Targeted Mutagenesis of the Oligopeptide Repeat Domain of the Yeast Prion Sup35

The formation of prions in the baker’s yeast Saccharomyces cerevisiae is determined by amino acid composition rather than the primary sequence of amino acids. The infectious amyloid proteins known as prions undergo nucleation and propagation, two distinct activities critical for prion formation. The ability for prions to be transferred from cell to cell, or propagate, is of interest not only in yeast prions but also in prion diseases such as the mammalian spongiform encephalopathies. Prion formation has been widely studied in yeast prions, however, the fundamental mechanisms behind the specific process of propagation of prions from cell to cell are not yet understood. In the most well-studied yeast prion, the prion form [PSI+] of Sup35, a domain of 5 ½ degenerate oligopeptide repeats called the oligopeptide repeat domain (ORD) has been shown to be important for prion propagation and to have a distinct amino acid composition as compared to the nucleation domain region. A library mutagenesis experiment has identified amino acids that favor or disfavor prion propagation in yeast cells. To confirm the results of the random library mutagenesis experiment, we generated several clones in which a portion of the ORD (the fourth oligopeptide repeat) was replaced with defined sequences expected to propagate or fail to propagate

Child sexual abuse and subsequent offending and victimisation: A 45 year follow-up study

This study investigates whether a disproportionate number of CSA victims subsequently perpetrate offences and experience future victimisation compared with people who have not been sexually abused. In a sample of 2,759 CSA victims who were abused between 1964 and 1995, it was found CSA victims were almost five times more likely than the general population to be charged with any offence than their non-abused counterparts, with strongest associations found for sexual and violent offences. CSA victims were also more likely to have been victims of crime, particularly crimes of a sexual or violent nature. This research highlights the need for therapeutic interventions targeted at adolescent male CSA victims, particularly with regard to offender treatment programs, where many programs currently do not allow for exploration of offenders’ own sexual victimisation

Mapping the Beta-Sheet Structure of the Yeast Prion Sup35 through Creation of Targeted Mutant Forms

Proteins with an aggregated form rich in beta-sheet structure are known as amyloids, of which a subset are infectious. These infectious proteins are known as prions and cause diseases including bovine spongiform encephalopathy (“Mad Cow” disease). Several prions have been identified in the baker’s yeast, Saccharomyces cerevisiae. One of the most well-studied yeast prions is the protein Sup35. To understand the fine protein structure of Sup35 better, we used PCR-based mutagenesis to introduce a lysine residue (a charged amino acid) at five defined places in the protein sequence of Sup35. We describe our process for creating these mutant versions and the results of DNA sequencing of each mutant version. The next step will be to assess prion formation and stability of clones with the correct sequences. Understanding the behavior of yeast prions has proven helpful in understanding human amyloid diseases and further studies on these yeast prions, including Sup35, will expand our knowledge further

Milk Consumption Following Exercise Reduces Subsequent Energy Intake in Female Recreational Exercisers

The aim of this study was to evaluate the effects of skimmed milk as a recovery drink following moderate–vigorous cycling exercise on subsequent appetite and energy intake in healthy, female recreational exercisers. Utilising a randomised cross-over design, nine female recreational exercisers (19.7 ± 1.3 years) completed a V̇O2peak test followed by two main exercise trials. The main trials were conducted following a standardised breakfast. Following 30 min of moderate-vigorous exercise (65% V̇O2peak), either 600 mL of skimmed milk or 600 mL of orange drink (475 mL orange juice from concentrate, 125 mL water), which were isoenergetic (0.88 MJ), were ingested, followed 60 min later with an ad libitum pasta meal. Absolute energy intake was reduced 25.2% ± 16.6% after consuming milk compared to the orange drink (2.39 ± 0.70 vs. 3.20 ± 0.84 MJ, respectively; p = 0.001). Relative energy intake (in relation to the energy content of the recovery drinks and energy expenditure) was significantly lower after milk consumption compared to the orange drink (1.49 ± 0.72 vs. 2.33 ± 0.90 MJ, respectively; p = 0.005). There were no differences in AUC (× 1 h) subjective appetite parameters (hunger, fullness and desire to eat) between trials. The consumption of skimmed milk following 30 min of moderate-vigorous cycling exercise reduces subsequent energy intake in female recreational exercisers

55 Strong

Undergraduate Fil