Chloroplast remodeling during state transitions in Chlamydomonas reinhardtii as revealed by noninvasive techniques in vivo

International audiencePlants respond to changes in light quality by regulating the absorption capacity of their photosystems. These short-term adaptations use redox-controlled, reversible phosphorylation of the light-harvesting complexes (LHCIIs) to regulate the relative absorption cross-section of the two photosystems (PSs), commonly referred to as state transitions. It is acknowledged that state transitions induce substantial reorganizations of the PSs. However, their consequences on the chloroplast structure are more controversial. Here, we investigate how state transitions affect the chloroplast structure and function using complementary approaches for the living cells of Chlamydomonas reinhardtii. Using small-angle neutron scattering, we found a strong periodicity of the thylakoids in state 1, with characteristic repeat distances of ∼200 Å, which was almost completely lost in state 2. As revealed by circular dichroism, changes in the thylakoid periodicity were paralleled by modifications in the long-range order arrangement of the photosynthetic complexes, which was reduced by ∼20% in state 2 compared with state 1, but was not abolished. Furthermore, absorption spectroscopy reveals that the enhancement of PSI antenna size during state 1 to state 2 transition (∼20%) is not commensurate to the decrease in PSII antenna size (∼70%), leading to the possibility that a large part of the phosphorylated LHCIIs do not bind to PSI, but instead form energetically quenched complexes, which were shown to be either associated with PSII supercomplexes or in a free form. Altogether these noninvasive in vivo approaches allow us to present a more likely scenario for state transitions that explains their molecular mechanism and physiological consequences

Accurate GPS Time-Linked data Acquisition System (ATLAS II) user's manual.

The Accurate Time-Linked data Acquisition System (ATLAS II) is a small, lightweight, time-synchronized, robust data acquisition system that is capable of acquiring simultaneous long-term time-series data from both a wind turbine rotor and ground-based instrumentation. This document is a user's manual for the ATLAS II hardware and software. It describes the hardware and software components of ATLAS II, and explains how to install and execute the software

Atmospheric conditions and their effect on ball-milled magnesium diboride

Magnesium diboride bulk pellets were fabricated from pre-reacted MgB2 powder ball milled with different amounts of exposure to air. Evidence of increased electron scattering including increased resistivity, depressed Tc, and enhanced Hc2 of the milled and heat treated samples were observed as a result of increased contact with air. These and other data were consistent with alloying with carbon as a result of exposure to air. A less clear trend of decreased connectivity associated with air exposure was also observed. In making the case that exposure to air should be considered a doping process, these results may explain the wide varibability of "undoped" MgB2 properties extant in the literature.Comment: Work presented at ASC 2006 in Seattl

Parental role conflict: the nursing diagnosis in mothers of hospitalized newborns

OBJECTIVE: To verify if mothers of newborns hospitalized recognize the defining characteristics of parental role conflict as representative of that experience. METHODS: A cross-sectional and descriptive study, developed in a neonatal unit of a public teaching hospital in the state of São Paulo. The sample consisted of 100 women who assigned scores of 1 to 5 to the defining characteristics of the diagnosis, where 1 meant not at all characteristic and 5 meant completely characteristic of what I am experiencing. RESULT: Of the total sample, 96 women self-identified with the diagnosis. The most prevalent defining characteristics were: anxiety, mother expresses concern(s) in relation to changes in maternal role; verbalizes feelings of frustration, reports concern about family and fear. Women who were with their children less often during hospitalization had a higher number of defining characteristics. CONCLUSION: There was a high prevalence of the defining characteristics of the studied diagnosis, suggesting the relevance of the topic and the need for further studies to be developed in the neonatal unit.OBJETIVO: Verificar si las madres de los recién nacidos hospitalizados reconocen las características definitorias de conflicto de rol parental como representativas de esa experiencia. MÉTODOS: Estudio transversal y descriptivo realizado en una unidad neonatal de un hospital de enseñanza pública en el estado de São Paulo. La muestra consistió en 100 mujeres que le asignaron puntuaciones de 1 a 5 para las características que definen el diagnóstico, en la que 1 significa nada característico y 5 significa completamente característico de lo que estoy viviendo. RESULTADOS: De la muestra total, 96 mujeres se auto-identificaron con el diagnóstico. Las características más comunes que definen fueron: ansiedad,expresa preocupación por los cambios en el rol parental,expresa sentimientos de frustración,expresa preocupación sobre la familia (p. ej., funcionamiento, comunicación, salud),y temor. Las mujeres que estaban con sus hijos con menor frecuencia durante la hospitalización tenían un mayor número de características definitorias. CONCLUSIÓN: Se observó una alta prevalencia de las características definitorias del diagnóstico estudiado, lo que sugiere la relevancia del tema y la necesidad de nuevos estudios que se desarrollarán en la unidad neonatal.OBJETIVO: verificar se mães de recém-nascidos hospitalizados reconhecem as Características Definidoras do conflito no desempenho do papel de mãe como representativas do que vivenciam. MÉTODO: estudo transversal e descritivo, desenvolvido em uma unidade neonatal de um hospital público de ensino do Estado de São Paulo. A amostra foi constituída por 100 mulheres que atribuíram escores de 1 a 5 às características definidoras do diagnóstico, em que 1 significava absolutamente não característico e 5 totalmente característico do que estou vivenciando. RESULTADO: do total da amostra, 96 mulheres identificaram-se com o diagnóstico. As características definidoras mais prevalentes foram: ansiedade; mãe expressa preocupação(ões) em relação a mudanças no papel materno; verbaliza sentimentos de frustração; mãe expressa preocupação(ões) em relação à família e medo. As mulheres que estiveram menos vezes com os filhos, durante a internação, apresentaram maior número de características definidoras. CONCLUSÃO: verificou-se alta prevalência de características definidoras do diagnóstico estudado, o que sugere a pertinência da temática e a necessidade de que mais estudos sejam desenvolvidos na unidade neonatal.Universidade Estadual de Campinas, Campinas Faculdade de EnfermagemUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de EnfermagemUNIFESP, EPESciEL