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211.
The rice leaf blast pathogen undergoes developmental processes typical of root-infecting fungi 总被引:5,自引:0,他引:5
Pathogens have evolved different strategies to overcome the various barriers that they encounter during infection of their hosts. The rice blast fungus Magnaporthe grisea causes one of the most damaging diseases of cultivated rice and has emerged as a paradigm system for investigation of foliar pathogenicity. This fungus undergoes a series of well-defined developmental steps during leaf infection, including the formation of elaborate penetration structures (appressoria). This process has been studied in great detail, and over thirty M. grisea genes that condition leaf infection have been identified. Here we show a new facet of the M. grisea life cycle: this fungus can undergo a different (and previously uncharacterized) set of programmed developmental events that are typical of root-infecting pathogens. We also show that root colonization can lead to systemic invasion and the development of classical disease symptoms on the aerial parts of the plant. Gene-for-gene type specific disease resistance that is effective against rice blast in leaves also operates in roots. These findings have significant implications for fungal development, epidemiology, plant breeding and disease control. 相似文献
212.
213.
Seo HC Edvardsen RB Maeland AD Bjordal M Jensen MF Hansen A Flaat M Weissenbach J Lehrach H Wincker P Reinhardt R Chourrout D 《Nature》2004,431(7004):67-71
Tunicate embryos and larvae have small cell numbers and simple anatomical features in comparison with other chordates, including vertebrates. Although they branch near the base of chordate phylogenetic trees, their degree of divergence from the common chordate ancestor remains difficult to evaluate. Here we show that the tunicate Oikopleura dioica has a complement of nine Hox genes in which all central genes are lacking but a full vertebrate-like set of posterior genes is present. In contrast to all bilaterians studied so far, Hox genes are not clustered in the Oikopleura genome. Their expression occurs mostly in the tail, with some tissue preference, and a strong partition of expression domains in the nerve cord, in the notochord and in the muscle. In each tissue of the tail, the anteroposterior order of Hox gene expression evokes spatial collinearity, with several alterations. We propose a relationship between the Hox cluster breakdown, the separation of Hox expression domains, and a transition to a determinative mode of development. 相似文献
214.
Mattii L Bianchi F Pellegrini S Dolfi A Bernardini N 《Cellular and molecular life sciences : CMLS》2000,57(13-14):1990-1996
The small G protein Rho subfamily controls several cellular events such as growth, movement, proliferation and differentiation by rearranging actin and cytoskeleton proteins. Most of these effects are mediated by the activation of growth factor and extracellular matrix molecule receptors, suggesting a role for Rho molecules in the transduction pathway of these receptors. Despite the importance of Rho peptides in fundamental cellular events, data on their subcellular immunolocalisation are sparse: here we investigated the expression and subcellular localisation of RhoA in resting (cultured on plastic) and activated (Matri-cell or hepatocyte growth factor) MDCK cells by immunoperoxidase and immunogold techniques. Resting MDCK cells contain detectable amounts of RhoA mainly localised in the cytoplasm; RhoA expression is significantly enhanced by Matri-cell substrates that promote translocation of RhoA at the membrane level. This enhancing effect is reduced after exposure to hepatocyte growth factor. 相似文献
215.
ESCRT-III recognition by VPS4 ATPases 总被引:1,自引:0,他引:1
Stuchell-Brereton MD Skalicky JJ Kieffer C Karren MA Ghaffarian S Sundquist WI 《Nature》2007,449(7163):740-744
The ESCRT (endosomal sorting complex required for transport) pathway is required for terminal membrane fission events in several important biological processes, including endosomal intraluminal vesicle formation, HIV budding and cytokinesis. VPS4 ATPases perform a key function in this pathway by recognizing membrane-associated ESCRT-III assemblies and catalysing their disassembly, possibly in conjunction with membrane fission. Here we show that the microtubule interacting and transport (MIT) domains of human VPS4A and VPS4B bind conserved sequence motifs located at the carboxy termini of the CHMP1-3 class of ESCRT-III proteins. Structures of VPS4A MIT-CHMP1A and VPS4B MIT-CHMP2B complexes reveal that the C-terminal CHMP motif forms an amphipathic helix that binds in a groove between the last two helices of the tetratricopeptide-like repeat (TPR) of the VPS4 MIT domain, but in the opposite orientation to that of a canonical TPR interaction. Distinct pockets in the MIT domain bind three conserved leucine residues of the CHMP motif, and mutations that inhibit these interactions block VPS4 recruitment, impair endosomal protein sorting and relieve dominant-negative VPS4 inhibition of HIV budding. Thus, our studies reveal how the VPS4 ATPases recognize their CHMP substrates to facilitate the membrane fission events required for the release of viruses, endosomal vesicles and daughter cells. 相似文献
216.
Wetzel C Hu J Riethmacher D Benckendorff A Harder L Eilers A Moshourab R Kozlenkov A Labuz D Caspani O Erdmann B Machelska H Heppenstall PA Lewin GR 《Nature》2007,445(7124):206-209
Touch and mechanical pain are first detected at our largest sensory surface, the skin. The cell bodies of sensory neurons that detect such stimuli are located in the dorsal root ganglia, and subtypes of these neurons are specialized to detect specific modalities of mechanical stimuli. Molecules have been identified that are necessary for mechanosensation in invertebrates but so far not in mammals. In Caenorhabditis elegans, mec-2 is one of several genes identified in a screen for touch insensitivity and encodes an integral membrane protein with a stomatin homology domain. Here we show that about 35% of skin mechanoreceptors do not respond to mechanical stimuli in mice with a mutation in stomatin-like protein 3 (SLP3, also called Stoml3), a mammalian mec-2 homologue that is expressed in sensory neurons. In addition, mechanosensitive ion channels found in many sensory neurons do not function without SLP3. Tactile-driven behaviours are also impaired in SLP3 mutant mice, including touch-evoked pain caused by neuropathic injury. SLP3 is therefore indispensable for the function of a subset of cutaneous mechanoreceptors, and our data support the idea that this protein is an essential subunit of a mammalian mechanotransducer. 相似文献
217.
218.
A putative RUNX1 binding site variant between SLC9A3R1 and NAT9 is associated with susceptibility to psoriasis 总被引:24,自引:0,他引:24
Helms C Cao L Krueger JG Wijsman EM Chamian F Gordon D Heffernan M Daw JA Robarge J Ott J Kwok PY Menter A Bowcock AM 《Nature genetics》2003,35(4):349-356
Psoriasis (OMIM 177900) is a chronic inflammatory skin disorder of unknown pathogenesis affecting approximately 2% of the Western population. It occurs more frequently in individuals with human immunodeficiency virus, and 20-30% of individuals with psoriasis have psoriatic arthritis. Psoriasis is associated with HLA class I alleles, and previous linkage analysis by our group identified a second psoriasis locus at 17q24-q25 (PSORS2; ref. 7). Linkage to this locus was confirmed with independent family sets. Additional loci have also been proposed to be associated with psoriasis. Here we describe two peaks of strong association with psoriasis on chromosome 17q25 separated by 6 Mb. Associated single-nucleotide polymorphisms (SNPs) in the proximal peak lie in or near SLC9A3R1 (also called EBP50 and NHERF1) and NAT9, a new member of the N-acetyltransferase family. SLC9A3R1 is a PDZ domain-containing phosphoprotein that associates with members of the ezrin-radixin-moesin family and is implicated in diverse aspects of epithelial membrane biology and immune synapse formation in T cells. The distal peak of association is in RAPTOR (p150 target of rapamycin (TOR)-scaffold protein containing WD-repeats). Expression of SLC9A3R1 is highest in the uppermost stratum Malpighi of psoriatic and normal skin and in inactive versus active T cells. A disease-associated SNP lying between SLC9A3R1 and NAT9 leads to loss of RUNX1 binding. This is the second example of loss of a RUNX1 binding site associated with susceptibility to an autoimmune disease. It also suggests defective regulation of SLC9A3R1 or NAT9 by RUNX1 as a susceptibility factor for psoriasis. 相似文献
219.
Since colonising land,plants have undergone massive metabolic diversification.This is reflected by the numbers of metabolites that they collectively produce (es... 相似文献
220.
Lewisia longipetala (Piper) Clay is a high-altitude endemic found in the northern Sierra Nevada. The characteristics of 12 sites with L. longipetala , which represent all known populations, were studied to define habitat requirements of the species. Meso- and microscale characteristics of the habitat were examined, including characteristics of the associated plant community. Average plant size and plant density of L. longipetala were also determined for each population. Similar measurements were made on 6 populations of Lewisia pygmaea (A. Gray) Robinson, a more common Lewisia . Populations of L. longipetala that had larger plants and higher plant density were associated with gently sloped, north-facing sites that were near large, persistent snowbanks and had low vegetative cover. Plant species associated with populations of L. longipetala were similar among the 12 sites and were indicative of mesic, rocky alpine sites. These types of plant communities found near persistent snowbanks are often termed snow-bed vegetation. In contrast, L. pygmaea was found to be less site specific. Lewisia pygmaea was found adjacent to or interspersed with L. longipetala at 5 sites, but was found in areas associated with a higher percentage of herbaceous cover and a wider variety of species. This integration of ecological community information for L. longipetala populations contributes to the interim management and long-term monitoring of this species by providing needed information concerning its habitat and environmental specificity. 相似文献