Figure 3.

The effect of Notch blockade on Hes1/5 mRNA levels and on dendrite morphology of EGFP-labeled hippocampal neurons in culture. (A) Neurons from E17 mouse hippocampi were plated at an initial cell density of 50,000/cm². After 7 DIV the recombinant Notch ligand Delta-Fc (14 nM) was added for 3.5 h. The mRNA levels of Hes1 and Hes5 were determined by RT and quantitative PCR. Observe that under the given experimental conditions Delta-Fc behaved as an antagonist of Notch activity, inducing a decrease in the mRNA levels of both Hes1 and Hes5. (B and C) Digital fluorescence images of EGFP-labeled hippocampal neurons. Same cell density as in A. Note Delta-Fc induced the appearance of additional primary dendrites and second-order dendrite branches and decreased the fraction of dendrites >50 μm. (D-F) Summary of morphometric evaluation. The difference in absolute number of dendrites >50 μm was not significantly different in this experiment. Symbols and parameters as in Figure 2.