The evolution of productive organizations.

Organizations devoted to the production of goods and services, such as guilds, partnerships and modern corporations, have dominated the economic landscape in our species' history. We develop an explanation for their evolution drawing from cultural evolution theory. A basic tenet of this theory is that social learning, under certain conditions, allows for the diffusion of innovations in society and, therefore, the accumulation of culture. Our model shows that these organizations provide such conditions by possessing two characteristics, both prevalent in real world organizations: exclusivity of membership and more effective social learning within their boundaries. The model and its extensions parsimoniously explain the cooperative nature of the social learning advantage, organizational specialization, organizational rigidity and the locus of innovation. We find supportive evidence for our predictions using a sample of premodern societies drawn from the Ethnographic Atlas. Understanding the nature of these organizations informs the debate about their role in society.

Scavenger Receptor-A deficiency impairs immune response of microglia and astrocytes potentiating Alzheimer's disease pathophysiology.

Late onset Alzheimer disease's (LOAD) main risk factor is aging. Although it is not well known which age-related factors are involved in its development, evidence points out to the involvement of an impaired amyloid-ß (Aß) clearance in the aged brain among possible causes. Glial cells are the main scavengers of the brain, where Scavenger Receptor class A (SR-A) emerges as a relevant player in AD because of its participation in Aß uptake and in the modulation of glial cell inflammatory response. Here, we show that SR-A expression is reduced in the hippocampus of aged animals and APP/PS1 mice. Given that Aß deposition increases in the aging brain, we generated a triple transgenic mouse, which accumulates Aß and is knockout for SR-A (APP/PS1/SR-A-/-) to evaluate Aß accumulation and the inflammatory outcome of SR-A depletion in the aged brain. The lifespan of APP/PS1/SR-A-/- mice was greatly reduced, accompanied by a 3-fold increase in plasmatic pro-inflammatory cytokines, and reduced performance in a working memory behavioral assessment. Microglia and astrocytes lacking SR-A displayed impaired oxidative response and nitric oxide production, produced up to 7-fold more pro-inflammatory cytokines and showed a 12-fold reduction in anti-inflammatory cytokines release, with conspicuous changes in lipopolysaccharide-induced glial activation. Isolated microglia from young and adult mice lacking SR-A showed a 50% reduction in phagocytic activity. Our results indicate that reduced expression of SR-A can deregulate glial inflammatory response and potentiate Aß accumulation, two mechanisms that could contribute to AD progression.

Chitosan microparticles loaded with yeast-derived PCV2 virus-like particles elicit antigen-specific cellular immune response in mice after oral administration.

BACKGROUND: Porcine circovirus type 2 (PCV2)-associated diseases are a major problem for the swine industry worldwide. In addition to improved management and husbandry practices, the availability of several anti-PCV2 vaccines provides an efficient immunological option for reducing the impact of these diseases. Most anti-PCV2 vaccines are marketed as injectable formulations. Although these are effective, there are problems associated with the use of injectable products, including laborious and time-consuming procedures, the induction of inflammatory responses at the injection site, and treatment-associated stress to the animals. Oral vaccines represent an improvement in antigen delivery technology; they overcome the problems associated with injection management and facilitate antigen boosting when an animals' immunity falls outside the protective window. METHODS: Chitosan microparticles were used as both a vehicle and mucosal adjuvant to deliver yeast-derived PCV2 virus-like particles (VLPs) in an attempt to develop an oral vaccine. The physical characteristics of the microparticles, including size, Zeta potential, and polydispersity, were examined along with the potential to induce PCV2-specific cellular immune responses in mice after oral delivery. RESULTS: Feeding mice with PCV2 VLP-loaded, positively-charged chitosan microparticles with an average size of 2.5 µm induced the proliferation of PCV2-specific splenic CD4+/CD8+ lymphocytes and the subsequent production of IFN-γ to levels comparable with those induced by an injectable commercial formulation. CONCLUSION: Chitosan microparticles appear to be a safe, simple system on which to base PCV2 oral vaccines. Oral chitosan-mediated antigen delivery is a novel strategy that efficiently induces anti-PCV2 cellular responses in a mouse model. Further studies in swine are warranted.