In Situ Contaminated Sediments Project – Work Package 1A Report

Project aims Defra is seeking to understand the magnitude of risks (e.g. to aquatic ecology and human health) or impacts (e.g. on the way that water bodies are managed) posed by contaminated sediment in England, as part of its work towards meeting its environmental objectives. In the context of this project, in-situ contaminated sediment is defined as: Chemically contaminated sediment within the water column, bed, banks and floodplain of a surface water body that has been transported alongside the normal sediment load and deposited by fluvial or coastal processes. This project considers the risk posed by non-agricultural diffuse pollution sources in England that result in the contamination of in-situ sediments (for example, contamination from toxic metals, hydrocarbons and surfactants). The scope encompasses both freshwater and marine sediments in England and extends to one nautical mile off-shore (the seaward limit of coastal waters under the Water Framework Directive (WFD) in England). Previous national strategies, including the 2007 Defra UK Strategy for Managing Contaminated Marine Sediments (CDMS), focussed on characterising the risks associated with contaminated sediments in the marine environment. However, while extensive research has been carried out in many locations (including as part of WFD implementation studies) and for particular sources of contamination (e.g. historical metal mining; Environment Agency, 2008) there has not been a comprehensive overview of sediment contamination on a national scale. This project seeks to build on the existing evidence base, drawing together information on the freshwater environment to complement that already gathered for marine waters. This project’s overall aim is to provide a sound evidence base on the contamination of in-situ sediments, which can underpin the development of tools and methods that will help Defra, the Environment Agency and other bodies engaged in regulation and protection of water quality

Developing Retina and PNS Segments for Transplantation Into the Adult Host Eye: Reconstruction of the Mammalian Visual System. 1. Methodology

Various techniques have been explored to determine the uses and limitations of techniques that enable the adult CNS to regenerate, but relatively little attention has been given to the consideration of a "reconstructed" visual system. Using this approach, one can design experiments to study the uses of exogenous tissues in reestablishing neuronal circuits that have been damaged. Toward this end, experiments were designed to determine whether embryonic retinal ganglion cells can project axons into a grafted PNS "bridge", and enter adult host targets that were partially deafferented. Embryonic eyes of E11, E14, E18 and E21 rats were sutured to peripheral nerve segments which served as bridges between the host eye and frontal cortex. Projections between the developing retina and the host brain could then be evaluated using HRP tracing techniques. From a methodological standpoint, the preparations are 65% effective; i.e., a viable bridge results between the embryonic eye and the host forebrain. The results presented in the accompanying paper demonstrate that the technique can yield results indicative of embryonic retinal development and axonal projection through the graft and into the host brain. This partial reconstruction of the visual system may prove a useful tool in understanding the uses and limitations of grafting in the CNS