Table 1.
Particle type | Proportion in chloroplast sectionsa | Proportion in purified extractsa | Dimensions (nm)b,c |
---|---|---|---|
Cyanobium carboxysomes | n.a. | 100% | 101.3 ± 0.7 |
CyLS-S1S2 carboxysomes | 96% (n = 565) | 84% (n = 412) | 100.3 ± 1.5 |
CyLS-S1S2 elongated rods | 4% (n = 24) | 16% (n = 78) | 59 ± 5 (n = 16) × 437 ± 190 (n = 12) |
aProportions in each particle type in chloroplast sections and purified extracts were determined from analysis of TEM images. Elongated rods were defined as structures with average widths <75 nm and disproportionate length
bCarboxysome dimensions were determined as the mode (±s.e.m.) of particle distributions measured using a Nanosight NS300 from 12 analyses of two independent preparations of Cyanobium carboxysomes and 19 analyses of three independent preparations of CyLS-S1S2 carboxysomes
cElongated rod dimensions were determined as mean widths and lengths (±s.d.) of particles analysed in TEM images of purified carboxysome preparations from CyLS-S1S2 leaves. Note that there is a greater proportion of elongated particles observed in purified extracts, which we assume to be due to a combination of: breakage of very long particles during isolation, giving rise to a greater proportion of rods and, difficulty in accurately identifying elongated carboxysomes in random cross-sections of chloroplasts. n.a. not applicable