Tetrapyrrole Metabolism in Arabidopsis thaliana

Higher plants produce four classes of tetrapyrroles, namely, chlorophyll (Chl), heme, siroheme, and phytochromobilin. In plants, tetrapyrroles play essential roles in a wide range of biological activities including photosynthesis, respiration and the assimilation of nitrogen/sulfur. All four classes of tetrapyrroles are derived from a common biosynthetic pathway that resides in the plastid. In this article, we present an overview of tetrapyrrole metabolism in Arabidopsis and other higher plants, and we describe all identified enzymatic steps involved in this metabolism. We also summarize recent findings on Chl biosynthesis and Chl breakdown. Recent advances in this field, in particular those on the genetic and biochemical analyses of novel enzymes, prompted us to redraw the tetrapyrrole metabolic pathways. In addition, we also summarize our current understanding on the regulatory mechanisms governing tetrapyrrole metabolism. The interactions of tetrapyrrole biosynthesis and other cellular processes including the plastid-to-nucleus signal transduction are discussed

Building a climate of trust during organizational change: The mediating role of justice perceptions and emotion

Over the years, research has shown that, although there are various factors which contribute to failed change, one of the key reasons people resist change is due to the inability of leaders to convince employees to support change and to commit the energy and effort necessary to implement it. Senior management can ensure an organization is change-ready by developing and maintaining a supportive culture and climate that positively influence the emotional health and welfare of employees. Despite the obvious importance of leadership to change efforts, little previous research has investigated, holistically and in the context of major change, the relationship between senior management actions and employee responses. Furthermore, the change literature largely ignores the role that emotions play in employee responses to change initiatives. This chapter addresses both areas, and develops a model of organizational change from a justice and emotions perspective, which depicts employees’ justice perceptions related to senior executives as affecting trust directly and indirectly, through associated emotional responses