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61.
Michael C. Kruer Mustafa A. Salih Catherine Mooney Jawahir Alzahrani Salah A. Elmalik Mohammad M. Kabiraj Arif O. Khan Reema Paudel Henry Houlden Hamid Azzedine Fowzan Alkuraya 《Gene》2014
Pallido-pyramidal syndromes combine dystonia with or without parkinsonism and spasticity as part of a mixed neurodegenerative disorder. Several causative genes have been shown to lead to pallido-pyramidal syndromes, including FBXO7, ATP13A2, PLA2G6, PRKN and SPG11. Among these, ATP13A2 and PLA2G6 are inconsistently associated with brain iron deposition. Using homozygosity mapping and direct sequencing in a multiplex consanguineous Saudi Arabian family with a pallido-pyramidal syndrome, iron deposition and cerebellar atrophy, we identified a homozygous p.G53R mutation in C19orf12. Our findings add to the phenotypic spectrum associated with C19orf12 mutations. 相似文献
62.
Nous rapportons les résultats sur la distinction entre deux espèces sympatriques du genre Phlebotomus, vecteurs de la leishmaniose viscérale à Leishmania infantum en Algérie. Dans les pays circum mediterranéen, Phlebotomus perniciosus Newstead 1911 a révélé l’existence de morphes atypiques qui sont à l’origine d’erreurs d’identification et par conséquent d’une confusion avec l’espèce voisine Phlebotomus longicuspis Nitzulescu 1930. Nous avons utilisé les critères morphologiques comme une première approche sur les variations morphologiques de ces espèces. L’identification repose, outre les caractères des appareils génitaux, sur le dénombrement des soies médianes des coxites qui permettent de déterminer l’existence de morphotypes particuliers de Phlebotomus perniciosus dans les localités prospectées. 相似文献
63.
Azzedine Boukerche Alba Cristina Magalhaes Alves de Melo Edans Flavius de Oliveira Sandes Mauricio Ayala-Rincon 《Cluster computing》2007,10(2):187-202
Biological Sequence Comparison is one of the most important operations in Computational Biology since it is used to determine
how similar two sequences are. Smith and Waterman proposed an exact algorithm (SW), based on dynamic programming, that is
able to obtain the best local alignment between two sequences in quadratic time and space.
In order to compare long biological sequences, SW is rarely used since the computation time and the amount of memory required
becomes prohibitive. For this reason, heuristic methods like BLAST are widely used. Although faster, these heuristic methods
do not guarantee that the best result will be produced.
In this paper, we propose an exact parallel variant of the SW algorithm that obtains the best local alignments in quadratic
time and reduced space. The results obtained in two clusters (8-machine and 16-machine) for DNA sequences longer than 32 KBP
(kilo base-pairs) were very close to linear and, in some cases, superlinear. For very long DNA sequences (1.6 MBP), we were
able to reduce execution time from 12.25 hours to 1.54 hours, in our 8-machine cluster. As far as we know, this is the first
time 1.6 MBP sequences are compared with an exact SW variant. In this case, 30240 best local alignments were obtained.
相似文献
Azzedine BoukercheEmail: |
64.
In the course of our studies on the putative role of pectins in the control of cell growth, we have investigated the effect
of cadmium on their composition, remodelling and distribution within the epidermis and fibre tissues of flax hypocotyl (Linum usitatissimum L.). Cadmium-stressed seedlings showed a significant inhibition of growth whereas the hypocotyl volume did not significantly
change, due to the swelling of most tissues. The structural alterations consisted of significant increase of the thickness
of all cell walls and the marked collapse of the sub-epidermal layer. The pectic epitopes recognized by the anti-PGA/RGI and
JIM5 antibodies increased in the outer parts of the epidermis (external tangential wall and junctions) and fibres (primary
wall and junctions). Concomitantly, there was a remarkable decrease of JIM7 antibody labelling and consequently an increase
of the ratio JIM5/JIM7. Conversely, the ratio JIM7/JIM5 increased in the wall domains closest to the plasmalemma, which would
expel the cadmium ions from the cytoplasm. The hydrolysis of cell walls revealed a cadmium-induced increase of uronic acid
in the pectic matrix. Sequential extractions showed a remodelling of both homogalacturonan and rhamnogalacturonan I. In fractions
enriched in primary walls, the main part of the pectins became cross-linked and could be extracted only with alkali. In fractions
enriched in secondary walls, the homogalacturonan moieties were found more abundantly in the calcium-chelator extract while
the rhamnogacturonan level increased in the boiling water extract. 相似文献
65.
Arnaud Lehner Laurence Menu-Bouaouiche Flavien Dardelle Fran?ois Le Mauff Azeddine Driouich Patrice Lerouge Jean-Claude Mollet 《Plant signaling & behavior》2015,10(6)
Two independent studies have shown that the cell wall of pollen tubes from tobacco and tomato species contained fucosylated xyloglucan (XyG). These findings are intriguing as many reports have shown that XyG of somatic cells of these species is not fucosylated but instead is arabinosylated. In order to produce fucosylated XyG, plants must express a functional galactoside α-2-fucosyltransferase. Here, using a bioinformatics approach, we show that several candidate genes coding for XyG fucosyltransferases are present in the genome of coffee and several Solanaceae species including tomato, tobacco, potato, eggplant and pepper. BLAST and protein alignments with the 2 well-characterized XyG fucosyltransferases from Arabidopsis thaliana and Pisum sativum revealed that at least 6 proteins from different Solanaceae species and from coffee displayed the 3 conserved motifs required for XyG fucosyltransferase activity. 相似文献
66.
Mait�� Montero-Hadjadje Salah Elias Laurence Chevalier Magalie Benard Yannick Tanguy Val��rie Turquier Ludovic Galas Laurent Yon Maria M. Malagon Azeddine Driouich St��phane Gasman Youssef Anouar 《The Journal of biological chemistry》2009,284(18):12420-12431
Chromogranin A (CgA) has been proposed to play a major role in the
formation of dense-core secretory granules (DCGs) in neuroendocrine cells.
Here, we took advantage of unique features of the frog CgA (fCgA) to assess
the role of this granin and its potential functional determinants in hormone
sorting during DCG biogenesis. Expression of fCgA in the constitutively
secreting COS-7 cells induced the formation of mobile vesicular structures,
which contained cotransfected peptide hormones. The fCgA and the hormones
coexpressed in the newly formed vesicles could be released in a regulated
manner. The N- and C-terminal regions of fCgA, which exhibit remarkable
sequence conservation with their mammalian counterparts were found to be
essential for the formation of the mobile DCG-like structures in COS-7 cells.
Expression of fCgA in the corticotrope AtT20 cells increased
pro-opiomelanocortin levels in DCGs, whereas the expression of N- and
C-terminal deletion mutants provoked retention of the hormone in the Golgi
area. Furthermore, fCgA, but not its truncated forms, promoted
pro-opiomelanocortin sorting to the regulated secretory pathway. These data
demonstrate that CgA has the intrinsic capacity to induce the formation of
mobile secretory granules and to promote the sorting and release of peptide
hormones. The conserved terminal peptides are instrumental for these
activities of CgA.Eukaryotic cells share the capacity to rapidly secrete proteins through the
constitutive secretory pathway. The fundamental feature of neuroendocrine and
endocrine cells is the occurrence of dense-core secretory granules
(DCGs),3
which are key cytoplasmic organelles responsible for secretion of hormones,
neuropeptides, and neurotransmitters through the regulated secretory pathway
(RSP). Storage at high concentrations of these secretory products is required
for their finely tuned release in response to extracellular stimulation
(1,
2). DCG biogenesis starts with
the budding of immature secretory granules (ISGs) from the
trans-Golgi network (TGN) through interactions between lipid rafts
and protein components, in a similar manner to constitutive vesicle budding
(2,
3). The ISG budding is followed
by a multistep maturation process to form the mature secretory granules,
including removal of the constitutive secretory proteins and lysosomal enzymes
inadvertently packaged into ISGs
(4).Despite increasing knowledge of the various steps of DCG formation, the
nature of the sorting signals for entry of proteins into the DCGs and the
molecular machinery required to generate secretory granules are not fully
elucidated (5,
6). Several recent studies
highlighted the role of members of the granin family, which may represent the
driving force for granulogenesis in the TGN
(2), although this notion has
been a matter of debate (7).
Granins are soluble acidic proteins widely distributed in endocrine and
neuroendocrine cells, which are characterized by the ability to aggregate at
acidic pH and a high Ca2+ environment
(8,
9). These conditions are found
in the lumen of the TGN allowing granins to aggregate in this compartment and
to be segregated from constitutively secreted proteins
(10,
11). The granin aggregates are
believed to associate directly or indirectly with lipid rafts at the TGN to
induce budding and formation of the ISGs. A prominent role of chromogranin A
(CgA) in the regulation of DCG formation in endocrine and neuroendocrine cells
has been proposed. Thus, depletion of CgA in PC12 cells led to a dramatic
decrease in the number of DCGs
(12), and exogenously
expressed CgA in these depleted PC12 cells, as in DCG-deficient endocrine A35C
and 6T3 cells, restored DCG biogenesis
(12,
13). Besides, expression of
granins in non-endocrine, constitutively secreting cells such as CV-1, NIH3T3,
or COS-7 cells provoked the formation of DCG-like structures that release
their content in response to Ca2+ influx
(12,
14,
15). Further investigations
performed in CgA null mice and transgenic mice expressing antisense RNA
against CgA also revealed a reduction in the number of DCGs in chromaffin
cells that was associated with an impairment of catecholamine storage, thus
demonstrating the crucial role of CgA in normal DCG biogenesis
(16,
17). In CgA knockout mice, the
introduction of the gene expressing human CgA restored the regulated secretory
phenotype (16). A different
CgA null mice strain exhibited no discernable effect on DCG formation, but
elevated catecholamine secretion
(18), proving that CgA
deficiency is associated with hormone storage impairment in neuroendocrine
cells in vivo, a finding that was confirmed in vitro
(19). The CgA-/-
mice strain generated by Hendy et al.
(18) exhibited a compensatory
overexpression of other granins, pointing to a possible overlap in granin
function in secretory granule biogenesis.We reported previously that the frog CgA (fCgA) gene is coordinately
regulated with the pro-opiomelanocortin (POMC) gene in the pituitary pars
intermedia during the neuroendocrine reflex of skin color change, which allows
amphibia to adapt to their environment through the release of POMC-derived
melanotropic peptides (20,
21). Sequence comparison of
fCgA with its mammalian orthologs revealed a high conservation of the N- and
C-terminal domains, and far less conservation of the central part of the
protein (Fig. 1A),
suggesting that these domains may play a role in DCG formation and hormone
release in various species (9,
20,
21). To assess the role of
fCgA and its conserved N- and C-terminal regions in hormone sorting, storage,
and secretion, we engineered different constructs that produce the native
unmodified (no tag added) protein and truncated forms lacking the conserved N-
and C-terminal domains, and we developed an antibody that specifically
recognizes the central region of fCgA. Using the constitutively secreting
COS-7 cells, which are devoid of DCGs, we could demonstrate for the first time
that CgA is essential for targeting peptide hormones to newly formed mobile
DCG-like structures. In the CgA-expressing AtT20 cells, which exhibit an only
moderate capacity to sort secretory proteins to the regulated pathway
(22), the granin plays a
pivotal role in the sorting and release of POMC. The conserved terminal
peptides of CgA are instrumental for these activities.Open in a separate windowFIGURE 1.Specificity of the antibody directed against frog CgA. A,
scheme depicting the structure of fCgA and showing the high conservation of
the terminal regions and the percentages of amino acid identity between frog
and human CgA sequences. The highly conserved peptide WE14 and dibasic
cleavage sites are also indicated. B, Western blot showing that the
antibody developed against fCgA recognized the protein and several processing
intermediates in frog but not rat pituitary extracts, whereas an antibody,
directed against the WE14 conserved peptide, detected CgA and its processing
products in both rat and frog pituitary extracts. C,
immunofluorescence analysis of frog pituitary and adrenal glands, and rat
adrenal gland using the antibodies against fCgA and WE14. cx, cortex;
DL, distal lobe; IL, intermediate lobe; and m,
medulla. Scale bars equal 10 μm. 相似文献
67.
Harholt J Jensen JK Verhertbruggen Y Søgaard C Bernard S Nafisi M Poulsen CP Geshi N Sakuragi Y Driouich A Knox JP Scheller HV 《Planta》2012,236(1):115-128
Glycosyltransferase complexes are known to be involved in plant cell wall biosynthesis, as for example in cellulose. It is not known to what extent such complexes are involved in biosynthesis of pectin as well. To address this question, work was initiated on ARAD1 (ARABINAN DEFICIENT 1) and its close homolog ARAD2 of glycosyltransferase family GT47. Using bimolecular fluorescence complementation, Förster resonance energy transfer and non-reducing gel electrophoresis, we show that ARAD1 and ARAD2 are localized in the same Golgi compartment and form homo-and heterodimeric intermolecular dimers when expressed transiently in Nicotiana benthamiana. Biochemical analysis of arad2 cell wall or fractions hereof showed no difference in the monosaccharide composition, when compared with wild type. The double mutant arad1 arad2 had an arad1 cell wall phenotype and overexpression of ARAD2 did not complement the arad1 phenotype, indicating that ARAD1 and ARAD2 are not redundant enzymes. To investigate the cell wall structure of the mutants in detail, immunohistochemical analyses were carried out on arad1, arad2 and arad1 arad2 using the arabinan-specific monoclonal antibody LM13. In roots, the labeling pattern of arad2 was distinct from both that of wild type, arad1 and arad1 arad2. Likewise, in epidermal cell walls of inflorescence stems, LM13 binding differed between arad2 and WILD TYPE, arad1 or arad1 arad2. Altogether, these data show that ARAD2 is associated with arabinan biosynthesis, not redundant with ARAD1, and that the two glycosyltransferases may function in complexes held together by disulfide bridges. 相似文献
68.
Arabinogalactan proteins in root and pollen-tube cells: distribution and functional aspects 总被引:1,自引:0,他引:1
BACKGROUND: Arabinogalactan proteins (AGPs) are complex proteoglycans of the cell wall found in the entire plant kingdom and in almost all plant organs. AGPs encompass a large group of heavily glycosylated cell-wall proteins which share common features, including the presence of glycan chains especially enriched in arabinose and galactose and a protein backbone particularly rich in hydroxyproline residues. However, AGPs also exhibit strong heterogeneities among their members in various plant species. AGP ubiquity in plants suggests these proteoglycans are fundamental players for plant survival and development. SCOPE: In this review, we first present an overview of current knowledge and specific features of AGPs. A section devoted to major tools used to study AGPs is also presented. We then discuss the distribution of AGPs as well as various aspects of their functional properties in root tissues and pollen tubes. This review also suggests novel directions of research on the role of AGPs in the biology of roots and pollen tubes. 相似文献
69.
Ray B Loutelier-Bourhis C Lange C Condamine E Driouich A Lerouge P 《Carbohydrate research》2004,339(2):201-208
Hemicellulose polymers were isolated from Argania spinosa leaf cell walls by sequential extractions with alkali. The structure of the two main polymers, xylan and xyloglucan, was investigated by enzyme degradation with specific endoglycosidases followed by analysis of the resulting fragments by high performance anion exchange chromatography (HPAEC) and matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF MS). The results show that A. spinosa xylan is composed of a beta-(1-->4)-linked-D-xylopyranose backbone substituted with 4-O-methyl-D-glucuronic acid residues. Xyloglucan oligosaccharide subunits were generated by treatment with an endo-(1-->4)-beta-D-glucanase of the xyloglucan-rich hemicellulosic fractions. MALDI-TOF mass spectra and HPAE-PAD chromatography of the pool of endoglucanase-generated xyloglucan oligomers indicated that A. spinosa cell wall contains a XXXG-type xyloglucan. In addition to XXXG, XXFG, XLXG/XXLG, XLFG fragments previously characterised in various plants, a second group of XXXG-type fragments was detected. The primary structure of the major subunit was determined by a combination of sugar analysis, methylation analysis, post-source decay (PSD) fragment analysis of MALDI-TOF MS and 1H NMR spectroscopy. This fragment, termed XUFG, contains a novel beta-D-Xylp-(1-->2)-alpha-D-Xylp side chain linked to C-6 of the second glucose unit from the nonreducing end of the cellotetraose sequence. 相似文献
70.
Identification and partial characterization of proteins and proteoglycans encrusting the secondary cell walls of flax fibres 总被引:3,自引:0,他引:3
Four proteins were isolated from depectinised elementary fibres of flax (Linum usitatissimum L.), using either alkali or cellulase digestion treatments. All the four proteins were characterized by a deficiency or low
contents of hydroxyproline and by high levels of glutamic acid/glutamine and/or aspartic acid/asparagine. The two proteoglycans
solubilized with cellulase strongly reacted with β-glucosyl Yariv reagent but not with α-glucosyl Yariv reagent and contained
appreciable amounts of alanine, glycine, serine and threonine, suggesting a relationship with cell wall hydroxyproline-deficient
arabinogalactan-proteins. The two alkali-extracted proteins did not show any reaction with β-glucosyl Yariv dye. Due to the
harsh treatment, they might only partially represent the original proteins. Due to its high level of glycine (41%), one of
these proteins might be classified as a glycine-rich protein. The latter polypeptide, of low molecular molar mass, contained
14.6% leucine and might consist of a domain related to leucine-rich proteins. The data show that these proteins and arabinogalactan-protein-like
proteoglycans were strongly associated with the secondary walls of flax fibres. Their presence in small amounts (0.1–0.4%),
raises the problem of their putative structural role.
Received: 22 October 1999 / Accepted: 17 January 2000 相似文献