Table 1.

Quantitation of immuno-EM labeling

Preparation	No. of particles <23 nm from ribbon/fibrila	% of particles <23 nm from end of ribbon/fibril	No. of particles >23 nm from ribbon/fibrilc	Unassigned particlesd
Area examined	Normalizedb		Normalized	Normalized
Control: no sample
1∶200 primary Abe	0	0	7 (in 1 cluster)	0
1∶50 secondary Abf	0		11	0
65 μm2
Control: no sample
0 primary Ab	0	0	0	0
1∶50 secondary Ab	0		0	0
65 μm2
Control: sample
0 primary Ab	1	Xg	0	0
1∶50 secondary Ab	1		0	0
113 μm2
Sample
1∶500 primary Ab	147	27	146	39
1∶200 secondary Ab	130		129	35
113 μm2
Sample
1∶200 primary Ab	411	ND	138	40
1∶200 secondary Ab	548		184	53
75 μm2

Total particles counted: 921. 

^aThe measure of specific antibody binding to ribbons and fibrils. 

^bNormalized values = number of particles/μm² × 100. 

^cMaximum estimate of nonlabeling; however, particles may be labeling single, unresolved protein subunits. 

^dIncludes particles positioned near edge of field or over unrecognizable material. 

^ePrimary, affinity-purified, rabbit anti-rib43aΔN64 antibodies. 

^fSecondary, 5-nm gold-conjugated, goat anti-rabbit IgG. Note that a higher concentration was used on controls than on experimental samples. 

^gThe only particle observed was at the end of a ribbon.