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131.
Specific regions within the embryonic midbrain and cerebellum require different levels of FGF signaling during development 总被引:1,自引:0,他引:1
Basson MA Echevarria D Ahn CP Sudarov A Joyner AL Mason IJ Martinez S Martin GR 《Development (Cambridge, England)》2008,135(5):889-898
Prospective midbrain and cerebellum formation are coordinated by FGF ligands produced by the isthmic organizer. Previous studies have suggested that midbrain and cerebellum development require different levels of FGF signaling. However, little is known about the extent to which specific regions within these two parts of the brain differ in their requirement for FGF signaling during embryogenesis. Here, we have explored the effects of inhibiting FGF signaling within the embryonic mouse midbrain (mesencephalon) and cerebellum (rhombomere 1) by misexpressing sprouty2 (Spry2) from an early stage. We show that such Spry2 misexpression moderately reduces FGF signaling, and that this reduction causes cell death in the anterior mesencephalon, the region furthest from the source of FGF ligands. Interestingly, the remaining mesencephalon cells develop into anterior midbrain, indicating that a low level of FGF signaling is sufficient to promote only anterior midbrain development. Spry2 misexpression also affects development of the vermis, the part of the cerebellum that spans the midline. We found that, whereas misexpression of Spry2 alone caused loss of the anterior vermis, reducing FGF signaling further, by decreasing Fgf8 gene dose, resulted in loss of the entire vermis. Our data suggest that cell death is not responsible for vermis loss, but rather that it fails to develop because reducing FGF signaling perturbs the balance between vermis and roof plate development in rhombomere 1. We suggest a molecular explanation for this phenomenon by providing evidence that FGF signaling functions to inhibit the BMP signaling that promotes roof plate development. 相似文献
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Background and Aims
The bacterium Xylella fastidiosa (Xf), responsible for Pierce''s disease (PD) of grapevine, colonizes the xylem conduits of vines, ultimately killing the plant. However, Vitis vinifera grapevine varieties differ in their susceptibility to Xf and numerous other plant species tolerate Xf populations without showing symptoms. The aim of this study was to examine the xylem structure of grapevines with different susceptibilities to Xf infection, as well as the xylem structure of non-grape plant species that support or limit movement of Xf to determine if anatomical differences might explain some of the differences in susceptibility to Xf.Methods
Air and paint were introduced into leaves and stems to examine the connectivity between stem and leaves and the length distribution of their vessels. Leaf petiole and stem anatomies were studied to determine the basis for the free or restricted movement of Xf into the plant.Key Results
There were no obvious differences in stem or petiole vascular anatomy among the grape varieties examined, nor among the other plant species that would explain differences in resistance to Xf. Among grape varieties, the more tolerant ‘Sylvaner’ had smaller stem vessel diameters and 20 % more parenchyma rays than the other three varieties. Alternative hosts supporting Xf movement had slightly longer open xylem conduits within leaves, and more connection between stem and leaves, when compared with alternative hosts that limit Xf movement.Conclusions
Stem–leaf connectivity via open xylem conduits and vessel length is not responsible for differences in PD tolerance among grape varieties, or for limiting bacterial movement in the tolerant plant species. However, it was found that tolerant host plants had narrower vessels and more parenchyma rays, possibly restricting bacterial movement at the level of the vessels. The implications of xylem structure and connectivity for the means and regulation of bacterial movement are discussed. 相似文献135.
Monteiro AP Pinheiro CS Luna-Gomes T Alves LR Maya-Monteiro CM Porto BN Barja-Fidalgo C Benjamim CF Peters-Golden M Bandeira-Melo C Bozza MT Canetti C 《Journal of immunology (Baltimore, Md. : 1950)》2011,186(11):6562-6567
High concentrations of free heme found during hemolytic events or cell damage leads to inflammation, characterized by neutrophil recruitment and production of reactive oxygen species, through mechanisms not yet elucidated. In this study, we provide evidence that heme-induced neutrophilic inflammation depends on endogenous activity of the macrophage-derived lipid mediator leukotriene B(4) (LTB(4)). In vivo, heme-induced neutrophil recruitment into the peritoneal cavity of mice was attenuated by pretreatment with 5-lipoxygenase (5-LO) inhibitors and leukotriene B(4) receptor 1 (BLT1) receptor antagonists as well as in 5-LO knockout (5-LO(-/-)) mice. Heme administration in vivo increased peritoneal levels of LTB(4) prior to and during neutrophil recruitment. Evidence that LTB(4) was synthesized by resident macrophages, but not mast cells, included the following: 1) immuno-localization of heme-induced LTB(4) was compartmentalized exclusively within lipid bodies of resident macrophages; 2) an increase in the macrophage population enhanced heme-induced neutrophil migration; 3) depletion of resident mast cells did not affect heme-induced LTB(4) production or neutrophil influx; 4) increased levels of LTB(4) were found in heme-stimulated peritoneal cavities displaying increased macrophage numbers; and 5) in vitro, heme was able to activate directly macrophages to synthesize LTB(4). Our findings uncover a crucial role of LTB(4) in neutrophil migration induced by heme and suggest that beneficial therapeutic outcomes could be achieved by targeting the 5-LO pathway in the treatment of inflammation associated with hemolytic processes. 相似文献
136.
Proteome analysis of rat liver mitochondria reveals a possible compensatory response to endotoxic shock 总被引:2,自引:0,他引:2
Miller I Gemeiner M Gesslbauer B Kungl A Piskernik C Haindl S Nürnberger S Bahrami S Redl H Kozlov AV 《FEBS letters》2006,580(5):1257-1262
Organ failure induced by endotoxic shock has recently been associated with affected mitochondrial function. In this study, effects of in vivo lipopolysaccharide-challenge on protein patterns of rat liver mitochondria in treated animals versus controls were studied by two-dimensional electrophoresis (differential image gel electrophoresis). Significant upregulation was found for ATP-synthase alpha chain and superoxide dismutase [Mn]. Our data suggest that endotoxic shock mediated changes in the mitochondrial proteome contribute to a compensatory reaction (adaptation to endotoxic shock) rather than to a mechanism of cell damage. 相似文献
137.
Marjuki H Alam MI Ehrhardt C Wagner R Planz O Klenk HD Ludwig S Pleschka S 《The Journal of biological chemistry》2006,281(24):16707-16715
138.
Baudrimont A Penkner A Woglar A Machacek T Wegrostek C Gloggnitzer J Fridkin A Klein F Gruenbaum Y Pasierbek P Jantsch V 《PLoS genetics》2010,6(11):e1001219
The Caenorhabditis elegans inner nuclear envelope protein matefin/SUN-1 plays a conserved, pivotal role in the process of genome haploidization. CHK-2-dependent phosphorylation of SUN-1 regulates homologous chromosome pairing and interhomolog recombination in Caenorhabditis elegans. Using time-lapse microscopy, we characterized the movement of matefin/SUN-1::GFP aggregates (the equivalent of chromosomal attachment plaques) and showed that the dynamics of matefin/SUN-1 aggregates remained unchanged throughout leptonene/zygotene, despite the progression of pairing. Movement of SUN-1 aggregates correlated with chromatin polarization. We also analyzed the requirements for the formation of movement-competent matefin/SUN-1 aggregates in the context of chromosome structure and found that chromosome axes were required to produce wild-type numbers of attachment plaques. Abrogation of synapsis led to a deceleration of SUN-1 aggregate movement. Analysis of matefin/SUN-1 in a double-strand break deficient mutant revealed that repair intermediates influenced matefin/SUN-1 aggregate dynamics. Investigation of movement in meiotic regulator mutants substantiated that proper orchestration of the meiotic program and effective repair of DNA double-strand breaks were necessary for the wild-type behavior of matefin/SUN-1 aggregates. 相似文献
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C. Scott Mahan Maria Walusimbi Denise F. Johnson Christina Lancioni Edwin Charlebois Joyce Baseke Keith A. Chervenak Roy D. Mugerwa Diane V. Havlir Harriet Mayanja-Kizza Christopher C. Whalen W. Henry Boom for the Uganda-Case Western Research Collaboration 《PloS one》2010,5(2)