1,720,961 research outputs found
Haplo-deficiency of ODF1/HSPB10 in mouse sperm causes relaxation of head-to-tail linkage
No full textThe small heat shock protein ODF1/HSPB10 is essential for male fertility in mice. Targeted deletion of Odf1 resulted in acephalic sperm in homozygous mice of mixed background (C57BL/6J//129/Sv), whereas heterozygous animals are fully fertile. To further elucidate the function of ODF1, we generated incipient congenic mice with targeted deletion of Odf1 by successive backcrossing on the 129/Sv background. We observed that fecundity of heterozygous Odf1(+/-) male mice was severely reduced over backcross generations. However, neither aberrant sperm parameters nor sperm anomalies could be observed. Ultra-structural analyses of sperm from incipient congenic heterozygous Odf1(+/-) males of backcross generation N7 revealed no obvious pathological findings. However, we observed an enlargement of the distance between nuclear membrane and capitulum, indicating a weakening of the sperm head-to-tail coupling. Severe male subfertility provoked by haplo-deficiency of ODF1 is therefore most probably caused by impaired head-to-tail coupling that eventually might induce sperm decapitation on the specific conditions of in vivo fertilisation. As subfertility in haplo-deficient ODF1 male mice could not be diagnosed by semen analysis, it seems to be a paradigm for unexplained infertility that is a frequent diagnosis for male fertility impairment in humans.Deutsche Forschungsgemeinschaft [HO 1440/13-1, 13-2
Pax6 controls centriole maturation in cortical progenitors through Odf2.
No full textCortical glutamatergic neurons are generated by radial glial cells (RGCs), specified by the expression of transcription factor (TF) Pax6, in the germinative zones of the dorsal telencephalon. Here, we demonstrate that Pax6 regulates the structural assembly of the interphase centrosomes. In the cortex of the Pax6-deficient Small eye (Sey/Sey) mutant, we find a defect of the appendages of the mother centrioles, indicating incomplete centrosome maturation. Consequently, RGCs fail to generate primary cilia, and instead of staying in the germinative zone for renewal, RGCs detach from the ventricular surface thus affecting the interkinetic nuclear migration and they exit prematurely from mitosis. Mechanistically, we show that TF Pax6 directly regulates the activity of the Odf2 gene encoding for the appendage-specific protein Odf2 with a role for the assembly of mother centriole. Our findings demonstrate a molecular mechanism that explains important characteristics of the centrosome disassembly and malfunctioning in developing cortex lacking Pax6
Ultra-structure of the sperm head-to-tail linkage complex in the absence of the spermatid-specific LINC component SPAG4
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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
Transcriptional activation of Odf2/Cenexin by cell cycle arrest and the stress activated signaling pathway (JNK pathway)
No full textAbstractThe centrosome/basal body protein ODF2/Cenexin is necessary for the formation of the primary cilium. Primary cilia are essential organelles that sense and transduce environmental signals. Primary cilia are therefore critical for embryonic and postnatal development as well as for tissue homeostasis in adulthood. Impaired function of primary cilia causes severe human diseases. ODF2 deficiency prevents formation of the primary cilium and is embryonically lethal. To explore the regulation of primary cilia formation we analyzed the promoter region of Odf2 and its transcriptional activity. In cycling cells, Odf2 transcription is depressed but becomes up-regulated in quiescent cells. Low transcriptional activity is mediated by sequences located upstream from the basal promoter, and neither transcription factors with predicted binding sites in the Odf2 promoter nor Rfx3 or Foxj, which are known to control ciliary gene expression, could activate Odf2 transcription. However, co-expression of either C/EBPα, c-Jun or c-Jun and its regulator MEKK1 enhances Odf2 transcription in cycling cells. Our results provide the first analysis of transcriptional regulation of a ciliary gene. Furthermore, we suggest that transcription of even more ciliary genes is largely inhibited in cycling cells but could be activated by cell cycle arrest and by the stress signaling JNK pathway
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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