405 research outputs found

    The Saccharomyces cerevisiae high mobility group box protein HMO1 contains two functional DNA binding domains

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    High mobility group box (HMGB) proteins are architectural proteins whose HMG DNA binding domains confer significant preference for distorted DNA, such as 4-way junctions. HMO1 is one of 10 Saccharomyces cerevisiae HMGB proteins, and it is required for normal growth and plasmid maintenance and for regulating the susceptibility of yeast chromatin to nuclease. Using electrophoretic mobility shift assays, we have shown here that HMO1 binds 26-bp duplex DNA with K d = 39.6 ± 5.0 nM and that its divergent box A domain participates in DNA interactions, albeit with low affinity. HMO1 has only modest preference for DNA with altered conformations, including DNA with nicks, gaps, overhangs, or loops, as well as for 4-way junction structures and supercoiled DNA. HMO1 binds 4-way junctions with half-maximal saturation of 19.6 ± 2.2 nM, with only a modest increase in affinity in the absence of magnesium ions (half-maximal saturation 6.1 ± 1.1 nM). Whereas the box A domain contributes modest structure-specific binding, the box B domain is required for high affinity binding. HMO1 bends DNA, as measured by DNA cyclization assays, facilitating cyclization of 136-, 105-, and 87-bp DNA, but not 75-bp DNA, and it has a significantly longer residence time on DNA minicircles compared with linear duplex DNA. The unique DNA binding properties of HMO1 are consistent with global roles in the maintenance of chromatin structure

    Interactions between N- and C-terminal domains of the Saccharomyces cerevisiae high-mobility group protein HMO1 are required for DNA bending

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    The Saccharomyces cerevisiae high-mobility group protein HMO1 is composed of two DNA-binding domains termed box A and box B, of which only box B is predicted to adopt a HMG fold, and a lysine-rich C-terminal extension. To assess the interaction between individual domains and their contribution to DNA binding, several HMO1 variants were analyzed. Using circular dichroism spectroscopy, thermal stability was measured. While the melting temperatures of HMO1-boxA and HMO1-boxB are 57.2 and 47.2 °C, respectively, HMO1-boxBC, containing box B and the entire C-terminal tail, melts at 46.1 °C, suggesting little interaction between box B and the tail. In contrast, full-length HMO1 exhibits a single melting transition at 47.9 °C, indicating that interaction between box A and either box B or the tail destabilizes this domain. As HMO1-boxAB, lacking only the lysine-rich C-terminal segment, exhibits two melting transitions at 46.0 and 63.3 °C, we conclude that the destabilization of the box A domain seen in full-length HMO1 is due primarily to its interaction with the lysine-rich tail. Determination of DNA substrate specificity using electrophoretic mobility shift assays shows unexpectedly that the lysine-rich tail does not increase DNA binding affinity but instead is required for DNA bending by full-length HMO1; HMO1-boxBC, lacking the box A domain, also fails to bend DNA. In contrast, both HMO1 and HMO1-boxAB, but not the individual HMG domains, exhibit preferred binding to constrained DNA minicircles. Taken together, our data suggest that interactions between box A and the C-terminal tail induce a conformation that is required for DNA bending. © 2006 American Chemical Society

    Digitalization of Records for Transparency and Accountability at the Office of Controller of Budget in Nairobi, Kenya

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    In public agencies, records are the main source of information. Consequently, availability and accessibility of public information is a critical avenue for promoting transparency and accountability. Therefore, information held by the public agencies should be disseminated widely to allow citizens to interact with the information for them to use it by keeping public officers accountable for their actions. There is limited knowledge on how digitalization of records in public institutions promotes transparency and accountability in the public sector. The aim of this study was to examine the influence of digitalization of records for transparency and accountability at the Office of Controller of Budget (OCOB) in Nairobi, Kenya. The objectives of this paper therefore were to: Investigate factors affecting the process of digitalization of public records at the Office of Controller of Budget in Nairobi, Kenya and determine the relationship between digitalization of public records and the level of transparency and accountability.  The study was guided by the Diffusion of Innovation Theory. The study was undertaken at the OCOB, Nairobi, Kenya. The OCOB staffs were the main participants. However, views from OCOB stakeholders were sought to validate the findings obtained from OCOB. The stakeholders were consumers of budget implementation information created by OCOB. The study used mixed method approach which involved administering questionnaires and interviewed key informants from OCOB. Quantitative data was collected through semi-structured questionnaires and analyzed using Statistical Package for Social Sciences (SPSS) and presented graphically in tables, graphs and charts while qualitative data was analyzed thematically. The findings of the study revealed that proper digitalization of records at Office of the Budget had enhanced transparency and accountability; proper leadership at OCOB had also enhanced transparency and accountability at OCOB; Inadequate financial support had to some extent affected the digitalization process at OCOB; inadequate infrastructure was a challenge to the digitalization process; reliance on OCOB data had enabled Auditor general to carry out audits on the use of public funds among others. The study concluded that digitalization of records at OCOB had enhanced access to records thus promoting transparency and accountability at the Office of the Controller of Budget. The study recommends that there is need for the management to provide finances to support digitalization at OCOB and proper infrastructure to be put in place to enhance digitalization process; there is need for political good will to prosecute leaders who hold public office but mismanage public finances and there is need to build capacity in terms of digitalization to enhance skills of staff so that the public can access timely and reliable budget information among others. Keywords: Accountability; Digitalization of Records; Office of the Controller of Budget; Public Records, Records Management; Transparency; Kenya. DOI: 10.7176/IKM/13-4-04 Publication date:July 31st 202

    Genetic differentiation of Anopheles gambiae populations from East and West Africa : comparison of microsatellite and allozyme loci

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    Genetic variation of #Anopheles gambiae$ was analysed to assess interpopulation divergence over a 6000 km distance using short tandem repeat (microsatellite) loci and allozyme loci. Differentiation of populations from Kenya and Senegal measured by allele length variation at five microsatellite loci was compared with estimates calculated from published data on six allozyme loci (Miles, 1978). The average Wright's F(ST) of microsatellite loci (0.016) was lower than that of allozymes (0.036). Slatkin's R(ST) values for microsatellite loci were generally higher than their F(ST) values, but the average R(ST) value was virtually identical (0.036) to the average allozyme F(ST). These low estimates of differentiation correspond to an effective migration index (Nm) larger than 3, suggesting that gene flow across the continent is only weakly restricted. Polymorphism of microsatellite loci was significantly higher than that of allozymes, probably because the former experience considerably higher mutation rates. That microsatellite loci did not measure greater interpopulation divergence than allozyme loci suggested constraints on microsatellite evolution. Alternatively, extensive mosquito dispersal, aided by human transportation during the last century, better explains the low differentiation and the similarity of estimates derived from both types of genetic markers. (Résumé d'auteur

    A student teamwork induction protocol

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    Faulty group processes have harmful effects on performance but there is little research about intervention protocols to pre-empt them in HE. This naturalistic experiment compared a control cohort with an inducted cohort. The inducted cohort attended a workshop, consultations, elected a leader and used tools (a group log and group contract) designed to minimize social loafing, optimize coordination (by boosting good information sampling) and orient group dynamics towards the task. In the absence of inductions, a faulty system of processes was in play and this had a significant impact on group performance. In contrast, the inductions created a buffer. Structural equation modeling showed that the intervention made both group cohesion and conflict beneficial to group performance. The induction protocols enhanced students’ individual accountability, a sense of unique responsibility and dissent during group decision-making (which improved its quality). The implication is that inductions help optimize the processes within student teamwork

    Organisations, race and trauma

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    SIGNPOSTING RESOURCES IN THE WAKE OF GEORGE FLOYD’S DEATH This brief guide is intended as a ‘first stop’ resource to help individuals understand: a) A brief outline of Institutional Racism so that individuals can read up and better inform themselves about the context– with the caveat that some content might be distressing b) The role of Activism c) An explanation of Racially Traumatic Events which affect people at work and in their private lives d) Some Practical Strategies to help individuals cope with the trauma they have witnessed e) Further resources about Tackling Racism in Education and decolonising the curriculum which contain advice, facts and guidance. Much of this information may be of interest to the wider community

    Immune responses to gametocyte antigens in a malaria endemic population-the African falciparum context: a systematic review and meta-analysis

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    Background: Malaria elimination remains a priority research agenda with the need for interventions that reduce and/or block malaria transmission from humans to mosquitoes. Transmission-blocking vaccines (TBVs) are in development, most of which target the transmission stage (i.e., gametocyte) antigens Pfs230 and Pfs48/45. For these interventions to be implemented, there is a need to understand the naturally acquired immunity to gametocytes. Several studies have measured the prevalence of immune responses to Pfs230 and Pfs48/45 in populations in malaria-endemic areas. Methods: We conducted a systematic review of studies carried out in African populations that measured the prevalence of immune responses to the gametocyte antigens Pfs230 and Pfs48/45. We assessed seroprevalence of antibody responses to the two antigens and investigated the effects of covariates such as age, transmission intensity/endemicity, season, and parasite prevalence on the prevalence of these antibody responses by meta-regression. Results: We identified 12 studies covering 23 sites for inclusion in the analysis. We found that the range of reported seroprevalence to Pfs230 and Pfs48/45 varied widely across studies, from 0 to 64% for Pfs48/45 and from 6 to 72% for Pfs230. We also found a modest association between increased age and increased seroprevalence to Pfs230: adults were associated with higher seroprevalence estimates in comparison to children (β coefficient 0.21, 95% CI: 0.05–0.38, p = 0.042). Methodological factors were the most significant contributors to heterogeneity between studies which prevented calculation of pooled prevalence estimates. Conclusions: Naturally acquired sexual stage immunity, as detected by antibodies to Pfs230 and Pfs48/45, was present in most studies analyzed. Significant between-study heterogeneity was seen, and methodological factors were a major contributor to this, and prevented further analysis of epidemiological and biological factors. This demonstrates a need for standardized protocols for conducting and reporting seroepidemiological analyses

    Fish and complementary feeding practices for young children: Qualitative research findings from coastal Kenya

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    This study examines barriers to fish consumption during the complementary feeding period in two coastal counties of Kenya with high rates of child malnutrition. Study findings indicate that young child fish consumption is impacted by factors related to accessibility, food preferences, and caregiver’s knowledge and beliefs about fish during the complementary feeding period. These factors are influenced by prominent community figures such as elder women and health workers, whose own beliefs and understandings are impacted by underlying cultural norms, potentially limiting fish consumption. To our knowledge, this is the first study conducted in the coastal region of Kenya to focus on understanding fish consumption attitudes and beliefs during the complementary feeding phase. Our findings represent a critical first step towards the creation of more effective policies and interventions to address the significant nutritional disparities that exist in the study population

    TgPRELID, a Mitochondrial Protein Linked to Multidrug Resistance in the Parasite Toxoplasma gondii

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    New drugs to control infection with the protozoan parasite Toxoplasma gondii are needed as current treatments exert toxic side effects on patients. Approaches to develop novel compounds for drug development include screening of compound libraries and targeted inhibition of essential cellular pathways. We identified two distinct compounds that display inhibitory activity against the parasite's replicative stage: F3215-0002, which we previously identified during a compound library screen, and I-BET151, an inhibitor of bromodomains, the "reader" module of acetylated lysines. In independent studies, we sought to determine the targets of these two compounds using forward genetics, generating resistant mutants and identifying the determinants of resistance with comparative genome sequencing. Despite the dissimilarity of the two compounds, we recovered resistant mutants with nonsynonymous mutations in the same domain of the same gene, TGGT1_254250, which we found encodes a protein that localizes to the parasite mitochondrion (designated TgPRELID after the name of said domain). We found that mutants selected with one compound were cross resistant to the other compound, suggesting a common mechanism of resistance. To further support our hypothesis that TgPRELID mutations facilitate resistance to both I-BET151 and F3215-0002, CRISPR (clustered regularly interspaced short palindromic repeat)/CAS9-mediated mutation of TgPRELID directly led to increased F3215-0002 resistance. Finally, all resistance mutations clustered in the same subdomain of TgPRELID. These findings suggest that TgPRELID may encode a multidrug resistance factor or that I-BET151 and F3215-0002 have the same target(s) despite their distinct chemical structures. IMPORTANCE We report the discovery of TgPRELID, a previously uncharacterized mitochondrial protein linked to multidrug resistance in the parasite Toxoplasma gondii. Drug resistance remains a major problem in the battle against parasitic infection, and understanding how TgPRELID mutations augment resistance to multiple, distinct compounds will reveal needed insights into the development of new therapies for toxoplasmosis and other related parasitic diseases
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