Discussion Questions V


Read the assigned article by Chen and Schier.


1.  The authors injected sqt or cyc RNA into single cells of Zebrafish embryos, and they assayed the activity of the ligands using several markers, including ntl and bik.  Describe the results depicted in Figs 1l, 1m, and 1n.  What do the authors conclude from these experiments?


2.  Consider the experiments in Figure 4.  The authors designed these experiments to distinguish between two alternative hypotheses or models. 

a)    What are the alternative hypotheses being tested?

b)    Describe the experimental design.  In your answer, include an explanation of why the authors used MZoep mutants.  Also, why did the authors transplant wild type cells ³at a distance² from the injected cells?

c)    What results were predicted by each of the hypotheses being tested?