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. Author manuscript; available in PMC: 2010 Feb 12.
Published in final edited form as: Neuron. 2009 Feb 12;61(3):412–424. doi: 10.1016/j.neuron.2008.12.029

Figure 2. Homozygous but not heterozygous deletion of snapin reduces presynaptic density.

Figure 2

(A) Representative images of presynaptic terminals labeled with anti-Synapsin antibody along a dendritic process marked by MAP2 from snapin (+/+), (+/−) and (−/−) neurons as indicated.

(B) Bar graph of averaged number of Synapsin punta per μm dendritic length for snapin (+/+), (+/−), and (−/−) neurons. Significant decrease (p=0.03, t test) was only observed in (−/−) neurons relative to (+/+) control.

(C) Representative images of active presynaptic boutons loaded with FM 4–64 from snapin (+/+), (+/−) and (−/−) neurons as indicated. Scale bars for A and C: 5 μm.

(D) Bar graph of averaged number of FM puncta (active synapse) per μm axon length for snapin (+/+), (+/−) and (−/−) neurons. Significant decrease (p=0.0009, t test) was only observed in (−/−) neurons relative to (+/+) control.

(E) Representative ultrastructural images of a synapse from cultured snapin (+/+), (+/−) and (−/−) cortical neurons at DIV 14. Scale bars: 100 nm.

(F) Analysis of morphological features of synapses from all genotypes of neurons. The length of the active zone (AZ), the width of the synaptic cleft (space of cleft) and the averaged diameter of synaptic vesicles were measured, and no significant differences (NS) were found across all genotypes of neurons. Number of vesicles relative to its AZ length or terminal area was also compared among all genotypes of neurons. Significant decreases were only observed in (−/−) neurons for the density of docked vesicles (p=0.045, u test) and the density of total vesicles (p=0.016, u test).