Localization of a putative ClC chloride channel in spinach chloroplasts

AbstractSeven genes seem to encode for putative ClC chloride channels (AtClC-a to AtClC-g) in Arabidopsis thaliana. Their function and localization is still largely unknown. AtClC-f shares considerable sequence similarity with putative ClC channel proteins from Synechocystis, considered to represent the precursor of chloroplasts. We show by biochemical and mass spectrometry analysis that ClC-f is located in the outer envelope membrane of spinach chloroplasts. Consistent with the plastidial localization of ClC-f, p-chlorophenoxy-acetic acid (CPA) reduces photosynthetic activity and the protein is expressed in etioplasts and chloroplasts but not in root tissue. These findings may represent a step toward the molecular identification of ion channel activities in chloroplast membranes

Dissecting stimulus-specific Ca2+ signals in amyloplasts and chloroplasts of Arabidopsis thaliana cell suspension cultures

Calcium is used by plants as an intracellular messenger in the detection of and response to a plethora of environmental stimuli and contributes to a fine-tuned internal regulation. Interest in the role of different subcellular compartments in Ca(2+) homeostasis and signalling has been growing in recent years. This work has evaluated the potential participation of non-green plastids and chloroplasts in the plant Ca(2+) signalling network using heterotrophic and autotrophic cell suspension cultures from Arabidopsis thaliana plant lines stably expressing the bioluminescent Ca(2+) reporter aequorin targeted to the plastid stroma. Our results indicate that both amyloplasts and chloroplasts are involved in transient Ca(2+) increases in the plastid stroma induced by several environmental stimuli, suggesting that these two functional types of plastids are endowed with similar mechanisms for handling Ca(2+). A comparison of the Ca(2+) trace kinetics recorded in parallel in the plastid stroma, the surface of the outer membrane of the plastid envelope, and the cytosol indicated that plastids play an essential role in switching off different cytosolic Ca(2+) signals. Interestingly, a transient stromal Ca(2+) signal in response to the light-to-dark transition was observed in chloroplasts, but not amyloplasts. Moreover, significant differences in the amplitude of specific plastidial Ca(2+) changes emerged when the photosynthetic metabolism of chloroplasts was reactivated by light. In summary, our work highlights differences between non-green plastids and chloroplasts in terms of Ca(2+) dynamics in response to environmental stimuli

ATP-sensitive cation-channel in wheat (triticum durum Desf.): Identification and characterization of a plant mitochondrial channel by patch-clamp

Indirect evidence points to the presence of K + channels in plant mitochondria. In the present study, we report the results of the first patch clamp experiments on plant mitochondria. Single-channel recordings in 150 mM potassium gluconate have allowed the biophysical characterization of a channel with a conductance of 150 pS in the inner mitochondrial membrane of mitoplasts obtained from wheat (Triticum durum Desf.). The channel displayed sharp voltage sensitivity, permeability to potassium and cation selectivity. ATP in the mM concentration range completely abolished the activity. We discuss the possible molecular identity of the channel and its possible role in the defence mechanisms against oxidative stress in plants

A Mitochondrial calcium dynamics - checks and balances of energy physiology

Mitochondria conserve the energy released from metabolic redox reactions and supply the cell with ATP. When the rate of respiratory metabolism does not match ATP demand active regulation of mitochondrial function is essential. For plants particularly sophisticated regulation strategies can be expected, to ensure maintenance of homeostasis in the presence of frequent environmental changes. Yet, the mechanisms by which such control is achieved in vivo are poorly understood. Calcium acts as a key regulator of mitochondrial energy metabolism in mammals by modulating the activity TCA cycle dehydrogenases. Calcium flux into the matrix is controlled by the recently identified mitochondrial uniporter complex. Plants contain homologues of components of the uniporter, but their function has been unclear. To understand how mitochondrial calcium dynamics are regulated and what their impact is on energy metabolism, we have combined reverse genetics with in vivo sensing of calcium. Fluorescent protein sensors and quantitative confocal imaging allow monitoring of mitochondrial energy physiology in living Arabidopsis tissues. We have found that several homologues of components of the mitochondrial calcium uniporter complex localize to mitochondria in Arabidopsis. Mutant lines have shown severely altered mitochondrial calcium levels and abnormal organellar calcium transients, providing a novel genetic handle on the dissection of the role of calcium regulation in plant mitochondria. We will discuss the specific impact of de-regulated mitochondrial calcium on the physiological network and the function of plant mitochondria

Examining the Conditions of a Successful Women's Leadership Program

openAttempts to combat gender inequality in all facets of life have become more prevalent in recent years. Despite these efforts, there remains a need to increase gender diversity in leadership roles within organizations, Women’s Leadership Programs are aiming to facilitate opportunity for all women within the workplace, their career paths and improve access to leadership roles. This body of research aims to examine the conditions under which Women Leadership Programs can be effective in attaining these goals. Utilizing a qualitative research design, a thematic analysis of scholarly literature was performed in order to identify patterns, concepts and key factors that contribute to the effectiveness of Women’s Leadership Programs. Intersectionality, networking, being seen, heard and vulnerable, women only programs, and transformational learning are the major themes that emerged from the existing literature. Analysis of five specific Women’s Leadership Programs takes into consideration many factors influencing the success of these programs, such as program goals, long-term effectiveness, funding and diversity in order to evaluate how these factors further the success of WLP’s. This research aims to contribute to the conversation around gender equality and provide insight into which qualities foster inclusive and equitable leadership programs. Additionally, it aims to add to the body of knowledge on the optimal composition of a WLP to yield the highest success.Attempts to combat gender inequality in all facets of life have become more prevalent in recent years. Despite these efforts, there remains a need to increase gender diversity in leadership roles within organizations, Women’s Leadership Programs are aiming to facilitate opportunity for all women within the workplace, their career paths and improve access to leadership roles. This body of research aims to examine the conditions under which Women Leadership Programs can be effective in attaining these goals. Utilizing a qualitative research design, a thematic analysis of scholarly literature was performed in order to identify patterns, concepts and key factors that contribute to the effectiveness of Women’s Leadership Programs. Intersectionality, networking, being seen, heard and vulnerable, women only programs, and transformational learning are the major themes that emerged from the existing literature. Analysis of five specific Women’s Leadership Programs takes into consideration many factors influencing the success of these programs, such as program goals, long-term effectiveness, funding and diversity in order to evaluate how these factors further the success of WLP’s. This research aims to contribute to the conversation around gender equality and provide insight into which qualities foster inclusive and equitable leadership programs. Additionally, it aims to add to the body of knowledge on the optimal composition of a WLP to yield the highest success

Alla conquista della scena: donne e scrittura negli anni cinquanta e sessanta

This dissertation focuses on women's writing in the fifties and sixties, a period that marks a transition for the italiane who are called to actively participate in the life of the new Republic. I explore the questions elicited by women's visibility in the social and cultural scene and the representations of new models of female identity in women's popular press and in narrative works published between 1950 and 1967. In particular, I analyze Laudomia Bonanni's L'adultera, Fausta Cialente's Un inverno freddissimo, and Alba de Céspedes' Quaderno proibito and La bambolona. By examining how the markers of modernity, such as the setting of the newly industrialized city, the female flanêrie, and the adoption of cinematic techniques, influenced the structure of these women's writers texts, I draw attention to the important narrative role played by liminal milieux. Theoretical as well as historical, this dissertation chronicles the growing phenomenon of women's magazines and popular publications, which functioned, I argue, as a transitional space for models of female identity that both continued and broke with tradition. By investigating the multiple intersections between "high" and "low" literature, I claim that periodicals, fotoromanzi, romance novels, and so-called "high" literature both aim to differently educate a new readership. In order to neutralize the conservative ideology implicitly conveyed by the rosa, women writers parodied or re-elaborated the cliché and language of popular literature. Ultimately, I assert that the various forms of women's popular writing deserve reevaluation, if we are to draw an accurate landscape of women's writing in the boom decades of the Italian Novecento.Ph.D.Includes bibliographical references (p. 170-183)by Sara Teard