Fitocromo(s) y cierre nictinástico foliar: Intermediarios y sistemas efectores implicados

[spa] El presente trabajo se enmarca en la línea de investigación del Departamento de Biología Vegetal de la Facultad de Biología de la Universidad de Barcelona que estudia el fotocontrol vía fitocromos (Pr, forma inactiva; Pfr, forma activa) de los movimientos rítmicos y nictinásticos de Albizia lophantha y Robinia pseudoacacia. Los objetivos planteados en el trabajo han sido: a) estudiar el efecto de la aplicación de polioles (sorbitol, manitol y polietilenglicol), sacarosa y fusicoccina, (toxina estimuladora de la actividad ATPasa-H+), sobre el cierre nictinástico dependiente de fitocromos de A. lophantha; b) investigar la incorporación de sacarosa-3H y manitol-3H en los pulvínulos de R. pseudoacacia, después de irradiaciones con luz roja (R) y luz roja lejana (FR); c) investigar la implicación del Ca2+ en el cierre nictinástico dependiente de fitocromos en R. pseudoacacia, mediante la localización citoquímica de Ca2+ intercambiable en las distintas zonas pulvinulares. Los resultados obtenidos demuestran que la aplicación de fusicoccina inhibe el cierre nictinástico de los foliolos de A. lophantha, a las 2 h y a las 8 h del fotoperiodo, tanto en presencia de Pfr como de Pr. Ello indica la presencia de ATPasa(s)-H+ en las células extensoras y el consiguiente aumento de turgencia de dichas células, provocando la inhibición del cierre y estimulando la reabertura. La sacarosa exógena estimula el cierre nictinástico dependiente de fitocromos en A. lophantha. La aplicación simultánea o secuencial de fusicoccina y sacarosa inhibe el efecto de la sacarosa y potencia la acción de la fusicoccina inhibiendo el cierre y estimulando la reabertura. Este sinergismo sugiere que la fusicoccina al incrementar la actividad ATPasa-H+ estimularía el cotransporte sacarosa-H+ dando lugar a un sistema de retroalimentación positivo. La aplicación de sorbitol y manitol incrementa el cierre nictinástico de los foliolos de A. lophantha siendo este más acusado en presencia de Pfr. Sacarosa-3H 50 mM y manitol-3H 50 mM, se incorporan, vía tejidos vasculares, durante el cierre nictinástico a los pulvínulos secundarios de R. pseudoacacia, siendo la cantidad total de sacarosa incorporada casi el doble que la de manitol y en ambos casos independiente de fitocromos. Asimismo se distribuyen en todos los tejidos pulvinulares, desde el cilindro central hasta la epidermis, preferentemente en paredes celulares, citoplasmas y vacuolas. La distribución de sacarosa-3H en los protoplastos extensores y flexores depende del estado de fotoequilibrio de los fitocromos. Después de una irradiación con luz FR se reduce drásticamente la incorporación de sacarosa en los protoplastos extensores y aumenta ligeramente en los protoplastos flexores internos. La incorporación de sacarosa en los protoplastos extensores y flexores no presenta diferencias después de un tratamiento con luz R. La distribución de manitol-3H en protoplastos extensores y flexores también depende del estado de fotoequilibrio de los fitocromos. No presenta diferencias después de un tratamiento con luz R y se acumula en los protoplastos flexores después de una irradiación con FR. Sacarosa-3H y manitol-3H no parecen actuar como osmóticos ya que su incorporación no esta relacionada con los cambios de turgencia celular. La presencia de Ca2+ intercambiable en todos los tejidos pulvinulares de R. pseudoacacia durante el cierre nictinástico corrobora resultados anteriores, e implica al Ca2+ como segundo mensajero de los fitocromos durante el cierre, ya que se evidencia un aumento transitorio de Ca2+ citosólico intercambiable en las células extensoras pulvinulares en presencia de Pfr. Se discuten los resultados obtenidos, relacionándolos con sistemas de transporte descritos en órganos motores de Leguminosas. El trabajo ha sido subvencionado a través de distintos proyectos de investigación como el concedido por el Ministerio de Ciencia e Innovación (ref. CGL2011-26310) y dentro del grupo 2009SGR1016 (AGAUR, Generalitat de Catalunya).[eng] The aims of the work reported here were to study: a) the effect of polyols (sorbitol, mannitol and polyethylene glycol), sucrose and fusicoccin on the nyctinastic closure mediated by phytochromes of Albizzia lophantha leaflets; b) the effect of phytochrome photoconversion on the incorporation of 3H-sucrose and 3H-mannitol into Robinia pseudoacacia pulvini during nyctinastic closure; and c) the involvement of Ca2+ in the nyctinastic closure mediated by phytochromes of R. pseudoacacia leaflets by cytochemical localization of interchangeable Ca2+ in the secondary pulvini. The results show that fusicoccin inhibited nyctinastic closure of A. lophantha, after both red (R) and far-red (FR) irradiation. Exogenous sucrose enhanced the nyctinastic closure of A. lophantha and when sucrose was applied simultaneously with fusicoccin, the inhibitory effect of fusicoccin on nyctinastic closure was enhanced. 3H-Sucrose 50 mM and 3H-mannitol 50 mM were incorporated into R. pseudoacacia pulvini through the vascular tissues. The total amount of sucrose incorporated into the pulvini was almost twice the amount of mannitol and neither amount was dependent on phytochromes. 3H-Sucrose was distributed in pulvinar tissues from the central core to the epidermis and it was mainly localized in cell walls, cytoplasm and vacuoles. 3H-Sucrose distribution in extensor and flexor protoplasts depends on phytochrome photoconversion. After FR irradiation, 3H-sucrose incorporation into the extensor protoplasts was drastically reduced while in the internal flexor protoplasts it was slightly increased. R light irradiation did not modify 3H-sucrose localization in the pulvini. 3H-Mannitol localization was also phytochrome dependent since, after FR irradiation, it increased in the flexor protoplasts but no differences were detected after R irradiation. 3H-Sucrose and 3H-mannitol apparently did not act as osmotica since their distribution was not related with turgor changes of the pulvinar cells. The presence of interchangeable Ca2+ in R. pseudoacacia pulvini during nyctinastic closure corroborates previous results which indicate that Ca2+ could be a second messenger in the phytochrome control of nyctinastic closure. The present work demonstrates that there is a transient and important increase in interchangeable Ca2+ in extensor motor cells in the presence of Pfr. This work was supported by the Spanish Ministerio de Ciencia e Innovación (CGL2011-26310)

Analysis of DNA methylation at birth and in childhood reveals changes associated with season of birth and latitude

BACKGROUND: Seasonal variations in environmental exposures at birth or during gestation are associated with numerous adult traits and health outcomes later in life. Whether DNA methylation (DNAm) plays a role in the molecular mechanisms underlying the associations between birth season and lifelong phenotypes remains unclear. METHODS: We carried out epigenome-wide meta-analyses within the Pregnancy And Childhood Epigenetic Consortium to identify associations of DNAm with birth season, both at differentially methylated probes (DMPs) and regions (DMRs). Associations were examined at two time points: at birth (21 cohorts, N?=?9358) and in children aged 1-11 years (12 cohorts, N?=?3610). We conducted meta-analyses to assess the impact of latitude on birth season-specific associations at both time points. RESULTS: We identified associations between birth season and DNAm (False Discovery Rate-adjusted p values?<?0.05) at two CpGs at birth (winter-born) and four in the childhood (summer-born) analyses when compared to children born in autumn. Furthermore, we identified twenty-six differentially methylated regions (DMR) at birth (winter-born: 8, spring-born: 15, summer-born: 3) and thirty-two in childhood (winter-born: 12, spring and summer: 10 each) meta-analyses with few overlapping DMRs between the birth seasons or the two time points. The DMRs were associated with genes of known functions in tumorigenesis, psychiatric/neurological disorders, inflammation, or immunity, amongst others. Latitude-stratified meta-analyses [higher (=?50°N), lower (<?50°N, northern hemisphere only)] revealed differences in associations between birth season and DNAm by birth latitude. DMR analysis implicated genes with previously reported links to schizophrenia (LAX1), skin disorders (PSORS1C, LTB4R), and airway inflammation including asthma (LTB4R), present only at birth in the higher latitudes (=?50°N). CONCLUSIONS: In this large epigenome-wide meta-analysis study, we provide evidence for (i) associations between DNAm and season of birth that are unique for the seasons of the year (temporal effect) and (ii) latitude-dependent variations in the seasonal associations (spatial effect). DNAm could play a role in the molecular mechanisms underlying the effect of birth season on adult health outcomes

Analysis of DNA methylation at birth and in childhood reveals changes associated with season of birth and latitude.

BACKGROUND: Seasonal variations in environmental exposures at birth or during gestation are associated with numerous adult traits and health outcomes later in life. Whether DNA methylation (DNAm) plays a role in the molecular mechanisms underlying the associations between birth season and lifelong phenotypes remains unclear. METHODS: We carried out epigenome-wide meta-analyses within the Pregnancy And Childhood Epigenetic Consortium to identify associations of DNAm with birth season, both at differentially methylated probes (DMPs) and regions (DMRs). Associations were examined at two time points: at birth (21 cohorts, N = 9358) and in children aged 1-11 years (12 cohorts, N = 3610). We conducted meta-analyses to assess the impact of latitude on birth season-specific associations at both time points. RESULTS: We identified associations between birth season and DNAm (False Discovery Rate-adjusted p values < 0.05) at two CpGs at birth (winter-born) and four in the childhood (summer-born) analyses when compared to children born in autumn. Furthermore, we identified twenty-six differentially methylated regions (DMR) at birth (winter-born: 8, spring-born: 15, summer-born: 3) and thirty-two in childhood (winter-born: 12, spring and summer: 10 each) meta-analyses with few overlapping DMRs between the birth seasons or the two time points. The DMRs were associated with genes of known functions in tumorigenesis, psychiatric/neurological disorders, inflammation, or immunity, amongst others. Latitude-stratified meta-analyses [higher (≥ 50°N), lower (< 50°N, northern hemisphere only)] revealed differences in associations between birth season and DNAm by birth latitude. DMR analysis implicated genes with previously reported links to schizophrenia (LAX1), skin disorders (PSORS1C, LTB4R), and airway inflammation including asthma (LTB4R), present only at birth in the higher latitudes (≥ 50°N). CONCLUSIONS: In this large epigenome-wide meta-analysis study, we provide evidence for (i) associations between DNAm and season of birth that are unique for the seasons of the year (temporal effect) and (ii) latitude-dependent variations in the seasonal associations (spatial effect). DNAm could play a role in the molecular mechanisms underlying the effect of birth season on adult health outcomes

Analysis of DNA methylation at birth and in childhood reveals changes associated with season of birth and latitude

BACKGROUND: Seasonal variations in environmental exposures at birth or during gestation are associated with numerous adult traits and health outcomes later in life. Whether DNA methylation (DNAm) plays a role in the molecular mechanisms underlying the associations between birth season and lifelong phenotypes remains unclear.METHODS: We carried out epigenome-wide meta-analyses within the Pregnancy And Childhood Epigenetic Consortium to identify associations of DNAm with birth season, both at differentially methylated probes (DMPs) and regions (DMRs). Associations were examined at two time points: at birth (21 cohorts, N = 9358) and in children aged 1-11 years (12 cohorts, N = 3610). We conducted meta-analyses to assess the impact of latitude on birth season-specific associations at both time points.RESULTS: We identified associations between birth season and DNAm (False Discovery Rate-adjusted p values &lt; 0.05) at two CpGs at birth (winter-born) and four in the childhood (summer-born) analyses when compared to children born in autumn. Furthermore, we identified twenty-six differentially methylated regions (DMR) at birth (winter-born: 8, spring-born: 15, summer-born: 3) and thirty-two in childhood (winter-born: 12, spring and summer: 10 each) meta-analyses with few overlapping DMRs between the birth seasons or the two time points. The DMRs were associated with genes of known functions in tumorigenesis, psychiatric/neurological disorders, inflammation, or immunity, amongst others. Latitude-stratified meta-analyses [higher (≥ 50°N), lower (&lt; 50°N, northern hemisphere only)] revealed differences in associations between birth season and DNAm by birth latitude. DMR analysis implicated genes with previously reported links to schizophrenia (LAX1), skin disorders (PSORS1C, LTB4R), and airway inflammation including asthma (LTB4R), present only at birth in the higher latitudes (≥ 50°N).CONCLUSIONS: In this large epigenome-wide meta-analysis study, we provide evidence for (i) associations between DNAm and season of birth that are unique for the seasons of the year (temporal effect) and (ii) latitude-dependent variations in the seasonal associations (spatial effect). DNAm could play a role in the molecular mechanisms underlying the effect of birth season on adult health outcomes.</p

Additional file 5 of Analysis of DNA methylation at birth and in childhood reveals changes associated with season of birth and latitude

Additional file 5. Table S4: “Direction of differential methylation of CpGs in DMRs of the at-birth and childhood analyses (preliminary analysis”)

Additional file 8 of Analysis of DNA methylation at birth and in childhood reveals changes associated with season of birth and latitude

Additional file 8. Table S8: “Genes mapped to DMR identified in the childhood samples of children born in the latitude ≥ 50°N and some examples of their associations with biological functions”. Provides examples of known functional associations of genes mapped to significant differentially methylated regions identified in this study

Additional file 9 of Analysis of DNA methylation at birth and in childhood reveals changes associated with season of birth and latitude

Additional file 9. “Trait Enrichment Analysis (EWAS Atlas)”. Trait names and the odds ratios for their association with CpG sites for all the models meta-analysed in this study