| 1 | Establishing a human pancreatic stem cell line and transplanting induced pancreatic islets to reverse experimental diabetes in rats显示文摘The major obstacle in using pancreatic islet transplantation to cure type I and some type II diabetes is the shortage of the donors. One of ways to overcome such obstacle is to isolate and clone pancreatic stem cells as 'seed cells' and induce their differentiation into functional islets as an abundant trans-plantation source. In this study, a monoclonal human pancreatic stem cell (mhPSC) line was obtained from abortive fetal pancreatic tissues. Pancreatic tissues were taken from abortive fetus by sterile procedures, and digested into single cells and cell clusters with 0.1% type IV collagenase. Cultured in modified glucose-low DMEM with 10% fetal bovine serum (FBS), these single cells and cell clusters adhered to culture dishes, and then primary epidermal-like pancreatic stem cells started to clone. After digesting with 0.25% trypsin and 0.04% EDTA, fibroblasts and other cells were gradually eliminated and epithelioid pancreatic stem cells were gradually purified during generations. Using clone-ring selection, the mhPSCs were obtained. After addition of 10 ng/mL epidermal growth factor (EGF) in cell culture medium, the mhPSCs quickly grew and formed a gravelstone-like monolayer. Continuously proliferated, a mhPSC line, which was derived from a male abortive fetus of 4 months old, has been passed through 50 generations. More than 1×109 mhPSCs were cryo-preserved in liquid nitrogen. Karyotype analysis showed that the chromosome set of the mhPSC line was normal diploid. Immunocytochemistry results demonstrated that the mhPSC line was positive for the pdx1, glucagon, nestin and CK19, and negative for the insulin, CD34, CD44 and CD45 protein expression. RT-PCR revealed further that the mhPSCs expressed transcription factors of the pdx1, glucagon, nestin and CK19. Also, in vitro induced with β-mercaptoethanol, the mhPSCs differentiated into nerve cells that expressed the NF protein. Induced with nicotinamide, the mhPSCs differentiated into functional islet-like clusters, as identified by di-thizone staining, which expressed the transcription factor of the insulin and secreted the insulin and C-peptide. Furthermore, the transplantation of mhPSCs-induced pancreatic islets into the subcapsular region of the kidney in streptozotocin-induced diabetic rats could reduce blood glucose levels and prolong the life time. | XIAO Mei AN LiLong YANG XueYi GE Xin QIAO Hai ZHAO Ting MA XiaoFei FAN JingZhuang ZHU MengYang DOU ZhongYing | 2008 | Science China(Life Sciences)2008，51，9： | 9 |
| 2 | Patterns of leaf N:P stoichiometry along climatic gradients in sandy region, north of China显示文摘Aims Biological and environmental factors determine geographic patterns of plant nutrient stoichiometry jointly.Unraveling the distribution pattern and the potential drivers of nutrient stoichiometry is therefore critical for understanding the adaptive strategies and biogeochem-istry cycling.Aimed to determine how leaf nitrogen(N):phosphorus(P)stoichiometry is linked to biological and environmental factors,we investigated the patterns of psammophyte leaf N:P stoichiometry in sandy region,northern China,and the potential factors affecting leaf N:P stoichiometry were explored.Methods Based on 10 m×10 m quadrates survey,the leaves of 352 dominant psammophyte samples belonging to 167 species were collected cross a 3000 km east-west transect in sandy environments,north-ern China.The samples were further classified into the following groups on the basis of plant life forms and functional groups(pho-tosynthesis pathways and nitrogen fixation).The structural equation modeling was employed to clarify the importance of biological and environmental factors on leaf N:P stoichiometry.Important Findings Generally,the higher leaf N and P concentrations,but lower N:P ratio were found in psammophyte compared with other ecosystems.Mean annual temperature(MAT)influenced the leaf N,P concentra-tions negatively,while mean annual precipitation(MAP)did posi-tively.MAP played greater influence on leaf N,P concentrations than MAT did.MAP affected leaf N,P concentrations directly or indirectly through phylogeny,while MAT only shown direct effect on leaf N concentration.The psammophyte was more limited by N,rather P,in sandy region of northern China.These results suggest that phylogeny of psammophyte and climate jointly influence leaf N:P stoichiometry,and the results could be helpful in modeling bio-geochemical nutrients cycling in vulnerable ecosystems like sandy environment. | Lifang Zhang Lilong Wang Wenliang He Xinfang Zhang Lizhe An Shijian Xu | 2018 | Journal of Plant Ecology2018，11，2： | 2 |
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