1,720,964 research outputs found
Role of ubiquitylation in autophagic degradation of cytosolic soluble protein in Saccharomyces cerevisiae
No full text泛素是種小而保守的蛋白質，普遍的被用來標定在真核生物中將要被蛋白脢體分解的異常構型蛋白質。細胞自噬則是真核生物中另一條降解蛋白質的路徑；透過由雙層膜包裹的細胞質所形成的自噬小體與細胞中的液胞或溶小體進行融合，細胞能有效的分解胞器以及蛋白質，以獲得養分應付充滿壓力的環境。已知在哺乳動物細胞中，被泛素所標定的蛋白質除了透過蛋白脢體分解外，也會形成蛋白質聚集體，堆積在細胞質當中，而這些蛋白質聚集體，已被證實能選擇性的透過細胞自噬所清除。這次研究，我們發現在酵母菌中泛素修飾並不會促進蛋白質形成聚集體，且泛素化的修飾不但不會促進蛋白質透過細胞自噬分解，反而扮演著抑制性的角色。我們同時發現，泛素的一個已知的突變能破壞泛素與大部分泛素結合區的交互作用，而這種泛素突變也喪失抑制細胞自噬分解蛋白質的作用。我們認為，透過泛素與某種未知蛋白質的交互作用，阻礙了泛素化蛋白質被自噬小體包裹的過程。這個發現，是泛素抑制細胞自噬分解作用的首件案例。Ubiquitin is a small, conserved molecule among eukaryotes that serves as a tag for the breakdown of misfolded-proteins by the 26s proteasome in eukaryotes. Autophagy is another protein turnover process, which sequesters cytoplasm into double membrane vesicles, called autophagosomes. Subsequent fusion with the vacuole/lysosome mediates breakdown of proteins or organelles in eukaryotes facing stressful environments. In mammalian cells, ubiquitylated protein aggregates in cytosol associated with neural degeneration diseases were shown to be specific substrates for autophagic degradation. However, in this study, we showed that the ubiquitin modification does not trigger the formation of protein aggregates in saccharomyces cerevisiae. Moreover, we found that ubiquitylation impedes, instead promotes, the degradation of cytosolic proteins by starvation-induced autophagy in yeast. We also identified an ubiquitin mutant, which was previously shown defective in interacting with most known ubiquitin-binding domains (UBD), lost the delay on autophagic degradation of cytosolic proteins. We propose that the interaction of ubiquitin with an unknown factor prevents sequestration of ubiquitylated cytosolic soluble proteins into autophagosomes for degradation. This is the first report indicating that ubiquitylation of cargo proteins hinder their autophagic degradation
Primulina cataractarum sp. nov. (Gesneriaceae) from limestone landform in Southern Hunan, China
No full textDing, Cong, Liu, Ang, Yu, Xun-Lin, Zhang, Chun-Ping (2021): Primulina cataractarum sp. nov. (Gesneriaceae) from limestone landform in Southern Hunan, China. Phytotaxa 511 (1): 51-64, DOI: 10.11646/phytotaxa.511.1.4, URL: http://dx.doi.org/10.11646/phytotaxa.511.1.
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
FIGURE 3 in Primulina cataractarum sp. nov. (Gesneriaceae) from limestone landform in Southern Hunan, China
No full textFIGURE 3. The Bayesian phylogenetic tree from atpB-rbcL sequence data with BI posterior probability/MP bootstrap support values (>0.5 or 50%) shown above and below the corresponding branches. * indicates the new species.Published as part of Ding, Cong, Liu, Ang, Yu, Xun-Lin & Zhang, Chun-Ping, 2021, Primulina cataractarum sp. nov. (Gesneriaceae) from limestone landform in Southern Hunan, China, pp. 51-64 in Phytotaxa 511 (1) on page 57, DOI: 10.11646/phytotaxa.511.1.4, http://zenodo.org/record/542649
FIGURE 2. The Bayesian phylogenetic tree from trnL-F in Primulina cataractarum sp. nov. (Gesneriaceae) from limestone landform in Southern Hunan, China
No full textFIGURE 2. The Bayesian phylogenetic tree from trnL-F sequence data with BI posterior probability/MP bootstrap support values (>0.5 or 50%) shown above and below the corresponding branches. * indicates the new species.Published as part of Ding, Cong, Liu, Ang, Yu, Xun-Lin & Zhang, Chun-Ping, 2021, Primulina cataractarum sp. nov. (Gesneriaceae) from limestone landform in Southern Hunan, China, pp. 51-64 in Phytotaxa 511 (1) on page 56, DOI: 10.11646/phytotaxa.511.1.4, http://zenodo.org/record/542649
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
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