博士研究生课——生命科学前沿进展——胰腺的发育.ppt

The Development of Pancreas The Development of Pancreas The Structure of Pancreas Transcriptional Specification Transcriptional Specification Early Hormone Expression Adult Insulin- and Glucagon-Producing Cells Differentiate From Two Independent Cell Lineages Pedro Luis Herrera Development 127, 2000 Islet Precursor Cell Labeling Translational STOP Both Alpha and Beta Cells Derive From PDX-1 Expressing Precursors Direct evidence for the pancreatic lineage: NGN3+ cells are islet progenitors and are distinct from duct progenitors Guoqiang Gu, Jolanta Dubauskaite and Douglas A. Melton Development 129, 2002 Generation of The Transgenic Mice NGN3+ Precursor Cells Give Rise to Islets NGN3+ cells contribute to the renewal of islets in adult mice Notch Signaling Controls Multiple Steps of Pancreatic Differentiation L. Charles Murtaugh, Ben Z. Stanger, Kristen M. Kwan, and Douglas A. Melton PNAS December 9, 2003 Cre Activation By PDX1 Promoter Cre Activation at E11.5-E13.5 Cre Activation By Ngn3 Promoter Late Cre Activation Adult pancreatic ?-cells are formed byself-duplication rather than stem-celldifferentiation Yuval Dor, Juliana Brown, Olga I. Martinez Douglas A. Melton Nature 426, 2004 A pulse-chase system for determining the origin of ?-cells Specificity and Dose Dependence of Recombination ?-cells are formed by self-duplication of pre-existing ?-cells ?-cell regeneration pre-existing ?-cells Fission of pancreatic islets during postnatal growth of the mouse Philip A. Seymour, William R. Bennett and Jonathan M. W. Slack J. Anatomy 204, 2004 23.17 X chromosomes undergo global changes. ?X染色体经历了整体的变化. 在真哺乳动物亚纲的细胞胚胎发育过程中,两条X染色体中的其中一条会随机地失活. 在例外的情况下,自然界存在着大于2条的X染色体,除了一条外,其他都失活. Xic(X染色体失活中心)是X染色体的顺式作用区域,它是只让一条X染色体保持活性的充分必要条件. Xic包括Xist基因,它编码一个只在失活X染色体中发现的RNA. 负责阻止Xist RNA在活性染色体上积累的机制还不明白. 在前体细胞中,一条X染色体的随机失活引起X连锁的成斑现象.阳性等位基因在活性染色体的细胞有野生表型;而阴性等位基因在活性染色体细胞有突变表型. X染色体的失活涉及Xist RNA的稳定,它能将失活染色体包被起来. X-gal staining for β-gal activityin the intestinal crypts Neonatal islets