Assessment of Inactivating Stop Codon Mutations in Forty Saccharomyces cerevisiae Strains: Implications for [PSI+] Prion- Mediated Phenotypes

The yeast prion [PSI+] has been implicated in the generation of novel phenotypes by a mechanism involving a reduction in translation fidelity causing readthrough of naturally occurring stop codons. Some [PSI+] associated phenotypes may also be generated due to readthrough of inactivating stop codon mutations (ISCMs). Using next generation sequencing we have sequenced the genomes of two Saccharomyces cerevisiae strains that are commonly used for the study of the yeast [PSI+] prion. We have identified approximately 26,000 and 6,500 single nucleotide polymorphisms (SNPs) in strains 74-D694 and G600 respectively, compared to reference strain S288C. In addition to SNPs that produce non-synonymous amino acid changes we have also identified a number of SNPs that cause potential ISCMs in these strains, one of which we show is associated with a [PSI+]-dependent stress resistance phenotype in strain G600. We identified twenty-two potential ISCMs in strain 74-D694, present in genes involved in a variety of cellular processes including nitrogen metabolism, signal transduction and oxidative stress response. The presence of ISCMs in a subset of these genes provides possible explanations for previously identified [PSI+]-associated phenotypes in this strain. A comparison of ISCMs in strains G600 and 74-D694 with S. cerevisiae strains sequenced as part of the Saccharomyces Genome Resequencing Project (SGRP) shows much variation in the generation of strain-specific ISCMs and suggests this process is possible under complex genetic control. Additionally we have identified a major difference in the abilities of strains G600 and 74-D694 to grow at elevated temperatures. However, this difference appears unrelated to novel SNPs identified in strain 74-D694 present in proteins involved in the heat shock response, but may be attributed to other SNP differences in genes previously identified as playing a role in high temperature growth

Protein Folding Activity of the Ribosome is involved in Yeast Prion Propagation.

6AP and GA are potent inhibitors of yeast and mammalian prions and also specific inhibitors of PFAR, the protein-folding activity borne by domain V of the large rRNA of the large subunit of the ribosome. We therefore explored the link between PFAR and yeast prion [PSI(+)] using both PFAR-enriched mutants and site-directed methylation. We demonstrate that PFAR is involved in propagation and de novo formation of [PSI(+)]. PFAR and the yeast heat-shock protein Hsp104 partially compensate each other for [PSI(+)] propagation. Our data also provide insight into new functions for the ribosome in basal thermotolerance and heat-shocked protein refolding. PFAR is thus an evolutionarily conserved cell component implicated in the prion life cycle, and we propose that it could be a potential therapeutic target for human protein misfolding diseases

Fleet safety countermeasures in a large Australian fleet

The available evidence suggests that work-related drivers are over-involved in crashes compared with other drivers. However, despite this over-involvement in crashes there has been limited research examining the social-psychological factors that impact on crash risk in work-related drivers. While industry reports suggest that organisational culture can affect work related-driver behaviour, there is limited empirical evidence that has explored the influence of management systems on workplace road safety outcomes and driver behaviour. This study will thus examine (a) social-psychological factors that influence driver behaviour and (b) managerial and organisational system factors that influence workplace road safety outcomes. The research will draw on psychological theory (Theory of Planned Behaviour) and organisational theory (Cooper’s Reciprocal Safety Culture Model). This study will also examine the efficacy of existing fleet safety countermeasures (e.g., driver training, financial incentive schemes and newsletters) in a large government organisation, on the behaviour of work-related drivers and how these countermeasures are implemented, utilised, and evaluated by the fleet management system

Workplace road safety and culture : Safety practices for employees and the community

Road trauma remains a significant concern internationally. Traffic crashes rank within the top three leading causes of death for individuals aged between 15-44 years old, with nonfatal casualties occurring at around 30 times the rate of fatal incidents. Historically, road safety research has not captured factors relating to driving purpose. However, more recently, researchers have focused on the importance of driving for work. Over a third of traffic volume represents commuting or driving in the line of employment; improving workplace road safety practices represents a tangi¬ble way of reducing road trauma. This chapter considers the link between safety culture and best practice in workplace road safety. It is argued that best practice is not a term to define individual safety practices, but a system of practices that create a culture of safety. This research uses data collected on organizations workplace road safety practices within the Australian con¬text. This data has been collected by the National Road Safety Partnership Program (NRSPP); an initiative that constitutes a network of organizations and academics working together to develop a positive road safety culture. Twenty-four case studies are presented of organizations that have imple¬mented workplace road safety programs to improve their safe driving cul¬ture. Qualitative analysis was conducted to systematically categorize the safety initiatives and their indicators of success. Almost all case studies expressed the importance of developing a safety-first culture in the work¬place. Third-party regulation, internal policy and corporate social responsi¬bility form the foundation of workplace safety. However, it was the culture and attitude towards the safety initiatives that achieved effectiveness in the long-term. The findings of this research support the argument that best practice is best achieved when integrated within a culture that values and prioritizes safety, rather than implemented in isolation to other elements in the workplace system.</p

Multiple-shot laser damage thresholds of ultraviolet reflectors at 248 and 308 nanometers

Multiple-shot damage thresholds of dielectric reflectors have been measured at 248 and 308 nm. Standard irradiation conditions were a 10-ns pulsewidth, 0.6-mm spot diameter and 35-Hz pulse repetition frequency. The reflectors, from various sources, were composed of oxide and fluoride films. Although damage was generally initiated at visible film defects, there was no correlation between damage susceptibility and the appearance of these defects. At levels near threshold, damage was most often observed as an increase in white-light scatter of a site with no growth upon continued irradiation; at higher levels, the damage site grew with successive shots. Test sites were subjected to at least 10/sup 3/ shots and some sites received as many as 2.5 x 10/sup 4/ shots; however, with only one exception damage was found to occur within the first few shots or not at all. Reflectors at 248 nm typically had damage thresholds in the 1.0 to 1.8 J/cm/sup 2/ range with two samples exhibiting unexpectedly high thresholds of 2.8 and 3.0 J/cm/sup 2/. In some cases, a subthreshold pre-irradiation treatment resulted in a 20 to 25% enhancement in damage resistance

Evaluation of a Fleet Safety Management Information System

The aim of this innovative research is to conceptualise an evaluation framework and utilize it to assess fleet coordinators’ attitudes toward and the usage of a fleet safety management system. This management system is designed to provide diagnostic capabilities through an internet-based monitoring system and its associated performance databases. Also, this research represents one of the few studies that examine fleet safety in a public sector