The effect of water deficit on stem reserve mobilization and sink activity in wheat (Triticum aestivum L.) cultivars, viz., C306 (drought tolerant) and PBW343 (drought sensitive) was studied. Drought was maintained in...The effect of water deficit on stem reserve mobilization and sink activity in wheat (Triticum aestivum L.) cultivars, viz., C306 (drought tolerant) and PBW343 (drought sensitive) was studied. Drought was maintained in pot raised plants by withholding irrigation at 95 days after sowing (DAS), i.e. just five days before the initiation of anthesis. Drought induced a significant reduction in mean biomass of all the internodes of sensitive cultivar as compared to those of tolerant one. Mobilized dry matter and mobilization efficiency were observed to be higher in the internodes of tolerant cultivar, both under control and stress conditions, which resulted in enhanced translocation of stem reserves to the grains. Water soluble carbohydrates (WSC), which mainly occur as fructans, were observed to be higher in the internodes of tolerant cultivar than those of sensitive one. When drought was applied, fructans were mobilized more effectively from the internodes of tolerant cultivar. A significantly higher sucrose synthase activity in the grains of tolerant cultivar, under drought conditions, increased the sink strength by unloading the assimilates in the sink, thereby increasing further mobilization of assimilates to the grains. Grains of sensitive cultivar attained maturity much earlier as compared to the tolerant one, both under control and stress conditions. The longer duration of grain maturation in tolerant cultivar supported enhanced mobilization of stem reserves, thus restricting heavy decrease in grain yield, under stress conditions, as compared to the sensitive cultivar. It may, therefore, be concluded that certain characteristics viz., enhanced capability of fructan storage, higher mobilization efficiency, stronger sink activity and longer duration of grain maturation might help the drought tolerant cultivar in coping the stress展开更多
Cell therapy has the potential to improve healing of ischemic heart, repopulate injured myocardium and restore cardiac function. The tremendous hope and potential of stem cell therapy is well understood, yet recent tr...Cell therapy has the potential to improve healing of ischemic heart, repopulate injured myocardium and restore cardiac function. The tremendous hope and potential of stem cell therapy is well understood, yet recent trials involving cell therapy for cardiovascular diseases have yielded mixed results with inconsistent data thereby readdressing controversies and unresolved questions regarding stem cell efficacy for ischemic cardiac disease treatment. These controversies are believed to arise by the lack of uniformity of the clinical trial methodologies, uncertainty regarding the underlying reparative mechanisms of stem cells, questions concerning the most appropriate cell population to use, the proper delivery method and timing in relation to the moment of infarction, as well as the poor stem cell survival and engraftment especially in a diseased microenvironment which is collectively acknowledged as a major hindrance to any form of cell therapy. Indeed, the microenvironment of the failing heart exhibits pathological hypoxic, oxidative and inflammatory stressors impairing the survival of transplanted cells. Therefore, in order to observe any significant therapeutic benefit there is a need to increase resilience of stem cells to death in the transplant microenvironment while preserving or better yet improving their reparative functionality. Although stem cell differentiation into cardiomyocytes has been observed in some instance, the prevailing reparative benefits are afforded through paracrine mechanisms that promote angiogenesis, cell survival, transdifferentiate host cells and modulate immune responses. Therefore, to maximize their reparative functionality, ex vivo manipulation of stem cells through physical, genetic and pharmacological means have shown promise to enable cells to thrive in the postischemic transplant microenvironment. In the present work, we will overview the current status of stem cell therapy for ischemic heart disease, discuss the most recurring cell populations employed, the mechanisms by whic展开更多
文摘The effect of water deficit on stem reserve mobilization and sink activity in wheat (Triticum aestivum L.) cultivars, viz., C306 (drought tolerant) and PBW343 (drought sensitive) was studied. Drought was maintained in pot raised plants by withholding irrigation at 95 days after sowing (DAS), i.e. just five days before the initiation of anthesis. Drought induced a significant reduction in mean biomass of all the internodes of sensitive cultivar as compared to those of tolerant one. Mobilized dry matter and mobilization efficiency were observed to be higher in the internodes of tolerant cultivar, both under control and stress conditions, which resulted in enhanced translocation of stem reserves to the grains. Water soluble carbohydrates (WSC), which mainly occur as fructans, were observed to be higher in the internodes of tolerant cultivar than those of sensitive one. When drought was applied, fructans were mobilized more effectively from the internodes of tolerant cultivar. A significantly higher sucrose synthase activity in the grains of tolerant cultivar, under drought conditions, increased the sink strength by unloading the assimilates in the sink, thereby increasing further mobilization of assimilates to the grains. Grains of sensitive cultivar attained maturity much earlier as compared to the tolerant one, both under control and stress conditions. The longer duration of grain maturation in tolerant cultivar supported enhanced mobilization of stem reserves, thus restricting heavy decrease in grain yield, under stress conditions, as compared to the sensitive cultivar. It may, therefore, be concluded that certain characteristics viz., enhanced capability of fructan storage, higher mobilization efficiency, stronger sink activity and longer duration of grain maturation might help the drought tolerant cultivar in coping the stress
文摘Cell therapy has the potential to improve healing of ischemic heart, repopulate injured myocardium and restore cardiac function. The tremendous hope and potential of stem cell therapy is well understood, yet recent trials involving cell therapy for cardiovascular diseases have yielded mixed results with inconsistent data thereby readdressing controversies and unresolved questions regarding stem cell efficacy for ischemic cardiac disease treatment. These controversies are believed to arise by the lack of uniformity of the clinical trial methodologies, uncertainty regarding the underlying reparative mechanisms of stem cells, questions concerning the most appropriate cell population to use, the proper delivery method and timing in relation to the moment of infarction, as well as the poor stem cell survival and engraftment especially in a diseased microenvironment which is collectively acknowledged as a major hindrance to any form of cell therapy. Indeed, the microenvironment of the failing heart exhibits pathological hypoxic, oxidative and inflammatory stressors impairing the survival of transplanted cells. Therefore, in order to observe any significant therapeutic benefit there is a need to increase resilience of stem cells to death in the transplant microenvironment while preserving or better yet improving their reparative functionality. Although stem cell differentiation into cardiomyocytes has been observed in some instance, the prevailing reparative benefits are afforded through paracrine mechanisms that promote angiogenesis, cell survival, transdifferentiate host cells and modulate immune responses. Therefore, to maximize their reparative functionality, ex vivo manipulation of stem cells through physical, genetic and pharmacological means have shown promise to enable cells to thrive in the postischemic transplant microenvironment. In the present work, we will overview the current status of stem cell therapy for ischemic heart disease, discuss the most recurring cell populations employed, the mechanisms by whic
