1,721,007 research outputs found
Characterisation of the Saccharomyces cerevisiae cell separation machinery: Sdm1 and its possible role in cell separation
Full text linkThe final act of the cell cycle in Saccharomyces cerevisiae is cell separation. Inactivation of the transcription factor encoding gene, ACE2, leads to a defect in cell separation. Ace2 plays a central role in cell separation by regulating daughter cell specific expression of endochitinase (CTS1) and at least 3 putative glucanase encoding genes, DSE2, DSE4 (ENG1) and SCW11. The products of these genes degrade the tri-laminar septum that holds mother and daughter cells together. ACE2, itself, is regulated by the RAM (Regulation of Ace2 activity and cellular Morphogenesis) network; inactivation of RAM network proteins results in defects in cell separation and mis-localisation of Ace2.
To define the components of the cell separation machinery in S. cerevisiae, a screen for mutants that fail to separate was undertaken. A total of 178 novel cell separation mutants were identified; 11 were uncharacterised genes implicated in cell separation, and of these, 6 were implicated in cell wall integrity, while one was implicated in the MAP kinase pathway. Furthermore, ubquitination and glycosylation were implicated to play a role in cell separation.
The uncharacterised gene, YIR016W, termed Defective in Separation of Daughter and Mother Cell 1 (SDM1), was identified to play an important role in cell separation. A yeast-2-hybrid screen identified 15 novel protein-protein interactions not previously described for Sdm1. The uncharacterised gene, YOL036W, was identified to interact with Sdm1, and the RAM proteins, Mob2 and Cbk1, in a yeast-2-hybrid screen. Furthermore, Sdm1 and Yol036w are paralogues. We propose that Sdm1 and Yol036w are involved in ER to golgi trafficking.
Data presented here shows that Ace2 appears to be mis-localised in sdm1 cells; we also show that there may be a potential budding pattern defect in sdm1 cells. We propose that Sdm1 is involved in the regulation of Ace2 localisation to the daughter cell nucleus at the end of M/G1, and that Sdm1 is a negative regulator of cell cycle progression at G1/M
Basal expression of the Aspergillus fumigatus transcriptional activator CpcA is sufficient to support pulmonary aspergillosis
No full textAspergillosis is a disease determined by various factors that influence fungal growth and fitness. A conserved signal transduction cascade linking environmental stress to amino acid homeostasis is the Cross-Pathway Control (CPC) system that acts via phosphorylation of the translation initiation factor eIF2 by a sensor kinase to elevate expression of a transcription factor. Ingestion of Aspergillus fumigatus conidia by macrophages does not trigger this stress response, suggesting that their phagosomal microenvironment is not deficient in amino acids. The cpcC gene encodes the CPC eIF2α kinase, and deletion mutants show increased sensitivity towards amino acid starvation. CpcC is specifically required for the CPC response but has limited influence on the amount of phosphorylated eIF2α. Strains deleted for the cpcC locus are not impaired in virulence in a murine model of pulmonary aspergillosis. Accordingly, basal expression of the Cross-Pathway Control transcriptional activator appears sufficient to support aspergillosis in this disease model. © 2008 Elsevier Inc. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Functional Characterisation of Candida Glabrata Open Reading Frames with no Orthologue in Saccharomyces Cerevisiae
No full textCandida glabrata is a significant and increasingly common pathogen of humans yet its mechanism of virulence remains unclear. Comparative genomic studies revealed that C. glabrata is more closely related to the non-pathogenic yeast Saccharomyces cerevisiae and that both these genomes are distinct from C. albicans. In order to explore C. glabrata virulence attributes, C. glabrata ORFs with no orthologue in S. cerevisiae were studied since these ORFs may have accompanied the adaptation of C. glabrata to the human host.
Reciprocal best hit searches identified C. glabrata ORFs with no S. cerevisiae orthologue. A barcoded deletion library targeting 65 C. glabrata-specific ORFs was constructed. To functionally characterise the deletion library, mutants were tested for fitness and phenotypically screened to identify gene products required for growth in response to biologically relevant stresses. As such, novel phenotypes associated with the deletion of previously uncharacterised ORFs were uncovered. Mutants were also tested for infection-related properties including biofilm formation, antifungal agent susceptibility and for virulence in a Drosophila melanogaster infection model, resulting in the identification of two C. glabrata-specific ORFs, CAGL0K05687g and CAGL0H01749g, which were required for virulence.
Three ORFs with notable phenotypes were taken forward for further characterisation. An adapted genome-wide synthetic genetic interaction approach was used to create genetic interaction networks for C. glabrata ORFs over-expressed in S. cerevisiae. Genetic interaction analysis of a C. glabrata chromatin remodeler CAGL0D05434g revealed a role for this ORF in metal ion homeostasis and DNA damage repair. Genetic interaction profiling for an oxidoreductase encoded by CAGL0K05687g was used to reveal mechanisms related to transport by which this ORF may be required for virulence
- …
