Yeast POS5 NADH Kinase: Effects of a Mitochondrial Mutator Mutation on Mitochondrial Nucleotides

Saccharomyces cerevisiae contains three NAD⁺/NADH kinases, one of which is localized in mitochondria and phosphorylates NADH in preference to NAD⁺. Strand et al (Euk. Cell 2:809 (2003)) reported that a yeast mutation in POS5, which encodes the mitochondrial NADH kinase, is a mutator, specific for mitochondrial genes. Because of the involvement of NADPH in deoxyribonucleotide biosynthesis, we asked whether mitochondria in a pos5 deletion mutant contain abnormal deoxyribonucleoside triphosphate pools. We found pools of the four dNTPs² to be more than doubled in mutant mitochondrial extracts relative to wild-type. This might partly explain the mitochondrial mutator phenotype. However, the loss of antioxidant protection is also likely to be significant. To this end, we measured pyridine nucleotide pools in mutant and wild-type mitochondrial extracts and found levels of NADPH to be diminished about fourfold in Δpos5 mitochondrial extracts, with NADP⁺ diminished to a lesser degree. Our data suggest that both dNTP abnormalities and lack of antioxidant protection contribute to elevated mitochondrial gene mutagenesis in cells lacking the mitochondrial NADH kinase. The data also confirm previous reports of the specific function of POS5p in mitochondrial NADP⁺ and NADPH biosynthesis.Keywords: NADH kinase, Deoxyribonucleoside triphosphates, Mitochondria, Mutator, Pyridine nucleotidesKeywords: NADH kinase, Deoxyribonucleoside triphosphates, Mitochondria, Mutator, Pyridine nucleotide

A critical evaluation of students' attitudes to electronic learning at the University of Chester

The research described in this thesis reports the results of a study into the adoption of e-learning strategies based on the use of the World Wide Web (WWW) and Internet. Through an extensive and critical literature review, it exemplifies how higher education uses intranets to deliver learning and support services to their student population. The overall aim of this research was to investigate how e-learning at the University of Chester might more effectively support students' learning needs, thereby improving their experience of e-learning. Students were given a mode of study, either face-to-face (64 subjects) or experimental using online intranet delivery (66 subjects). The course used for this study was a 13 week, Level Two undergraduate computer course taken by non-computing students. Quantitative and qualitative data were collected and analysed. The results reveal significant differences between the performance of the e-learning and face-to-face groups with e-learning students performing poorly when compared to their face-to-face peers. A lack of responsiveness in tutor support and student motivation were established as being major contributing factors as well as differences in the students' individual learning profiles. The research concludes that e-learning, although promoted as being anytime and anywhere is limited in its flexibility and responsiveness in the context in which it was assessed. Most e-learning activities at the University of Chester can be described as 'one size fits all'. They require students to read printed text, carry out further work, research or exercises, and post written comments to a discussion board. There is little evidence that individual student needs and preferences are being considered or supported. With the move towards blended learning in educational institutions, e-learning strategies are being used as a regular part of the curriculum to enhance the student experience. This research provides alternatives for the development and delivery of more individually tailored e-learning courses and provides strategies for supporting students in virtual environments more effectively. The thesis concludes by proposing a new model for e-learning based on these results coupled with a self-critical review and proposals for further research.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Surfing, sweeping, and assembly of particles by a moving liquid crystal phase boundary

Non-equilibrium transport of particles embedded in a liquid crystal host can, by cooling through a phase transition, be exploited to create a remarkable variety of structures including shells, foams, and gels. Due to the complexity of the multicomponent system and protocol-dependent experimental results, the physical mechanisms behind structure selection remain only partially understood. Here we formulate a new model coupling LC physics to a Fokker-Planck equation as is commonly used in studies of transport. The resulting model allows us to draw an analogy between the LC-nanocomposite system and chemotaxis, enriching the space of possible target structures that could be produced. We study the model in one dimension both analytically and numerically to identify different parameter regimes where soliton-like pulses of particles ``surf'' the phase boundary or where the interface ``sweeps'' particles from one domain to another. We also consider an extended model that includes agglomeration of the particles and observe formation of periodic structures as a prototypical example of hierarchical self assembly. Results are compared with experimental observations of transport by isolated phase boundaries.Comment: 11 pages, 6 figure

Radial spoke protein 9 is necessary for axoneme assembly in <i>Plasmodium</i> but not in trypanosomatid parasites

Flagella are important for eukaryote cell motility, including in sperm, and are vital for life cycle progression of many unicellular eukaryotic pathogens. The ‘9+2’ axoneme in most motile flagella comprises nine outer doublet and two central-pair singlet microtubules. T-shaped radial spokes protrude from the outer doublets towards the central pair and are necessary for effective beating. We asked whether there were radial spoke adaptations associated with parasite lineage-specific properties in apicomplexans and trypanosomatids. Following an orthologue search for experimentally uncharacterised radial spoke proteins (RSPs), we identified and analysed RSP9. Trypanosoma brucei and Leishmania mexicana have an extensive RSP complement, including two divergent RSP9 orthologues, necessary for flagellar beating and swimming. Detailed structural analysis showed that neither orthologue is needed for axoneme assembly in Leishmania. In contrast, Plasmodium has a reduced set of RSPs including a single RSP9 orthologue, deletion of which in Plasmodium berghei leads to failure of axoneme formation, failed male gamete release, greatly reduced fertilisation and inefficient life cycle progression in the mosquito. This indicates contrasting selection pressures on axoneme complexity, likely linked to the different mode of assembly of trypanosomatid versus Plasmodium flagella

Type II-P Supernovae from the SDSS-II Supernova Survey and the Standardized Candle Method

We apply the Standardized Candle Method (SCM) for Type II Plateau supernovae (SNe II-P), which relates the velocity of the ejecta of a SN to its luminosity during the plateau, to 15 SNe II-P discovered over the three season run of the Sloan Digital Sky Survey - II Supernova Survey. The redshifts of these SNe - 0.027 < z < 0.144 - cover a range hitherto sparsely sampled in the literature; in particular, our SNe II-P sample contains nearly as many SNe in the Hubble flow (z > 0.01) as all of the current literature on the SCM combined. We find that the SDSS SNe have a very small intrinsic I-band dispersion (0.22 mag), which can be attributed to selection effects. When the SCM is applied to the combined SDSS-plus-literature set of SNe II-P, the dispersion increases to 0.29 mag, larger than the scatter for either set of SNe separately. We show that the standardization cannot be further improved by eliminating SNe with positive plateau decline rates, as proposed in Poznanski et al. (2009). We thoroughly examine all potential systematic effects and conclude that for the SCM to be useful for cosmology, the methods currently used to determine the Fe II velocity at day 50 must be improved, and spectral templates able to encompass the intrinsic variations of Type II-P SNe will be needed.Comment: Accepted for publication by ApJ; data used in this paper can be downloaded from http://sdssdp47.fnal.gov/sdsssn/photometry/SNIIp.tgz; citation errors correcte

First-Year Spectroscopy for the SDSS-II Supernova Survey

This paper presents spectroscopy of supernovae discovered in the first season of the Sloan Digital Sky Survey-II Supernova Survey. This program searches for and measures multi-band light curves of supernovae in the redshift range z = 0.05 - 0.4, complementing existing surveys at lower and higher redshifts. Our goal is to better characterize the supernova population, with a particular focus on SNe Ia, improving their utility as cosmological distance indicators and as probes of dark energy. Our supernova spectroscopy program features rapid-response observations using telescopes of a range of apertures, and provides confirmation of the supernova and host-galaxy types as well as precise redshifts. We describe here the target identification and prioritization, data reduction, redshift measurement, and classification of 129 SNe Ia, 16 spectroscopically probable SNe Ia, 7 SNe Ib/c, and 11 SNe II from the first season. We also describe our efforts to measure and remove the substantial host galaxy contamination existing in the majority of our SN spectra.Comment: Accepted for publication in The Astronomical Journal(47pages, 9 figures

The Special Sauce of the Cancer Prevention and Control Research Network: 20 Years of Lessons Learned in Developing the Evidence Base, Building Community Capacity, and Translating Research into Practice

PURPOSE: The Cancer Prevention and Control Research Network (CPCRN) is a national network focused on accelerating the translation of cancer prevention and control research evidence into practice through collaborative, multicenter projects in partnership with diverse communities. From 2003 to 2022, the CPCRN included 613 members. METHODS: We: (1) characterize the extent and nature of collaborations through a bibliometric analysis of 20 years of Network publications; and (2) describe key features and functions of the CPCRN as related to organizational structure, productivity, impact, and focus on health equity, partnership development, and capacity building through analysis of 22 in-depth interviews and review of Network documentation. RESULTS: Searching Scopus for multicenter publications among the CPCRN members from their time of Network engagement yielded 1,074 collaborative publications involving two or more members. Both the overall number and content breadth of multicenter publications increased over time as the Network matured. Since 2004, members submitted 123 multicenter grant applications, of which 72 were funded (59%), totaling more than $77 million secured. Thematic analysis of interviews revealed that the CPCRN\u27s success-in terms of publication and grant productivity, as well as the breadth and depth of partnerships, subject matter expertise, and content area foci-is attributable to: (1) its people-the inclusion of members representing diverse content-area interests, multidisciplinary perspectives, and geographic contexts; (2) dedicated centralized structures and processes to enable and evaluate collaboration; and (3) focused attention to strategically adapting to change. CONCLUSION: CPCRN\u27s history highlights organizational, strategic, and practical lessons learned over two decades to optimize Network collaboration for enhanced collective impact in cancer prevention and control. These insights may be useful to others seeking to leverage collaborative networks to address public health problems

Population-level impact and herd effects following the introduction of human papillomavirus vaccination programmes: updated systematic review and meta-analysis

Background More than 10 years have elapsed since human papillomavirus (HPV) vaccination was implemented. We did a systematic review and meta-analysis of the population-level impact of vaccinating girls and women against human papillomavirus on HPV infections, anogenital wart diagnoses, and cervical intraepithelial neoplasia grade 2+ (CIN2+)to summarise the most recent evidence about the effectiveness of HPV vaccines in real-world settings and to quantify the impact of multiple age-cohort vaccination.Methods In this updated systematic review and meta-analysis, we used the same search strategy as in our previous paper. We searched MEDLINE and Embase for studies published between Feb 1, 2014, and Oct 11, 2018. Studies were eligible if they compared the frequency (prevalence or incidence) of at least one HPV-related endpoint (genital HPV infections, anogenital wart diagnoses, or histologically confirmed CIN2+) between pre-vaccination and post-vaccination periods among the general population and if they used the same population sources and recruitment methods before and after vaccination. Our primary assessment was the relative risk (RR) comparing the frequency (prevalence or incidence) of HPV-related endpoints between the pre-vaccination and post-vaccination periods. We stratified all analyses by sex, age, and years since introduction of HPV vaccination. We used random-effects models to estimate pooled relative risks.Findings We identified 1702 potentially eligible articles for this systematic review and meta-analysis, and included 65 articles in 14 high-income countries: 23 for HPV infection, 29 for anogenital warts, and 13 for CIN2+.After 5\u20138 years of vaccination, the prevalence of HPV 16 and 18 decreased significantly by 83% (RR 0\ub717, 95% CI 0\ub711\u20130\ub725) among girls aged 13\u201319 years, and decreased significantly by 66% (RR 0\ub734, 95% CI 0\ub723\u20130\ub749) among women aged 20\u201324 years. The prevalence of HPV 31, 33, and 45 decreased significantly by 54% (RR 0\ub746, 95% CI 0\ub733\u20130\ub766) among girls aged 13\u201319 years. Anogenital wart diagnoses decreased significantly by 67% (RR 0\ub733, 95% CI 0\ub724\u20130\ub746) among girls aged 15\u201319 years, decreased significantly by 54% (RR 0\ub746, 95% CI 0.36\u20130.60) among women aged 20\u201324 years, and decreased significantly by 31% (RR 0\ub769, 95% CI 0\ub753\u20130\ub789) among women aged 25\u201329 years. Among boys aged 15\u201319 years anogenital wart diagnoses decreased significantly by 48% (RR 0\ub752, 95% CI 0\ub737\u20130\ub775) and among men aged 20\u201324 years they decreased significantly by 32% (RR 0\ub768, 95% CI 0\ub747\u20130\ub798). After 5\u20139 years of vaccination, CIN2+ decreased significantly by 51% (RR 0\ub749, 95% CI 0\ub742\u20130\ub758) among screened girls aged 15\u201319 years and decreased significantly by 31% (RR 0\ub769, 95% CI 0\ub757\u20130\ub784) among women aged 20\u201324 years.Interpretation This updated systematic review and meta-analysis includes data from 60 million individuals and up to 8 years of post-vaccination follow-up. Our results show compelling evidence of the substantial impact of HPV vaccination programmes on HPV infections and CIN2+ among girls and women, and on anogenital warts diagnoses among girls, women, boys, and men. Additionally, programmes with multi-cohort vaccination and high vaccination coverage had a greater direct impact and herd effects