influyen en la realización de ejercicio físico?

OBJECTIVES: The purpose of this study was analyzed the influence of attitude, subjective norm, and Perceived behavioral control (PBC) on intention of doing physical exercise in a group of people. DESIGN: Cross-sectional and observational study. LOCATION: Questionnaire was applied to general population in the province of Alicante PARTICIPANTS: 679 people who practiced physical exercise in the province of Alicante. MAIN MEASUREMENTS: It was applied a questionnaire measuring the components of the Theory of Plan Behavior model (TPB). RESULTS: Results showed that variables of the model (TPB) had good fit to the data. Moreover, subjective norm and perceived behavioural control had a significant impact on intention and the three variables explained 61% of its variance. CONCLUSIONS: Findings supported the important role of TPB in the context of physical exercise. Perceived behavioral control was the strongest predictor of intention to practice physical exercise. A possible intervention might lead to implement programs focused in increasing control perception of people to engage in physical exercise.

High root temperature affects the tolerance to high light intensity in Spathiphyllum plants.

Spathiphyllum wallisii plants were sensitive to temperature stress under high illumination, although the susceptibility of leaves to stress may be modified by root temperature. Leaves showed higher tolerance to high illumination, in both cold and heat conditions, when the roots were cooled, probably because the chloroplast were protected by excess excitation energy dissipation mechanisms such as cyclic electron transport. When the roots were cooled both the activity of electron donation by NADPH and ferredoxin to plastoquinone and the amount of PGR5 polypeptide, an essential component of cyclic electron flow around PSI, increased. However, when the stems were heated or cooled under high illumination, but the roots were heated, the quantum yield of PSII decreased considerably and neither the electron donation activity by NADPH and ferredoxin to plastoquinone nor the amount of PGR5 polypeptide increased. In such conditions, the cyclic electron flow cannot be enhanced by high light and PSII is damaged as a result of insufficient dissipation of excess light energy. Additionally, the damage to PSII induced the increase in both chlororespiratory enzymes, NDH complex and PTOX.

Water deficit and heat affect the tolerance to high illumination in hibiscus plants.

This work studies the effects of water deficit and heat, as well as the involvement of chlororespiration and the ferredoxin-mediated cyclic pathway, on the tolerance of photosynthesis to high light intensity in Hibiscus rosa-sinensis plants. Drought and heat resulted in the down-regulation of photosynthetic linear electron transport in the leaves, although only a slight decrease in variable fluorescence (Fv)/maximal fluorescence (Fm) was observed, indicating that the chloroplast was protected by mechanisms that dissipate excess excitation energy to prevent damage to the photosynthetic apparatus. The incubation of leaves from unstressed plants under high light intensity resulted in an increase of the activity of electron donation by nicotinamide adenine dinucleotide phosphate (NADPH) and ferredoxin to plastoquinone, but no increase was observed in plants exposed to water deficit, suggesting that cyclic electron transport was stimulated by high light only in control plants. In contrast, the activities of the chlororespiration enzymes (NADH dehydrogenase (NDH) complex and plastid terminal oxidase (PTOX)) increased after incubation under high light intensity in leaves of the water deficit plants, but not in control plants, suggesting that chlororespiration was stimulated in stressed plants. The results indicate that the relative importance of chlororespiration and the cyclic electron pathway in the tolerance of photosynthesis to high illumination differs under stress conditions. When plants were not subjected to stress, the contribution of chlororespiration to photosynthetic electron flow regulation was not relevant, and another pathway, such as the ferredoxin-mediated cyclic pathway, was more important. However, when plants were subjected to water deficit and heat, chlororespiration was probably essential.

Stimulation of chlororespiration by drought under heat and high illumination in Rosa meillandina.

Rosa meillandina plants were used to study the effects of water deficit on photosynthesis and chlororespiration. Plants showed high tolerance to heat and high illumination in controlled conditions that ensured that there was no water deficit. However, when heat and high illumination were accompanied by low watering photosynthetic linear electron transport was down regulated, as indicated by the reduced photochemistry efficiency of PS II, which was associated with an increase in the non-photochemical quenching of fluorescence. In addition to the effects on the photosynthetic activity, changes were also observed in the plastidial NDH complex, PTOX and PGR5. In plants exposed to heat and high illumination without water deficit, the activities and amounts of the chlororespiration enzymes, NDH complex and PTOX, remained similar to the control and only increased in response to drought, high light and heat stress, applied together. In contrast, both the PS I activity and the amount of PGR5 polypeptide were higher in plants exposed to heat and high illumination without water deficit than in those with water deficit. The results indicated that in the conditions studied, the contribution of chlororespiration to regulating photosynthetic electron flow is not relevant when there is no water deficit, and another pathway, such as cyclic electron flow involving PGR5 polypeptide, may be more important. However, when PS II activity is inhibited by drought, chlororespiration, together with other routes of electron input to the electron transfer chain, is probably essential.

Chlororespiration and tolerance to drought, heat and high illumination.

Sun (Chrysanthemum morifolium) and shade (Spathiphyllum wallisii) plants were used to study the effects of drought, heat and high illumination. The stress conditions caused a greater accumulation of hydrogen peroxide in Chrysanthemum morifolium than in Spathiphyllum wallisii leaves. They also resulted in down-regulation of linear electron transport in the leaves of both species, as indicated by a gradual reduction in the photochemistry efficiency of PS II, which was associated with an increase in the non-photochemical quenching of fluorescence. Only a slight decrease in F(v)/F(m) was observed under stress conditions in either plant species, suggesting that the chloroplast is protected by mechanisms that dissipate excess excitation energy to prevent damage to the photosynthetic apparatus. In addition to the effects on photosynthetic activity, changes were also observed by immunoblot analysis in the plastidial NADH DH complex, PTOX and PGR5. The quantities of the PTOX and NDH-H subunit of the thylakoidal NADH DH complex, and the NADH DH activity in the thylakoid membranes were similar in control plants of both species and increased in stressed plants, particularly in Spathiphyllum wallisii. The level of PGR5 polypeptide was higher in Chrysanthemum morifolium than in Spathiphyllum wallisii control plants, while after stress, the quantity of PGR5 increased significantly in Chrysanthemum morifolium and remained constant in Spathiphyllum wallisii. These results indicate that the relative importance of chlororespiration and the cyclic electron pathways in the tolerance to drought, heat and high illumination differs in sun and shade plants, indicating different adaptive mechanisms to the environment. In the conditions studied, the PGR5-dependent cyclic pathway is more active in Chrysanthemum morifolium, a sun species, whereas in Spathiphyllum wallisii, a shade species, other ways involving the NADH DH complex and PTOX are stimulated in response to stress, which results in lower levels of ROS accumulation in the leaves.