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51.
52.
Transdifferentiation of Mature Cortical Cells to Functional
Abscission Cells in Bean 总被引:2,自引:0,他引:2 下载免费PDF全文
Michael T. McManus D. Stuart Thompson Cledwyn Merriman Linden Lyne Daphne J. Osborne 《Plant physiology》1998,116(3):891-899
Abscission explants of bean (Phaseolus vulgaris L.) were treated with ethylene to induce cell separation at the primary abscission zone. After several days of further incubation of the remaining petiole in endogenously produced ethylene, the distal two-thirds of the petiole became senescent, and the remaining (proximal) portion stayed green. Cell-to-cell separation (secondary abscission) takes place precisely at the interface between the senescing yellow and the enlarging green cells. The expression of the abscission-associated isoform of β-1,4-glucanhydrolase, the activation of the Golgi apparatus, and enhanced vesicle formation occurred only in the enlarging cortical cells on the green side. These changes were indistinguishable from those that occur in normal abscission cells and confirm the conversion of the cortical cells to abscission-type cells. Secondary abscission cells were also induced by applying auxin to the exposed primary abscission surface after the pulvinus was shed, provided ethylene was added. Then, the orientation of development of green and yellow tissue was reversed; the distal tissue remained green and the proximal tissue yellowed. Nevertheless, separation still occurred at the junction between green and yellow cells and, again, it was one to two cell layers of the green side that enlarged and separated from their senescing neighbors. Evaluation of Feulgen-stained tissue establishes that, although nuclear changes occur, the conversion of the cortical cell to an abscission zone cell is a true transdifferentiation event, occurring in the absence of cell division. 相似文献
53.
Isopentenyladenine was isolated from a strain of the cyanobacterium Arthronema africanum (Schwabe et Simons) Komárek et Lukavský using a combination of biological and chemophysical techniques, including the soybean callus bioassay, cation exchange resin chromatography, paper chromatography, HPLC, and GC-MS. Positive identification of the major biologically active compound was achieved. 相似文献
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Vince JE Wong WW Khan N Feltham R Chau D Ahmed AU Benetatos CA Chunduru SK Condon SM McKinlay M Brink R Leverkus M Tergaonkar V Schneider P Callus BA Koentgen F Vaux DL Silke J 《Cell》2007,131(4):682-693
XIAP prevents apoptosis by binding to and inhibiting caspases, and this inhibition can be relieved by IAP antagonists, such as Smac/DIABLO. IAP antagonist compounds (IACs) have therefore been designed to inhibit XIAP to kill tumor cells. Because XIAP inhibits postmitochondrial caspases, caspase 8 inhibitors should not block killing by IACs. Instead, we show that apoptosis caused by an IAC is blocked by the caspase 8 inhibitor crmA and that IAP antagonists activate NF-kappaB signaling via inhibtion of cIAP1. In sensitive tumor lines, IAP antagonist induced NF-kappaB-stimulated production of TNFalpha that killed cells in an autocrine fashion. Inhibition of NF-kappaB reduced TNFalpha production, and blocking NF-kappaB activation or TNFalpha allowed tumor cells to survive IAC-induced apoptosis. Cells treated with an IAC, or those in which cIAP1 was deleted, became sensitive to apoptosis induced by exogenous TNFalpha, suggesting novel uses of these compounds in treating cancer. 相似文献
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Lee Taylor Adrian W. Midgley Bryna Chrismas Angela R. Hilman Leigh A. Madden Rebecca V. Vince Lars R. McNaughton 《Amino acids》2011,40(2):393-401
Heat shock protein 72 (HSP72) performs vital roles within the body at rest and during periods of stress. In vitro, research
demonstrates HSP72 induction in response to hypoxia. Recently, in vivo, an acute hypoxic exposure (75 min at 2,980 m) was
sufficient to induce significant increases in monocyte expressed HSP72 (mHSP72) and a marker of oxidative stress in healthy human subjects. The purpose of the current study was to identify the impact
of 10 consecutive days of hypoxic exposures (75 min at 2,980 m) on mHSP72 and erythropoietin (EPO) expression, markers of oxidative stress, and maximal oxygen consumption in graded incremental aerobic
exercise. Eight male subjects were exposed to daily normobaric hypoxic exposures for 75 min at 2,980 m for 10 consecutive
days, commencing and ceasing at 0930 and 1045, respectively. This stressor was sufficient to induce significant increases
in mHSP72, which was significantly elevated from day 2 of the hypoxic exposures until 48 h post-final exposure. Notably, this increase
had an initial rapid (30% day on day compared to baseline) and final slow phase (16% day on day compared to baseline) of expression.
The authors postulate that 7-day hypoxic exposure in this manner would be sufficient to induce near maximum hypoxia-mediated
basal mHSP72 expression. Elevated levels of mHSP72 are associated with acquired thermotolerance and provide cross tolerance to non-related stressors in vivo, the protocol used
here may provide a useful tool for elevating mHSP72 in vivo. Aside from these major findings, significant transient daily elevations were seen in a marker of oxidative stress,
alongside sustained increases in EPO expression. However, no physiologically significant changes were seen in maximal oxygen
consumption or time to exhaustion. 相似文献
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Question: Does the increase in Populus tremuloides cover within the Picea mariana–feathermoss domain enhance establishment and growth conditions for Abies balsamea regeneration? Location: Boreal forest of northwest Quebec, Canada. Method: To document the effect of Populus tremuloides on A. balsamea regeneration, mixed stands with a heterogeneous presence of P. tremuloides adjacent to Picea mariana‐dominated stands were selected. Abies balsamea regeneration, understorey environment and canopy composition were characterized from 531 sampling units distributed along transects covering the mixed–coniferous gradient. Abundance of understorey A. balsamea regeneration was described using three height groups: seedling (<30 cm), small sapling (30 to <100 cm) and tall sapling (100 to 300 cm). Growth characteristics were measured from 251 selected individuals of A. balsamea (<3 m). Results: Results showed that A. balsamea regeneration was generally more abundant when P. tremuloides was present in the canopy. Differences between seedling and sapling abundance along the mixed–coniferous gradient suggest that while establishment probably occurs over a wide range of substrates, the better growth conditions found under mixed stands ensure a higher survival rate for A. balsamea seedlings. Conclusions: The abundant A. balsamea regeneration observed within mixed stands of the Picea mariana–feathermoss domain suggests that the increase in P. tremuloides cover, favoured by intensive management practices and climatic change, could contribute to acceleration of the northward expansion of the A. balsamea–Betula papyrifera domain into the northern boreal forest dominated by Picea mariana. 相似文献
59.
Phillip A. Wadl Arnold M. Saxton Xinwang Wang Vince R. Pantalone Timothy A. Rinehart Robert N. Trigiano 《Molecular breeding : new strategies in plant improvement》2011,27(3):409-416
The objective of our investigation was to acquire information on the association between molecular markers and foliage color
in flowering dogwood in order to improve our understanding of the inheritance of this trait and to make possible early selection
of red foliage genotypes in breeding programs. A segregating pseudo-F2 population of 94 individuals of flowering dogwood (Cornus florida L.), together with 255 simple sequence repeat markers, was used to identify putative quantitative trait loci (QTL) for foliage
color. Foliage color segregated into green- and red-leaved phenotypes and was visually rated for color on five spring dates
over 3 years (2007–2009). Repeated measures single-marker categorical analysis of variance (ANOVA) identified four putative
QTL (CF309C, CF792A, CF367B, and CF367C) on three linkage groups. Single-marker categorical ANOVA was then used to determine
stability of QTL across dates. We identified different QTL, found a low percentage of phenotypic variance explained by the
QTL, and detected QTL instability over time, providing evidence of the complex genetics for red pigment expression in flowering
dogwood. 相似文献
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