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Carotenuto R De Marco N Biffo S Wilding M Vaccaro MC Marchisio PC Capriglione T Russo GL Campanella C 《Cellular and molecular life sciences : CMLS》2005,62(14):1641-1652
p27BBP/eIF6 is an evolutionarily conserved regulator of ribosomal function. It is necessary for 60S biogenesis and impedes improper joining of 40S and 60S subunits, regulated by protein kinase C or Efl1p. No data on p27BBP/eIF6 during early development of Metazoa are available. We studied the distribution, post-translational changes and association with the cytoskeleton of p27BBP/ eIF6 during Xenopus oogenesis and early development. Results indicate that p27BBP/eIF6 is present throughout oogenesis, partly associated with 60S subunits, partly free and with little cytoskeleton bound. During prophase I, p27BBP/eIF6 is detected as a single band of 27-kDa. Upon maturation induced by progesterone or protein kinase C, a serine-phosphorylated 29 kDa isoform appears and is kept throughout development to the neurula stage. Confocal microscopy showed that the distribution of p27BBP/eIF6 and its association with the cytoskeleton varies according to oogenesis stages. Briefly, in stage 6 oocytes, p27BBP/eIF6 has a limited dot-like distribution, and does not co-localize with cytokeratin, whereas upon maturation it spreads throughout the cytoplasm. After fertilization, a large fraction coalesces around cytomembranes and a cytochalasin B-sensitive co-localization with cytokeratin occurs. RNAse removes p27BBP/eIF6 from the cytokeratin fibres. Developmental data suggest a role of p27BBP/eIF6 in controlling ribosomal availability or regulating cross-talk between ribosomes and the cytoskeleton.Received 7 April 2005; received after revision 11 May 2005; accepted 25 May 2005R. Carotenuto and N. De Marco contributed equally to the paper 相似文献
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Lucio Russo 《Archive for History of Exact Sciences》1998,52(3):195-219
OElig;he thesis is sustained that the definitions of fundamental geometric entities which open Euclids Elements actually are excerpts from the Definitions by Heron of Alexandria, interpolated in late antiquity into Euclids treatise. As a consequence, one of the main bases of
the traditional Platonist interpretation of Euclid is refuted. Arguments about the constructivist nature of Euclids mathematical
philosophy are given.
(Received June 6, 1997) 相似文献
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Federica Russo 《Foundations of Science》2006,11(3):221-247
A careful analysis of Salmon’s Theoretical Realism and van Fraassen’s Constructive Empiricism shows that both share a common
origin: the requirement of literal construal of theories inherited by the Standard View. However, despite this common starting
point, Salmon and van Fraassen strongly disagree on the existence of unobservable entities. I argue that their different ontological
commitment towards the existence of unobservables traces back to their different views on the interpretation of probability
via different conceptions of induction. In fact, inferences to statements claiming the existence of unobservable entities
are inferences to probabilistic statements, whence the crucial importance of the interpretation of probability. 相似文献
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Cryptic striations in the upper mantle revealed by hafnium isotopes in southeast Indian ridge basalts 总被引:1,自引:0,他引:1
The Earth's mantle is isotopically heterogeneous on length scales ranging from centimetres to more than 10(4) kilometres. This heterogeneity originates from partial melt extraction and plate tectonic recycling, whereas stirring during mantle convection tends to reduce it. Here we show that mid-ocean ridge basalts from 2,000 km along the southeast Indian ridge (SEIR) display a bimodal hafnium isotopic distribution. This bimodality reveals the presence of ancient compositional striations (streaks) in the Indian Ocean upper mantle. The number density of the streaks is described by a Poisson distribution, with an average thickness of approximately 40 km. Such a distribution is anticipated for a well-stirred upper mantle, in which heterogeneity is continually introduced by plate tectonic recycling, and redistributed by viscous stretching and convective refolding. 相似文献
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Chromosome instability and immunodeficiency syndrome caused by mutations in a DNA methyltransferase gene 总被引:71,自引:0,他引:71
Xu GL Bestor TH Bourc'his D Hsieh CL Tommerup N Bugge M Hulten M Qu X Russo JJ Viegas-Péquignot E 《Nature》1999,402(6758):187-191
The recessive autosomal disorder known as ICF syndrome (for immunodeficiency, centromere instability and facial anomalies; Mendelian Inheritance in Man number 242860) is characterized by variable reductions in serum immunoglobulin levels which cause most ICF patients to succumb to infectious diseases before adulthood. Mild facial anomalies include hypertelorism, low-set ears, epicanthal folds and macroglossia. The cytogenetic abnormalities in lymphocytes are exuberant: juxtacentromeric heterochromatin is greatly elongated and thread-like in metaphase chromosomes, which is associated with the formation of complex multiradiate chromosomes. The same juxtacentromeric regions are subject to persistent interphase self-associations and are extruded into nuclear blebs or micronuclei. Abnormalities are largely confined to tracts of classical satellites 2 and 3 at juxtacentromeric regions of chromosomes 1, 9 and 16. Classical satellite DNA is normally heavily methylated at cytosine residues, but in ICF syndrome it is almost completely unmethylated in all tissues. ICF syndrome is the only genetic disorder known to involve constitutive abnormalities of genomic methylation patterns. Here we show that five unrelated ICF patients have mutations in both alleles of the gene that encodes DNA methyltransferase 3B (refs 5, 6). Cytosine methylation is essential for the organization and stabilization of a specific type of heterochromatin, and this methylation appears to be carried out by an enzyme specialized for the purpose. 相似文献