The aseptic seedlings of Albizia julibrissin were divided into two groups. One group was inoculated by rhizobia and the other was designed as control without inoculation. These two groups were all cultivated in steril...The aseptic seedlings of Albizia julibrissin were divided into two groups. One group was inoculated by rhizobia and the other was designed as control without inoculation. These two groups were all cultivated in sterilized cultured liquid for about two weeks. In the first group,the root hairs did not form on the main roots,but formed a lot on the base part of the lateral roots. In the second group, the root hairs did not form not only on the main roots but also on the lateral roots. The root segments which have distinctive deformation of root hairs from first group were cut off and fixed, in the meanwhile the corresponding root segments were cut off from the contrastive group and fixed. These two groups of roots segments were treated as semi-thin section and ultrathin sections, then were observed by optical microscope and transmission electron microscope. The result showed that the transfer cells with wall ingrowths on the tangential exowall of the root’s epiderm and exodermis cells, are easy to be found in the root segments which has distinctive deformation of root hair. The wall ingrowth lies not only in root epidermal cells but also in the root exodermis cells, while there is no wall ingrowth in root epiderm and exodermis cells of A. julibrissin which is not inoculated by rhizobia. This suggested that the forming of root hairs and transfer cells in epiderm and exodermis of A. julibrissin is resulted from the inducement of rhizobia of A. julibrissin.展开更多
The inter-cellular translocation of nutrients in plant is mediated by highly specialized transfer cells （TCs）. TCs share similar functional and structural features across a wide range of plant species, including loc...The inter-cellular translocation of nutrients in plant is mediated by highly specialized transfer cells （TCs）. TCs share similar functional and structural features across a wide range of plant species, including location at plant exchange surfaces, rich in secondary wall ingrowths, facilitation of nutrient flow, and passage of select molecules. The fate of endosperm TCs is determined in the TC fate acquisition stage （TCF）, before the structure features are formed in the TC differentiation stage （TCD）. At present, the molecular basis of TC development in plants remains largely unknown. In this review, we summarize the important roles of the signaling molecules in different development phases, such as sugars in TCF and phytohormones in TCD, and discuss the genetic and epigenetic factors, including TC-specific genes and endogenous plant peptides, and their crosstalk with these signaling molecules as a complex regulatory network in regulation of TC develonment in olants.展开更多
One of the strategies of treating Parkinson's disease(PD) is the replacement of lost neurons in the substantia nigra with healthy dapamingergic cells.Potential sources for cells range from autologous grafts of dop...One of the strategies of treating Parkinson's disease(PD) is the replacement of lost neurons in the substantia nigra with healthy dapamingergic cells.Potential sources for cells range from autologous grafts of dopamine secreting cells,fetal ventral mesencephalon tissue,to various stem cell types.Over the past quarter century,many experimental replacement therapies have been tried on PD animal models as well as human patients,yet none resulted in satisfactory outcomes that warrant wide applications.Recent progress in stem cell biology has shown that nuclear transfer embryonic stem cells(ntES) or induced pluripotent stem cells(iPS) derived cells can be used to successfully treat rodent PD models,thus solving the problem of immunorejection and paving the way for future autologous transplantations for treating PD.Meanwhile,however,post mortem analysis of patients who received fetal brain cell transplantation revealed that implanted cells are prone to degeneration just like endogenous neurons in the same pathological area,indicating long-term efficacy of cell therapy of PD needs to overcome the degenerating environment in the brain.A better understanding of neurodegeneration in the midbrain appeared to be a necessary step in developing new cell therapies in Parkinson's disease.It is likely that future cell replacement will focus on not only ameliorating symptoms of the disease but also trying to slow the progression of the disease by either neuroprotection or restoring the micro-environment in the midbrain.展开更多
文摘The aseptic seedlings of Albizia julibrissin were divided into two groups. One group was inoculated by rhizobia and the other was designed as control without inoculation. These two groups were all cultivated in sterilized cultured liquid for about two weeks. In the first group,the root hairs did not form on the main roots,but formed a lot on the base part of the lateral roots. In the second group, the root hairs did not form not only on the main roots but also on the lateral roots. The root segments which have distinctive deformation of root hairs from first group were cut off and fixed, in the meanwhile the corresponding root segments were cut off from the contrastive group and fixed. These two groups of roots segments were treated as semi-thin section and ultrathin sections, then were observed by optical microscope and transmission electron microscope. The result showed that the transfer cells with wall ingrowths on the tangential exowall of the root’s epiderm and exodermis cells, are easy to be found in the root segments which has distinctive deformation of root hair. The wall ingrowth lies not only in root epidermal cells but also in the root exodermis cells, while there is no wall ingrowth in root epiderm and exodermis cells of A. julibrissin which is not inoculated by rhizobia. This suggested that the forming of root hairs and transfer cells in epiderm and exodermis of A. julibrissin is resulted from the inducement of rhizobia of A. julibrissin.
基金supported by the National Natural Science Foundation of China (Grant No.31300241)
文摘The inter-cellular translocation of nutrients in plant is mediated by highly specialized transfer cells （TCs）. TCs share similar functional and structural features across a wide range of plant species, including location at plant exchange surfaces, rich in secondary wall ingrowths, facilitation of nutrient flow, and passage of select molecules. The fate of endosperm TCs is determined in the TC fate acquisition stage （TCF）, before the structure features are formed in the TC differentiation stage （TCD）. At present, the molecular basis of TC development in plants remains largely unknown. In this review, we summarize the important roles of the signaling molecules in different development phases, such as sugars in TCF and phytohormones in TCD, and discuss the genetic and epigenetic factors, including TC-specific genes and endogenous plant peptides, and their crosstalk with these signaling molecules as a complex regulatory network in regulation of TC develonment in olants.
基金Support by the National Key Basic Research and Development Program of China (Grant No. 2006CB0F0603)Science and Technology Plan, Beijing Municipal Science &Technology Commission (Grant No. H020220010290)
文摘One of the strategies of treating Parkinson's disease(PD) is the replacement of lost neurons in the substantia nigra with healthy dapamingergic cells.Potential sources for cells range from autologous grafts of dopamine secreting cells,fetal ventral mesencephalon tissue,to various stem cell types.Over the past quarter century,many experimental replacement therapies have been tried on PD animal models as well as human patients,yet none resulted in satisfactory outcomes that warrant wide applications.Recent progress in stem cell biology has shown that nuclear transfer embryonic stem cells(ntES) or induced pluripotent stem cells(iPS) derived cells can be used to successfully treat rodent PD models,thus solving the problem of immunorejection and paving the way for future autologous transplantations for treating PD.Meanwhile,however,post mortem analysis of patients who received fetal brain cell transplantation revealed that implanted cells are prone to degeneration just like endogenous neurons in the same pathological area,indicating long-term efficacy of cell therapy of PD needs to overcome the degenerating environment in the brain.A better understanding of neurodegeneration in the midbrain appeared to be a necessary step in developing new cell therapies in Parkinson's disease.It is likely that future cell replacement will focus on not only ameliorating symptoms of the disease but also trying to slow the progression of the disease by either neuroprotection or restoring the micro-environment in the midbrain.
