The gap between marginal revenues and marginal costs of inputs (i.e., distortions or wedges) at establishments potentially lower aggregate total factor productivity (TFP) by preventing efficient allocation of resources among incumbents, deterring entry and exit, and affecting technology choices. We investigate the impacts of distortions on aggregate TFP, entry and exit, and establishment-level ...

The unicellular yeast Saccharomyces cerevisiae is a model system for the establishment of cell polarity. Yeast cells proliferate by budding, which involves specialization of a small patch of the mother cell cortex and polarization of many cell constituents towards that patch, promoting growth of the bud. Genetic approaches have uncovered a large number of genes involved in these processes, yiel...

Wormwood sagebrush (Artemisia sieberi Besser) is one of the most widely distributed shrub species in Iran and Turkistan steppes, its establishment on dry lands has generally been proven difficult because of low seedling vigor, inability to compete with herbaceous species, poor seed quality, and altered edaphic conditions. In order to evaluation of planting methods and seedling establishment, se...

Communication between cortical cell polarity cues and the mitotic spindle ensures proper orientation of cell divisions within complex tissues. Defects in mitotic spindle positioning have been linked to various developmental disorders and have recently emerged as a potential contributor to tumorigenesis. Despite the importance of this process to human health, the molecular mechanisms that regula...

How does a living cell deal with basic concepts of physics such as length and force? The cell has to measure distances and regulate forces to dynamically organize its interior. This is to a large extent based on microtubules (MTs) and motor proteins. Two concepts are emerging from recent studies as key to the positioning of cell components: preferred disassembly of longer MTs and preferred deta...

The second touch hypothesis states that T cell activation, proliferation, induction of homing receptors and polarization are distinguishable and, at least in part, sequential. The second touch hypothesis maintains that full T cell polarization requires T cell interaction with antigen-presenting cells (DCs, macrophages, B cells and certain activated stromal cells) in the non-lymphoid tissue wher...

Embryology and genetics have given rise to a mechanistic framework that explains the architecture of a developing organism. Until recently, however, such studies suffered from a lack of quantification and real-time visualization at the subcellular level, limiting their ability to monitor the dynamics of developmental processes. Live imaging using fluorescent proteins has overcome these limitati...

A. Veglio, 2 A. Gamba, 2 M. Nicodemi, F. Bussolino, and G. Serini Department of Oncological Sciences and Division of Molecular Angiogenesis, Institute for Cancer Research and Treatment, University of Torino School of Medicine, Candiolo (TO), Italy. CNISM, Corso Duca degli Abruzzi 24, 10125 Torino, Italy. Politecnico di Torino, Corso Duca degli Abruzzi 24, 10125 Torino, Italy; and INFN Torino, I...

Cellular polarization is often a response to distinct extracellular or intracellular cues, such as nutrient gradients or cortical landmarks. However, in the absence of such cues, some cells can still select a polarization axis at random. Positive feedback loops promoting localized activation of the GTPase Cdc42p are central to this process in budding yeast. Here, we explore spontaneous polariza...

Neurons in the developing mammalian brain are generated from progenitor cells in the proliferative ventricular zone, and control of progenitor division is essential to produce the correct number of neurons during neurogenesis. Here we establish that Gbetagamma subunits of heterotrimeric G proteins are required for proper mitotic-spindle orientation of neural progenitors in the developing neocor...