Saccharomyces cerevisiae chitin biosynthesis activation by N-acetylchitooses depends on size and structure of chito-oligosaccharides

<p>Abstract</p> <p>Background</p> <p>To explore chitin synthesis initiation, the effect of addition of exogenous oligosaccharides on <it>in vitro </it>chitin synthesis was studied. Oligosaccharides of various natures and lengths were added to a chitin synthase assay performed on a <it>Saccharomyces cerevisiae </it>membrane fraction.</p> <p>Findings</p> <p><it>N</it>-acetylchito-tetra, -penta and -octaoses resulted in 11 to 25% [¹⁴C]-GlcNAc incorporation into [¹⁴C]-chitin, corresponding to an increase in the initial velocity. The activation appeared specific to <it>N</it>-acetylchitooses as it was not observed with oligosaccharides in other series, such as beta-(1,4), beta-(1,3) or alpha-(1,6) glucooligosaccharides.</p> <p>Conclusions</p> <p>The effect induced by the <it>N</it>-acetylchitooses was a saturable phenomenon and did not interfere with free GlcNAc and trypsin which are two known activators of yeast chitin synthase activity <it>in vitro</it>. The magnitude of the activation was dependent on both oligosaccharide concentration and oligosaccharide size.</p

What's new pussycat? A genealogy of animal celebrity

Animal celebrity is a human creation informing us about our socially constructed natural world. It is relational, expressive of cultural proclivities, political power plays and the quotidian everyday, as well as serious philosophical reflections on the meaning of being human. This article attempts to outline some key contours in the genealogy of animal celebrity, showing how popular culture, including fairground attractions, public relations, Hollywood movies, documentary films, zoo attractions, commercial sport and mediatised moral panics - particularly those accompanying scientific developments such as cloning - help to order, categorise and license aspects of human understanding and feelings. The nature of [animal] charisma and celebrity are explored with assistance from Jumbo the Elephant, Guy the Gorilla, Paul the clairvoyant octopus, Uggie the film star, Nénette the orang-utan and Dolly the sheep. It argues that the issue of what it is to be human lies beneath the celebritised surface or, as Donna Haraway noted, the issue 'of having to face oneself'

Genome-scale modeling of the protein secretory machinery in yeast

The protein secretory machinery in Eukarya is involved in post-translational modification (PTMs) and sorting of the secretory and many transmembrane proteins. While the secretory machinery has been well-studied using classic reductionist approaches, a holistic view of its complex nature is lacking. Here, we present the first genome-scale model for the yeast secretory machinery which captures the knowledge generated through more than 50 years of research. The model is based on the concept of a Protein Specific Information Matrix (PSIM: characterized by seven PTMs features). An algorithm was developed which mimics secretory machinery and assigns each secretory protein to a particular secretory class that determines the set of PTMs and transport steps specific to each protein. Protein abundances were integrated with the model in order to gain system level estimation of the metabolic demands associated with the processing of each specific protein as well as a quantitative estimation of the activity of each component of the secretory machinery

The posthuman way of war

Recent interventions from a ‘posthumanist’ or ‘new materialist’ perspective have highlighted the embedded character of human systems within a ‘panarchy’ of human and non-human systems. This article brings attention to a very particular element of materiality, one with a profound significance for issues of security – relations between human and non-human animals in instances of conflict. It is an indication of the deeply human-centred character of both international relations and security studies that almost none of the central texts mention the very significant roles that non-human animals have in the conduct of war. We argue that the character of war would have been radically different but for the forced participation by an enormous range of non-human animals. Even though, with the improvements in transportation over the last century, non-human animals are less evident in the context of the movement of people and equipment, they still play a significant number of roles in the contemporary war-machines of wealthy countries. Drawing on literature from critical animal studies, sociology and memoirs, this article discusses the enormous variety of roles that non-human animals have played in the conduct of war, and examines the character of human–non-human animal relations in times of war

Demand Dynamics in a Psycho-Socio-Economic Evolving Network of Consumers

In a model of demand dynamics, consumers are linked to each other both in the agent space and in the commodity space and are subject to viability constraints stipulating that only specific configurations of demand are possible. The viability of demand is re-established through both centralized and decentralized, social and learning coordination mechanisms. The framework leads to different results depending on the field of application. In market dynamics theory, the framework characterizes an a posteriori supply and demand law, where social mechanisms are market prices and learning mechanisms the endogenous adaptation of supply. In monetary regulation theory, coordination mechanisms are interest rates and agents' solvability is allowed through both micro and macro-monetary regulation. In a demand model with frustration, agents control their frustration using the representative frustration of society, and the decentralized learning mechanism leads to a selection of neighbors. In a model with consumer sub-groups, the demand regulation adds an identity-building process to lifestyles and mimetic behaviors to lifestyles.consumers, endogenous preferences, reaction functions, evolutionary economics, dynamical networks, connectionist operators,