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991.
J-domain protein CDJ2 and HSP70B are a plastidic chaperone pair that interacts with vesicle-inducing protein in plastids 1 下载免费PDF全文
Liu C Willmund F Whitelegge JP Hawat S Knapp B Lodha M Schroda M 《Molecular biology of the cell》2005,16(3):1165-1177
J-domain cochaperones confer functional specificity to their heat shock protein (HSP)70 partner by recruiting it to specific substrate proteins. To gain insight into the functions of plastidic HSP70s, we searched in Chlamydomonas databases for expressed sequence tags that potentially encode chloroplast-targeted J-domain cochaperones. Two such cDNAs were found: the encoded J-domain proteins were named chloroplast DnaJ homolog 1 and 2 (CDJ1 and CDJ2). CDJ2 was shown to interact with a approximately 28-kDa protein that by mass spectrometry was identified as the vesicle-inducing protein in plastids 1 (VIPP1). In fractionation experiments, CDJ2 was detected almost exclusively in the stroma, whereas VIPP1 was found in low-density membranes, thylakoids, and in the stroma. Coimmunoprecipitation and mass spectrometry analyses identified stromal HSP70B as the major protein interacting with soluble VIPP1, and, as confirmed by cross-linking data, as chaperone partner of CDJ2. In blue native-PAGE of soluble cell extracts, CDJ2 and VIPP1 comigrated in complexes of >669, approximately 150, and perhaps approximately 300 kDa. Our data suggest that CDJ2, presumably via coiled-coil interactions, binds to VIPP1 and presents it to HSP70B in the ATP state. Our findings and the previously reported requirement of VIPP1 for the biogenesis of thylakoid membranes point to a role for the HSP70B/CDJ2 chaperone pair in this process. 相似文献
992.
Cilia-driven fluid flow in the zebrafish pronephros, brain and Kupffer's vesicle is required for normal organogenesis 总被引:6,自引:0,他引:6
Kramer-Zucker AG Olale F Haycraft CJ Yoder BK Schier AF Drummond IA 《Development (Cambridge, England)》2005,132(8):1907-1921
Cilia, as motile and sensory organelles, have been implicated in normal development, as well as diseases including cystic kidney disease, hydrocephalus and situs inversus. In kidney epithelia, cilia are proposed to be non-motile sensory organelles, while in the mouse node, two cilia populations, motile and non-motile have been proposed to regulate situs. We show that cilia in the zebrafish larval kidney, the spinal cord and Kupffer's vesicle are motile, suggesting that fluid flow is a common feature of each of these organs. Disruption of cilia structure or motility resulted in pronephric cyst formation, hydrocephalus and left-right asymmetry defects. The data show that loss of fluid flow leads to fluid accumulation, which can account for organ distension pathologies in the kidney and brain. In Kupffer's vesicle, loss of flow is associated with loss of left-right patterning, indicating that the 'nodal flow' mechanism of generating situs is conserved in non-mammalian vertebrates. 相似文献
993.
The dendritic trees of different neuronal types display an astonishing diversity in structure and function. How this diversity is generated remains incompletely understood. However, recent studies have revealed some of the underlying mechanisms by which intrinsic programs of cell-type specification and extrinsic factors exert their effects on the dendritic cytoskeleton to regulate patterns of growth and branching. 相似文献
994.
995.
Kempson J Pitts WJ Barbosa J Guo J Omotoso O Watson A Stebbins K Starling GC Dodd JH Barrish JC Felix R Fischer K 《Bioorganic & medicinal chemistry letters》2005,15(7):1829-1833
A series of fused pyrimidine based inhibitors of PDE7 have been derived from an earlier screening lead 1. The synthesis, structure-activity relationships (SAR) and selectivity against several other PDE family members are described. 相似文献
996.
Bao J Miao S Kayser F Kotliar AJ Baker RK Doss GA Felix JP Bugianesi RM Slaughter RS Kaczorowski GJ Garcia ML Ha SN Castonguay L Koo GC Shah K Springer MS Staruch MJ Parsons WH Rupprecht KM 《Bioorganic & medicinal chemistry letters》2005,15(2):447-451
Kv1.3, the voltage-gated potassium channel in human T cells, represents a new target for treating immunosuppression and autoimmune diseases. Correolide (1), a pentacyclic natural product, is a potent and selective Kv1.3 channel blocker. Simplification of correolide via removal of its E-ring generates enone 4, whose modification produced a new series of tetracyclic Kv1.3 blockers. The structure-activity relationship for this class of compounds in two functional assays, Rb_Kv and human T cell proliferation, is presented herein. The most potent analog 43 is 15-fold more potent than correolide as inhibitor of human T cell proliferation. 相似文献
997.
Many lichen species produce both sexual and asexual propagules, but, aside from being minute, these diaspores lack special adaptations for long-distance dispersal. So far, molecular studies have not directly addressed isolation and genetic differentiation of lichen populations, both being affected by gene flow, at a regional scale. We used six mycobiont-specific microsatellite loci to investigate the population genetic structure of the epiphytic lichen Lobaria pulmonaria in two regions that strongly differed with respect to anthropogenic impact. In British Columbia, L. pulmonaria grows in continuous old-growth forests, while its populations in the old cultural landscape of Switzerland are comparably small and fragmented. Populations from both British Columbia and Switzerland were genetically diverse at the loci. Geographically restricted alleles, low historical gene flow, and analyses of genetic distance (upgma tree) and of differentiation (amova) indicated that populations from Vancouver Island and from the Canadian mainland were separated from each other, except for one, geographically intermediate population. This differentiation was attributed to different glacial and postglacial histories of coastal and inland populations in British Columbia. In contrast to expectations, the three investigated Swiss populations were genetically neither isolated nor differentiated from each other despite the long-lasting negative human impact on the lichen's range size in Central Europe. We propose that detailed studies integrating local landscape and regional scales are now needed to understand the processes of dispersal and gene flow in lichens. 相似文献
998.
Lack of suitable sugar sources for adult parasitic wasps is an important cause of failure in biological control programs, but the metabolic constraints of sugar feeding are poorly understood. Here we investigated the suitability of 11 naturally occurring sugars as energy sources for the parasitoid Cotesia glomerata (L.) (Hymenoptera: Braconidae). By feeding energy-deprived individuals with given quantities of a 40% (w:w) sugar solution, we assessed recovery time and lifespan after feeding. More than 50% of the wasps recovered within 20 min, and at least 80% within 60 min after uptake of one of the monosaccharides fructose or glucose, the disaccharide sucrose, or the trisaccharide melezitose. Between 40 to 80% of the test insects recovered within an hour after intake of maltose, raffinose, galactose, or mannose. Less than 25% recovered within 1 h after uptake of melibiose, trehalose, rhamnose, or water (control). Parasitoids obtained the highest lifespan benefits after intake of glucose, fructose, sucrose, or melezitose, indicating and confirming their convertibility as an energy source for C. glomerata. In contrast, no lifespan increase was found after consumption of rhamnose and trehalose. The differences in recovery time and lifespan are discussed in terms of parasitoid enzyme activity and metabolic processes. 相似文献
999.
Growth suppression induced by downregulation of E6-AP expression in human papillomavirus-positive cancer cell lines depends on p53 总被引:1,自引:0,他引:1 下载免费PDF全文
Hengstermann A D'silva MA Kuballa P Butz K Hoppe-Seyler F Scheffner M 《Journal of virology》2005,79(14):9296-9300
The ubiquitin-protein ligase E6-AP is utilized by the E6 oncoprotein of human papillomaviruses (HPVs) associated with cervical cancer to target the tumor suppressor p53 for degradation. Here, we report that downregulation of E6-AP expression by RNA interference results in both the accumulation of p53 and growth suppression of the HPV-positive cervical cancer cell lines HeLa and SiHa. In addition, HeLa cells, in which p53 expression was suppressed by RNA interference, are significantly less sensitive to the downregulation of E6-AP expression with respect to growth suppression than parental HeLa cells. These data indicate that the anti-growth-suppressive properties of E6-AP in HPV-positive cells depend on its ability to induce p53 degradation. 相似文献
1000.
The stimulatory role of lumichrome, a rhizosphere metabolite, was assessed on the growth of legume and cereal seedlings. At a very low nanomolar concentration (5 nm), lumichrome elicited growth promotion in cowpea, soybean, sorghum, millet and maize, but not in common bean, Bambara groundnut and Sudan grass. In soybean and cowpea only, 5 nm lumichrome caused early initiation of trifoliate leaf development, expansion in unifoliate and trifoliate leaves, increased stem elongation and, as a result, an increase in shoot and plant total biomass relative to control. Lumichrome (5 nm) also increased leaf area in maize and sorghum, and thus raised shoot and total biomass but there was no effect on the leaf area of the other cereals. Root growth was also stimulated in sorghum and millet by the supply of 5 nm lumichrome. By contrast, the application of a higher dose of lumichrome (50 nm) depressed development of unifoliate leaves in soybean, the second trifoliate leaf in cowpea, and shoot biomass in soybean. The 50 nm concentration also consistently decreased root development in cowpea and millet, but had no effect on the other species. These data show that lumichrome is a rhizosphere signal molecule that affects seedling development in both monocots and dicots. 相似文献