Patterning and lineage specification in the amphibian embryo

Author(s):  
Agnes P Chan ◽  
Laurence D Etkin
Author(s):  
Ray Keller

The amphibian embryo offers advantages of size, availability, and ease of use with both microsurgical and molecular methods in the analysis of fundamental developmental and cell biological problems. However, conventional wisdom holds that the opacity of this embryo limits the use of methods in optical microscopy to resolve the cell motility underlying the major shape-generating processes in early development.These difficulties have been circumvented by refining and adapting several methods. First, methods of explanting and culturing tissues were developed that expose the deep, nonepithelial cells, as well as the superficial epithelial cells, to the view of the microscope. Second, low angle epi-illumination with video image processing and recording was used to follow patterns of cell movement in large populations of cells. Lastly, cells were labeled with vital, fluorescent dyes, and their behavior recorded, using low-light, fluorescence microscopy and image processing. Using these methods, the details of the cellular protrusive activity that drives the powerful convergence (narrowing)


Blood ◽  
2011 ◽  
Vol 118 (5) ◽  
pp. 1264-1273 ◽  
Author(s):  
Melanie G. Cornejo ◽  
Vinciane Mabialah ◽  
Stephen M. Sykes ◽  
Tulasi Khandan ◽  
Cristina Lo Celso ◽  
...  

Abstract The NOTCH signaling pathway is implicated in a broad range of developmental processes, including cell fate decisions. However, the molecular basis for its role at the different steps of stem cell lineage commitment is unclear. We recently identified the NOTCH signaling pathway as a positive regulator of megakaryocyte lineage specification during hematopoiesis, but the developmental pathways that allow hematopoietic stem cell differentiation into the erythro-megakaryocytic lineages remain controversial. Here, we investigated the role of downstream mediators of NOTCH during megakaryopoiesis and report crosstalk between the NOTCH and PI3K/AKT pathways. We demonstrate the inhibitory role of phosphatase with tensin homolog and Forkhead Box class O factors on megakaryopoiesis in vivo. Finally, our data annotate developmental mechanisms in the hematopoietic system that enable a decision to be made either at the hematopoietic stem cell or the committed progenitor level to commit to the megakaryocyte lineage, supporting the existence of 2 distinct developmental pathways.


2017 ◽  
Vol 50 (1) ◽  
pp. 96-105 ◽  
Author(s):  
Yu Zhang ◽  
Yunlong Xiang ◽  
Qiangzong Yin ◽  
Zhenhai Du ◽  
Xu Peng ◽  
...  

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