Figure 2.

Indian Muntjac Kinetochores Show Typical Structural Organization and Their Microtubule Binding Capacity Scales with Kinetochore Size

(A) Selected optical planes from an Indian muntjac fibroblast stably expressing Centrin-1-GFP to label the centrioles (green), showing kinetochore pairs for C3X (A′) and neighbor chromosome with smaller (A″) centromere. The inner and outer parts of the kinetochores were delineated by CENP-A (green) and Ndc80/Hec1 (red). DNA was counterstained with DAPI (blue).

(A′ and A″) Higher-magnification views of C3X (A′) and smaller kinetochores (A″). Dashed lines denote where intra-kinetochore distances were measured. Scale bars, 5 μm (A) and 1 μm (A′ and A″). Differences between large and small kinetochores were not statistically significant (t test). KT, kinetochore.

(B) Single electron microscopy section from consecutive series highlighting the standard organization of the Indian muntjac centromere and kinetochore plates. L1 and L2 correspond to the plates on chromosome C3X; S1 and S2 correspond to the plates on a neighboring chromosome with smaller kinetochores. Scale bar, 2 μm.

(C) Z projection of the entire volume of the corresponding series shown in Figure S1. K fibers on the C3X chromosome comprise a larger number of microtubules (green). Kinetochore plates (magenta) and chromosomes (blue) are indicated. Scale bar, 1 μm. MT, microtubule.

(D) Surface-rendered model of the volume shown in Figure S1. C3X kinetochores are approximately twice as large as in chromosomes with smaller kinetochores.

(E) Quantification of the number of attached microtubules as a function of the approximate kinetochore area. Plot shows serial-section electron microscopy data from 26 kinetochores from 13 chromosomes and 3 cells.

See also Figure S1.