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Kui Lin Erik Limpens Zhonghua Zhang Sergey Ivanov Diane G. O. Saunders Desheng Mu Erli Pang Huifen Cao Hwangho Cha Tao Lin Qian Zhou Yi Shang Ying Li Trupti Sharma Robin van Velzen Norbert de Ruijter Duur K. Aanen Joe Win Sophien Kamoun Ton Bisseling René Geurts Sanwen Huang 《PLoS genetics》2014,10(1)
Nuclei of arbuscular endomycorrhizal fungi have been described as highly diverse due to their asexual nature and absence of a single cell stage with only one nucleus. This has raised fundamental questions concerning speciation, selection and transmission of the genetic make-up to next generations. Although this concept has become textbook knowledge, it is only based on studying a few loci, including 45S rDNA. To provide a more comprehensive insight into the genetic makeup of arbuscular endomycorrhizal fungi, we applied de novo genome sequencing of individual nuclei of Rhizophagus irregularis. This revealed a surprisingly low level of polymorphism between nuclei. In contrast, within a nucleus, the 45S rDNA repeat unit turned out to be highly diverged. This finding demystifies a long-lasting hypothesis on the complex genetic makeup of arbuscular endomycorrhizal fungi. Subsequent genome assembly resulted in the first draft reference genome sequence of an arbuscular endomycorrhizal fungus. Its length is 141 Mbps, representing over 27,000 protein-coding gene models. We used the genomic sequence to reinvestigate the phylogenetic relationships of Rhizophagus irregularis with other fungal phyla. This unambiguously demonstrated that Glomeromycota are more closely related to Mucoromycotina than to its postulated sister Dikarya. 相似文献
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A Kamoun A Ben Hassen C Fendri S Ben Redjeb 《Archives de l'Institut Pasteur de Tunis》1992,69(3-4):263-271
366 strains of P. aeruginosa were studied. More than half of samples were issued from urology (40%) and general surgery (21%) and samples are mostly urine specimens (46%). The phenotypes of resistance to 3 beta-lactams (respectively ticarcillin, cefotaxime and ceftazidime) showed that 73% of the strains were wild phenotype (SSS-SIS-SRS). The MIC of ticarcillin +/- clavulanic acid, azlocillin, cefoperazone, cefsulodin, cefotaxime and ceftazidime against 93 strains chosen among different phenotypes of resistance showed that ceftazidime is the most active beta-lactam, 93% of strains being inhibited by 16 micrograms/ml. These MIC and iodometric test performed on 33 strains with ticarcillin MIC > 128 mg/l showed that acquired resistance was non enzymatic in 21% of cases and was related to beta-lactamase production in 79% of cases. 相似文献
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Human T cells express HLA class II molecules upon activation. The factors that regulate the induction of expression of these molecules are for the most part unknown. Here we report preliminary results indicating that tumor necrosis factor-alpha (TNF-alpha) regulates the induction of cell-surface HLA-DR, DO, and DP molecules in human T cells stimulated with PHA. In contrast, recombinant interferon-gamma (rIFN-gamma), recombinant interleukin-1 alpha (rIL-1 alpha), or rIL-4 appear to have no effect on class II expression. The role of class II molecules on activated T cells is discussed in relationship to immunoregulation and the progression of HIV infection. Three non-mutually exclusive hypotheses are discussed. In the first hypothesis, we consider the role of these class II molecules in antigen presentation of endogenously synthesized HIV envelope by CD4+ cells. The second is a clonal inactivation of virus-specific helper T cells that might occur as a consequence of a direct T cell to T cell interaction and a bypass of the "accessory signal" normally delivered by antigen-presenting cells such as macrophages. The third is a molecular mimicry between HIV envelope proteins and HLA class II molecules, which may lead to the development of autoimmunity against CD4+ T-cell-expressing class II molecules. 相似文献
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Jean François Chassé Véronique Paul Raphael Escañez Pierre Kamoun Jacqueline London 《Mammalian genome》1997,8(12):917-921
The human cystathionine β-synthase (CBS) gene spans in excess of 30 kb and consists of 19 exons, with three different 5′ untranslated regions including three different exons 1 (exons 1 a, b, and c). Exon la and 1b are 390 bp apart from each other and are linked to exon 2 in cDNA « a » and cDNA « b ». Exon 1c, which linked to exon 5 in cDNA « c », is 7 kb apart from exon 1b. All splice sites conform to the GT/AG rule, including those from exon la or 1b to exon 2 and from exon 1c to exon 5. Upstream of exons la and 1b, we found two putative promoter sequences with high C + G nucleotide content, one CAAT box at —70 nucleotides (for exon lb), no TATA box, several Sp1 binding regulatory consensus sequences, and some other regulatory sequences. Human adult and fetal Northern blots hybridized with total cDNA containing exon 1b, or specific probes from exons 1 (b and c) showed mRNAs of 2.5 kb, 2.7 kb, and 3.7 kb. These results suggest that the mRNAs containing the different exons 1 are under the control of different promoters. 相似文献
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Effector genomics accelerates discovery and functional profiling of potato disease resistance and phytophthora infestans avirulence genes 总被引:2,自引:0,他引:2
Vleeshouwers VG Rietman H Krenek P Champouret N Young C Oh SK Wang M Bouwmeester K Vosman B Visser RG Jacobsen E Govers F Kamoun S Van der Vossen EA 《PloS one》2008,3(8):e2875
Potato is the world's fourth largest food crop yet it continues to endure late blight, a devastating disease caused by the Irish famine pathogen Phytophthora infestans. Breeding broad-spectrum disease resistance (R) genes into potato (Solanum tuberosum) is the best strategy for genetically managing late blight but current approaches are slow and inefficient. We used a repertoire of effector genes predicted computationally from the P. infestans genome to accelerate the identification, functional characterization, and cloning of potentially broad-spectrum R genes. An initial set of 54 effectors containing a signal peptide and a RXLR motif was profiled for activation of innate immunity (avirulence or Avr activity) on wild Solanum species and tentative Avr candidates were identified. The RXLR effector family IpiO induced hypersensitive responses (HR) in S. stoloniferum, S. papita and the more distantly related S. bulbocastanum, the source of the R gene Rpi-blb1. Genetic studies with S. stoloniferum showed cosegregation of resistance to P. infestans and response to IpiO. Transient co-expression of IpiO with Rpi-blb1 in a heterologous Nicotiana benthamiana system identified IpiO as Avr-blb1. A candidate gene approach led to the rapid cloning of S. stoloniferum Rpi-sto1 and S. papita Rpi-pta1, which are functionally equivalent to Rpi-blb1. Our findings indicate that effector genomics enables discovery and functional profiling of late blight R genes and Avr genes at an unprecedented rate and promises to accelerate the engineering of late blight resistant potato varieties. 相似文献
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Propionate and succinate effects on acetyl glutamate biosynthesis by rat liver mitochondria 总被引:2,自引:0,他引:2
D Rabier L Cathelineau P Briand P Kamoun 《Biochemical and biophysical research communications》1979,91(2):456-460
Acetylglutamate biosynthesis in isolated rat liver mitochondria is dependent on glutamate and stimulated by arginine. Propionate and succinate inhibit this glutamate-dependent synthesis and their effects seem to be cumulative. 相似文献