Table 1 Severe reduction of synapse number and synaptic vesicles in rpm-1; syd-1 or rpm-1; syd-2 mutants
GenotypeNerve cordTypeNo. of synapses/10 µmAverage length of synapses, µm
worm1worm2
juIs1VCACh8.74.40.58 ± 0.03 (n = 49)
GABA4.21.80.86 ± 0.05 (n = 23)
DCACh5.14.90.66 ± 0.05 (n = 34)
GABA2.41.81.01 ± 0.07 (n = 15)
juIs1; rpm-1(ju41); syd-2(ju37)VCACh1.83.60.47 ± 0.06 (n = 6)
GABA0.90.90.50 ± 0.09 (n = 2)
DCACh0.90.90.47 ± 0.11 (n = 2)
GABA0.00.90.36 (n = 1)
syd-1(ju82); juIs1; rpm-1(ju44)VCACh0.04.40.68 ± 0.10 (n = 5)
GABA0.00.90.54 (n = 1)
DCACh0.06.20.43 ± 0.06 (n = 7)
GABA0.91.80.56 ± 0.11 (n = 3)
  • Young adult worms were chemically fixed, processed, and serially sectioned. The ventral and dorsal cords of two worms per genotype were examined by electron microscope. Numbers of sections analyzed were ∼1000 for juIs1 worm 1 (45 µm), ∼500 for juIs1 worm 2 (22.5 µm), and ∼250 for the others (11.25 µm). The synapses were defined as a varicosity containing synaptic vesicles and one or a few active zones (White et al. 1986). Synaptic vesicles were counted in the sections containing an active zone and averaged over sections. The length of a synapse was calculated by multiplying the number of sections containing synaptic vesicles by 50 nm. n = no. of synapses.