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Chemical Induction (chemical + induction)
Selected AbstractsMitochondrial morphology transition is an early indicator of subsequent cell death in ArabidopsisNEW PHYTOLOGIST, Issue 1 2008Iain Scott Summary ,,Mitochondrial morphology and dynamics were investigated during the onset of cell death in Arabidopsis thaliana. Cell death was induced by either chemical (reactive oxygen species (ROS)) or physical (heat) shock. ,,Changes in mitochondrial morphology in leaf tissue, or isolated protoplasts, each expressing mitochondrial-targeted green fluorescent protein (GFP), were observed by epifluorescence microscopy, and quantified. ,,Chemical induction of ROS production, or a mild heat shock, caused a rapid and consistent change in mitochondrial morphology (termed the mitochondrial morphology transition) that preceded cell death. Treatment of protoplasts with a cell-permeable superoxide dismutase analogue, TEMPOL, blocked this morphology change. Incubation of protoplasts in micromolar concentrations of the calcium channel-blocker lanthanum chloride, or the permeability transition pore inhibitor cyclosporin A, prevented both the mitochondrial morphology transition and subsequent cell death. ,,It is concluded that the observed mitochondrial morphology transition is an early and specific indicator of cell death and is a necessary component of the cell death process. [source] Chemical induction of rapid and reversible plastid filamentation in Arabidopsis thaliana rootsPHYSIOLOGIA PLANTARUM, Issue 2 2010Ryuuichi D. Itoh Plastids assume various morphologies depending on their developmental status, but the basis for developmentally regulated plastid morphogenesis is poorly understood. Chemical induction of alterations in plastid morphology would be a useful tool for studying this; however, no such chemicals have been identified. Here, we show that antimycin A, an effective respiratory inhibitor, can change plastid morphology rapidly and reversibly in Arabidopsis thaliana. In the root cortex, hypocotyls, cotyledon epidermis and true leaf epidermis, significant differences in mitochondrial morphology were not observed between antimycin-treated and untreated tissues. In contrast, antimycin caused extreme filamentation of plastids in the mature cortices of main roots. This phenomenon was specifically observed in the mature root cortex. Other mitochondrial respiratory inhibitors (rotenone and carbonyl cyanide m -chlorophenylhydrazone), hydrogen peroxide, S -nitroso- N -acetylpenicillamine [a nitric oxide (NO) donor] and 3-(3,4-dichlorophenyl)-1,1-dimethylurea did not mimic the phenomenon under the present study conditions. Antimycin-induced plastid filamentation was initiated within 5 min after the onset of chemical treatment and appeared to complete within 1 h. Plastid morphology was restored within 7 h after the washout of antimycin, suggesting that the filamentation was reversible. Co-applications of antimycin and cytoskeletal inhibitors (demecolcine or latrunculin B) or protein synthesis inhibitors (cycloheximide or chloramphenicol) still caused plastid filamentation. Antimycin A was also effective for plastid filamentation in the chloroplast division mutants atftsZ1-1 and atminE1. Salicylhydroxamic acid, an alternative oxidase inhibitor, was solely found to suppress the filamentation, implying the possibility that this phenomenon was partly mediated by an antimycin-activated alternative oxidase in the mitochondria. [source] Chemical induction of HO-1 suppresses lupus nephritis by reducing local iNOS expression and synthesis of anti-dsDNA antibodyCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 2 2004Y. TAKEDA SUMMARY There is accumulating evidence that haem oxygenase (HO)-1 plays a protective role in various disorders. The beneficial efficacy of HO-1 induction therapy has been shown in renal diseases such as glomerulonephritis, interstitial nephritis and drug induced nephrotoxicity. However, involvement of HO-1 in the development of autoimmune renal diseases remains uncertain. To assess the clinical efficacy of HO-1 induction therapy for lupus glomerulonephritis, MRL/lpr mice were intraperitoneally injected with 100 µmol/kg hemin, a potent HO-1 inducer, or PBS as controls, once a week from 6 weeks of age to 21,24 weeks-old. We found that treatment with hemin led to a significant reduction of proteinuria and remarkable amelioration of glomerular lesions accompanied by decreased immune depositions. In addition, the circulating IgG anti-double-stranded DNA antibody level was significantly decreased in hemin treated mice when compared with controls. A single intraperitoneal injection with hemin resulted in reduction of inducible nitric oxide synthase expression in the kidney and spleen, and serum interferon- , level. Our results suggest that HO-1 induction therapy ameliorates lupus nephritis by suppressing nitric oxide (NO) dependent inflammatory responses and attenuating production of pathogenic autoantibodies. [source] Stretching the limits: Stem cells in regeneration scienceDEVELOPMENTAL DYNAMICS, Issue 12 2008David L. Stocum Abstract The focus of regenerative medicine is rebuilding damaged tissues by cell transplantation or implantation of bioartificial tissues. In either case, therapies focus on adult stem cells (ASCs) and embryonic stem cells (ESCs) as cell sources. Here we review four topics based on these two cell sources. The first compares the current performance of ASCs and ESCs as cell transplant therapies and the drawbacks of each. The second explores somatic cell nuclear transfer (SCNT) as a method to derive ESCs that will not be immunorejected. The third topic explores how SCNT and ESC research has led to the ability to derive pluripotent ESCs by the dedifferentiation of adult somatic cells. Lastly, we discuss how research on activation of intrinsic adult stem cells and on somatic cell dedifferentiation can evolve regenerative medicine from a platform consisting of cell transplantation to one that includes the chemical induction of regeneration from the body's own cells at the site of injury. Developmental Dynamics 237:3648,3671, 2008. © 2008 Wiley-Liss, Inc. [source] Mesenchymal stem cell interaction with a non-woven hyaluronan-based scaffold suitable for tissue repairJOURNAL OF ANATOMY, Issue 5 2008G. Pasquinelli Summary The fabrication of biodegradable 3-D scaffolds enriched with multipotent stem cells seems to be a promising strategy for the repair of irreversibly injured tissues. The fine mechanisms of the interaction of rat mesenchymal stem cells (rMSCs) with a hyaluronan-based scaffold, i.e. HYAFF®11, were investigated to evaluate the potential clinical application of this kind of engineered construct. rMSCs were seeded (2 × 106 cells cm,2) on the scaffold, cultured up to 21 days and analysed using appropriate techniques. Light (LM), scanning (SEM) and transmission (TEM) electron microscopy of untreated scaffold samples showed that scaffolds have a highly porous structure and are composed of 15-µm-thick microfibres having a rough surface. As detected by trypan blue stain, cell adhesion was high at day 1. rMSCs were viable up to 14 days as shown by CFDA assay and proliferated steadily on the scaffold as revealed by MTT assay. LM showed rMSCs in the innermost portions of the scaffold at day 3. SEM revealed a subconfluent cell monolayer covering 40 ± 10% of the scaffold surface at day 21. TEM of early culture showed rMSCs wrapping individual fibres with regularly spaced focal contacts, whereas confocal microscopy showed polarized expression of CD44 hyaluronan receptor; TEM of 14-day cultures evidenced fibronexus formation. Immunohistochemistry of 21-day cultures showed that fibronectin was the main matrix protein secreted in the extracellular space; decorin and versican were seen in the cell cytoplasm only and type IV collagen was minimally expressed. The expression of CD90, a marker of mesenchymal stemness, was found unaffected at the end of cell culture. Our results show that HYAFF®11 scaffolds support the adhesion, migration and proliferation of rMSCs, as well as the synthesis and delivery of extracellular matrix components under static culture conditions without any chemical induction. The high retention rate and viability of the seeded cells as well as their fine modality of interaction with the substrate suggest that such scaffolds could be potentially useful when wide tissue defects are to be repaired as in the case of cartilage repair, wound healing and large vessel replacement. [source] Phenotypic plasticity in seedling defense strategies: compensatory growth and chemical inductionOIKOS, Issue 6 2008Kasey E. Barton Phenotypic plasticity in growth (leading to compensation) and secondary chemical production (leading to induction) in response to herbivory are key defense strategies in adult plants, but their role in seedling defense remains unclear. A pair of greenhouse studies was conducted to investigate compensation and induction in seedlings and juvenile plants, using Plantago lanceolata (Plantaginaceae) and the specialist buckeye caterpillar Junonia coenia (Nymphalidae) as a model system. Plants received 50% defoliation at two and four weeks of age, and groups of plants were harvested one week after herbivory and six to eight weeks after herbivory to investigate the duration of the responses. Plants damaged at two weeks showed no chemical induction and fully compensated for the lost leaf tissue by ten weeks of age. Plants damaged at four weeks showed a significant reduction in iridoid glycosides one week after herbivory and achieved full shoot compensation by ten weeks of age at the expense of root biomass. These results indicate that P. lanceolata seedlings use compensation, but not chemical induction, as a defense strategy. This research highlights the importance of considering ontogeny in studies of plant,herbivore interactions and suggests that seedling defense may differ markedly from adult plant defense. [source] Factors underpinning the responsiveness and higher levels of virus resistance realised in potato genotypes carrying virus-specific R genesANNALS OF APPLIED BIOLOGY, Issue 2 2010A.L. Vuorinen Responses to Potato virus A (PVA, genus Potyvirus) segregate to three phenotypic groups in a diploid cross between Solanum tuberosum subsp. andigena and a highly interspecific potato hybrid. The aim of this study was to compare gene expression between the progeny genotypes which react with hypersensitive response (HR) to PVA, allow PVA accumulation in inoculated leaves but restrict PVA infection to the inoculated leaf by blocking systemic movement [non-necrotic resistance (nnr)], or are susceptible (S) and systemically infected with PVA. Expression levels of ca 10 000 genes were compared using probes arranged in a microarray format, and real-time RT-PCR was applied for quantitative comparison of the expression of selected defense-related genes (DRGs). Results showed that a few DRGs were autoactivated in HR genotypes at an early stage of plant growth in the absence of PVA infection, which was not observed in the two other phenotypic groups (nnr and S). More detailed studies on the DRGs encoding a beta-1,3-glucanase, a chitinase and a basic PR-1b protein showed that autoactivation of the genes was not evident in vitro and up to 2 weeks of growth in soil in a controlled growth cabinet but was apparent 2 weeks later. Hence, autoinduction of these DRGs in the HR genotypes could be associated with growth stage, environmental factors or both. Furthermore, a number of other DRGs were induced in the inoculated leaves of HR genotypes as a response to infection with PVA, which was not observed in nnr and S genotypes. These results provide some novel information about factors underpinning the higher levels of virus resistance realised in potato genotypes carrying virus-specific R genes and suggest that part of the resistance is attributable to additional ,minor' genes functioning simultaneously, hence adding to the overall responsiveness and level of resistance against infection. These results also imply that some genotypes might be more responsive to chemical induction of pathogen and pest resistance, which could be considered in screening of progenies in plant-breeding programs. [source] High-Level Transient Production of a Heterologous Protein in Plants by Optimizing Induction of a Chemically Inducible Viral Amplicon Expression SystemBIOTECHNOLOGY PROGRESS, Issue 6 2007Michael A. Plesha We have demonstrated that the method of chemical induction using a chemically inducible viral amplicon expression system can be optimized to increase expression of a heterologous protein in plants. A cucumber mosaic virus inducible viral amplicon (CMViva) expression system was used to transiently produce a recombinant human blood protein, ,-1-antitrypsin (AAT), by co-infiltrating intact and detached Nicotiana benthamiana leaves with two Agrobacterium tumefaciens strains, one containing the CMViva expression cassette carrying the AAT gene and the other containing a binary vector carrying the gene silencing suppressor p19. Infiltrated plants were induced by either topical applications or pressure injections and inducer was applied at either a single or multiple time points. Applying induction solution every 2 days via topical application resulted in increasing maximum levels of biologically functional rAAT from 0.71% to 1.3% of the total soluble protein (TSP) in detached plant leaves, a 1.8-fold improvement. Multiple applications of induction solution via pressure injection into intact leaves resulted in maximum levels of biologically functional rAAT being elevated 3-fold up to 2.4% of TSP compared to 0.8% of TSP when using the conventional method of a single topical application, and expression levels remained high 6 days post-induction. Overall production of rAAT in intact leaves was found to have a maximum level of 5.8% of TSP or 390 mg rAAT per kg leaf tissue when applying multiple injections of chemical induction solution. [source] | ||||||||||