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Search Results: 1 - 10 of 3991 matches for " Jacques Puechberty "
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Molecular and evolutionary characteristics of the fraction of human alpha satellite DNA associated with CENP-A at the centromeres of chromosomes 1, 5, 19, and 21
Nathalie Pironon, Jacques Puechberty, Gérard Roizès
BMC Genomics , 2010, DOI: 10.1186/1471-2164-11-195
Abstract: In this paper, we show that the molecular mechanisms by which these arrays evolve are identical in multiple chromosomes: i) accumulation of crossovers that homogenise and expand the arrays into different domains and subdomains that are mostly unshared between homologues and ii) sporadic mutations and conversion events that simultaneously differentiate them from one another. Individual arrays are affected by these mechanisms to different extents that presumably increase with time. Repeats associated with CENP-A, where the centromere is formed, are subjected to the same evolutionary mechanisms, but constitute minor subsets that exhibit subtle sequence differences from those of the bulk repeats. While the DNA sequence per se is not essential for centromere localisation along an array, it appears that certain sequences can be selected against. On chromosomes 1 and 19, which are more affected by the above evolutionary mechanisms than are chromosomes 21 and 5, CENP-A associated repeats were also recovered from a second homogeneous array present on each chromosome. This could be a way for chromosomes to sustain mitosis and meiosis when the normal centromere locus is ineluctably undermined by the above mechanisms.We discuss, in light of these observations, possible scenarios for the normal evolutionary fates of human centromeric regions.Although human alpha satellite DNA sequences have been studied for decades, a number of their structural and evolutionary characteristics remain obscure. It is generally accepted that sequences constituting highly homogeneous arrays, including those within which the active centromere is formed, evolve in a concerted way [1]. In view of this concerted evolution, many authors have supposed that the repeats are homogenised with high efficiency, both intra-chromosomally and between homologues. At the same time, it has been shown that meiotic recombination is highly suppressed in the centromeric chromosomal regions [2-5]. Indeed, it was recently
Phenotypic and Cytogenetic Variety of Pure Partial Trisomy
Noruzinia Mehrdad,Lefort Genevieve,Chaze Anne Marie,Puechberty Jacques
Acta Medica Iranica , 2009,
Abstract: Duplications of chromosome 16p are often the products of unbalanced maternal reciprocal translocations and consequently the phenotype of patients is not typical of pure partial trisomy 16p. R-banding and fluorescence in situ hybridization (FISH) in our patients were in favour of de novo pure partial trisomy of 16p. Furthure clinical and paraclinical analysis of our three cases in addition to a review of literature and analysis of published clinical and cytogenetic data on five cases of pure partial duplications of chromosome 16p reported until now lead to the delineation of three groups of duplications. Patients with short proximal 16p11~p12 euchromatic duplication considered as "silent" duplication and no clinical anomaly are included in the first group. The second group with a larger 16p11-p12~p13 duplication is caracterised by a particular phenotype including severe mental retardation, dysmorphism, variable malformations and recurrent infections. The third group has terminal 16p13-pter duplication and is not well defined to date. Based on our cases and reported cases of pure partial trisomy of 16p in the literature we propose diagnostic measures in case of an elongated 16p chromosome encountered in prenatal chromosome analysis.
Compared genomics of the strand switch region of Leishmania chromosome 1 reveal a novel genus-specific gene and conserved structural features and sequence motifs
Jacques Puechberty, Christine Blaineau, Sabrina Meghamla, Lucien Crobu, Michel Pagès, Patrick Bastien
BMC Genomics , 2007, DOI: 10.1186/1471-2164-8-57
Abstract: We isolated, and compared the structure and nucleotide sequence of, this SSR in 15 widely divergent species of Leishmania and Sauroleishmania. As regards its intrachromosomal position, size and AT content, the general structure of this SSR appears extremely stable among species, which is another demonstration of the remarkable structural stability of these genomes at the evolutionary level. Sequence alignments showed several interesting features. Overall, only 30% of nucleotide positions were conserved in the SSR among the 15 species, versus 74% and 62% in the 5' parts of the adjacent XPP and PAXP genes, respectively. However, nucleotide divergences were not distributed homogeneously along this sequence. Thus, a central fragment of approximately 440 bp exhibited 54% of identity among the 15 species. This fragment actually represents a new Leishmania-specific CDS of unknown function which had been overlooked since the annotation of this chromosome. The encoded protein comprises two trans-membrane domains and is classified in the "structural protein" GO category. We cloned this novel gene and expressed it as a recombinant green fluorescent protein-fused version, which showed its localisation to the endoplasmic reticulum. The whole of these data shorten the actual SSR to an 887-bp segment as compared with the original 1.6 kb. In the rest of the SSR, the percentage of identity was much lower, around 22%. Interestingly, the 72-bp fragment where the putatively single transcription initiation site of chromosome 1 was identified is located in a low-conservation portion of the SSR and is itself highly polymorphic amongst species. Nevertheless, it is highly C-rich and presents a unique poly(C) tract in the same position in all species.This inter-specific comparative study, the first of its kind, (a) allowed to reveal a novel genus-specific gene and (b) identified a conserved poly(C) tract in the otherwise highly polymorphic region containing the putative transcription initiat
Dark Energy as a Property of Dark Matter  [PDF]
Jacques Leibovitz
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.212181
Abstract: A novel model of dark matter (DM), elastically compressible, can contribute to the acceleration of our Universe expansion. While each galaxy compresses its own DM within its gravitation field, the DM bordering neighboring galaxies, far from their centers, is pulled apart. It is shown that, although the DM pressure tends to zero at such locations, the DM compressibility tends to infinity. This allows the DM to expand between galaxies without gravitation hindrance. The model is consistent with the coupled distributions of baryonic and dark matters, with black hole formation at the centers of large galaxies, with galactic flat rotation curves, with a Tully-Fisher relation, and with Milgrom’s MOND relation. Results are discussed.
Mechanism and evolution of multidomain aminoacyl-tRNA synthetases revealed by their inhibition by analogues of a reaction intermediate, and by properties of truncated forms  [PDF]
Jacques Lapointe
Journal of Biomedical Science and Engineering (JBiSE) , 2013, DOI: 10.4236/jbise.2013.610115
Abstract: Many enzymes which catalyze the conversion of large substrates are made of several structural domains belonging to the same polypeptide chain. Transfer RNA (tRNA), one of the substrates of the multidomain aminoacyl-tRNA synthetases (aaRS), is an L-shaped molecule whose size in one dimension is similar to that of its cognate aaRS. Crystallographic structures of aaRS/tRNA complexes show that these enzymes use several of their structural domains to interact with their cognate tRNA. This mini review discusses first some aspects of the evolution and of the flexibility of the pentadomain bacterial glutamyl-tRNA synthetase (GluRS) revealed by kinetic and interaction studies of complementary truncated forms, and then illustrates how stable analogues of aminoacyl-AMP intermediates have been used to probe conformational changes in the active sites of Escherichia coli GluRS and of the nondiscriminating aspartyl-tRNA synthetase (ND-AspRS) of Pseudomonas aeruginosa.
A Review on Tectonic Record of Strain Buildup and Stress Release across the Andean Forearc along the Gulf of Guayaquil-Tumbes Basin (GGTB) near Ecuador-Peru Border  [PDF]
Jacques Bourgois
International Journal of Geosciences (IJG) , 2013, DOI: 10.4236/ijg.2013.43057
Abstract:

Gravimetric and geologic data show that the reactivation of the Neogene Interandean depression and/or the ~75 - 65 Ma ophiolite suture into the modern dynamic of the Andes controlled the Gulf of Guayaquil Tumbes basin (GGTB) location and evolution during the past 1.8 - 1.6 Myr at least. Depending on whether the remobilization occurred along the interandean depression or the ophiolite suture, the GGTB evolved trough pure or simple shear mechanisms, respectively. Because the GGTB exhibits an along strike tectonic asymmetry associated with a pervasive seismic gap, the simple shear solution is more likely. Tectonic inversion occurred along a mid-crust detachment (the Mid-Crust detachment hereafter) matching the ophiolite suture that accommodates the North Andean Block (NAB) northward drift. The so-called Decoupling Strip located at the shelf slope break accommodated the tensional stress rotation from N-S along the shelf area i.e. NAB-drift induced to E-W along the continental margin i.e. subduction-erosion-induced. The landward dipping Woollard detachment system located at the Upper-Lower slope boundary connects the subduction channel at depth, allowing the Upper slope to evolve independently from the Lower slope wedge. The long-term recurrence interval between earthquakes, the strong interplate coupling, and the aseismic creeping deformation acting along the main low-angle detachments i.e. the Woollard and the Mid-Crust detachments may account for the pervasive seismic gap at the GGTB area. Because the subduction channel exhibits no record of significant seismic activity, no evidence exists to establish a link between the GGTB sustained subsidence and a basin-centered asperity. Because the

Mind-Language, the Expanding Heart of Cognition  [PDF]
Jacques Coulardeau
Open Journal of Social Sciences (JSS) , 2018, DOI: 10.4236/jss.2018.66004
Abstract:
On the basis of already published research on the phylogeny of language during the emergence of Homo Sapiens starting around 300,000 years ago, and on still-to-be-published research in its final phase on the psychogenesis of language starting in the 24th week of gestation, I will present my work on the central role of two virtual human constructs of man’s nervous system and brain confronted to their real environment, both natural and social. These two constructs, the mind and language, are the results of the development of the general pattern-capturing potential of the brain’s architecture. The mind and language develop simultaneously, reciprocally and in close coordination transforming the pattern-capturing potential of the brain into the mental and linguistic conceptualizing power of men and women. This long process of development can be captured in six stages: to sense; to perceive; to discriminate (or recognize) patterns; to experiment; to speculate, and to conceptualize spatial items and temporal processes. In psychogenetics, these six stages are essential for education. Lev Vygotsky, among others, has proposed the best approach to this conceptualizing competence in children and young adults, and expanding in our whole life.
Cell-type specific regulation of MARCH1 E3 ubiquitin ligase by the anti-inflammatory cytokine IL-10  [PDF]
Tristan Galbas, Jacques Thibodeau
Open Journal of Immunology (OJI) , 2012, DOI: 10.4236/oji.2012.24020
Abstract: Membrane-associated RING-CH-1 (MARCH1) is an E3 ubiquitin ligase which targets MHC-II, CD86 and various other molecules for degradation. It is one of the most efficient post-translational regulators of antigen presentation. MARCH1 is expressed in resting immature dendritic cells and B cells but can be induced in other cell types. While activation of most immune cells results in a reduction in MARCH1 gene expression, its anti-inflammatory properties are highlighted by its induction in response to IL-10. Here, we review what is known about the regulation of MARCH1 gene expression in response to IL-10 by various immune cells. We speculate on the role of MARCH1 ininfection, its differential expression pattern and the promise that this E3 ubiquitin ligase holds to influence immune responses and mitigate immune pathologies.
Optical Coherence in Astrophysics: The Powerful Alternative of Big Bang  [PDF]
Jacques Moret-Bailly
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.48A019
Abstract:

The coherence of the interaction of light with a collisionless gas (Einstein 1917) founds the theory of gas lasers. It is, for the understanding of universe, a simpler and more powerful tool than the big bang which requires questionable supplements (dark matter, MOND, etc.). The Impulsive Stimulated Raman Scattering (ISRS) redshifts gradually light pulses which cross excited atomic hydrogen H*, so that the redshift is a measure of the column density of H*. Thus, the distance of the hot stars, surrounded by much H*, is exaggerated by the use of Hubble’s law. Local exaggerated distances create voids in the maps of galaxies which become spongy. The interpretation of spectra of quasars, the periodicity of galaxy redshifts introduce an experimental “Karlsson’s constant” exactly computed by ISRS. The need for dark matter comes from the exaggeration of the distance, therefore the size of galaxies. Without dark matter, celestial mechanics provides a reliable distance of spiral galaxies. Coherence also introduces superradiance and mode competition that explain that only the limbs of Stromgren spheres are visible as circles maybe punctuated by an even number of dots: Too numerous, the figures assigned to gravitational lenses can be such limbs. The coincidence of the ignition of the rings of SNR1987A with the extinction of the star is due to a multiphoton coherent scattering of star light, which amplifies the superradiant emission of the rings. A blueshift of microwaves crossing H* resulting, between 10 and 15 AU, of the expansion of solar wind, explains the “anomalous acceleration” of Pioneer probes. All is obtained without any change in theories of standard spectroscopy.

Creating a “Faraday Ghost” inside the Rotation Measure Synthesis Technique, through a Wide Observational “Gap” in Wavelength Coverage  [PDF]
Jacques P. Vallée
International Journal of Astronomy and Astrophysics (IJAA) , 2013, DOI: 10.4236/ijaa.2013.32011
Abstract:

Several recently published Faraday rotation measures (RM) derived using the novel RM synthesis technique are likely in error. If a set of polarimetric observations contains a large gap in the wavelength coverage, the rotation measure determination is sometimes ambiguous; this is also true even when two long wavelength ranges are observed but are separated by a wide gap. Essentially, there are 180° ambiguities in the observed Position Angle of the electric polarisation vector between the two wavelength ranges; these ambiguities are not resolved because the extent of wavelengths2 covered, within each of the two ranges, is too small to uniquely determine the RM in isolation. We find that unphysical “Faraday ghosts” can be mathematically constructed with a np ambiguity (±180° times an integer) at predictable polarization position angles when using only two wavelength ranges separated by a gap, as a function of the width of the gap (Equation (4)). Our computations suggest an empirical correlation between an observational gap between two wavelength ranges and the appearance of “Faraday ghosts”.

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