1,720,981 research outputs found
Defective SERCA1protein causing bovine Pseudomyotonia and human Brody disease: from pathogenic mechanism to a novel therapeutic approach
No full textCattle congenital pseudomyotonia (PMT) is an inherited recessive autosomal muscular disorder due to missense mutations in ATP2A1 gene, encoding SERCA1 protein (Sarco-endo-plasmic reticulum Ca2+-ATPase, isoform1) [1]. SERCA1 is responsible for transporting Ca2+ from cytosol back into the lumen of sarcoplasmic reticulum (SR) playing a crucial role in muscle relaxation. Bovine PMT has been described in the Chianina and Romagnola italian breeds. Even though clinical symptoms were homogeneous, PMT has been found genetically heterogeneous. All PMT Chianina animals were homozygous for a single point mutation leading to an Arg164His (R164H) substitution, while most of PMT Romagnola cases were compound heterozygous, carrying a mutation identical to that of Chianina breed, in addition to two point mutations leading to Gly211Val and Gly286Val (G211V/G286V) substitutions [2]. In spite of this heterogeneity of SERCA1 gene mutations, a striking selective reduction of SERCA1 protein has been described in SR membranes isolated from bovine muscles of different PMT-affected cattle breeds. Recently we have clarified the pathogenic mechanism underlying Chianina PMT: the R164H SERCA1 mutation generates a protein functionally active but corrupted in proper folding that was ubiquitinated and prematurely degraded by the ubiquitin-proteasome system [3].
The relevance of cattle PMT is based on phenotypic and genotypic similarities with human Brody myopathy, a “rare” genetic muscular disorder. Clinical symptoms genetic and biochemical findings, clearly demonstrated that cattle PMT is the true animal model of Brody disease. This is not surprising since, in the last years, the counterparts of human pathologies have been found in many domestic mammalian species.
Using the heterologous cellular model HEK293 overexpressing SERCA1 mutants, we have deeply investigated SERCA1 mutations found in Romagnola breed. G211V and G286V mutations were introduced separately or together into bovine SERCA1 cDNA. Using both immunofluorescence and western blot analyses we have found that only the G211V mutation is responsible for the PTM phenotype of Romagnola and the treatment with proteasome inhibitor rescues the expression level of G211V mutated SERCA1 at ER membranes in HEK293 cell model.
At present, neither specific therapy nor mouse model for Brody myopathy exists. Our findings opened new perspectives for a therapy of this rare disease. To this aim, in the same cell model we have tested small molecules known as “CFTR correctors” specifically developed for rescuing type II Cystic Fibrosis Transmembrane Regulator (CFTR) mutants, causing Cystic Fibrosis. We have observed, by western blot analysis, that treatments with these compounds induce an increase of SERCA1 mutant content. So, a possible pharmacological therapy could be hypothesized for the specific population of Brody patients in which, as in bovine PMT, ATP2A1 mutations impair SERCA1 protein folding causing its rapid degradation.
[1] Sacchetto et al. A defective SERCA1 protein is responsible for congenital pseudomyotonia in Chianina cattle, Am J Pathol ,174:565-573, 2009.
[2] Murgiano, Sacchetto et al. Pseudomyotonia in Romagnola cattle caused by novel ATP2A1 mutations, BMC Vet. Res, 8:186. 2012.
[3] Bianchini et al. Inhibition of ubiquitin proteasome system rescues the defective sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA1) protein causing Chianina cattle pseudomyotonia, J Biol Chem. 289:33073-33082, 2014
Identification of two ryanodine receptor transcripts in neonatal, slow-, and fast-twitch rabbit skeletal muscles
No full textAnalysis of the primary structure of the rabbit skeletal muscle ryanodine receptor led to the identification of two molecules of 5032 and 5037 residues, respectively. Such a sequence discrepancy is likely to be due to the alternative splicing of a 15 bp exon (1) encoding a 5 amino acid insertion (Ala-Gly-Asp-Ala-Gln) after residue 3479. By using PCR on first strand cDNA, we searched for the 15 base pair insertion in the ryanodine receptor mRNA from adult slow- and fast-twitch skeletal muscle, as well as from fast-muscles, at various stages of post-natal development. All rabbit skeletal muscle mRNAs, regardless of their developmental stage and twitch properties, contain two RYR transcripts, suggesting the coexistence of two RYR isoforms in mammalian skeletal muscl
BIOCHEMICAL AND MORPHOLOGICAL-CHANGES IN ESCHERICHIA-COLI IRRADIATED BY COHERENT AND NONCOHERENT 632.8 NM LIGHT
No full textIrradiation of Escherichia coli cells with either coherent or non-coherent 632.8 nm light (4 J cm-2) causes a transient acceleration of cell proliferation, which is maximal about 60 min after the end of the phototreatment. The stimulatory effect is dose dependent and is especially evident in the case of defective E. coli strains which are in the logarithmic phase of growth, while it becomes less important when cells are exposed to non-coherent 600-700 nm light. Stimulated cells exhibit biochemical and morphological changes, such as an intensified synthesis of cytoplasmic membrane proteins, increased cell volume and ribosomal content, which are suggestive of an enhanced cell metabolism
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
Myostatin shows a specific expression pattern in pig skeletal and extraocular muscles during pre- and post-natal growth
No full textMyogenesis is driven by an extraordinary array of cellular signals that follow a common expression pattern among different animal phyla. Myostatin (mstn) is a secreted growth factor that plays a pivotal role in skeletal muscle mass regulation. The aim of the present study was to investigate mstn expression in a large mammal (the pig) in order to ascertain whether distinct expression changes of this factor might be linked to the fiber-type composition of the muscle examined and/or to specific developmental stages. To assess the expression pattern of mstn in relation to myogenic proliferative (Pax7 and MyoD) and differentiative (myogenin) markers, we evaluated muscles with different myosin heavy-chain compositions sampled during pre- and post-natal development and on myogenic cells isolated from the same muscles. Skeletal muscles showed higher levels of mRNA for mstn and all other genes examined during fetal development than after birth. The wide distribution of mstn was also confirmed by immunohistochemistry experiments supporting evidence for cytoplasmic staining in early fetal periods as well as the localization in type 1 fibers at the end of the gestation period. Extraocular muscles, in contrast, did not exhibit decreasing mRNA levels for mstn or other genes even in adult samples and expressed higher levels of both mstn mRNA and protein compared with skeletal muscles. Experiments carried out on myogenic cells showed that mstn mRNA levels decreased when myoblasts entered the differentiation program and that cells isolated at early post-natal stages maintained a high level of Pax7 expression. Our results showed that mstn had a specific expression pattern whose variations depended on the muscle type examined, thus supporting the hypothesis that at birth, porcine myogenic cells continue to be influenced by hyperplastic/ proliferative mechanisms. © 2007, Copyright the Author
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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