Institutional Impediments to Groundwater Trading: the case of the Gnangara groundwater system of Western Australia

The development of a market in groundwater usage rights can be inhibited by constraints arising from the institutional context. Such impediments may reduce the potential gains from trade and may generate high transaction costs for prospective traders. We analyse the regulations and policies influencing groundwater transfers in a case-study area -- the Gnangara groundwater system around Perth, Western Australia -- and identify significant impediments to a groundwater market. Property rights are found to be conditional, temporary, and vulnerable to amendment. Regulatory approval is required for all transfers. Facilitating infrastructure is lacking, and price information is unavailable. Management area boundaries reflect land ownership and use rather than hydrogeological realities; the limitation of transfers to within these boundaries eliminates much of the potential for gains from trade. Over-allocation and weak monitoring also impede the development of a market. The current management system is likely to obscure unmet demand for water-rights transfers between users and usage-types.Agricultural and Food Policy, Environmental Economics and Policy, Institutional and Behavioral Economics, Land Economics/Use, Political Economy, Public Economics, Resource /Energy Economics and Policy, Q15, Q25, Q28, Q38, Q56, Q57, Q58, D02, R52, H41, H23, H11, D23, D47, D78, H44,

Functional analyses reveal an important role for tyrosine residues in the staphylococcal multidrug efflux protein QacA

<p>Abstract</p> <p>Background</p> <p>The staphylococcal QacA multidrug efflux protein confers resistance to an exceptional number of structurally unrelated antimicrobial compounds. Aromatic amino acid residues have been shown to be highly important for the transport function of several multidrug transporters and are intimately involved in multidrug binding. This study investigated the structural and functional importance of the seven tyrosine residues in QacA by examining the phenotypic effect of incorporating conservative (aromatic) and non-conservative (non-aromatic) substitutions for these residues.</p> <p>Results</p> <p>Determination of the resistance profiles and analysis of drug transport assays revealed that non-conservative substitutions for most tyrosine residues influenced the QacA drug recognition spectrum. However, an aromatic residue at three tyrosine positions, 63, 410 and 429, was of importance for QacA-mediated transport and resistance to the majority of substrates tested.</p> <p>Conclusion</p> <p>A tyrosine or phenylalanine residue at amino acid positions corresponding to 63 of QacA in related drug efflux proteins is found to be highly conserved. Therefore, an aromatic side chain at this position is likely to partake in a function common to these drug transporters, such as proton translocation or essential intramolecular contacts, whereas aromatic residues at the non-conserved 410 and 429 positions are expected to mediate a QacA-specific function, possibly forming or stabilising part of the QacA drug binding region.</p

The staphylococcal QacR multidrug regulator binds a correctly spaced operator as a pair of dimers

Expression of the Staphylococcus aureus plasmid-encoded QacA multidrug transporter is regulated by the divergently encoded QacR repressor protein. To circumvent the formation of disulfide-bonded degradation products, site-directed mutagenesis to replace the two cysteine residues in wild-type QacR was undertaken. Analysis of a resultant cysteineless QacR derivative indicated that it retained full DNA-binding activities in vivo and in vitro and continued to be fully proficient for the mediation of induction of qacA expression in response to a range of structurally dissimilar multidrug transporter substrates. The cysteineless QacR protein was used in cross-linking and dynamic light-scattering experiments to show that its native form was a dimer, whereas gel filtration indicated that four QacR molecules bound per DNA operator site. The addition of inducing compounds led to the dissociation of the four operator-bound QacR molecules from the DNA as dimers. Binding of QacR dimers to DNA was found to be dependent on the correct spacing of the operator half-sites. A revised model proposed for the regulation of qacA expression by QacR features the unusual characteristic of one dimer of the regulatory protein binding to each operator half-site by a process that does not appear to require the prior self-assembly of QacR into tetramers

A Single Acidic Residue Can Guide Binding Site Selection but Does Not Govern QacR Cationic-Drug Affinity

Structures of the multidrug-binding repressor protein QacR with monovalent and bivalent cationic drugs revealed that the carboxylate side-chains of E90 and E120 were proximal to the positively charged nitrogens of the ligands ethidium, malachite green and rhodamine 6G, and therefore may contribute to drug neutralization and binding affinity. Here, we report structural, biochemical and in vivo effects of substituting these glutamate residues. Unexpectedly, substitutions had little impact on ligand affinity or in vivo induction capabilities. Structures of QacR(E90Q) and QacR(E120Q) with ethidium or malachite green took similar global conformations that differed significantly from all previously described QacR-drug complexes but still prohibited binding to cognate DNA. Strikingly, the QacR(E90Q)-rhodamine 6G complex revealed two mutually exclusive rhodamine 6G binding sites. Despite multiple structural changes, all drug binding was essentially isoenergetic. Thus, these data strongly suggest that rather than contributing significantly to ligand binding affinity, the role of acidic residues lining the QacR multidrug-binding pocket is primarily to attract and guide cationic drugs to the “best available” positions within the pocket that elicit QacR induction

Compliance, cooperation, and credibility: institutions and enforcement in California groundwater

The success of any groundwater management plan depends on user compliance. There is an intimate relationship between regulatory regimes and pumper perceptions. As well as its enforcement powers, an agency's behavior sends information to users. While enforcement power need not always be used to be effective, it must be seen as credible as well as legitimate. Perceived legitimacy has different sources – or may be lacking – depending on the origins, and implementation, of the regulatory apparatus. This paper examines a number of California groundwater basins, employing variables from Ostrom's analytical frameworks. In comparison with a West Australian regulated basin - where compliance is low, monitoring weak, and enforcement ineffective - we examine the effect on compliance of the adjudicated basin approach. We focus on the role of enforcement provisions, and their origins and implementation, in shaping appropriator attitudes towards compliance. Key attributes of effective systems include perceived legitimacy among users, mutual visibility of actions, and the credible threat of enforcement or sanction. We examine the extent to which 'administrative adjudications' may more cost-effectively provide the benefits of court adjudications. The paper illustrates that monitoring and enforcement are more effective and less costly when institutions encourage cooperation than when they promote competition. While norms, social capital, and trust must bear upon and inform the types of rules chosen at the collective-choice level, they also arise from the operation of those rules – i.e., from users' iterative reactions to the arrangements chosen. Groundwater management plans should incorporate design elements encouraging collaborative attitudes among users