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Author response
Full text linkNanobodies are single-domain antibodies of camelid origin. We generated nanobodies against the vertebrate nuclear pore complex (NPC) and used them in STORM imaging to locate individual NPC proteins with
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
Crystal structure of the nuclear export receptor CRM1 in complex with Snurportin1 and RanGTP.
No full textCRM1 mediates nuclear export of numerous unrelated cargoes, which may carry a short leucine rich nuclear export signal or export signatures that include folded domains. How CRM1 recognizes such a variety of cargoes has been unknown up to this point. Here we present the crystal structure of the SPN1 amp; 8901;CRM1 amp; 8901;RanGTP export complex at 2.5 angstrom resolution where SPN1 is snurportin1 and RanGTP is guanosine 5 amp; 8242; triphosphate bound Ran . SPN1 is a nuclear import adapter for cytoplasmically assembled, m3G capped spliceosomal U snRNPs small nuclear ribonucleoproteins . The structure shows how CRM1 can specifically return the cargo free form of SPN1 to the cytoplasm. The extensive contact area includes five hydrophobic residues at the SPN1 amino terminus that dock into a hydrophobic cleft of CRM1, as well as numerous hydrophilic contacts of CRM1 to m3G cap binding domain and carboxyl terminal residues of SPN1. The structure suggests that RanGTP promotes cargo binding to CRM1 solely through long range conformational changes in the exporti
Effects of the Bowen-Conradi syndrome mutation in EMG1 on its nuclear import, stability and nucleolar recruitment.
Full text linkBowen-Conradi syndrome (BCS) is a severe genetic disorder that is characterised by various developmental abnormalities, bone marrow failure and early infant death. This disease is caused by a single mutation leading to the aspartate 86 to glycine (D86G) exchange in the essential nucleolar RNA methyltransferase EMG1. EMG1 is required for the synthesis of the small ribosomal subunit and is involved in modification of the 18S ribosomal RNA. Here, we identify the pre-ribosomal factors NOP14, NOC4L and UTP14A as members of a nucleolar subcomplex that contains EMG1 and is required for its recruitment to nucleoli. The BCS mutation in EMG1 leads to reduced nucleolar localisation, accumulation of EMG1(D86G) in nuclear foci and its proteasome-dependent degradation. We further show that EMG1 can be imported into the nucleus by the importins (Imp) Imp alpha/beta or Imp beta/7. Interestingly, in addition to its role in nuclear import, binding of the Imp beta/7 heterodimer can prevent unspecific aggregation of both EMG1 and EMG1(D86G) on RNAs in vitro, indicating that the importins act as chaperones by binding to basic regions of the RNA methyltransferase. Our findings further indicate that in BCS, nuclear disassembly of the import complex and release of EMG1(D86G) lead to its nuclear aggregation and degradation, resulting in the reduced nucleolar recruitment of the RNA methyltransferase and defects in the biogenesis of the small ribosomal subunit
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
Author response image 1. Scatter plot shows correlation of molar fractions of given protein species within the ‘CRM1+RanGTP’-bound fractions of the two biological replicates.
Full text linkCRM1 is a highly conserved, RanGTPase-driven exportin that caries proteins and RNPs from the nucleus to the cytoplasm. We now explored the cargo-spectrum of CRM1 in depth and identified surprisingly large numbers, namely >700 export substrates from the yeast S. cerevisiae, ≈ 1000 from Xenopus oocytes and >1050 from human cells. In addition, we quantified the partitioning of ≈5000 unique proteins between nucleus and cytoplasm of Xenopus oocytes. The data suggest new CRM1 functions in spatial control of vesicle coat-assembly, centrosomes, autophagy, peroxisome biogenesis, cytoskeleton, ribosome maturation, translation, mRNA degradation, and more generally in precluding a potentially detrimental action of cytoplasmic pathways within the nuclear interior. There are also numerous new instances where CRM1 appears to act in regulatory circuits. Altogether, our dataset allows unprecedented insights into the nucleocytoplasmic organisation of eukaryotic cells, into the contributions of an exceedingly promiscuous exportin and it provides a new basis for NES prediction
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