Signaling

Background: Cells continuously secrete a large number of microvesicles, macromolecular complexes, and small molecules into the extracellular space. Of the secreted microvesicles, the nanoparticles called exosomes are currently undergoing intense scrutiny. These are small vesicles (30-120 nm) containing nucleic acid and protein, perceived to be carriers of this cargo between diverse locations in the body. They are distinguished in their genesis by being budded into endosomes to form multivesicular bodies (MVBs) in the cytoplasm. The exosomes are released to extracellular fluids by fusion of these multivesicular bodies with the cell surface, resulting in secretion in bursts. Exosomes are secreted by all types of cells in culture, and also found in abundance in body fluids including blood, saliva, urine, and breast milk. Scope of review: In this review, we summarize strategies for exosome isolation, our understanding to date of exosome composition, functions, and pathways, and discuss their potential for diagnostic and therapeutic applications. Major conclusions: Currently, the control of exosome formation, the makeup of the "cargo", biological pathways and resulting functions are incompletely understood. One of their most intriguing roles is intercellular communicationexosomes are thought to function as the messengers, delivering various effectors or signaling macromolecules between supposedly very specific cells. General significance: Both seasoned and newer investigators of nanovesicles have presented various viewpoints on what exosomes are, with some differences but a large common area. It would be useful to develop a codified definition of exosomes in both descriptive and practical terms. We hope this in turns leads to a consistent set of practices for their isolation, characterization and manipulation.

Recently, game theory and evolutionary game theory – mathematical frameworks from economics and biology designed to model and explain interactive behavior – have proved fruitful tools for philosophers in areas such as ethics, philosophy of language, social epistemology, and political philosophy. This methodological osmosis is part of a trend where philosophers have blurred disciplinary lines to import the best epistemic tools available. In this vein, experimental philosophers have drawn on practices from the social sciences, and especially from psychology, to expand philosophy's grasp on issues from morality to consciousness. We argue that the recent prevalence of formal work on human interaction in philosophy opens the door for new methods in experimental philosophy. In particular, we discuss methods from experimental economics, focusing on a small literature we have been developing investigating signaling and communication in humans. We describe results from a novel experiment showing how environmental structure can shape signaling behavior.

Investment by wealthy individuals, known as 'angels,' in startup firms is quite significant and has taken off in the last few years. Angels invest in the company at an earlier stage than venture capitalists (VCs) do. This paper examines the relationship between an entrepreneur, an angel, and a VC from the seed investment made by the angel to the exit stage. The study characterizes the equilibrium contracts among the players and provides insights into the related institutional arrangements. Next, the study examines the signaling aspects of the game. The paper also analyzes the moral hazard problems of the entrepreneur and the VC. It shows that the outcome in a startup firm is not efficient because of the freerider phenomenon. D

This paper draws on information economics to examine when signals and endorsements obtained from multiple information sources enhance or diminish one another’s effects. We propose that signals through startup actions (use of media) and characteristics (crowdfunding experience) can mitigate information asymmetry concerns about project quality and founder credibility, enhancing the project’s likelihood of attaining funding. Further, we posit that while startup-originated signals offset each other’s effects, third party endorsements (sentiment expressed in backer comments) validate and complement startup-originated signals. Empirical analyses based on a comprehensive dataset of crowdfunding projects on the Kickstarter website during 2009-2015 confirm our predictions.

J. Neurochem. (2012) 121, 4–27.J. Neurochem. (2012) 121, 4–27.AbstractNeuroglial cells define brain homeostasis and mount defense against pathological insults. Astroglia regulate neurogenesis and development of brain circuits. In the adult brain, astrocytes enter into intimate dynamic relationship with neurons, especially at synaptic sites where they functionally form the tripartite synapse. At these sites, astrocytes regulate ion and neurotransmitter homeostasis, metabolically support neurons and monitor synaptic activity; one of the readouts of the latter manifests in astrocytic intracellular Ca2+ signals. This form of astrocytic excitability can lead to release of chemical transmitters via Ca2+-dependent exocytosis. Once in the extracellular space, gliotransmitters can modulate synaptic plasticity and cause changes in behavior. Besides these physiological tasks, astrocytes are fundamental for progression and outcome of neurological diseases. In Alzheimer’s disease, for example, astrocytes may contribute to the etiology of this disorder. Highly lethal glial-derived tumors use signaling trickery to coerce normal brain cells to assist tumor invasiveness. This review not only sheds new light on the brain operation in health and disease, but also points to many unknowns.Neuroglial cells define brain homeostasis and mount defense against pathological insults. Astroglia regulate neurogenesis and development of brain circuits. In the adult brain, astrocytes enter into intimate dynamic relationship with neurons, especially at synaptic sites where they functionally form the tripartite synapse. At these sites, astrocytes regulate ion and neurotransmitter homeostasis, metabolically support neurons and monitor synaptic activity; one of the readouts of the latter manifests in astrocytic intracellular Ca2+ signals. This form of astrocytic excitability can lead to release of chemical transmitters via Ca2+-dependent exocytosis. Once in the extracellular space, gliotransmitters can modulate synaptic plasticity and cause changes in behavior. Besides these physiological tasks, astrocytes are fundamental for progression and outcome of neurological diseases. In Alzheimer’s disease, for example, astrocytes may contribute to the etiology of this disorder. Highly lethal glial-derived tumors use signaling trickery to coerce normal brain cells to assist tumor invasiveness. This review not only sheds new light on the brain operation in health and disease, but also points to many unknowns.

The patrons of Raphael, among the most powerful men in Europe, paid far more for his paintings than they did for those by most of his celebrated contemporaries. The present study aims to bring attention to this impressive , albeit rarely discussed, observation. A combination of approaches from different disciplines provides a methodological framework for analyzing extraordinary compensation for artists in a wide range of areas and time periods. Signaling, risk management, and the superstar model, all concepts from economic theory, together with distinction, a theory from sociology, help to explain this phenomenon and to understand its importance.