Mutations in the Chaperone Hsp104 Differentially Propagate Yeast Prions

Molecular chaperones are critical elements of the protein quality control network and are responsible for protecting cells from protein misfolding and aggregation. In yeast, molecular chaperones also participate in the propagation of self-replicating, protein-only elements called prions. The AAA+ ATPase Hsp104 is a disaggregase essential for yeast prion maintenance and is responsible for fragmentation of prions to generate the transmissible prion propagons. This work focuses on further understanding the role of Hsp104 in prion propagation and protein aggregate resolubilization. To do this, I first identified novel mutations in Hsp104 which altered [PSI+] propagation and characterized their effects on Hsp104 function, protein disaggregation, and prion variant propagation. One mutant propagated a phenotypically undetectable [PSI+] phenotype that resulted from soluble oligomers of Sup35. I discovered that soluble, more SDS-sensitive oligomers of Sup35 were sufficient to transmit the prion state but were not capable of producing the nonsense suppression phenotype associated with Sup35 aggregation in the [PSI+] state. I found that these oligomers are also present in wild type [PSI+] cells and can be distinguished from the large Sup35 aggregates and still transmit the prion conformation. Next, I characterized another set of mutations that are located in a less well-understood domain of Hsp104. I used these mutations to elucidate the function of the middle domain in prion maintenance and its affect on the biochemical activities of Hsp104. I found that this domain mediates the disaggregation and ATPase activities of Hsp104 and has differential effects on the propagation of specific prion variants. I hypothesize that the regulation of Hsp104 function by the middle domain plays a significant role in the selective amplification of specific conformational variants. Finally, I investigated the affect that changes in Hsp104 activity have on prion variant propagation and protein disaggregation. I utilized two novel mutations which significantly decreased the activity of Hsp104 to examine the requirements of two individual yeast prions, [PSI+] and [RNQ+], for Hsp104. I found that propagation of both prions was altered when the activity of Hsp104 was significantly decreased, although specific conformational variants of each could be maintained. I hypothesize that structural variants of yeast prions require varying amounts of Hsp104 activity for optimal propagation. These experiments elucidate how alterations in the activity of the molecular chaperone Hsp104 affect remodeling of prions and specific prion conformational variants as well as amorphous aggregates. As an essential chaperone in yeast prion propagation, characterizing the disaggregation mechanism of Hsp104 is important for understanding the mechanism of amyloid aggregation and thus, has broad implications for both functional and disease-related amyloid models

Addressing online information resources’ access challenges: potentials of resource discovery tools’ application

This study was designed to assess the awareness and usage of a discovery tool known as LibHub among undergraduate students in their research projects’ undertakings. The study involved respondents who were randomly selected from purposively chosen four degree courses in the Faculty of Agriculture at the Sokoine University Agriculture in Tanzania. Copies of semi-structured questionnaire were distributed to 200 respondents for self-administration. Of the returned copies of the questionnaire, 158 (79%) were found complete and useful for further analysis. The findings of the study indicate that majority of respondents who knew and used LibHub were those who previously attended information literacy trainings at the University as compared to those who had never attended such trainings. Respondents who acknowledged to have used LibHub in their online information search endeavours cited ability to access information from various sources using a single authentication as the major advantage of this research tool. They also pointed out that a single search interface provided by LibHub saved time they spent in searching literature. However, respondents complained of limited number of computers at the University, few wireless points for internet access, and low internet speed as hindrances for effective utilisation of the LibHub in accessing online information resources. The study recommends more institutions to consider adoption of discovery tools in fulfilling their campaigns to foster the utilisation of online information resources

Low activity of select Hsp104 mutants is sufficient to propagate unstable prion variants

The molecular chaperone network plays a critical role in the formation and propagation of self-replicating yeast prions. Not only do individual prions differ in their requirements for certain chaperones, but structural variants of the same prion can also display distinct dependences on the chaperone machinery, specifically Hsp104. The AAA+ ATPase Hsp104 is a disaggregase required for the maintenance of most known yeast prions. As a key component in the propagation of prions, understanding how Hsp104 differs in its interaction with specific variants is crucial to understanding how prion variants may be selected or evolve. Here, we investigate two novel mutations in Hsp104, hsp104-G254D, and hsp104-G730D, which allow us to elucidate some mechanistic features of Hsp104 disaggregation and its requirement for activity in propagating specific prion variants. Both Hsp104 mutants propagate the [PSI+] prion to some extent, but show a high rate of prion loss. Both Hsp104-G254D and Hsp104-G730D display reduced biochemical activity, yet differ in their ability to efficiently resolubilize disordered, heat-aggregated substrates. Additionally, both mutants impair weak [PSI+] propagation, but are capable of propagating the less stable strong [PSI+] variant to some extent. One of the Hsp104 mutants also has the ability to propagate one variant of the [RNQ+] prion. Thus, our data suggest that changes in Hsp104 activity limit substrate disaggregation in a manner that depends more on the stability of the substrate than the nature of the aggregated species

The suitability of the Unified Theory of Acceptance and Use of Technology (UTAUT) model in open access adoption studies

Technology acceptance models or theories are commonly used in studies aiming at predicting and explaining the individual behaviours towards the acceptance and usage of new technologies. This paper reports part of the findings from a doctoral research project which focused at analysing the acceptance and usage of open access within public universities in Tanzania. The study was guided by the Unified Theory of Technology Acceptance and Usage (UTAUT) model). The survey questionnaire targeted 544 respondents selected through stratified random sampling from a population of 1088 university researchers at six public universities in Tanzania. A response rate of 73 percent was achieved and the binary logistic regression statistics of the Statistical Package for Social Sciences (SPSS) was used for data analysis. The study findings suggest support for the application of the UTAUT model in studying the adoption of open access in a research environment. Among the findings, attitude, awareness, effort expectancy and performance expectancy were established as the key determinants for the researchers’ behavioural intentions of open access usage. Similarly, age, awareness, behavioural intention, facilitating conditions and social influence were found to significantly affect researchers’ actual usage of open access. These factors should therefore be taken into account in the planning and implementation of open access projects. A further validation of the open access research model in similar research institutions in Tanzania and elsewhere is recommende

Office-Based Small Bore Needle Arthroscopy of the Knee

Advanced imaging, such as MRI, can sometimes provide inconclusive results with knee pathology, leaving both patients and providers with a diagnostic challenge. In-office arthroscopy is a newer, low-risk, diagnostic procedure that allows the physician to use a small bore needle arthroscope to view the intra-articular anatomy of the joint. The patient and provider are provided with immediate results of the pathology found. This prevents having to undergo repeat imaging, which can be a costly, time-consuming, and inconclusive process. Ideal indications are patients who are claustrophobic, have previously undergone meniscal or chondral surgery, or whose MRI results are inconclusive. This chapter will review the background, indications, technique, and risks of this novel procedure

The adoption of open access scholarly communication in Tanzanian public universities: some Influencing factors

Open access is a means for free availability of scholarly content via the internet. It is an emerging opportunity for wider and unlimited access to scholarly literature. Scholarly communication, through open access journals and self-arching, are the two main approaches of open access publishing. However, this mode of scholarly communication is not widely utilised in developing countries such as Tanzania. This article discusses the factors that influence the adoption of open access for scholarly communication in Tanzanian public universities, based on a study conducted in 2008 using a survey questionnaire. A sample of 544 researchers, selected through stratified random sampling from a population of 1 088 researchers and 69 policymakers at six public universities in Tanzania, provided their views. It was evident from the findings that researchers’ internet usage skills and self-efficacy, social influence, performance expectancy, effort expectancy, and the respondents’ general perceptions about open access were the positive factors likely to facilitate open access adoption. The current poor research conditions and researchers’ low internet self-efficacy (such as inadequate information search skills) were cited as the main hindrances for researchers to use open access outlets to access scholarly content. It is therefore recommended that university policies on scholarly communication should be revised to incorporate the use of open access publishing. Furthermore, universities should accelerate the establishment of institutional repositories, advocacy campaigns and training directed at researchers, policymakers, readers and information managers of scholarly content, and the improvement of internet speed through subscription to more bandwidth, so as to meet the demand from the scholarly communit

Zur Ökonomisierung der europäischen Hochschulpolitik

Die Diplomarbeit widmet sich zwei Zielen. Zum einen soll die zunehmende Ökonomisierung der Europäischen Hochschulpolitik aus der Historie der Europäischen Gemeinschaft seit den Römischen Verträgen erläutert werden. Zum anderen wird die finanzielle Diskrepanz zwischen geistes- und sozialwissenschaftlichen Studienrichtungen zu wirtschafts-, naturwissenschaftlichen und technischen Studien aufgezeigt. Hierbei wird sich der Theorie der Policy-Analyse nach Schumann und Sabatier bedient, die vor allem die Akteursebene im europäischen Bildungsprozess beleuchten soll und damit Erklärungsbedarf liefert, wie Akteure Politikinhalte über längere Zeiträume verändern und entscheidend mitbestimmen können. Als letzten Punkt stellt die Diplomarbeit ein Plädoyer für Geistes- und Sozialwissenschaften dar und beleuchtet diesbezüglich auch die widersprüchliche Entwicklung der Politikwissenschaft in Österreich