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Chapter 8 Web links and web activities

Cell differentiation and stem cells

The plasticity of gene expression 
Understanding the historical significance of nuclear transfer and cloning experiments will allow you to appreciate how “plastic” the pattern of gene expression is in adult tissues (refer to page 378 Wolpert text). Visit Proceedings of the National Academy of Science’s summary of the classic work that led to the successful nuclear transplantation experiments in the 1950s, which in turn set the stage for the cloning successes in mammals in the 1990s. 

  • 1. Why was the concept of nuclear transfer considered “a hare-brained scheme”? 
  • 2. How did they answer the question “does a cell remain totipotent as it continues to age and differentiate?”

Advances in stem cell technology are driving the fields of regenerative medicine as well as expanding our ideas of what it means to be a differentiated cell type. One way of staying on top of the latest news in this arena is to frequently visit sites dedicated to highlighting groundbreaking work. The following sites are great places to start:
Celebrate the anniversary of the first cloned mammal, or find out how different countries are regulating human stem cell research at the International Society for Stem Cell Research. Follow the “Public” links for basic information on stem cells, including videos of stem cells in culture and opinion poll reports. Follow the link to the interactive map and locate all countries with permissive policies on human embryonic stem cell research.

At Nature’s Web Focus on Stem Cells: 
scroll down to the Web Links section, and click on the “Woo Suk Hwang Special”to learn about the details of one of the largest investigations of scientific fraud in recent memory and gain an appreciation for why the stakes were so high in this case. Return to this site frequently for the latest updates on new stem cell advances.

Maintenance and inheritance of patterns of gene activity may depend on chemical and structural modifications to chromatin as well as on regulatory proteins
The companion site to the NOVA production “Ghost in Your Genes” explores the role of epigenetics in twins, aging and cancer.