Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks

Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at its optimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and contribute to resistance; and strengthen the case for a role in survival of systems involved in manganese and iron homeostasis

House money effects, risk preferences and the public goods game

AbstractThis paper investigates whether risk preferences inform the decision of how much to put into the public account in the public goods game under the three different frames (the two house money effect frames: the standard and covered-loss frames, as well as the real-loss frame). The main contribution of this paper finds that the covered loss and real loss treatments are statistically equivalent. This assures researchers that just introducing the notion of loss into an experimental treatment without the need for participants to realize a real loss is still a valid experimental instrument. We also find that the house money effect is a better explanation for the difference in contributions between gain and loss framing than loss aversion

A comparison of the perceptions of Singapore’s 'holistic' university education amongst STEM and non-STEM undergraduates and its effect on their employability

With growing concerns about the employability of university fresh graduates in Singapore’s public universities, we study what undergraduates think of the Ministry of Education’s (MOE’s) definition and implementation of ‘holistic’ education, and how that impacts their perceptions of employability in Singapore. Using theories of Bourdieu’s cultural and economic capital, and the sociology of expectations, we conducted an online survey and face-to-face interviews with students and Recruitment Industry Experts (RIEs) to identify gaps between undergraduates’ and RIEs’ understandings of employability, and if those gaps could be due to differences in perceptions held by STEM and non-STEM undergraduates. We found no significant gaps in perceptions held between the students and RIEs and STEM and non-STEM undergraduates as students are generally highly aware of the industrys’ requirements. However, their primary motivation to learn does not align with MOE’s goal of instilling a passion for learning, but out of obligation to fulfil their employability requirements.Bachelor of Social Sciences in Sociolog

Preparation and Characterization of {3-[2-Pd(μ-Cl)-4-MeO-C₆H₃-]syd-P(Bu^t)₂}₂

A dimer of a six-membered metallacycle [Pd(C-P)X]2 (2) was prepared by reacting PdCl2 with 3-(4-methoxyphenyl)-4-(di-tert-butylphosphino)sydnone in an ethanol solution at 80 °C. This is the first report of the activation of a C−H bond in the arylsydnone system. The molecular structure of compound 2 was determined by a single-crystal X-ray crystallographic study