The ice exceeding one million years old has significant meaning for verifying and interpreting the middle Pleistocene transition （MPT） and the relationship between greenhouse gas and climate change. The region near ...The ice exceeding one million years old has significant meaning for verifying and interpreting the middle Pleistocene transition （MPT） and the relationship between greenhouse gas and climate change. The region near Dome A in Antarctica satisfies the conditions for obtaining million-years-old ice since it has low temperatures and low accumulation rates. We analyze the corresponding relation between radar wave features and the crystal orientation fabric （COF） types based on the results of multi-polarization plane radio echo sounding （RES）. The results show that, even in the summit of the ice sheet, the COF type is not perfect, but is an elongated single-pole COF. Principal-axis-orientation differences of the COF among the different periods exist and reveal that the ice flow orientations are not constant but deviate clockwise with the increasing depth. This may be related to the adjacent basal valley or both height and position changes of the summit during the glacial-interglacial periods.展开更多
Rat is a valuable model for pharmacological and physiological studies. Germline-competent rat embryonic stem （rES） cell lines have been successfully established and the molecular networks maintaining the self-renewi...Rat is a valuable model for pharmacological and physiological studies. Germline-competent rat embryonic stem （rES） cell lines have been successfully established and the molecular networks maintaining the self-renewing, undifferentiated state of rES cells have also been well uncovered. However, little is known about the differentiation strategies and the underlying mechanisms of how these authentic rat pluripotent stem ceils give rise to specific cell types. The aim of this study is to investigate the neural differentiation capacity of rES cells. By means of a modified procedure based on previous publications - combination of mitogen-activated protein kinase （MAPK） and glycogen synthase kinase 3 （GSK3） inhibitors （two inhibitors, ＂2i＂） with feeder-conditioned medium, we successfully obtained high- quality rat embryoid bodies （rEBs） from rES cells and then differentiated them to tripotent neural progenitors. These rES cell-derived neural progenitor cells （rNPCs） were capable of self-renewing and giving rise to all three neural lineages, including astrocytes, oligo- dendrocytes, and neurons. Besides, these rES cell-derived neurons stained positive for y-aminobutyric acid （GABA） and tyrosine hydroxylase （TH）. In summary, we develop an experimental system for differentiating rES cells to tripotent neural progenitors, which may provide a powerful tool for pharmacological test and a valuable platform for studying the pathogenesis of many neurodegenerative disorders such as Parkinson＇s disease and the development of rat nervous system.展开更多
The highest part of the East Antarctic Ice Sheet, more than 4000 m above sea level, has been an area that has seen a considerable scientific research effort undertaken by the Chinese National Antarctic Research Expedi...The highest part of the East Antarctic Ice Sheet, more than 4000 m above sea level, has been an area that has seen a considerable scientific research effort undertaken by the Chinese National Antarctic Research Expedition, and its international collaborators, since January 2005. That includes the establishment of the most remote Of the Chinese Antarctic stations, Kunlun, at Dome A in 2009. However, the exploration and mapping of this region had been commenced many decades earlier, most notably by inland traverses of the Union of Soviet Socialist Republics during the 1957-1958 International Geophysical Year 0GY） and later; and the extensive surveys of Antarctic surface and sub-ice topography by airborne radio-echo sounding made by the US National Science Foundation-Scott Polar Research Institute-Technical University of Denmark （NSF-SPRI-TUD） in the late-1960s and the 1970s. Here we provide a history of the activities and achievements of these earlier programs. Recent topographic maps of the ice sheet surface in the Dome A region, produced using Chinese GPS data and satellite altimetry, have shown the maps compiled from the earlier data were remarkably accurate.展开更多
基金the National Natural Science Foundation of China(Grant No.40874060)the 863 projection(Grant No.2006AA09Z152)
文摘The ice exceeding one million years old has significant meaning for verifying and interpreting the middle Pleistocene transition （MPT） and the relationship between greenhouse gas and climate change. The region near Dome A in Antarctica satisfies the conditions for obtaining million-years-old ice since it has low temperatures and low accumulation rates. We analyze the corresponding relation between radar wave features and the crystal orientation fabric （COF） types based on the results of multi-polarization plane radio echo sounding （RES）. The results show that, even in the summit of the ice sheet, the COF type is not perfect, but is an elongated single-pole COF. Principal-axis-orientation differences of the COF among the different periods exist and reveal that the ice flow orientations are not constant but deviate clockwise with the increasing depth. This may be related to the adjacent basal valley or both height and position changes of the summit during the glacial-interglacial periods.
基金supported in part by the grants from the National Basic Research Program of China(No.2012CB966501 to X.Z.and 2011CB965300 to L.W.)the"Strategic Priority Research Program"of the Chinese Academy of Sciences(No. XDA01020100 to Q.Z.)
文摘Rat is a valuable model for pharmacological and physiological studies. Germline-competent rat embryonic stem （rES） cell lines have been successfully established and the molecular networks maintaining the self-renewing, undifferentiated state of rES cells have also been well uncovered. However, little is known about the differentiation strategies and the underlying mechanisms of how these authentic rat pluripotent stem ceils give rise to specific cell types. The aim of this study is to investigate the neural differentiation capacity of rES cells. By means of a modified procedure based on previous publications - combination of mitogen-activated protein kinase （MAPK） and glycogen synthase kinase 3 （GSK3） inhibitors （two inhibitors, ＂2i＂） with feeder-conditioned medium, we successfully obtained high- quality rat embryoid bodies （rEBs） from rES cells and then differentiated them to tripotent neural progenitors. These rES cell-derived neural progenitor cells （rNPCs） were capable of self-renewing and giving rise to all three neural lineages, including astrocytes, oligo- dendrocytes, and neurons. Besides, these rES cell-derived neurons stained positive for y-aminobutyric acid （GABA） and tyrosine hydroxylase （TH）. In summary, we develop an experimental system for differentiating rES cells to tripotent neural progenitors, which may provide a powerful tool for pharmacological test and a valuable platform for studying the pathogenesis of many neurodegenerative disorders such as Parkinson＇s disease and the development of rat nervous system.
文摘The highest part of the East Antarctic Ice Sheet, more than 4000 m above sea level, has been an area that has seen a considerable scientific research effort undertaken by the Chinese National Antarctic Research Expedition, and its international collaborators, since January 2005. That includes the establishment of the most remote Of the Chinese Antarctic stations, Kunlun, at Dome A in 2009. However, the exploration and mapping of this region had been commenced many decades earlier, most notably by inland traverses of the Union of Soviet Socialist Republics during the 1957-1958 International Geophysical Year 0GY） and later; and the extensive surveys of Antarctic surface and sub-ice topography by airborne radio-echo sounding made by the US National Science Foundation-Scott Polar Research Institute-Technical University of Denmark （NSF-SPRI-TUD） in the late-1960s and the 1970s. Here we provide a history of the activities and achievements of these earlier programs. Recent topographic maps of the ice sheet surface in the Dome A region, produced using Chinese GPS data and satellite altimetry, have shown the maps compiled from the earlier data were remarkably accurate.
