Tetrahymena telomerase catalyzes nucleolytic cleavage and nonprocessive elongation

Telomerase is a ribonucleoprotein enzyme that adds telomeric repeats to chromosomes, maintaining telomere length and stabilizing chromosome ends. In vitro, telomerase from the ciliate Tetrahymena elongates single-stranded, guanosine-rich DNA primers by adding repeats of the Tetrahymena telomeric sequence, dT2G4. We have identified two activities of Tetrahymena telomerase in addition to the previously described processive elongation reaction: a 3'-5' nucleolytic cleavage of primer or product DNA and a nonprocessive mode of elongation. The nucleolytic cleavage activity removed residues not conforming to the telomeric repeat sequence from a primer 3' end, eliminating mismatch between DNA primer and RNA template sequences. Template-matched residues were also cleaved from primer or product DNA. Specific primer lengths, sequences, and concentrations stimulated cleavage and processive or nonprocessive elongation differentially. These newly identified activities suggest that telomerase may catalyze a range of telomere synthesis and repair functions and suggest mechanistic similarities between telomerase and RNA polymerase enzymes. On the basis of our results, we propose a model for telomerase primer binding, cleavage, and elongation

A Collaborative Approach to Developing Culturally Themed Digital Collections

The College of Arts and Sciences at the University of Kentucky (UK) has created the Passport to the World Program (PWP) to celebrate campus-wide the cultural heritage of a country or region every academic year. The UK Libraries International Programs has been an active contributor to PWP by collaborating with faculty and different library departments to develop unique digital collections that serve to connect viewers with the featured country or region. To begin with, the Director of the International Programs (DIP) consults faculty and librarians at the UK Libraries Special Collections Research Center to select relevant materials for digitization. She also sources interesting artifacts from the larger community to create compilations of digital photos. Afterward, DIP invites faculty to annotate the images in order to highlight the cultural and historical significance of the materials and artifacts. The images, their annotations, and the accompanying metadata are ingested into UK’s institutional repository to create a virtual exhibit that is freely accessible online. At the same time, a corresponding physical exhibit is set up in the library to showcase the images. People interested in learning more about the images can scan QR codes to view the virtual exhibit, read the annotations, and download the images. Since the institutional repository tracks download rates of available items, faculty who have contributed to the virtual exhibit receive periodical notifications of the download counts of the images. The repository platform also offers an online dashboard for DIP and the faculty to assess the page hits of the virtual exhibit and to analyze the geographical and institutional distributions of the downloads. As part of the repository holdings, the virtual exhibit is preserved through the library’s participation in the Digital Preservation Network. This presentation demonstrates that the library can play a significant role in supporting a campus-wide initiative by leveraging its resources and services to build, assess, and preserve culturally themed digital collections. The outcome not only helps promote the awareness of a foreign culture but also increases the visibility of some little-known artifacts and rare library materials

A Collaborative Approach to Developing Culturally Themed Digital Collections

The College of Arts and Sciences at the University of Kentucky (UK) has created the Passport to the World Program (PWP) to celebrate campus-wide the cultural heritage of a country or region every academic year. The UK Libraries International Programs has been an active contributor to PWP by collaborating with faculty and different library departments to develop unique digital collections that serve to connect viewers with the featured country or region. To begin with, the Director of the International Programs (DIP) consults faculty and librarians at the UK Libraries Special Collections Research Center to select relevant materials for digitization. She also sources interesting artifacts from the larger community to create compilations of digital photos. Afterward, DIP invites faculty to annotate the images in order to highlight the cultural and historical significance of the materials and artifacts. The images, their annotations, and the accompanying metadata are ingested into UK’s institutional repository to create a virtual exhibit that is freely accessible online. At the same time, a corresponding physical exhibit is set up in the library to showcase the images. People interested in learning more about the images can scan QR codes to view the virtual exhibit, read the annotations, and download the images. Since the institutional repository tracks download rates of available items, faculty who have contributed to the virtual exhibit receive periodical notifications of the download counts of the images. The repository platform also offers an online dashboard for DIP and the faculty to assess the page hits of the virtual exhibit and to analyze the geographical and institutional distributions of the downloads. As part of the repository holdings, the virtual exhibit is preserved through the library’s participation in the Digital Preservation Network. This presentation demonstrates that the library can play a significant role in supporting a campus-wide initiative by leveraging its resources and services to build, assess, and preserve culturally themed digital collections. The outcome not only helps promote the awareness of a foreign culture but also increases the visibility of some little-known artifacts and rare library materials

Going Global: The Library as a Critical Player in Internationalizing a University

To support the University of Kentucky’s (UK) strategic plan, UK Libraries created a Director of International Programs (DIP) position in 2010 to plan and manage its international initiatives. In consultation of the UK administration, the DIP identified areas in which the library could make major contributions toward internationalization. The DIP has made significant progress in the areas by participating in the College of Arts and Sciences’ Passport to the World Program. Each year the College celebrates the cultural heritage of a country/region. The DIP and liaison librarians collaborate with faculty from different departments to annotate and showcase relevant materials from the library’s special collections in physical and online exhibits. We also host lectures and movie screenings in which faculty introduce audiences to specific cultural features and practices. Assessment of the events is reported to the Provost’s Office annually. Thanks to positive feedback and faculty recommendations, the library’s involvement in the Passport to the World Program went from peripheral in 2010 to being a major organizer with the appointment of the DIP as a member of the Program’s steering committee in 2013. Meanwhile, the annual library budget for hosting international events jumped from a pittance to $8,000. This poster demonstrates using images and brochures that the library has been a crucial player in executing UK’s internationalization strategy. Liaison librarians have (and will continue to) played a pivotal role in building lasting relationships with various campus constituents to support UK’s strategic goals

Leadership, the logic of sufficiency and the sustainability of education

The notion of sufficiency has not yet entered mainstream educational thinking, and it still has to make its mark upon educational leadership. However, a number of related concepts – particularly those of sustainability and complexity theory – are beginning to be noticed. This article examines these two concepts and uses them to critique the quasi-economic notion of efficiency, before arguing that the concept of sufficiency arises naturally from this discussion. This concept, originally derived from environmental thinking, has both metaphorical and practical impact for educational organizations and their leadership. An examination of three possible meanings suggests that while an embrace of an imperative concept of sufficiency seems increasingly necessary, its adoption would probably lead to a number of other problems, as it challenges some fundamental societal values and assumptions. Nevertheless, the article argues that these need to be addressed for the sake of both sustainable leadership and a sustainable planet

Human Telomerase Reverse Transcriptase (hTERT) Q169 Is Essential for Telomerase Function In Vitro and In Vivo

BACKGROUND:Telomerase is a reverse transcriptase that maintains the telomeres of linear chromosomes and preserves genomic integrity. The core components are a catalytic protein subunit, the telomerase reverse transcriptase (TERT), and an RNA subunit, the telomerase RNA (TR). Telomerase is unique in its ability to catalyze processive DNA synthesis, which is facilitated by telomere-specific DNA-binding domains in TERT called anchor sites. A conserved glutamine residue in the TERT N-terminus is important for anchor site interactions in lower eukaryotes. The significance of this residue in higher eukaryotes, however, has not been investigated. METHODOLOGY/PRINCIPAL FINDINGS:To understand the significance of this residue in higher eukaryotes, we performed site-directed mutagenesis on human TERT (hTERT) Q169 to create neutral (Q169A), conservative (Q169N), and non-conservative (Q169D) mutant proteins. We show that these mutations severely compromise telomerase activity in vitro and in vivo. The functional defects are not due to abrogated interactions with hTR or telomeric ssDNA. However, substitution of hTERT Q169 dramatically impaired the ability of telomerase to incorporate nucleotides at the second position of the template. Furthermore, Q169 mutagenesis altered the relative strength of hTERT-telomeric ssDNA interactions, which identifies Q169 as a novel residue in hTERT required for optimal primer binding. Proteolysis experiments indicate that Q169 substitution alters the protease-sensitivity of the hTERT N-terminus, indicating that a conformational change in this region of hTERT is likely critical for catalytic function. CONCLUSIONS/SIGNIFICANCE:We provide the first detailed evidence regarding the biochemical and cellular roles of an evolutionarily-conserved Gln residue in higher eukaryotes. Collectively, our results indicate that Q169 is needed to maintain the hTERT N-terminus in a conformation that is necessary for optimal enzyme-primer interactions and nucleotide incorporation. We show that Q169 is critical for the structure and function of human telomerase, thereby identifying a novel residue in hTERT that may be amenable to therapeutic intervention

Ancestral Mutation in Telomerase Causes Defects in Repeat Addition Processivity and Manifests As Familial Pulmonary Fibrosis

The telomerase reverse transcriptase synthesizes new telomeres onto chromosome ends by copying from a short template within its integral RNA component. During telomere synthesis, telomerase adds multiple short DNA repeats successively, a property known as repeat addition processivity. However, the consequences of defects in processivity on telomere length maintenance are not fully known. Germline mutations in telomerase cause haploinsufficiency in syndromes of telomere shortening, which most commonly manifest in the age-related disease idiopathic pulmonary fibrosis. We identified two pulmonary fibrosis families that share two non-synonymous substitutions in the catalytic domain of the telomerase reverse transcriptase gene hTERT: V791I and V867M. The two variants fell on the same hTERT allele and were associated with telomere shortening. Genealogy suggested that the pedigrees shared a single ancestor from the nineteenth century, and genetic studies confirmed the two families had a common founder. Functional studies indicated that, although the double mutant did not dramatically affect first repeat addition, hTERT V791I-V867M showed severe defects in telomere repeat addition processivity in vitro. Our data identify an ancestral mutation in telomerase with a novel loss-of-function mechanism. They indicate that telomere repeat addition processivity is a critical determinant of telomere length and telomere-mediated disease

Angular Dependence of Neutrino Flux in KM3 Detectors in Low Scale Gravity Models

Cubic kilometer neutrino telescopes are capable of probing fundamental questions of ultra-high energy neutrino interactions. There is currently great interest in neutrino interactions caused by low-scale, extra dimension models. Above 1 PeV the cross section in low scale gravity models rises well above the total Standard Model cross section. We assess the observability of this effect in the 1 PeV - 100 PeV energy range of kilometer-scale detectors with several new points of emphasis that hinge on enhanced neutral current cross sections. A major point is the importance of ``feed-down'' regeneration of upward neutrino flux, driven by new-physics neutral current interactions in the flux evolution equations. Feed-down is far from negligible, and it is essential to include its effect. We then find that the angular distribution of events has high discriminating value in separating models. In particular the ``up-to-down'' ratio between upward and downward-moving neutrino fluxes is a practical diagnostic tool which can discriminate between models in the near future. The slope of the angular distribution, in the region of maximum detected flux, is also substantially different in low-scale gravity and the Standard Model. These observables are only weakly dependent on astrophysical flux uncertainties. We conclude that angular distributions can reveal a breakdown of the Standard Model and probe the new physics beyond, as soon as data become available.Comment: 25 pages, 6 figures, discussion of calculations expanded, references adde

Investigating the role of the Est3 protein in yeast telomere replication

The Est3 subunit of yeast telomerase, which adopts a predicted OB-fold, is essential for telomere replication. To assess the possible contributions that Est3 might make to enzyme catalysis, we compared telomerase activity from wild type and est3-Δ strains of Saccharomyces castellii, which revealed that loss of the Est3 subunit results in a 2- to 3-fold decline in nucleotide addition. This effect was not primer-specific, based on assessment of a panel of primers that spanned the template of the S. castellii telomerase RNA. Furthermore, using nuclear magnetic resonance chemical shift perturbation, no chemical shift change was observed at any site in the protein upon addition of single-stranded DNA, arguing against a role for Est3 in recognition of telomeric substrates by telomerase. Addition of exogenous Est3 protein, including mutant Est3 proteins that are severely impaired for telomere replication in vivo, fully restored activity in est3-Δ telomerase reactions. Thus, Est3 performs an in vivo regulatory function in telomere replication, which is distinct from any potential contribution that Est3 might make to telomerase activity