Influence of metals and metalloids on the composition and fluorescence quenching of the extracellular polymeric substances produced by the polymorphic fungus <i>Aureobasidium pullulans</i>

Aureobasidium pullulansis a ubiquitous and widely distributed fungus in the environment, and exhibits substantial tolerance against toxic metals. However, the interactions between metals and metalloids with the copious extracellular polymeric substances (EPS) produced byA. pullulansand possible relationships to tolerance are not well understood. In this study, it was found that mercury (Hg) and selenium (Se), as selenite, not only significantly inhibited growth ofA. pullulansbut also affected the composition of produced EPS. Lead (Pb) showed little influence on EPS yield or composition. The interactions of EPS fromA. pullulanswith the tested metals and metalloids depended on the specific element and their concentration. Fluorescence intensity measurements of the EPS showed that the presence of metal(loid)s stimulated the production of extracellular tryptophan-like and aromatic protein-like substances. Examination of fluorescence quenching and calculation of binding constants revealed that the fluorescence quenching process for Hg; arsenic (As), as arsenite; and Pb to EPS were mainly governed by static quenching which resulted in the formation of a stable non-fluorescent complexes between the EPS and metal(loid)s. Se showed no significant interaction with the EPS according to fluorescence quenching. These results provide further understanding of the interactions between metals and metalloids and EPS produced by fungi and their contribution to metal(loid) tolerance

Optimising engine performance and emissions using Bayesian techniques

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Creating a ‘planning emergency levels of service’ framework – a silver bullet, or something useful for target practice?

‘Planning Emergency Levels of Service’ (PELOS) are service delivery goals for infrastructure providers during and after an emergency event. These goals could be delivered through the existing infrastructure (e.g., pipes, lines, cables), or through other means (trucked water or the provision of generators). This paper describes how an operationalised framework of PELOS for the Wellington region, New Zealand was created, alongside the key stakeholders. We undertook interviews and workshops with critical infrastructure entities to create the framework. Through this process we found five themes that informed the context and development of the PELOS framework: interdependencies between critical infrastructure, the need to consider the vulnerabilities of some community members, emergency planning considerations, stakeholders’ willingness to collaborate on this research/project and the flexibility/adaptability of the delivery of infrastructure services following a major event. These themes are all explored in this paper. This research finds that the understanding of the hazardscape and potential outages from hazards is critical and that co-ordination between key stakeholders is essential to create such a framework. This paper may be used to inform the production of PELOS frameworks in other localities

From chemotherapy to phototherapy – changing the therapeutic action of a metallo-intercalating RuII-ReI luminescent system by switching its sub-cellular location

The synthesis of a new heterodinuclear ReIRuII metallointercalator containing RuII(dppz) and ReI(dppn) moieties is reported. Cell-free studies reveal that the complex has similar photophysical properties to its homoleptic M(dppz) analogue and it also binds to DNA with a similar affinity. However, the newly reported complex has very different in-cell properties to its parent. In complete contrast to the homoleptic system, the RuII(dppz)/ReI(dppn) complex is not intrinsically cytotoxic but displays appreciable phototoxic, despite both complexes displaying very similar quantum yields for singlet oxygen sensitization. Optical microscopy suggests that the reason for these contrasting biological effects is that whereas the homoleptic complex localises in the nuclei of cells, the RuII(dppz)/ReI(dppn) complex preferentially accumulates in mitochondria. These observations illustrate how even small structural changes in metal based therapeutic leads can modulate their mechanism of action