The Bacterial Carbon-Fixing Organelle Is Formed by Shell Envelopment of Preassembled Cargo

Background: Cyanobacteria play a significant role in the global carbon cycle. In Synechococcuselongatus, the carbon-fixing enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is concentrated into polyhedral, proteinaceous compartments called carboxysomes. Methodology/Principal Findings Using live cell fluorescence microscopy, we show that carboxysomes are first detected as small seeds of RuBisCO that colocalize with existing carboxysomes. These seeds contain little or no shell protein, but increase in RuBisCO content over several hours, during which time they are exposed to the solvent. The maturing seed is then enclosed by shell proteins, a rapid process that seals RuBisCO from the cytosol to establish a distinct, solvent-protected microenvironment that is oxidizing relative to the cytosol. These closure events can be spatially and temporally coincident with the appearance of a nascent daughter RuBisCO seed. Conclusions/Significance: Carboxysomes assemble in a stepwise fashion, inside-to-outside, revealing that cargo is the principle organizer of this compartment’s biogenesis. Our observations of the spatial relationship of seeds to previously formed carboxysomes lead us to propose a model for carboxysome replication via sequential fission, polymerization, and encapsulation of their internal cargo

Shaping the Future of Research: a perspective from junior scientists

The landscape of scientific research and funding is in flux as a result of tight budgets, evolving models of both publishing and evaluation, and questions about training and workforce stability. As future leaders, junior scientists are uniquely poised to shape the culture and practice of science in response to these challenges. A group of postdocs in the Boston area who are invested in improving the scientific endeavor, planned a symposium held on October 2 nd and 3 rd, 2014, as a way to join the discussion about the future of US biomedical research. Here we present a report of the proceedings of participant-driven workshops and the organizers’ synthesis of the outcomes

Diamond’s Edge: From Notebook to Table and Back Again

We discuss the interaction benefits derived from combining the collaborative nature of touch-sensitive tabletop interfaces with the paper affordances and personal space of digital pen and paper. The pen may be used as fluid input to create and transform content within the public table space, and the table’s top-down projection as a method to augment the physical paper with properties of digital output. Finally, we introduce Diamond’s Edge, a design brainstorming tool which incorporates the interaction techniques described. Author Keywords Augmented paper notebooks, tabletop interfaces, CSCW