This paper uses a multi-period economic-environmental Computable General Equilibrium (CGE) modelling framework to analyse local sustainability policy issues. Our focus is the small, open, labour-constrained regional economy of Jersey. The case of Jersey is of particular interest for two main reasons. The first is the unusually low degree of geographical labour market integration for such a small regional economy. This motivates our treatment of labour as a region-specific factor of production. The second is the availability of high quality, Jersey-specific economic-enviromental data. We employ CGE model simulations to track the impact of changes in population on a number of energy-consumption and pollution indicators in a recursive dynamic framework under alternative hypotheses regarding economic conditions over the time period under consideration. In the case of Jersey, we find that household consumption is the key factor governing the environmental impact of economic disturbances. Therefore the analysis includes an examination of the sensitivity of the simulation results to different assumptions affecting the wage elasticities of labour demand and supply, and the speed of adjustment to equilibrium on the responsiveness of household income to shifts in labour supply.

This paper uses a multi-period economic-environmental CGE modelling framework to analyse the impacts of natural population change and the relaxation of migration constraints in a labour-constrained economy. Population and environmental concerns are core elements of sustainable economic development policy in the target economy of Jersey. Specifically, CGE model simulations are used to track the impact of changes in population on a number of energy-consumption and pollution indicators under alternative hypotheses regarding economic conditions over the time period under consideration. In the case of Jersey, we find that household consumption is the key factor governing the environmental impact of economic disturbances. Therefore the analysis includes an examination of the sensitivity of the simulation results to different assumptions regarding demand and production elasticities that affect the elasticity of labour demand and therefore the responsiveness of household income to shifts in labour supply.

Single-chain antibody fragments (scAbs), which have a human C-kappa constant domain and a hexa-histidine tail attached to the carboxy terminus of the single-chain Fv (ScFv) fragments to facilitate purification, have been raised against the herbicides paraquat and atrazine and expressed in transgenic Nicotiana tabacum cv. Samsun NN. Prior to purification, the anti-atrazine scAb is expressed as up to 0.014% of soluble leaf protein and has a binding profile in ELISA, against an atrazine-bovine serum albumin (BSA) conjugate, similar to that of the scAb produced in Escherichia coli. Competition ELISA has shown that the plant-derived scAb also recognises free atrazine. Following antibody affinity purification to isolate dimers, the affinity for immobilised antigen approaches that of the parental monoclonal antibody. This was confirmed by surface plasmon resonance analysis. The purified scAb also recognises related triazine herbicides. When isolated from cell-suspension cultures, the anti-paraquat scAb binds to a paraquat conjugate in a concentration-dependent manner, with a profile similar to the parental monoclonal antibody. This is the first demonstration that functional scAbs against organic pollutants can be produced in transgenic plants and that the scAbs may be appropriate for the development of immunoassay-based detection systems.

A potato virus X (PVX) vector was used to express a single chain antibody fragment (scFv) against the herbicide diuron, as a fusion to the viral coat protein. The modified virus accumulated in inoculated Nicotiana clevelandii plants and assembled to give virus particles carrying the antibody fragment. Electron microscopy was used to show that virus particles from infected leaf sap were specifically trapped on grids coated with a diuron-BSA conjugate. The results demonstrate that the PVX vector can be used as a presentation system for functional scFv.

Single-chain antibody fragments (scAb), specific for the herbicide atrazine, have been expressed in the bacterium Escherichia coli and in transgenic tobacco plants. The scAb could be purified as a monomer (monovalent) via a hexa-histidine tail or as a dimer (divalent) by antibody affinity chromatography. In competition ELISA, the bacterial scAb showed the same specificity for atrazine and related triazine herbicides as the parental mAb cell line, but both plant and bacterial monomeric scAbs showed increased sensitivity to free atrazine. Surface plasmon resonance (BIAcore 2000) analysis confirmed that purified scAb, derived from plant or bacteria, retained similar association rates as the mAb. However, the monomeric plant and bacterial scAbs showed a lower affinity for immobilised antigen, than the equivalent dimeric scAbs or mAb. This decrease in affinity was due to a 10 fold slower dissociation rate and is likely due to loss of the avidity contribution of dimeric molecules.

The technology of humanization of rodent antibodies has opened the way for a broad range of therapeutic antibodies with very low immunogenicity, which are, therefore, suitable for repeated dosing. Such intact antibodies have extended serum half-lives and biodistribution profiles very similar to human antibodies. For some applications, however, the ideal therapeutic should have reduced serum half-life and altered biodistribution patterns typical of antibody fragments, such as Fab or single chain Fv. Bispecific antibody fragments offer exciting additional therapeutic possibilities, but their successful manufacture and purification on a large scale require the development of new methods. Antibody fragments often assemble in Escherichia coli as monovalent fragments with reduced affinities. We describe the spontaneous assembly of bivalent antibody fragments in E. coli and methods of purification that yield either bivalent or monovalent molecules as required.