How nature deals with stereoisomers

All natural proteins are composed of t-amino acids and are inherently chiral. The properties of both -and chemically synthesized -amino acids are identical except in optically asymmetric interactions. Structural studies of racemic mixtures of crystallographic interest are discussed. The review also gives some recent examples of stereospecificity: how -proteins deal with - or -substrates and how enzymes can function as racemases. Two particular examples of stereoselectivity are then discussed.     

How Echinococcus granulosus deals with complement

Here, Ana Mar a Ferreira and colleagues discuss the interplay between the larval stages of Echinococcus granulosus and an important effector arm of immunity: the host complement system. During early infection, the parasite activates complement, and hence complement-dependent inflammatory responses. However, on differentiation into the hydatid cyst, the parasite exposes to the host a structure - the cyst wall - that does not activate complement strongly. Mechanisms inhibiting complement activation on the cyst wall have been elucidated, contributing to the understanding of how this large, persistent, tissue-dwelling pathogen controls the inflammatory response.     

Decision support systems for aquaculture licensing

Models used to assess the environmental impacts of aquaculture are becoming increasingly numerous and complicated. It is therefore becoming more and more difficult to present these moiels to non-scientists, even though the ultimate clients of research on aquaculture impacts are administrators and producers who have to deal with ractical considerations and have little time or inclination to deal with the complexities of scientific morfels. The Aquaculture Research Group within the Habitat Ecology Division has therefore been exploring the development of a decision support system (DSS) as a tool for communicating scientific advice to managers, specifically addressing the use of models to evaluate environmental impacts in order to assess whether the licensing of finfish aquaculture sites is likely to lead to degradation of natural marine habitat. The proposed DSS will incorporate simplified versions of several models along with a geographical data base of relevant hydrographic and other environmental information. The user will be able to enter various scenarios in a simple fashion (for example, a mouse can be used to specify site locations) and see an evaluation of the proposal based on several scientific models. Although a computer program cannot be expected to represent more than a fraction of the expertise of real scientists, the DSS approach appears to have several advantages; these include the ability to deliver a degree of expertise in remote and isolated regions, and, perhaps most important, a chance for managers to access scientific resources in a private environment which lets them explore various options without having to justify their eventual actions to scientists who may not fully appreciate all the pressures which bear on their decisions. The material developed so far includes a prototype of the proposed DSS in form of a computer program which demonstrates what the user interface for a working DSf would look like. The program has only a crude graphical user interface and does not actually interact with a real database, but the models are realistic and the output offers a simplified representation of what a real Decision Support System might provide.