Post-crystallization treatments for improving diffraction quality of protein crystals

X-ray crystallography is the most powerful method for determining the three-dimensional structure of biological macromolecules. One of the major obstacles in the process is the production of high-quality crystals for structure determination. All too often, crystals are produced that are of poor quality and are unsuitable for diffraction studies. This review provides a compilation of post-crystallization methods that can convert poorly diffracting crystals into data-quality crystals. Protocols for annealing, dehydration, soaking and cross-linking are outlined and examples of some spectacular changes in crystal quality are provided. The protocols are easily incorporated into the structure-determination pipeline and a practical guide is provided that shows how and when to use the different post-crystallization treatments for improving crystal quality.

Towards an ethics of engagement in education in global times

Starting from the observation that patterns of educational inequality are widely known but largely invisible in public debates on education, this article argues for the importance of an ethics of education which challenges simple acceptance of 'things as they are'. It suggests possibilities for working with discourses of ethics, rights and citizenship in contingent and strategic ways, and argues for the importance of engaging ethically across difference in current global times. It proposes three interrelated dimensions for an ethics of engagement in education: an ethics of commitment to intellectual rigour; an ethics of civility; and an inter-human ethics of care.

The ethics of paying drug users who participate in research: a review and practical recommendations

THE PAYMENT OF RESEARCH PARTICIPANTS raises ethical and empirical questions that have special importance in addictions research involving drug-dependent participants. Despite a now large literature on human subjects payment, what is still needed is practical guidance for investigators and ethics committees. This paper reviews the literature on: current payment practices and guidelines; defining features of undue and due incentives and fair reimbursement; and the significance of risks and harms that may arise from paying drug using participants. We conclude that research payments are ethically acceptable in most circumstances of addictions research, but should be closely scrutinized in situations where these may exacerbate existing harms or create additional risks for participants and investigators. General principles, key questions and procedural options are highlighted for an applied approach to ethical research payments. Future research directions are identified.

Post-translational modification accounts for the presence of varied forms of nerve growth factor in Australian elapid snake venoms

The Australian elapid snakes are amongst the most venomous snakes in the world, but much less is known about the overall venom composition in comparison to Asian and American snakes. We have used a combined approach of cDNA cloning and 2-DE with MS to identify nerve growth factor (NGF) in venoms of the Australian elapid snakes and demonstrate its neurite outgrowth activity While a single 730 nucleotide ORF, coding for a 243 amino acid precursor protein was detected in all snakes, use of 2-DE identified NGF proteins with considerable variation in molecular size within and between the different snakes. The variation in size can be explained at least in part by Winked glycosylation. it is possible that these modifications alter the stability, is necessary to activity and other characteristics of the snake NGFs. Further characterisation delineate the function of the individual NGF isoforms.